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Sample records for nmr spectroscopic investigations

  1. Spectroscopic (vibrational, NMR and UV-vis.) and quantum chemical investigations on 4-hexyloxy-3-methoxybenzaldehyde

    Science.gov (United States)

    Abbas, Ashgar; Gökce, Halil; Bahçeli, Semiha

    2016-01-01

    In this study, the 4-hexyloxy-3-methoxybenzaldehyde compound as one of the derivatives of vanillin which is a well known flavoring agent, C14H20O3, has been investigated by experimentally and extensively utilizing density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. In this context, the optimized geometry, vibrational frequencies, 1H and 13C NMR chemical shifts, UV-vis. (in gas phase and in methanol solvent) spectra, HOMO-LUMO analysis, molecular electrostatic potential (MEP), thermodynamic parameters and atomic charges of 4-hexyloxy-3-methoxybenzaldehyde have been calculated. In addition, theoretically predicted IR, Raman and UV-vis. (in gas phase and in methanol solvent) spectra of the mentioned molecule have been constructed. The results calculated were compared with the experimental data.

  2. Spectroscopic (vibrational, NMR and UV-vis.) and quantum chemical investigations on 4-hexyloxy-3-methoxybenzaldehyde.

    Science.gov (United States)

    Abbas, Ashgar; Gökce, Halil; Bahçeli, Semiha

    2016-01-05

    In this study, the 4-hexyloxy-3-methoxybenzaldehyde compound as one of the derivatives of vanillin which is a well known flavoring agent, C14H20O3, has been investigated by experimentally and extensively utilizing density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. In this context, the optimized geometry, vibrational frequencies, (1)H and (13)C NMR chemical shifts, UV-vis. (in gas phase and in methanol solvent) spectra, HOMO-LUMO analysis, molecular electrostatic potential (MEP), thermodynamic parameters and atomic charges of 4-hexyloxy-3-methoxybenzaldehyde have been calculated. In addition, theoretically predicted IR, Raman and UV-vis. (in gas phase and in methanol solvent) spectra of the mentioned molecule have been constructed. The results calculated were compared with the experimental data.

  3. Computational Chemistry Meets Experiments for Explaining the Behavior of Bibenzyl: A Thermochemical and Spectroscopic (Infrared, Raman, and NMR) Investigation.

    Science.gov (United States)

    Latouche, Camille; Barone, Vincenzo

    2014-12-09

    The structure, conformational behavior, and spectroscopic parameters of bibenzyl have been investigated by a computational protocol including proper treatment of anharmonic and hindered rotor contributions. Conventional hybrid functionals overstabilize the anti conformer while low-order post-Hartree-Fock (MP2) approaches strongly favor the gauche conformer. However, inclusion of semiempirical dispersion effects in density functionals or coupled cluster post-Hartree-Fock models agree in forecasting the simultaneous presence of both conformers in the gas phase with a slightly larger stability (0.7 kcal·mol(-1)) of the gauche conformer. Addition of thermal and entropic effects finally leads to very close Gibbs free energies for both conformers and, thus, to a slight preference for the gauche form due to statistical factors (2 vs 1). The situation remains essentially the same in solution. On these grounds, perturbative vibrational computations including both electrical and mechanical anharmonicities lead to IR and Raman spectra in remarkable agreement with experiment. Full assignment of the IR spectra explains the presence of peaks from gauche or anti conformers. Comparison between computed and experimental Raman spectra confirms that both conformers are present in liquid phase, whereas the anti conformer seems to be preponderant in the solid state. Also computed NMR parameters are in good agreement with experiment.

  4. Investigation on Acute Biochemical Effects of Ce(NO3)3 on Liver and Kidney Tissues by MAS 1H NMR Spectroscopic-Based Metabonomic Approach

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    High resolution magic angle spinning (MAS)-1 H nuclear magnetic resonance (NMR) spectroscopic-based metabonomic approach was applied to the investigation on the acute biochemical effects of Ce(NO3)3. Male Wistar rats were liver and kidney tissues were analyzed using principal component analysis to extract toxicity information. The biochemical effects of Ce(NO3)3 were characterized by the increase of triglycerides and lactate and the decrease of glycogen in rat liver tissue, together with an elevation of the triglyceride level and a depletion of glycerophosphocholine and betaine in kidney tissues. The target lesions of Ce(NO3)3 on liver and kidney were found by MAS NMR-based metabonomic method. This study demonstrates that the combination of MAS 1H NMR and pattern recognition analysis can be an effective method for studies of biochemical effects of rare earths.

  5. Structural, NMR Spectroscopic, and Computational Investigation of Hemin Loading in the Hemophore HasAp from Pseudomonas aeruginosa

    Energy Technology Data Exchange (ETDEWEB)

    Jepkorir, Grace; Rodrguez, Juan Carlos; Rui, Huan; Im, Wonpil; Lovell, Scott; Battaile, Kevin P.; Alontaga, Aileen Y.; Yukl, Erik T.; Monne-Loccoz, Pierre; Rivera, Mario (Oregon State U.); (Kansas); (Hauptman)

    2010-08-16

    When challenged by low-iron conditions several Gram-negative pathogens secrete a hemophore (HasA) to scavenge hemin from its host and deliver it to a receptor (HasR) on their outer membrane for internalization. Here we report results from studies aimed at probing the structural and dynamic processes at play in the loading of the apo-hemophore secreted by P. aeruginosa (apo-HasAp) with hemin. The structure of apo-HasAp shows a large conformational change in the loop harboring axial ligand His32 relative to the structure of holo-HasAp, whereas the loop bearing the other axial ligand, Tyr75, remains intact. To investigate the role played by the axial ligand-bearing loops in the process of hemin capture we investigated the H32A mutant, which was found to exist as a monomer in its apo-form and as a mixture of monomers and dimers in its holo-form. We obtained an X-ray structure of dimeric H32A holo-HasAp, which revealed that the two subunits are linked by cofacial interactions of two hemin molecules and that the conformation of the Ala32 loop in the dimer is identical to that exhibited by the His32 loop in wild type apo-HasAp. Additional data suggest that the conformation of the Ala32 loop in the dimer is mainly a consequence of dimerization. Hence, to investigate the effect of hemin loading on the topology of the His32 loop we also obtained the crystal structure of monomeric H32A holo-HasAp coordinated by imidazole (H32A-imidazole) and investigated the monomeric H32A HasAp and H32A-imidazole species in solution by NMR spectroscopy. The structure of H32A-imidazole revealed that the Ala32 loop attains a 'closed' conformation nearly identical to that observed in wild type holo-HasAp, and the NMR investigations indicated that this conformation is maintained in solution. The NMR studies also highlighted conformational heterogeneity at the H32 loop hinges and in other key sections of the structure. Targeted molecular dynamics simulations allowed us to propose a

  6. Spectroscopic (infrared, Raman, UV and NMR) analysis, Gaussian hybrid computational investigation (MEP maps/HOMO and LUMO) on cyclohexanone oxime

    Science.gov (United States)

    Ramalingam, S.; Karabacak, M.; Periandy, S.; Puviarasan, N.; Tanuja, D.

    2012-10-01

    In the present analysis, FT-IR/FT-Raman spectra of the cyclohexanone oxime (CHO, C6H11NO) are recorded. The observed vibrational frequencies are assigned and the computational calculations are carried out by HF and DFT (B3LYP and B3PW91) methods with 6-311++G(d,p) basis set and the corresponding results are tabulated. In order to yield good coherence with observed values, the calculated frequencies are scaled by appropriate scale factors. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The alternation of structure of cyclohexanone due to the substitution of NOH is investigated. The vibrational sequence pattern of the molecule related to the substitutions is analyzed. Comparison of the observed fundamental vibrational frequencies of CHO and calculated results by density functional (B3LYP and B3PW91) and HF methods indicates that B3LYP is superior to the scaled HF and B3PW91 approach for molecular vibrational problems. Moreover, 13C NMR and 1H NMR chemical shifts are calculated by using the gauge independent atomic orbital (GIAO) method with HF/B3LYP/B3PW91 methods and the same basis set. A study on the electronic properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, are performed by HF and DFT methods. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. NLO properties and Mulliken charges of the CHO was also calculated and interpreted. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures are calculated in gas phase.

  7. Vibrational, NMR and UV-visible spectroscopic investigation and NLO studies on benzaldehyde thiosemicarbazone using computational calculations

    Science.gov (United States)

    Moorthy, N.; Prabakar, P. C. Jobe; Ramalingam, S.; Pandian, G. V.; Anbusrinivasan, P.

    2016-04-01

    In order to investigate the vibrational, electronic and NLO characteristics of the compound; benzaldehyde thiosemicarbazone (BTSC), the XRD, FT-IR, FT-Raman, NMR and UV-visible spectra were recorded and were analysed with the calculated spectra by using HF and B3LYP methods with 6-311++G(d,p) basis set. The XRD results revealed that the stabilized molecular systems were confined in orthorhombic unit cell system. The cause for the change of chemical and physical properties behind the compound has been discussed makes use of Mulliken charge levels and NBO in detail. The shift of molecular vibrational pattern by the fusing of ligand; thiosemicarbazone group with benzaldehyde has been keenly observed. The occurrence of in phase and out of phase molecular interaction over the frontier molecular orbitals was determined to evaluate the degeneracy of the electronic energy levels. The thermodynamical studies of the temperature region 100-1000 K to detect the thermal stabilization of the crystal phase of the compound were investigated. The NLO properties were evaluated by the determination of the polarizability and hyperpolarizability of the compound in crystal phase. The physical stabilization of the geometry of the compound has been explained by geometry deformation analysis.

  8. Solid-state NMR spectroscopic investigation at thermal waste products from embedded flame retardants and polymers; Festkoerper-NMR-Untersuchungen an thermischen Abbauprodukten von flammgeschuetzten Polymeren

    Energy Technology Data Exchange (ETDEWEB)

    Fichera, M.A.

    2008-07-01

    The author of the contribution under consideration describes the structural characterisation of embedded flame retardants and polymers. Analysis includes determination of the phase contents as well as description of their mutual interactions as a function of their thermal history in different atmospheres (air and nitrogen). Solid-state NMR spectroscopy enables structural information about the amorphous state of the decomposed products, determination of the thermal and thermo-oxidative conversion in different amorphous and crystalline structures, and predictions about the short-range order of the observed nuclei. In this context measurements of single pulse, rotor-synchronised spin echo (SP) and cross polarisation (CP) experiments, as well as REDOR (rotational echo double resonance) and TRAPDOR- (transfer of population in double resonance) have been conducted. Additionally, {sup 1}B SP and {sup 31}P RSE experiments have been used to study quantitatively the borate and both phosphorus and phosphate contents in the solid residues. Particular emphasis was put on quantifying crystalline and non-crystalline phosphate phases. The first system consists o a combination of the flame retardants red phosphorus and magnesium hydroxide in high impact polystyrene (HIPS). From the results of extensive NMR experiments it was deduced that most of inserted red phosphorus remains in amorphous phosphates phases (ortho, pyro, and chain/ring phosphates) besides some crystalline phosphate phases. Decomposition characteristics such as temperature and the availability of oxygen (N{sub 2} atmosphere/air) show a significant influence on the decomposition process and the formation of phosphate phases (crystalline/amorphous). By comparing the results of the annealing processes to the results of the cone calorimeter measurements an anaerobic decomposition way was confirmed. In a second system, thermal reactions between the two flame retardants bisphenol A bis diphenyl phosphate and zinc borate

  9. Structural, vibrational and NMR spectroscopic investigations of newly synthesized 3-((ethylthio)(4-nitrophenyl)methyl)-1H-indole

    Science.gov (United States)

    Bhat, Sheeraz Ahmad; Dar, Ajaz A.; Ahmad, Shabbir; Khan, Abu T.

    2017-10-01

    The compound 3-((ethylthio)(4-nitrophenyl)methyl)-1H-indole was synthesized at room temperature through one-pot three-component reaction from 1H-indole, 4-nitrobenzaldehyde, and ethanethiol using hydrated ferric sulfate as a Lewis acid catalyst. The structure was characterised by single crystal XRD, FTIR (4000-400 cm-1), FT-Raman (4000-50 cm-1) and 1H and 13C NMR analysis. The compound crystallizes in the monoclinic with volume 3238.3(9) Å3. The experimental vibrational data find the theoretical support through anharmonic frequency calculations using DFT/B3LYP level of theory in combination with 6-31G(d,p) basis set. It is observed that the predicted geometry well reproduces the XRD structural parameters. The experimental 1H and 13C NMR spectra in CDCl3 solvent and the simulated spectra predicted using gauge independent atomic orbital (GIAO) approach are also found in agreement with each other. HOMO-LUMO, MEP, atomic charges and various other thermodynamic and NLO properties of the title molecule are also reported in this paper.

  10. Crystal structure, magnetism, {sup 89}Y solid state NMR, and {sup 121}Sb Moessbauer spectroscopic investigations of YIrSb

    Energy Technology Data Exchange (ETDEWEB)

    Benndorf, Christopher [Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Heletta, Lukas; Block, Theresa; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Eckert, Hellmut [Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Institute of Physics in Sao Carlos, University of Sao Paulo, Sao Carlos (Brazil)

    2017-02-15

    The ternary antimonide YIrSb was synthesized from the binary precursor YIr and elemental antimony by a diffusion controlled solid-state reaction. Single crystals were obtained by a flux technique with elemental bismuth as an inert solvent. The YIrSb structure (TiNiSi type, space group Pnma) was refined from single-crystal X-ray diffractometer data: a = 711.06(9), b = 447.74(5), c = 784.20(8) pm, wR{sub 2} = 0.0455, 535 F{sup 2} values, 20 variables. {sup 89}Y solid state MAS NMR and {sup 121}Sb Moessbauer spectra show single resonance lines in agreement with single-crystal X-ray data. YIrSb is a Pauli paramagnet. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Syntheses, structures, and comprehensive NMR spectroscopic investigations of hetero-chalcogenidometallates: the right mix toward multinary complexes.

    Science.gov (United States)

    Ruzin, Eugen; Zent, Eldar; Matern, Eberhard; Massa, Werner; Dehnen, Stefanie

    2009-01-01

    Aqueous solutions of ternary ortho-chalcogenidostannate anions [SnE(1)(4-x)E(2)(x)](4-) (E(1), E(2) = S, Se, Te) have been generated following different routes that all lead to equilibria of all possible permutations of binary and ternary anions. This has been rationalized by means of NMR studies that can be explained by calculations using density functional theory (DFT) methods. Thus, if one reacts such solutions with transition-metal ions, quaternary M/Sn/E(1)/E(2) anions are obtained, which exhibit coordination by different ternary chalcogenidostannate ligands. The electronic excitation energies of the corresponding alkali metal salts lie between the E(g) values of compounds containing either M/Sn/E(1) or M/Sn/E(2) anions. In this way, we provide a simple approach toward a library of semiconductor compounds with finely-tuned optoelectronic properties.

  12. The spectroscopic properties of anticancer drug Apigenin investigated by using DFT calculations, FT-IR, FT-Raman and NMR analysis

    Science.gov (United States)

    Mariappan, G.; Sundaraganesan, N.; Manoharan, S.

    2012-09-01

    The FT-Raman and FT-Infrared spectra of solid Apigenin sample were measured in order to elucidate the spectroscopic properties of title molecule in the spectral range of 3500-50 cm-1 and 4000-400 cm-1, respectively. The recorded FT-IR and FT-Raman spectral measurements favor the calculated (by B3LYP/6-31G(d,p) method) structural parameters which are further supported by spectral simulation. Additional support is given by the collected 1H and 13C NMR spectra recorded with the sample dissolved in DMSO. The predicted chemical shifts at the B3LYP/6-31G(d) level obtained using the Gauge-Invariant Atomic Orbitals (GIAO) method with and without inclusion of solvent using the Polarizable Continuum Model (PCM). By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. The UV-visible absorption spectra of the compound that dissolved in Ethanol, Methanol and DMSO were recorded in the range of 800-200 nm. The formation of hydrogen bond and the most possible interaction are explained using natural bond orbital (NBO) analysis. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and atomic charges of the title compound were investigated using theoretical calculations. The results are discussed herein and compared with similar molecules whenever appropriate.

  13. NMR, FT-IR, Raman and UV-Vis spectroscopic investigation and DFT study of 6-Bromo-3-Pyridinyl Boronic Acid

    Science.gov (United States)

    Dikmen, Gökhan; Alver, Özgür

    2015-11-01

    Possible stable conformers and geometrical molecular structures of 6-Bromo-3-Pyridinyl Boronic acid (6B3PBA; C5H5BBrNO2) were studied experimentally and theoretically using FT-IR and Raman spectroscopic methods. FT-IR and Raman spectra were recorded in the region of 4000-400 cm-1 and 3700-400 cm-1, respectively. The structural properties were investigated further, using 1H, 13C, 1H coupled 13C, HETCOR, COSY and APT NMR techniques. The optimized geometric structures were searched by Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. Vibrational wavenumbers of 6B3PBA were calculated whereby B3LYP density functional methods including 6-311++G(d, p), 6-311G(d, p), 6-311G(d), 6-31G(d, p) and 6-31G(d) basis sets. The comparison of the experimentally and theoretically obtained results using mean absolute error and experimental versus calculated correlation coefficients for the vibrational wavenumbers indicates that B3LYP method with 6-311++G(d, p) gives more satisfactory results for predicting vibrational wavenumbers when compared to the 6-311G(d, p), 6-311G(d), 6-31G(d, p) and 6-31G(d) basis sets. However, this method and none of the mentioned methods here seem suitable for the calculations of OH stretching modes, most likely because increasing unharmonicity in the high wave number region and possible intra and inter molecular interactions at OH edges lead some deviations between experimental and theoretical results. Moreover, reliable vibrational assignments were made on the basis of total energy distribution (TED) calculated using scaled quantum mechanical (SQM) method.

  14. Synthesis, spectroscopic investigations (X-ray, NMR and TD-DFT), antimicrobial activity and molecular docking of 2,6-bis(hydroxy(phenyl)methyl)cyclohexanone.

    Science.gov (United States)

    Barakat, Assem; Ghabbour, Hazem A; Al-Majid, Abdullah Mohammed; Soliman, Saied M; Ali, M; Mabkhot, Yahia Nasser; Shaik, Mohammed Rafi; Fun, Hoong-Kun

    2015-07-21

    The synthesis of 2,6-bis(hydroxy(phenyl)methyl)cyclohexanone 1 is described. The molecular structure of the title compound 1 was confirmed by NMR, FT-IR, MS, CHN microanalysis, and X-ray crystallography. The molecular structure was also investigated by a set of computational studies and found to be in good agreement with the experimental data obtained from the various spectrophotometric techniques. The antimicrobial activity and molecular docking of the synthesized compound was investigated.

  15. nmr spectroscopic study and dft calculations of giao nmr shieldings ...

    African Journals Online (AJOL)

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    various fields of science and industry such as microelectronic and aerospace ... GIAO/DFT (Gauge Including Atomic Orbitals/Density Functional Theory) approach is .... successfully by using NMR and quantum chemical calculations.

  16. 2D NMR-spectroscopic screening reveals polyketides in ladybugs

    OpenAIRE

    Deyrup, Stephen T.; Eckman, Laura E.; McCarthy, Patrick H.; Smedley, Scott R.; Meinwald, Jerrold; Schroeder, Frank C.

    2011-01-01

    Small molecules of biological origin continue to yield the most promising leads for drug design, but systematic approaches for exploring nature’s cache of structural diversity are lacking. Here, we demonstrate the use of 2D NMR spectroscopy to screen a library of biorationally selected insect metabolite samples for partial structures indicating the presence of new chemical entities. This NMR-spectroscopic survey enabled detection of novel compounds in complex metabolite mixtures without prior...

  17. Spectroscopic (FT-IR, FT-Raman, UV, NMR, NBO) investigation and molecular docking study of (R)-2-Amino-1-PhenylEthanol

    Science.gov (United States)

    Subashini, K.; Periandy, S.

    2016-08-01

    A systematic spectroscopic study of (R)-2-Amino-1-Phenylethanol was carried out using FT-IR, FT-Raman, NMR and UV analysis. FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectrum of the title molecule were recorded in solid phase, the 1H and 13C NMR spectra were recorded in CDCl3 (deuterated chloroform) solution phase and the UV-Vis (200-800 nm) spectrum was recorded in gas phase and ethanol solution phase. Potential energy surface (PES) scan was performed using B3LYP functional with 6-311++G (d, p) basis set. The geometrical parameters (such as bond length, bond angle, dihedral angles) and theoretical frequencies of the title compound were studied from density functional theory (DFT) using B3LYP and B3PW91 functionals with 6-311++G (d, p) basis sets. The computed frequencies were scaled and compared with the experimental values and potential energy distribution (PED) has been tabulated. A comparative study of atomic charges was made by calculating Mulliken, Natural Population Analysis (NPA) and Electrostatic Potential (ESP) simultaneously, with B3LYP/6-311++G (d, p) basis set. 1H and 13C NMR spectra were recorded and chemical shifts were compared to TMS by Gauge-Independent Atomic Orbital (GIAO) method. Electronic properties such as excitation energy, energy gap between HOMO and LUMO was calculated using time dependent DFT technique. NBO analysis, which predicts the different possibilities of electronic transition in the molecule, was computed using B3PW91 functional with 6-311++G (d, p) basis set. The thermodynamic properties such as heat capacity, entropy and enthalpy at different temperatures were computed and analyzed. Molecular docking study shows that the secondary hydroxyl group and the primary amino group in the aliphatic chain attached to the benzene ring are crucial for binding and the title compound might exhibit inhibitory activity against Bacteroides fragilis (3P24) and may act as anti-bacterial agent.

  18. Spectroscopic Investigation of the Mechanism of Photocatalysis

    Directory of Open Access Journals (Sweden)

    Yoshio Nosaka

    2014-11-01

    Full Text Available Reaction mechanisms of various kinds of photocatalysts have been reviewed based on the recent reports, in which various spectroscopic techniques including luminol chemiluminescence photometry, fluorescence probe method, electron spin resonance (ESR, and nuclear magnetic resonance (NMR spectroscopy were applied. The reaction mechanisms elucidated for bare and modified TiO2 were described individually. The modified visible light responsive TiO2 photocatalysts, i.e., Fe(III-deposited metal-doped TiO2 and platinum complex-deposited TiO2, were studied by detecting paramagnetic species with ESR, •O2− (or H2O2 with chemiluminescence photometry, and OH radicals with a fluorescence probe method. For bare TiO2, the difference in the oxidation mechanism for the different crystalline form was investigated by the fluorescence probe method, while the adsorption and decomposition behaviors of several amino acids and peptides were investigated by 1H-NMR spectroscopy.

  19. Vibrational spectroscopic (FT-IR, FT-Raman, ¹H NMR and UV) investigations and computational study of 5-nitro-2-(4-nitrobenzyl) benzoxazole.

    Science.gov (United States)

    Bhagyasree, J B; Varghese, Hema Tresa; Panicker, C Yohannan; Samuel, Jadu; Van Alsenoy, Christian; Bolelli, Kayhan; Yildiz, Ilkay; Aki, Esin

    2013-02-01

    The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-nitro-2-(4-nitrobenzyl) benzoxazole have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of the normal modes of vibrations was done using GAR2PED program. The energy and oscillator strength calculated by time dependent density functional theory almost compliments with experimental findings. Gauge-including atomic orbital (1)H NMR chemical shifts calculations were carried out by using B3LYP functional with 6-31G basis set. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization have been analyzed using NBO analysis. MEP was performed by the DFT method and the predicted infrared intensities and Raman activities have also been reported. The calculated geometrical parameters are in agreement with that of similar derivatives.

  20. Electronic [UV-Visible] and vibrational [FT-IR, FT-Raman] investigation and NMR-mass spectroscopic analysis of terephthalic acid using quantum Gaussian calculations.

    Science.gov (United States)

    Karthikeyan, N; Prince, J Joseph; Ramalingam, S; Periandy, S

    2015-03-15

    In this research work, the vibrational IR, polarization Raman, NMR and mass spectra of terephthalic acid (TA) were recorded. The observed fundamental peaks (IR, Raman) were assigned according to their distinctiveness region. The hybrid computational calculations were carried out for calculating geometrical and vibrational parameters by DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The molecular mass spectral data related to base molecule and substitutional group of the compound was analyzed. The modification of the chemical property by the reaction mechanism of the injection of dicarboxylic group in the base molecule was investigated. The (13)C and (1)H NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method and the absolute chemical shifts related to TMS were compared with experimental spectra. The study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by hybrid Gaussian calculation methods. The orbital energies of different levels of HOMO and LUMO were calculated and the molecular orbital lobe overlapping showed the inter charge transformation between the base molecule and ligand group. From the frontier molecular orbitals (FMO), the possibility of electrophilic and nucleophilic hit also analyzed. The NLO activity of the title compound related to Polarizability and hyperpolarizability were also discussed. The present molecule was fragmented with respect to atomic mass and the mass variation depends on the substitutions have also been studied. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  1. Spectroscopic (FTIR, FT-Raman, UV and NMR) investigation and NLO, HOMO-LUMO, NBO analysis of 2-Benzylpyridine based on quantum chemical calculations.

    Science.gov (United States)

    Mathammal, R; Sudha, N; Guru Prasad, L; Ganga, N; Krishnakumar, V

    2015-02-25

    In this work, the vibrational characteristics of 2-Benzylpyridine have been investigated. The structure of the molecule has been optimized and the structural characteristics of the molecule have been determined by density functional theory B3LYP method with 6-31G(d,p) basis set. The infrared and Raman spectra have been simulated from calculated intensities. Both the experimental and theoretical vibrational data confirms the presence of functional groups in the title compound. The (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital method. UV-Visible spectrum of the title compound was recorded in the region 190-1100 nm and the electronic properties HOMO and LUMO energies were calculated by CIS approach. Nonlinear optical and thermodynamic properties were interpreted. All the calculated results were compared with the available experimental data of the title molecule. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. 2D NMR-spectroscopic screening reveals polyketides in ladybugs.

    Science.gov (United States)

    Deyrup, Stephen T; Eckman, Laura E; McCarthy, Patrick H; Smedley, Scott R; Meinwald, Jerrold; Schroeder, Frank C

    2011-06-14

    Small molecules of biological origin continue to yield the most promising leads for drug design, but systematic approaches for exploring nature's cache of structural diversity are lacking. Here, we demonstrate the use of 2D NMR spectroscopy to screen a library of biorationally selected insect metabolite samples for partial structures indicating the presence of new chemical entities. This NMR-spectroscopic survey enabled detection of novel compounds in complex metabolite mixtures without prior fractionation or isolation. Our screen led to discovery and subsequent isolation of two families of tricyclic pyrones in Delphastus catalinae, a tiny ladybird beetle that is employed commercially as a biological pest control agent. The D. catalinae pyrones are based on 23-carbon polyketide chains forming 1,11-dioxo-2,6,10-trioxaanthracene and 4,8-dioxo-1,9,13-trioxaanthracene derivatives, representing ring systems not previously found in nature. This study highlights the utility of 2D NMR-spectroscopic screening for exploring nature's structure space and suggests that insect metabolomes remain vastly underexplored.

  3. Microscale Syntheses, Reactions, and 1H NMR Spectroscopic Investigations of Square Planar Macrocyclic Tetraamido-N Cu(III) Complexes Relevant to Green Chemistry

    Science.gov (United States)

    Uffelman, Erich S.; Doherty, Jonathan R.; Schulze, Carl; Burke, Amy L.; Bonnema, Kristen R.; Watson, Tanya T.; Lee, Daniel W., III

    2004-01-01

    Microscale fusions, description, and spectroscopic analysis of the reactivity of a square planar Cu(III) complex significant to green chemistry, are presented. The experiment also includes nine focal points on which pre-lab and post-lab questions are based, and the final exams reflect the students' comprehension of these and other features of…

  4. Study of H/D exchange rates to derive the strength of intramolecular hydrogen bonds in halo substituted organic building blocks: An NMR spectroscopic investigation

    Science.gov (United States)

    Mishra, Sandeep Kumar; Suryaprakash, N.

    2015-10-01

    Rates of hydrogen/deuterium (H/D) exchange determined by 1H NMR spectroscopy are utilized to derive the strength of hydrogen bonds and to monitor the electronic effects in the site-specific halogen substituted benzamides and anilines. The theoretical fitting of the time dependent variation of the integral areas of 1H NMR resonances to the first order decay function permitted the determination of H/D exchange rate constants (k) and their precise half-lives (t1/2) with high degree of reproducibility. The comparative study also permitted the unambiguous determination of relative strength of hydrogen bonds and the contribution from electronic effects on the H/D exchange rate.

  5. Chromatographic, NMR and vibrational spectroscopic investigations of astaxanthin esters: application to "Astaxanthin-rich shrimp oil" obtained from processing of Nordic shrimps.

    Science.gov (United States)

    Subramanian, B; Thibault, M-H; Djaoued, Y; Pelletier, C; Touaibia, M; Tchoukanova, N

    2015-11-01

    Astaxanthin (ASTX) is a keto carotenoid, which possesses a non-polar linear central conjugated chain and polar β-ionone rings with ketone and hydroxyl groups at the extreme ends. It is well known as a super anti-oxidant, and recent clinical studies have established its nutritional benefits. Although it occurs in several forms, including free molecule, crystalline, aggregates and various geometrical isomers, in nature it exists primarily in the form of esters. Marine animals accumulate ASTX from primary sources such as algae. Nordic shrimps (P. borealis), which are harvested widely in the Atlantic Ocean, form a major source of astaxanthin esters. "Astaxanthin-rich shrimp oil" was developed as a novel product in a shrimp processing plant in Eastern Canada. A compositional analysis of the shrimp oil was performed, with a view to possibly use it as a nutraceutical product for humans and animals. Astaxanthin-rich shrimp oil contains 50% MUFAs and 22% PUFAs, of which 20% are omega-3. In addition, the shrimp oil contains interesting amounts of EPA and DHA, with 10%/w and 8%/w, respectively. Astaxanthin concentrations varied between 400 and 1000 ppm, depending on the harvesting season of the shrimp. Astaxanthin and its esters were isolated from the oil and analysed by NMR, FTIR and Micro-Raman spectroscopy. Astaxanthin mono- and diesters were synthesized and used as standards for the analysis of astaxanthin-rich shrimp oil. NMR and vibrational spectroscopy techniques were successfully used for the rapid characterization of monoesters and diesters of astaxanthin. Raman spectroscopy provided important intermolecular interactions present in the esterified forms of astaxanthin molecules. Also discussed in this paper is the use of NMR, FTIR and Micro-Raman spectroscopy for the detection of astaxanthin esters in shrimp oil.

  6. Primidone--an antiepileptic drug--characterisation by quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR and UV-Visible) investigations.

    Science.gov (United States)

    Arjunan, V; Santhanam, R; Subramanian, S; Mohan, S

    2013-05-15

    The solid phase FTIR and FT-Raman spectra of primidone were recorded in the regions 4000-400 cm(-1) and 4000-100 cm(-1), respectively. The vibrational spectra were analysed and the observed fundamentals were assigned and analysed. The experimental wavenumbers were compared with the theoretical scaled vibrational wavenumbers determined by DFT methods. The Raman intensities were also determined with B3LYP/6-31G(d,p) method. The total electron density and molecular electrostatic potential surface of the molecule were constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron+nuclei) distribution. The HOMO and LUMO energies were measured. Natural bond orbital analysis of primidone has been performed to indicate the presence of intramolecular charge transfer. The (1)H and (13)C NMR spectra were recorded and the chemical shifts of the molecule were calculated. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Spectroscopic (FT-IR, FT-Raman, UV, NMR, NBO, NLO) investigation and molecular docking study of (R)-2-Methylamino-1-Phenylethanol (Halostachine)

    Science.gov (United States)

    Subashini, K.; Govindarajan, R.; Surendran, R.; Mukund, K.; Periandy, S.

    2016-12-01

    FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectra of (R)-2-Methylamino-1-Phenylethanol have been recorded in solid phase, 1H and 13C NMR in deuterated chloroform (CDCl3) phase and UV spectrum (200-400 nm) in solid phase and in ethanol solution. The different conformers of the compound and their minimum energies were studied by potential energy surface scan, using semi-empirical method PM6. The computed wavenumbers obtained from B3LYP and B3PW91 functionals along with 6-311++G (d, p) basis sets were scaled so as to agree with the experimental values and the scaling factors have been reported. All the fundamental modes have been assigned based on the potential energy distribution (PED) values and the structure of the molecule was analyzed in parameters like bond length, bond angle and dihedral angles through B3LYP and B3PW91 functionals along with 6-311++G(d,p) basis set. The values of dipole moment (μ), polarizability (α) and hyper polarizability (β) of the molecule were calculated using which, the non-linear optical property of the molecule has been discussed. The observed HOMO-LUMO mappings reveals the different charge transfer possibilities within the molecule. Natural Bond Orbital analysis was computed and possible transitions were correlated with the electronic transitions. Mulliken charges, electrostatic potential charges and natural charges are also predicted. The theoretical 1H and 13C NMR chemical shifts were computed using B3LYP functionals using 6-311++G (2d, p) basis sets. The temperature dependence of the thermodynamic properties; heat capacity, entropy and enthalpy for the title compound were also determined by B3LYP functionals with 6-311++G (d, p) basis set. Molecular docking study shows that the title compound might exhibit inhibitory activity against Bacillus anthracis (3V5O).

  8. Spectroscopic (FT-IR, FT-Raman, UV, NMR, NLO) investigation and molecular docking study of 1-(4-Methylbenzyl) piperazine

    Science.gov (United States)

    Subashini, K.; Periandy, S.

    2017-04-01

    The title compound, 1-(4-Methylbenzyl) piperazine, was analyzed by recording FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectra in solid phase, 1H and 13C NMR in CDCl3 (deuterated chloroform) and UV spectrum (200-400 nm) in solid phase and in ethanol solution. The different conformers of the compound and their minimum energies were studied by potential energy surface scan, using semi-empirical method PM6. Density functional theory (DFT) calculation with 6-311++G (d, p) basis set along with B3LYP and B3PW91 functionals have been used to compute ground state molecular geometries and vibrational frequencies. The assignments of the vibrational spectra have carried out with the help of Potential Energy distribution (PED) analysis. Factor group analysis has also been tabulated. Charge distribution, Frontier Molecular Orbitals, UV-Vis spectra, Molecular Electrostatic Potential (MEP) maps, Non-linear optical (NLO) property and thermodynamic properties of the title compound at different temperatures, were determined using B3LYP functional along with 6-311++G (d, p) basis set. The theoretical 1H and 13C NMR chemical shifts were computed using B3LYP functional with 6-311++G (2d, p) basis sets. Natural Bond orbital analysis were computed and possible transitions were correlated with the electronic transitions. The title compound not only exhibits appreciable dipole moment and hyper polarizability (indicating good NLO properties) but also forms a stable complex with Bacillus cereus, (2HUC), with binding affinity -6.7 kcal/mol through molecular docking, suggesting that, it might exhibit inhibitory activity against Bacillus cereus.

  9. Spectroscopic (FT-IR, FT-Raman, UV, NMR, NLO) investigation, molecular docking and molecular simulation dynamics on 1-Methyl-3-Phenylpiperazine

    Science.gov (United States)

    Subashini, K.; Periandy, S.

    2017-09-01

    The title compound was analyzed, by recording FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectra in solid phase, 1H and 13C NMR in CDCl3 (deuterated chloroform) and UV spectrum (200-400 nm) in solid phase and in ethanol solution. Conformational analysis was done using semi-empirical method PM6. The computed wavenumbers obtained from B3LYP and B3PW91 functionals along with 6-311++G (d, p) basis sets were scaled so as to agree with the experimental values and the scaling factors have been reported. All fundamental modes have been assigned based on the potential energy distribution (PED) values and the structure of the molecule was analyzed in terms of parameters like bond length, bond angle and dihedral angles through B3LYP and B3PW91 functionals along with 6-311++G(d,p) basis set. The observed HOMO-LUMO mappings reveal the different charge transfer possibilities within the molecule. The percentage contribution of a group to each molecular orbital was calculated using Gauss Sum program. Natural bond orbital analysis was computed and possible transition were correlated with the electronic transitions. Mulliken charges, electrostatic potential charges and natural charges are also predicted. The theoretical 1H and 13C NMR chemical shifts were computed using B3LYP functionals using 6-311++G (2d, p) basis sets. The temperature dependence of the thermodynamic properties; heat capacity, entropy and enthalpy for the title compound were also determined by B3LYP functional with 6-311++G (d, p) basis set. Molecular docking study shows that the title compound might exhibit inhibitory activity against Clostridium botulinum (2J3X). The interaction of the ligand (title molecule) with 2J3X for 2 ns duration and radial distribution function have been observed through molecular dynamics simulations.

  10. Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of O-desmethyltramadol hydrochloride an active metabolite in tramadol - An analgesic drug

    Science.gov (United States)

    Arjunan, V.; Santhanam, R.; Marchewka, M. K.; Mohan, S.

    2014-03-01

    O-desmethyltramadol is one of the main metabolites of tramadol widely used clinically and has analgesic activity. The FTIR and FT-Raman spectra of O-desmethyl tramadol hydrochloride are recorded in the solid phase in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The observed fundamentals are assigned to different normal modes of vibration. Theoretical studies have been performed as its hydrochloride salt. The structure of the compound has been optimised with B3LYP method using 6-31G** and cc-pVDZ basis sets. The optimised bond length and bond angles are correlated with the X-ray data. The experimental wavenumbers were compared with the scaled vibrational frequencies determined by DFT methods. The IR and Raman intensities are determined with B3LYP method using cc-pVDZ and 6-31G(d,p) basic sets. The total electron density and molecular electrostatic potential surfaces of the molecule are constructed by using B3LYP/cc-pVDZ method to display electrostatic potential (electron + nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. Natural bond orbital analysis of O-desmethyltramadol hydrochloride has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR chemical shifts of the molecule have been anlysed.

  11. Molecular structure, spectroscopic (FT-IR, FT Raman, UV, NMR and THz) investigation and hyperpolarizability studies of 3-(2-Chloro-6-fluorophenyl)-1-(2-thienyl) prop-2-en-1-one

    Science.gov (United States)

    Kumar, Rajesh; Kumar, Amit; Deval, Vipin; Gupta, Archana; Tandon, Poonam; Patil, P. S.; Deshmukh, Prathmesh; Chaturvedi, Deepika; Watve, J. G.

    2017-02-01

    In the present work, a combined experimental and theoretical study on ground state molecular structure, spectroscopic and nonlinear optical properties of the chalcone derivative 3-(2-Chloro-6-fluorophenyl)-1-(2-thienyl) prop-2-en-1-one (2C6F2SC) is reported. Initial geometry generated from single crystal X-ray diffraction parameters was minimized at DFT level employing B3LYP/6-311++G (d,p) without any constraint to the potential energy surface. The molecule has been characterized using various experimental techniques FT-IR, FT-Raman, UV-Vis, 1H NMR, TD-THz and the spectroscopic data have been analyzed theoretically by Density Functional Theory (DFT) method. Harmonic vibrational frequencies were calculated theoretically using the optimized ground state geometry and the spectra were interpreted by means of potential energy distribution. Time Dependent Density Functional Theory (TD-DFT) has been used to calculate energies, absorption wavelengths, oscillator strengths of electronic singlet-singlet transitions. The calculated energy and oscillator strength complement with the experimental findings. The HOMO-LUMO energy gap explains the charge interaction taking place within the molecule. Good correlations between the experimental 1H NMR chemical shifts and calculated GIAO shielding tensors were found. Stability of the molecule, hyperconjugative interactions and charge delocalization has been analyzed by natural bond orbital (NBO) analysis. The first order hyperpolarizability (β) of this molecular system and related properties (μ, and Δα) have been calculated using the finite-field approach.

  12. Perturbed Angular Correlation (PAC)/NMR spectroscopic properties and dynamics of compounds containing metal ions

    DEFF Research Database (Denmark)

    Arcisauskaité, Vaida

    steps towards understanding how Zn(II) reaches its target position in biological systems in vivo and in vitro experiments in aqueous solution, is the detailed investigation of water exchange reactions for Zn(II)(aq). A very advanced (albeit not complete) picture of structure and dynamics of solvated Zn......199mHg PAC and 199Hg NMR spectroscopic properties, nuclear quadrupole coupling constants, Q, asymmetry parameters, , and chemical shifts, , respectively, are the fingerprint of the local molecular and electronic structure, at the probed Hg nuclei. For this reason, these spectroscopic techniques...... compounds in terms of the atomic constituents. The analysis provided a chemophysical interpretation of changes in Vzz upon structural distortions and ligand exchange. The gained insights can be useful when predicting and understanding changes in Q values for Hg binding sites in proteins. One of the first...

  13. NMR, MRI, and spectroscopic MRI in inhomogeneous fields

    Science.gov (United States)

    Demas, Vasiliki; Pines, Alexander; Martin, Rachel W; Franck, John; Reimer, Jeffrey A

    2013-12-24

    A method for locally creating effectively homogeneous or "clean" magnetic field gradients (of high uniformity) for imaging (with NMR, MRI, or spectroscopic MRI) both in in-situ and ex-situ systems with high degrees of inhomogeneous field strength. THe method of imaging comprises: a) providing a functional approximation of an inhomogeneous static magnetic field strength B.sub.0({right arrow over (r)}) at a spatial position {right arrow over (r)}; b) providing a temporal functional approximation of {right arrow over (G)}.sub.shim(t) with i basis functions and j variables for each basis function, resulting in v.sub.ij variables; c) providing a measured value .OMEGA., which is an temporally accumulated dephasing due to the inhomogeneities of B.sub.0({right arrow over(r)}); and d) minimizing a difference in the local dephasing angle .phi.({right arrow over (r)},t)=.gamma..intg..sub.0.sup.t{square root over (|{right arrow over (B)}.sub.1({right arrow over (r)},t')|.sup.2+({right arrow over (r)}{right arrow over (G)}.sub.shimG.sub.shim(t')+.parallel.{right arrow over (B)}.sub.0({right arrow over (r)}).parallel..DELTA..omega.({right arrow over (r)},t'/.gamma/).sup.2)}dt'-.OMEGA. by varying the v.sub.ij variables to form a set of minimized v.sub.ij variables. The method requires calibration of the static fields prior to minimization, but may thereafter be implemented without such calibration, may be used in open or closed systems, and potentially portable systems.

  14. Complexation of roxatidine acetate hydrochloride with beta-cyclodextrin: NMR spectroscopic study.

    Science.gov (United States)

    Ali, S M; Maheshwari, A; Asmat, F

    2004-08-01

    A NMR spectroscopic study of mixtures of varying ratios of roxatidine acetate hydrochloride (RAH) and beta-cyclodextrin (beta-CD) in D2O revealed the formation of a 1:1 inclusion compound. The aromatic ring of RAH selectively penetrates the beta-CD cavity in preference to the piperidine ring.

  15. Spectroscopic correlation analysis of NMR-based metabonomics in exercise science.

    Science.gov (United States)

    Kirwan, Gemma M; Coffey, Vernon G; Niere, Julie O; Hawley, John A; Adams, Michael J

    2009-10-12

    Spectroscopic studies of complex clinical fluids have led to the application of a more holistic approach to their chemical analysis becoming more popular and widely employed. The efficient and effective interpretation of multidimensional spectroscopic data relies on many chemometric techniques and one such group of tools is represented by so-called correlation analysis methods. Typical of these techniques are two-dimensional correlation analysis and statistical total correlation spectroscopy (STOCSY). Whilst the former has largely been applied to optical spectroscopic analysis, STOCSY was developed and has been applied almost exclusively to NMR metabonomic studies. Using a (1)H NMR study of human blood plasma, from subjects recovering from exhaustive exercise trials, the basic concepts and applications of these techniques are examined. Typical information from their application to NMR-based metabonomics is presented and their value in aiding interpretation of NMR data obtained from biological systems is illustrated. Major energy metabolites are identified in the NMR spectra and the dynamics of their appearance and removal from plasma during exercise recovery are illustrated and discussed. The complementary nature of two-dimensional correlation analysis and statistical total correlation spectroscopy are highlighted.

  16. Synthesis, spectroscopic investigations (FT-IR, NMR, UV-Vis, and TD-DFT), and molecular docking of (E)-1-(benzo[d][1, 3]dioxol-6-yl)-3-(6-methoxynaphthalen-2-yl)prop-2-en-1-one

    Science.gov (United States)

    Therasa Alphonsa, A.; Loganathan, C.; Athavan Alias Anand, S.; Kabilan, S.

    2017-02-01

    The compound (E)-1-(benzo [d] [1, 3] dioxol-6-yl)-3-(6-methoxy naphthalen-2-yl) prop-2-en-1-one (AKN) was synthesized and characterized by FT-IR, NMR, and UV-Vis spectrometer. The optimized molecular geometry, bond lengths, bond angles, atomic charges, harmonic vibrational wave numbers and intensities of vibrational bonds of the title compound have been investigated by Time dependent- Density Functional Theory (TD-DFT) using a standard B3LYP method with 6-31 G (d, p) basis set available in the Gaussian 09W package. 1H and 13C NMR chemical shifts of the molecule were calculated using Gauge-independent atomic orbital method (GIAO). Experimental excitation energies of the molecules were matched with the theoretically calculated energies. The atomic charge distributions of the various atoms present in the AKN were obtained by Mulliken charge population analysis. The Molecular Electrostatic Potential (MEP) analysis reveals the sites for electrophilic attack and nucleophilic reactions in the molecule. The difference between the observed and scaled frequencies was small. The HOMO to LUMO transition implies an electron density transfer. The intramolecular contacts have been interpreted using Natural Bond Orbital (NBO) analysis. The calculation results were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. To provide information about the interactions between human cytochrome protein and the novel compound theoretically, docking studies were carried out using Schrödinger software.

  17. NMR spectroscopic study on methanolysis reaction of vegetable oil

    Energy Technology Data Exchange (ETDEWEB)

    Fangming Jin; Kohei Kawasaki; Hisanori Kishida; Kazuyuki Tohji; Takehoko Moriya; Heiji Enomoto [Tohoku University, Sendai (Japan). Graduate School of Environmental Studies

    2007-05-15

    This study is to clarify the pathways of the transesterification of vegetable oil by applying NMR to the identification of intermediates in the transesterification reaction. Results showed that the significant methanolysis product was sn-1,3-diglycerides in diglycerides, and sn-2-monoglycerides was not found. These analytical results suggest that the methanolysis reaction may occur easily at the sn-2-position for both sn-tri- and sn-1,2-diglycerides. Short communication. 16 refs., 6 figs., 2 tabs.

  18. Spectroscopic (FT-IR, FT-Raman and UV-Visible) investigations, NMR chemical shielding anisotropy (CSA) parameters of 2,6-Diamino-4-chloropyrimidine for dye sensitized solar cells using density functional theory.

    Science.gov (United States)

    Gladis Anitha, E; Joseph Vedhagiri, S; Parimala, K

    2015-02-05

    The molecular structure, geometry optimization, vibrational frequencies of organic dye sensitizer 2,6-Diamino-4-chloropyrimidine (DACP) were studied based on Hartree-Fock (HF) and density functional theory (DFT) using B3LYP methods with 6-311++G(d,p) basis set. Ultraviolet-Visible (UV-Vis) spectrum was investigated by time dependent DFT (TD-DFT). Features of the electronic absorption spectrum in the UV-Visible regions were assigned based on TD-DFT calculation. The absorption bands are assigned to transitions. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer DACP is due to an electron injection process from excited dye to the semiconductor's conduction band. The observed and the calculated frequencies are found to be in good agreement. The energies of the frontier molecular orbitals (FMOS) have also been determined. The chemical shielding anisotropic (CSA) parameters are calculated from the NMR analysis, Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. GC-FID and NMR Spectroscopic Studies on Gamma Irradiated Walnut Lipids

    Directory of Open Access Journals (Sweden)

    Vassilia J. Sinanoglou

    2015-01-01

    Full Text Available Walnuts have an excellent fatty acid profile, beneficial for coronary heart diseases. A diet rich in walnuts has shown to decrease the total and LDL cholesterol levels as well as lipoprotein levels. In this study, the effects of different doses of γ-irradiation and different packaging conditions on proximate composition and fatty acid profile of walnuts (Juglans regia L. were investigated merging data from different spectroscopic techniques. Walnuts moisture, ash, fat, and protein content as well as fatty acid profile were evaluated immediately after irradiation. GC-FID results showed that SFA increased and MUFA and PUFA decreased with the increase of irradiation dose. Moreover, MUFA/SFA and PUFA/SFA ratios decreased P<0.05 compared to control samples. Furthermore, NMR spectroscopy was implemented to examine possible discrimination patterns based on irradiation dose and packaging. This approach revealed the role of PUFA decrease with the parallel increase of irradiation dose while indicating the protective role of vacuum and MAP compared to air packaging. In conclusion, at irradiation doses of up to 5 kGy, the walnuts retained the nutritional benefits of its fatty acids, in particular MUFA and PUFA. Concerning the different types of packaging, greater stability in the nuts was observed using MAP packaging.

  20. Application of phosphorus-31 and aluminum-27 NMR spectroscopic techniques to study aqueous and methanolic solutions of tetraphenylammonium aluminophosphate

    Science.gov (United States)

    Goudarzi, Nasser; Amin, Amir H.

    2017-01-01

    In this work, aluminum-27 and phosphorus-31 NMR spectroscopic techniques were used to investigate and characterize the distribution of aluminophosphate (AlPO) species soluble in the aqueous and methanolic solutions of tetraphenylammonium (TPhA) chloride. The reaction between hexaaquaaluminum cations, [A1(H2O)6]3+, and different phosphate ligands such as H3PO4, H2PO4-, and the acidic dimers H6P2O8 and H5P2O8- resulted in the formation of the soluble AlPO cations. The effective aluminum-27 and phosphorous-31 NMR spectroscopies can be employed to characterize the species present in a solution. Assignment of the peaks present in the aluminum-27 NMR spectra to the aluminate species or aluminate connectivities was done to acquire information about different AlPO complexes. Some resonance lines were observed in the phosphorus-31 {1H} NMR spectra, indicating the existence of different complexes in the AlPO solutions. Some peaks were observed in the methanolic solutions of AlPO at the chemical shifts of -0.41, -6.4, -7.5, -7.9, -13.1, -13.9, -16.6, -18.1, and -20.6 ppm. Four additional peaks were also observed in the phosphorus-31 {1H} NMR spectra of the methanolic solutions of AlPO, whose intensities changed with changes in the methanol:water volume ratio; they were observed in methanol but not in aqueous AlPO.

  1. {sup 1}H NMR spectroscopic studies establish that heparanase is a retaining glycosidase

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Jennifer C., E-mail: jennifer.wilson@griffith.edu.au [Institute for Glycomics, Griffith University Gold Coast Campus, QLD 4222 (Australia); Laloo, Andrew Elohim [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 (Australia); Singh, Sanjesh [Institute for Glycomics, Griffith University Gold Coast Campus, QLD 4222 (Australia); Ferro, Vito, E-mail: v.ferro@uq.edu.au [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072 (Australia)

    2014-01-03

    Highlights: •{sup 1}H and {sup 13}C NMR chemical shifts of fondaparinux were fully assigned by 1D and 2D NMR techniques. •Hydrolysis of fondaparinux by heparanase was monitored by {sup 1}H NMR spectroscopy. •Heparanase is established to be a retaining glycosidase. -- Abstract: Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains of proteoglycans in basement membranes and the extracellular matrix (ECM). Heparanase is implicated in several diverse pathological processes associated with ECM degradation such as metastasis, inflammation and angiogenesis and is thus an important target for anti-cancer and anti-inflammatory drug discovery. Heparanase has been classed as belonging to the clan A glycoside hydrolase family 79 based on sequence analysis, secondary structure predictions and mutagenic analysis, and thus it has been inferred that it is a retaining glycosidase. However, there has been no direct experimental evidence to support this conclusion. Herein we describe {sup 1}H NMR spectroscopic studies of the hydrolysis of the pentasaccharide substrate fondaparinux by heparanase, and provide conclusive evidence that heparanase hydrolyses its substrate with retention of configuration and is thus established as a retaining glycosidase. Knowledge of the mechanism of hydrolysis may have implications for future design of inhibitors for this important drug target.

  2. Low-temperature UV-visible and NMR spectroscopic investigations of O(2) binding to ((6)L)Fe(II), a ferrous heme bearing covalently tethered axial pyridine ligands.

    Science.gov (United States)

    Ghiladi, Reza A; Karlin, Kenneth D

    2002-05-06

    In this report, we describe the reversible dioxygen reactivity of ((6)L)Fe(II) (1) [(6)L = partially fluorinated tetraphenylporphyrin with covalently appended TMPA moiety; TMPA = tris(2-pyridylmethyl)amine] using a combination of low-temperature UV-vis and multinuclear ((1)H and (2)H) NMR spectroscopies. Complex 1, or its pyrrole-deuterated analogue ((6)L-d(8))Fe(II) (1-d(8)), exhibits downfield shifted pyrrole resonances (delta 28-60 ppm) in all solvents utilized [CH(2)Cl(2), (CH(3))(2)C(O), CH(3)CN, THF], indicative of a five-coordinate high-spin ferrous heme, even when there is no exogenous axial solvent ligand present (i.e., in methylene chloride). Furthermore, ((6)L)Fe(II) (1) exhibits non-pyrrolic upfield and downfield shifted peaks in CH(2)Cl(2), (CH(3))(2)C(O), and CH(3)CN solvents, which we ascribed to resonances arising from the intra- or intermolecular binding of a TMPA-pyridyl arm to the ferrous heme. Upon exposure to dioxygen at 193 K in methylene chloride, ((6)L)Fe(II) (1) [UV-vis: lambda(max) = 433 (Soret), 529 (sh), 559 nm] reversibly forms a dioxygen adduct [UV-vis: lambda(max) = 422 (Soret), 542 nm], formulated as the six-coordinate low-spin [delta(pyrrole) 9.3 ppm, 193 K] heme-superoxo complex ((6)L)Fe(III)-(O(2)(-)) (2). The coordination of the tethered pyridyl arm to the heme-superoxo complex as axial base ligand is suggested. In coordinating solvents such as THF, reversible oxygenation (193 K) of ((6)L)Fe(II) (1) [UV-vis: lambda(max) = 424 (Soret), 542 nm] also occurs to give a similar adduct ((6)L)Fe(III)-(O(2)(-)) (2) [UV-vis: lambda(max) = 418 (Soret), 537 nm. (2)H NMR: delta(pyrrole) 8.9 ppm, 193 K]. Here, we are unable to distinguish between a bound solvent ligand or tethered pyridyl arm as axial base ligand. In all solvents, the dioxygen adducts decompose (thermally) to the ferric-hydroxy complex ((6)L)Fe(III)-OH (3) [UV-vis: lambda(max) = 412-414 (Soret), 566-575 nm; approximately delta(pyrrole) 120 ppm at 193 K]. This study on the O(2

  3. Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of (1,2-epoxyethyl)benzene and (1,2-epoxy-2-phenyl)propane

    Science.gov (United States)

    Arjunan, V.; Anitha, R.; Devi, L.; Mohan, S.; Yang, Haifeng

    2015-01-01

    Aromatic epoxides are causative factors for mutagenic and carcinogenic activity of polycyclic arenes. The 1,2- or 2,3-epoxy compounds are widely used to a considerable extent in the textile, plastics, pharmaceutical, cosmetics, detergent and photochemical industries. The FTIR and FT-Raman spectra of (1,2-epoxyethyl)benzene and (1,2-epoxy-2-phenyl)propane are recorded in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The observed fundamentals are assigned to different normal modes of vibration. The structure of the compound has been optimised with B3LYP method using 6-311++G** and cc-pVTZ basis sets. The IR and Raman intensities are determined. The total electron density and molecular electrostatic potential surfaces of the molecule are constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron + nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. Natural bond orbital analysis of the compounds has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR chemical shifts of the molecules have been analysed.

  4. {sup 13}C NMR and EPR spectroscopic evaluation of oil shale mined soil recuperation

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J.V. dos, E-mail: mangrich@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil); Mangrich, A.S. [Instituto Nacional de Ciencia e Tecnologia: Energia e Ambiente, Salvador, BA (Brazil); Pereira, B.F. [EMBRAPA Clima Temperado, Pelotas, RS (Brazil); Pillon, C.N. [EMBRAPA Clima Temperado, Pelotas, RS (Brazil). Estacao Experimental Cascata; Novotny, E.H. [EMBRAPA Solos, Rio de Janeiro, RJ (Brazil); Bonagamba, T.J. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Fisica; Abbt-Braun, G.; Frimmel, F.H. [Engler-Bunte-Institut, Universitaet Karlsruhe, TH (Germany)

    2013-02-15

    In this work, native forest soil (NFS) organic matter (SOM) sample and SOM samples from a neighboring forest soil area of an oil shale mine which is being rehabilitated for thirty years (RFS) were analyzed. X-band electron paramagnetic resonance (EPR) and solid-state {sup 13}C nuclear magnetic resonance (NMR) spectroscopies were used to evaluate the soil reclamation of the Brazilian oil shale mining process. Two-dimensional heterospectral correlation studies of the results obtained from EPRand {sup 13}C NMR were used to obtain information about SOM structures and their interactions with residual paramagnetic metal ion. The signal of the residual metallic oxycation, VO{sup 2+} correlated positively with uronic acid-type hydrophilic organic structures, determined from the {sup 13}C NMR spectra, and correlated negatively with the organic free radical (OFR) signal associated with oxygen atoms (g = 2.0042). The hydrophobic aromatic structures correlate positively with the EPR OFR signal associated with carbon atoms (g = 2.0022). The data from the two spectroscopic magnetic techniques show that the used recuperation process is effective. (author)

  5. Structural Modifications of Deoxycholic Acid to Obtain Three Known Brassinosteroid Analogues and Full NMR Spectroscopic Characterization.

    Science.gov (United States)

    Herrera, Heidy; Carvajal, Rodrigo; Olea, Andrés F; Espinoza, Luis

    2016-08-27

    An improved synthesis route for obtaining known brassinosteroid analogues, i.e., methyl 2α,3α-dihydroxy-6-oxo-5α-cholan-24-oate (11), methyl 3α-hydroxy-6-oxo-7-oxa-5α-cholan-24-oate (15) and methyl 3α-hydroxy-6-oxa-7-oxo-5α-cholan-24-oate (16), from hyodeoxycholic acid (4) maintaining the native side chain is described. In the alternative procedure, the di-oxidized product 6, obtained in the oxidation of methyl hyodeoxycholate 5, was converted almost quantitatively into the target monoketone 7 by stereoselective reduction with NaBH₄, increasing the overall yield of this synthetic route to 96.8%. The complete ¹H- and (13)C-NMR assignments for all compounds synthesized in this work have been made by 1D and 2D heteronuclear correlation gs-HSQC and gs-HMBC techniques. Thus, it was possible to update the spectroscopic information of ¹H-NMR and to accomplish a complete assignment of all (13)C-NMR signals for analogues 5-16, which were previously reported only in partial form.

  6. Synthesis and Spectroscopic Investigation of Azoporphyrins

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The synthesis of a series of new covalently-connected azoporphyrin derivatives is described and the photochemical properties of the new compounds are discussed. The two chromophores of these derivatives exhibit their absorption spectroscopic properties respectively.In the fluorescence emission spectra, intermolecular fluorescence quenching is detected.

  7. Structural investigations on betacyanin pigments by LC NMR and 2D NMR spectroscopy.

    Science.gov (United States)

    Stintzing, Florian C; Conrad, Jürgen; Klaiber, Iris; Beifuss, Uwe; Carle, Reinhold

    2004-02-01

    Four betacyanin pigments were analysed by LC NMR and subjected to extensive NMR characterisation after isolation. Previously, low pH values were applied for NMR investigations of betalains resulting in rapid degradation of the purified substances thus preventing extensive NMR studies. Consequently, up to now only one single (13)C NMR spectrum of a betalain pigment, namely that of neobetanin (=14,15-dehydrobetanin), was available. Because of its sufficient stability under highly acidic conditions otherwise detrimental for betacyanins, this pigment remained an exemption. Since betalains are most stable in the pH range of 5-7, a new solvent system has been developed allowing improved data acquisition through improved pigment stability at near neutral pH. Thus, not only (1)H, but for the first time also partial (13)C data of betanin, isobetanin, phyllocactin and hylocerenin isolated from red-purple pitaya [Hylocereus polyrhizus (Weber) Britton & Rose, Cactaceae] could be indirectly obtained by gHSQC- and gHMQC-NMR experiments.

  8. (19)F NMR spectroscopic characterization of the interaction of niflumic acid with human serum albumin.

    Science.gov (United States)

    Kitamura, Keisuke; Omran, Ahmed A; Takegami, Shigehiko; Tanaka, Rumi; Kitade, Tatsuya

    2007-04-01

    The interaction of a non-steroidal anti-inflammatory drug, niflumic acid (NFA), with human serum albumin (HSA) has been investigated by (19)F nuclear magnetic resonance (NMR) spectroscopy. A (19)F NMR spectrum of NFA in a buffered (pH 7.4) solution of NaCl (0.1 mol L(-1)) contained a single sharp signal of its CF(3) group 14.33 ppm from the internal reference 2,2,2-trifluoroethanol. Addition of 0.6 mmol L(-1) HSA to the NFA buffer solution caused splitting of the CF(3) signal into two broadened signals, shifted to the lower fields of 14.56 and 15.06 ppm, with an approximate intensity ratio of 1:3. Denaturation of HSA by addition of 3.0 mol L(-1) guanidine hydrochloride (GU) restored a single sharp signal of CF(3) at 14.38 ppm, indicating complete liberation of NFA from HSA as a result of its denaturation. These results suggest that the binding is reversible and occurs in at least two HSA regions. Competitive (19)F NMR experiments using warfarin, dansyl-L: -asparagine, and benzocaine (site I ligands), and L: -tryptophan and ibuprofen (site II ligands) revealed that NFA binds to site I at two different regions, Ia and Ib, in the ratio 1:3. By use of (19)F NMR with NFA as an (19)F NMR probe the nonfluorinated site I-binding drugs sulfobromophthalein and iophenoxic acid were also found to bind sites Ia and Ib, respectively. These results illustrate the usefulness and convenience of (19)F NMR for investigation of the HSA binding of both fluorinated and nonfluorinated drugs.

  9. Interaction between new synthesized derivative of (E,E)-azomethines and BN(6,6-7) nanotube for medical applications: Geometry optimization, molecular structure, spectroscopic (NMR, UV/Vis, excited state), FMO, MEP and HOMO-LUMO investigations

    Science.gov (United States)

    Sheikhi, Masoome; Shahab, Siyamak; Filippovich, Liudmila; Khaleghian, Mehrnoosh; Dikusar, Evgenij; Mashayekhi, Mahsa

    2017-10-01

    In this present work, first time interaction between new synthesized derivative of the 4-((E)-((4-((E)-phenyldiazenyl)phenyl)imino)methyl)benzoic acid (E-PABA) and the BN(6,6-7) Nanotube for medical applications were studied. The geometries of the compounds E-PABA, the BN(6,6-7) Nanotube and the Complex BN(6,6-7)/E-PABA were optimized by Density Functional Theory (DFT) in the gas phase. The adsorption effect of the compound E-PABA on the electronic properties, chemical shift tensors and natural charge of the BN(6,6-7) Nanotube was investigated and discussed. The electronic spectra of the E-PABA and the Complex BN(6,6-7)/E-PABA in the gas phase carried out by Time Dependent Density Functional Theory (TD-DFT) for the foundation adsorption effect on maximum wavelength of the E-PABA.

  10. UV-visible and (1)H-(15)N NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors.

    Science.gov (United States)

    Farrugia, Kristina N; Makuc, Damjan; Podborska, Agnieszka; Szaciłowski, Konrad; Plavec, Janez; Magri, David C

    2015-02-14

    Four model thiosemicarbazide anion chemosensors containing three N-H bonds, substituted with phenyl and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide, fluoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in DMSO and 9 : 1 DMSO-H2O by UV-visible absorption and (1)H/(13)C/(15)N NMR spectroscopic techniques and corroborated with DFT studies. Significant changes were observed in the UV-visible absorption spectra with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye. These changes were determined to be due to the deprotonation of the central N-H proton and not due to hydrogen bonding based on (1)H/(15)N NMR titration studies with acetate in DMSO-d6-0.5% water. Direct evidence for deprotonation was confirmed by the disappearance of the central thiourea proton and the formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the central N-H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation mechanism of the central N-H proton rather than by hydrogen bonding as is often reported.

  11. NMR spectroscopic and analytical ultracentrifuge analysis of membrane protein detergent complexes

    Directory of Open Access Journals (Sweden)

    Choe Senyon

    2007-11-01

    Full Text Available Abstract Background Structural studies of integral membrane proteins (IMPs are hampered by inherent difficulties in their heterologous expression and in the purification of solubilized protein-detergent complexes (PDCs. The choice and concentrations of detergents used in an IMP preparation play a critical role in protein homogeneity and are thus important for successful crystallization. Results Seeking an effective and standardized means applicable to genomic approaches for the characterization of PDCs, we chose 1D-NMR spectroscopic analysis to monitor the detergent content throughout their purification: protein extraction, detergent exchange, and sample concentration. We demonstrate that a single NMR measurement combined with a SDS-PAGE of a detergent extracted sample provides a useful gauge of the detergent's extraction potential for a given protein. Furthermore, careful monitoring of the detergent content during the process of IMP production allows for a high level of reproducibility. We also show that in many cases a simple sedimentation velocity measurement provides sufficient data to estimate both the oligomeric state and the detergent-to-protein ratio in PDCs, as well as to evaluate the homogeneity of the samples prior to crystallization screening. Conclusion The techniques presented here facilitate the screening and selection of the extraction detergent, as well as help to maintain reproducibility in the detergent exchange and PDC concentration procedures. Such reproducibility is particularly important for the optimization of initial crystallization conditions, for which multiple purifications are routinely required.

  12. Spectroscopic investigations of carious tooth decay.

    Science.gov (United States)

    Thareja, R K; Sharma, A K; Shukla, Shobha

    2008-11-01

    We report on the elemental composition of healthy and infected part of human tooth using laser induced breakdown spectroscopy (LIBS). We have used prominent constituent transitions in laser-excited tooth to diagnose the state of the tooth. A nanosecond laser pulse (355nm, 5ns) was used as an ablating pulse and the sodium (3s2S-3p2P) at 588.99 and (3s2S-3p2P) at 589.99nm, strontium (5s21S-1s5P) at 460.55nm, and calcium (3d3D-4f 3F0) at 452.55nm transitions for spectroscopic analysis. The spectroscopic observations in conjunction with discriminate analysis showed that calcium attached to the hydroxyapatite structure of the tooth was affected severely at the infected part of the tooth. The position-time plots generated from two-dimensional (2D) images conclusively showed a decrease in calcium concentration in the infected region of the irradiated tooth. Using the technique, we could distinguish between the healthy and carious parts of the tooth with significant accuracy.

  13. Quantum Chemical Study of the Solvent Effect on the Anticancer Active Molecule of Iproplatin: Structural, Electronic, and Spectroscopic Properties (IR, 1H NMR, UV)

    Science.gov (United States)

    Sadeghi, N.; Ghiasi, R.; Fazaeli, R.; Jamehbozorgi, S.

    2017-01-01

    The structural, electronic, and spectroscopic properties of the anticancer active molecule of iproplatin were investigated in the gas and liquid phases. Based on the polarizable continuum model (PCM), the solvent effect on the structural parameters, frontier orbitals, and spectroscopic parameters of the complex was investigated. The results indicate that the polarity of solvents plays a significant role in the structure and pro perties of the complex. 1H and 13C NMR chemical shifts were calculated using the Gauge-invariant atomic orbital (GIAO) method. Pt-Cl and Pt-OH bonds were investigated through a vibrational analysis. Moreover, time dependent density functional theory (TD-DFT) was used to calculate the energy, oscillatory strength, and wavelength absorption maximum (λmax) of electronic transitions and its nature within the complex.

  14. Structural investigation of aluminium doped ZnO nanoparticles by solid-state NMR spectroscopy.

    Science.gov (United States)

    Avadhut, Yamini S; Weber, Johannes; Hammarberg, Elin; Feldmann, Claus; Schmedt auf der Günne, Jörn

    2012-09-07

    The electrical conductivity of aluminium doped zinc oxide (AZO, ZnO:Al) materials depends on doping induced defects and grain structure. This study aims at relating macroscopic electrical conductivity of AZO nanoparticles with their atomic structure, which is non-trivial because the derived materials are heavily disordered and heterogeneous in nature. For this purpose we synthesized AZO nanoparticles with different doping levels and narrow size distribution by a microwave assisted polyol method followed by drying and a reductive treatment with forming gas. From these particles electrically conductive, optically transparent films were obtained by spin-coating. Characterization involved energy-dispersive X-ray analysis, wet chemical analysis, X-ray diffraction, electron microscopy and dynamic light scattering, which provided a basis for a detailed structural solid-state NMR study. A multinuclear ((27)Al, (13)C, (1)H) spectroscopic investigation required a number of 1D MAS NMR and 2D MAS NMR techniques (T(1)-measurements, (27)Al-MQMAS, (27)Al-(1)H 2D-PRESTO-III heteronuclear correlation spectroscopy), which were corroborated by quantum chemical calculations with an embedded cluster method (EEIM) at the DFT level. From the combined data we conclude that only a small part of the provided Al is incorporated into the ZnO structure by substitution of Zn. The related (27)Al NMR signal undergoes a Knight shift when the material is subjected to a reductive treatment with forming gas. At higher (formal) doping levels Al forms insulating (Al, H and C containing) side-phases, which cover the surface of the ZnO:Al particles and increase the sheet resistivity of spin-coated material. Moreover, calculated (27)Al quadrupole coupling constants serve as a spectroscopic fingerprint by which previously suggested point-defects can be identified and in their great majority be ruled out.

  15. NMR spectroscopic search module for Spektraris, an online resource for plant natural product identification--Taxane diterpenoids from Taxus × media cell suspension cultures as a case study.

    Science.gov (United States)

    Fischedick, Justin T; Johnson, Sean R; Ketchum, Raymond E B; Croteau, Rodney B; Lange, B Markus

    2015-05-01

    Development and testing of Spektraris-NMR, an online spectral resource, is reported for the NMR-based structural identification of plant natural products (PNPs). Spektraris-NMR allows users to search with multiple spectra at once and returns a table with a list of hits arranged according to the goodness of fit between query data and database entries. For each hit, a link to a tabulated alignment of (1)H NMR and (13)C NMR spectroscopic peaks (query versus database entry) is provided. Furthermore, full spectroscopic records and experimental meta information about each database entry can be accessed online. To test the utility of Spektraris-NMR for PNP identification, the database was populated with NMR data (total of 466 spectra) for ∼ 250 taxanes, which are structurally complex diterpenoids (including the anticancer drug taxol) commonly found in the genus Taxus. NMR data generated with metabolites purified from Taxus cell suspension cultures were then used to search Spektraris-NMR, and enabled the identification of eight taxanes with high confidence. A ninth isolated metabolite could be assigned, based on spectral searches, to a taxane skeletal class, but no high confidence hit was produced. Using various spectroscopic methods, this metabolite was characterized as 2-deacetylbaccatin IV, a novel taxane. These results indicate that Spektraris-NMR is a valuable resource for rapid and reliable identification of known metabolites and has the potential to contribute to de-replication efforts in novel PNP discovery.

  16. Development and Investigation of NMR tools for chiral compound identification

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electronic, Optical and Nano Materials; Lansdon, Rick [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States)

    2014-09-01

    The goal behind the assigned summer project was to investigate the ability of nuclear magnetic resonance spectroscopy (NMR) to identify enantiomers of select chiral organo-fluorophosphates (OFPs) compounds which are analogs of chemical warfare agents (CWAs, e.g. Sarin). This involved investigations utilizing chiral solvating agents (CSAs) and characterizing the binding phenomena with cyclodextrins. The resolution of OFPs enantiomers using NMR would be useful for research into toxicodynamics and toxicokinetics in biological systems due to the widely differing properties of the CWA enantiomers [1]. The optimization of decontamination abilities in the case of a CWA events, with this method’s potential rapidity and robustness, as well as the development of models correlating chiral compounds with CSAs for optimal resolution are all rational benefits of this research.

  17. Terahertz spectroscopic investigation of methylenedioxy amphetamine

    Science.gov (United States)

    Wang, Guangqin; Shen, Jingling

    2008-03-01

    Experimental measurement and theoretical analysis of THz spectrum for methylenedioxy amphetamine are introduced. The refractive index and absorption coefficient of the sample were observed by terahertz time-domain spectroscopy (THz-TDS) technique in the range of 0.2~2.6 THz. It exhibits obvious absorption feature at 1.40 THz and weak THz absorption at around 1.68 and 2.21 THz. The spectral absorption characteristic in THz band was useful for the inspection and identification of drugs using THz-TDS. The theoretical calculation was performed using Density functional theory (DFT) with the GAUSSIAN 03 software package. Fully geometry optimization and frequency analysis of the optimized structure were performed at the B3LYP/6-21G levels. The simulated absorption spectrum was in agreement with the experimental data, and can hence be used for the assignment of observed THz spectrum. The theoretical simulation result showed that absorption peaks mainly result from intra-molecule and inter-molecule vibrations, different absorption peaks are corresponding to different vibrational modes and intensity. So the combination of the THz-TDS and DFT is an effective way to investigate characteristic spectra of illicit drugs.

  18. What Is the True Color of Fresh Meat? A Biophysical Undergraduate Laboratory Experiment Investigating the Effects of Ligand Binding on Myoglobin Using Optical, EPR, and NMR Spectroscopy

    Science.gov (United States)

    Linenberger, Kimberly; Bretz, Stacey Lowery; Crowder, Michael W.; McCarrick, Robert; Lorigan, Gary A.; Tierney, David L.

    2011-01-01

    With an increased focus on integrated upper-level laboratories, we present an experiment integrating concepts from inorganic, biological, and physical chemistry content areas. Students investigate the effects of ligand strength on the spectroscopic properties of the heme center in myoglobin using UV-vis, [superscript 1]H NMR, and EPR…

  19. What Is the True Color of Fresh Meat? A Biophysical Undergraduate Laboratory Experiment Investigating the Effects of Ligand Binding on Myoglobin Using Optical, EPR, and NMR Spectroscopy

    Science.gov (United States)

    Linenberger, Kimberly; Bretz, Stacey Lowery; Crowder, Michael W.; McCarrick, Robert; Lorigan, Gary A.; Tierney, David L.

    2011-01-01

    With an increased focus on integrated upper-level laboratories, we present an experiment integrating concepts from inorganic, biological, and physical chemistry content areas. Students investigate the effects of ligand strength on the spectroscopic properties of the heme center in myoglobin using UV-vis, [superscript 1]H NMR, and EPR…

  20. NMR-spectroscopic characterization of phosphodiester bond cleavage catalyzed by the minimal hammerhead ribozyme.

    Science.gov (United States)

    Fürtig, Boris; Richter, Christian; Schell, Peter; Wenter, Philipp; Pitsch, Stefan; Schwalbe, Harald

    2008-01-01

    In order to relate the conformational dynamics of the hammerhead ribozyme to its biological function the cleavage reaction catalyzed by the hammerhead ribozyme was monitored by time-resolved nuclear magnetic resonance (NMR) spectroscopy. For this purpose, the two nucleosides around the scissile phosphodiester bond were selectively (13)C labelled in multi-step organic syntheses starting from uniformly (13)C-labelled glucose. The phosphoamidites were incorporated using phosphoamidite chemistry in the hammerhead substrate strand. In addition, the 2'-OH group on the 5'-side of the hammerhead substrate strand was labelled with a photolabile protecting group. This labelling strategy enabled a detailed characterisation of the nucleotides around the scissile phosphodiester bond in the ground state conformation of the hammerhead ribozyme in the absence and presence of Mg(2+) ions as well as of the product state. Photochemical induction of the reaction in situ was further characterized by time-resolved NMR spectroscopy. The detailed structural and dynamic investigations revealed that the conformation of the hammerhead ribozyme is significantly affected by addition of Mg(2+) leading to an ensemble of conformations where dynamic transitions between energetically similar conformations occur on the ms-timescale in the presence of Mg(2+). The dynamic transitions are localized around the catalytic core. Cleavage from this ensemble cannot be described by mono-exponential kinetics but follows bi-exponential kinetics. A model is described to take into account these experimental data.

  1. A small-diameter NMR logging tool for groundwater investigations.

    Science.gov (United States)

    Walsh, David; Turner, Peter; Grunewald, Elliot; Zhang, Hong; Butler, James J; Reboulet, Ed; Knobbe, Steve; Christy, Tom; Lane, John W; Johnson, Carole D; Munday, Tim; Fitzpatrick, Andrew

    2013-01-01

    A small-diameter nuclear magnetic resonance (NMR) logging tool has been developed and field tested at various sites in the United States and Australia. A novel design approach has produced relatively inexpensive, small-diameter probes that can be run in open or PVC-cased boreholes as small as 2 inches in diameter. The complete system, including surface electronics and various downhole probes, has been successfully tested in small-diameter monitoring wells in a range of hydrogeological settings. A variant of the probe that can be deployed by a direct-push machine has also been developed and tested in the field. The new NMR logging tool provides reliable, direct, and high-resolution information that is of importance for groundwater studies. Specifically, the technology provides direct measurement of total water content (total porosity in the saturated zone or moisture content in the unsaturated zone), and estimates of relative pore-size distribution (bound vs. mobile water content) and hydraulic conductivity. The NMR measurements show good agreement with ancillary data from lithologic logs, geophysical logs, and hydrogeologic measurements, and provide valuable information for groundwater investigations.

  2. NMR spectroscopic characterization of β-cyclodextrin inclusion complex with vanillin

    Science.gov (United States)

    Pîrnau, Adrian; Bogdan, Mircea; Floare, Calin G.

    2009-08-01

    The inclusion of vanillin by β-cyclodextrin was investigated by 1H NMR. The continuous variation technique was used to evidence the formation of soluble 1:1 complex in aqueous solution. The association constant of vanillin with β-cyclodextrin has been obtained at 298 K by fitting the experimental chemical shifts differences, Δδobs = δfree - δobs of the observed guest and host protons, with a non-linear regression method. Besides the effective association constant, the fitting procedure allows a precise determination of all chemical shift parameters characterizing the pure complex. They can by used for an analysis of the geometry of the molecular complex in solution.

  3. NMR spectroscopic characterization of {beta}-cyclodextrin inclusion complex with vanillin

    Energy Technology Data Exchange (ETDEWEB)

    Pirnau, Adrian; Bogdan, Mircea; Floare, Calin G, E-mail: adrian.pirnau@itim-cj.r [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)

    2009-08-01

    The inclusion of vanillin by {beta}-cyclodextrin was investigated by {sup 1}H NMR. The continuous variation technique was used to evidence the formation of soluble 1:1 complex in aqueous solution. The association constant of vanillin with {beta}-cyclodextrin has been obtained at 298 K by fitting the experimental chemical shifts differences, {Delta}{delta}{sub obs} {delta}{sub free} - {delta}{sub obs} of the observed guest and host protons, with a non-linear regression method. Besides the effective association constant, the fitting procedure allows a precise determination of all chemical shift parameters characterizing the pure complex. They can by used for an analysis of the geometry of the molecular complex in solution.

  4. Using NMR Spectroscopy to Investigate the Solution Behavior of Nerve Agents and Their Binding to Acetylcholinesterase

    Science.gov (United States)

    2016-01-01

    USING NMR SPECTROSCOPY TO INVESTIGATE THE SOLUTION BEHAVIOR OF NERVE AGENTS AND THEIR BINDING TO...XX-01-2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) Jan – Jun 2015 4. TITLE AND SUBTITLE Using NMR Spectroscopy to Investigate the...MOLECULAR MOTIONS AND NMR SPECTROSCOPY ...................................................................................................3 4. THE

  5. Synthesis, structure, spectroscopic investigations, and computational studies of optically pure β-ketoamide

    Science.gov (United States)

    Mtat, D.; Touati, R.; Guerfel, T.; Walha, K.; Ben Hassine, B.

    2016-12-01

    Chemical preparation, X-ray single crystal diffraction, IR and NMR spectroscopic investigations of a novel nonlinear optical organic compound (C17H22NO2Cl) are described. The compound crystallizes in the orthorhombic system with the non-centrosymmetric sp. gr. P212121. In the crystal structure, molecules are interconnected by N-H…O hydrogen bonds forming infinite chains along a axis. The Hirshfeld surface and associated fingerprint plots of the compound are presented to explore the nature of intermolecular interactions and their relative contributions in building the solid-state architecture. The molecular HOMO-LUMO compositions and their respective energy gaps are also drawn to explain the activity of the compound. The first hyperpolarizability βtot of the title compound is determined using DFT calculations. The optical properties are also investigated by UV-Vis absorption spectrum.

  6. Spectroscopic approaches to resolving ambiguities of hyper-polarized NMR signals from different reaction cascades

    DEFF Research Database (Denmark)

    Jensen, Pernille Rose; Meier, Sebastian

    2016-01-01

    The influx of exogenous substrates into cellular reaction cascades on the seconds time scale is directly observable by NMR spectroscopy when using nuclear spin polarization enhancement. Conventional NMR assignment spectra for the identification of reaction intermediates are not applicable in thes...

  7. Purification and H-1 NMR spectroscopic characterization of phase II metabolites of tolfenamic acid

    DEFF Research Database (Denmark)

    Sidelmann, U. G.; Christiansen, E.; Krogh, L.;

    1997-01-01

    acid; the study shows the applicability of H-1 NMR for the identification of drug metabolites in biological fluids. In addition to NMR analysis, two metabolites were also identified by mass spectrometry (MS), The glucuronides of the following parent compounds, N-(2-methyl-3-chlorophenyl...

  8. Spectroscopic investigation of local mechanical impedance of living cells

    CERN Document Server

    Costa, Luca; Benseny-Cases, Núria; Mayeaux, Véronique; Chevrier, Joël; Comin, Fabio

    2013-01-01

    The mechanical properties of PC12 living cells have been studied at the nanoscale with a Force Feedback Microscope using two experimental approaches. Firstly, the local mechanical impedance of the cell membrane has been mapped simultaneously to the cell morphology at constant force. As the force of the interaction is gradually increased, we observed the appearance of the sub-membrane cytoskeleton. We shall compare the results obtained with this method with the measurement of other existing techniques. Secondly, a spectroscopic investigation has been performed varying the indentation of the tip in the cell membrane and consequently the force applied on it. In contrast with conventional dynamic atomic force microscopy techniques, here the small oscillation amplitude of the tip is not necessarily imposed at the cantilever first eigenmode. This allows the user to arbitrarily choose the excitation frequency in developing spectroscopic AFM techniques. The mechanical response of the PC12 cell membrane is found to be...

  9. Investigating albendazole desmotropes by solid-state NMR spectroscopy.

    Science.gov (United States)

    Chattah, Ana K; Zhang, Rongchun; Mroue, Kamal H; Pfund, Laura Y; Longhi, Marcela R; Ramamoorthy, Ayyalusamy; Garnero, Claudia

    2015-03-02

    Characterization of the molecular structure and physicochemical solid-state properties of the solid forms of pharmaceutical compounds is a key requirement for successful commercialization as potential active ingredients in drug products. These properties can ultimately have a critical effect on the solubility and bioavailability of the final drug product. Here, the desmotropy of Albendazole forms I and II was investigated at the atomic level. Ultrafast magic angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) spectroscopy, together with powder X-ray diffraction, thermal analysis, and Fourier transform infrared spectroscopy, were performed on polycrystalline samples of the two solids in order to fully characterize and distinguish the two forms. High-resolution one-dimensional (1)H, (13)C, and (15)N together with two-dimensional (1)H/(1)H single quantum-single quantum, (1)H/(1)H single quantum-double quantum, and (1)H/(13)C chemical shift correlation solid-state NMR experiments under MAS conditions were extensively used to decipher the intramolecular and intermolecular hydrogen bonding interactions present in both solid forms. These experiments enabled the unequivocal identification of the tautomers of each desmotrope. Our results also revealed that both solid forms may be described as dimeric structures, with different intermolecular hydrogen bonds connecting the tautomers in each dimer.

  10. Spectroscopic investigations on glasses, glass-ceramics and ceramics developed for nuclear waste immobilization

    Science.gov (United States)

    Caurant, D.

    2014-05-01

    Highly radioactive nuclear waste must be immobilized in very durable matrices such as glasses, glass-ceramics and ceramics in order to avoid their dispersion in the biosphere during their radioactivity decay. In this paper, we present various examples of spectroscopic investigations (optical absorption, Raman, NMR, EPR) performed to study the local structure of different kinds of such matrices used or envisaged to immobilize different kinds of radioactive wastes. A particular attention has been paid on the incorporation and the structural role of rare earths—both as fission products and actinide surrogates—in silicate glasses and glass-ceramics. An example of structural study by EPR of a ceramic (hollandite) irradiated by electrons (to simulate the effect of the β-irradiation of radioactive cesium) is also presented.

  11. Solid-State Spectroscopic Investigation of Molecular Interactions between Clofazimine and Hypromellose Phthalate in Amorphous Solid Dispersions.

    Science.gov (United States)

    Nie, Haichen; Su, Yongchao; Zhang, Mingtao; Song, Yang; Leone, Anthony; Taylor, Lynne S; Marsac, Patrick J; Li, Tonglei; Byrn, Stephen R

    2016-11-07

    It has been technically challenging to specify the detailed molecular interactions and binding motif between drugs and polymeric inhibitors in the solid state. To further investigate drug-polymer interactions from a molecular perspective, a solid dispersion of clofazimine (CLF) and hypromellose phthalate (HPMCP), with reported superior amorphous drug loading capacity and physical stability, was selected as a model system. The CLF-HPMCP interactions in solid dispersions were investigated by various solid state spectroscopic methods including ultraviolet-visible (UV-vis), infrared (IR), and solid-state NMR (ssNMR) spectroscopy. Significant spectral changes suggest that protonated CLF is ionically bonded to the carboxylate from the phthalyl substituents of HPMCP. In addition, multivariate analysis of spectra was applied to optimize the concentration of polymeric inhibitor used to formulate the amorphous solid dispersions. Most interestingly, proton transfer between CLF and carboxylic acid was experimentally investigated from 2D (1)H-(1)H homonuclear double quantum NMR spectra by utilizing the ultrafast magic-angle spinning (MAS) technique. The molecular interaction pattern and the critical bonding structure in CLF-HPMCP dispersions were further delineated by successfully correlating ssNMR findings with quantum chemistry calculations. These high-resolution investigations provide critical structural information on active pharmaceutical ingredient-polymer interaction, which can be useful for rational selection of appropriate polymeric carriers, which are effective crystallization inhibitors for amorphous drugs.

  12. Solid-state NMR spectroscopic trends for supramolecular assemblies and protein aggregates.

    Science.gov (United States)

    Linser, Rasmus

    2017-08-24

    Solid-state NMR is able to generate structural data on sample preparations that are explicitly non-crystalline. In particular, for amyloid fibril samples, which can comprise significant degrees of sample disorder, solid-state NMR has been used very successfully. But also solid-state NMR studies of other supramolecular assemblies that have resisted assessment by more standard methods are being performed with increasing ease and biological impact, many of which are briefly reviewed here. New technical trends with respect to structure calculation, protein dynamics and smaller sample amounts have reshaped the field of solid-state NMR recently. In particular, proton-detected approaches based on fast Magic-Angle Spinning (MAS) were demonstrated for crystalline systems initially. Currently, such approaches are being expanded to the above-mentioned non-crystalline targets, the characterization of which can now be pursued with sample amounts on the order of a milligram. In this Trends article, I am giving a brief overview about achievements of the last years as well as the directions that the field has been heading into and delineate some satisfactory perspectives for solid-state NMR's future striving. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. A novel Bayesian approach to quantify clinical variables and to determine their spectroscopic counterparts in 1H NMR metabonomic data

    Directory of Open Access Journals (Sweden)

    Kaski Kimmo

    2007-05-01

    Full Text Available Abstract Background A key challenge in metabonomics is to uncover quantitative associations between multidimensional spectroscopic data and biochemical measures used for disease risk assessment and diagnostics. Here we focus on clinically relevant estimation of lipoprotein lipids by 1H NMR spectroscopy of serum. Results A Bayesian methodology, with a biochemical motivation, is presented for a real 1H NMR metabonomics data set of 75 serum samples. Lipoprotein lipid concentrations were independently obtained for these samples via ultracentrifugation and specific biochemical assays. The Bayesian models were constructed by Markov chain Monte Carlo (MCMC and they showed remarkably good quantitative performance, the predictive R-values being 0.985 for the very low density lipoprotein triglycerides (VLDL-TG, 0.787 for the intermediate, 0.943 for the low, and 0.933 for the high density lipoprotein cholesterol (IDL-C, LDL-C and HDL-C, respectively. The modelling produced a kernel-based reformulation of the data, the parameters of which coincided with the well-known biochemical characteristics of the 1H NMR spectra; particularly for VLDL-TG and HDL-C the Bayesian methodology was able to clearly identify the most characteristic resonances within the heavily overlapping information in the spectra. For IDL-C and LDL-C the resulting model kernels were more complex than those for VLDL-TG and HDL-C, probably reflecting the severe overlap of the IDL and LDL resonances in the 1H NMR spectra. Conclusion The systematic use of Bayesian MCMC analysis is computationally demanding. Nevertheless, the combination of high-quality quantification and the biochemical rationale of the resulting models is expected to be useful in the field of metabonomics.

  14. Investigations of adsorption sites on oxide surfaces using solid-state NMR and TPD-IGC

    Science.gov (United States)

    Golombeck, Rebecca A.

    The number and chemical identity of reactive sites on surfaces of glass affects the processing, reliability, and lifetime of a number of important commercial products. Surface site densities, distributions, and structural identities are closely tied to the formation and processing of the glass surface, and exert a direct influence on strength and coating performance. The surface of a glass sample may vary markedly from the composition and chemistry of the bulk glass. We are taking a physicochemical approach to understanding adsorption sites on pristine multicomponent glass fibers surfaces, directly addressing the effect of processing on surface reactivity. This project aimed to understand the energy distributions of surface adsorption sites, the chemical/structural identity of those sites, and the relationship of these glasses to glass composition, thermal history, and in future work, surface coatings. We have studied the bulk and surface structure as well as the surface reactivity of the glass fibers with solid-state nuclear magnetic resonance (NMR) spectroscopy, inverse gas chromatography (IGC), and computational chemistry methods. These methods, solid-state NMR and IGC, typically require high surface area materials; however, by using probe molecules for NMR experiments or packing a column at high density for IGC measurements, lower surface area materials, such as glass fibers, can be investigated. The glasses used within this study were chosen as representative specimens of fibers with potentially different reactive sites on their surfaces. The two glass compositions were centered around a nominal E-glass, which contains very little alkali cations and mainly alkaline earth cations, and wool glass, which contains an abundance of alkali cations. The concentration of boron was varied from 0 to 8 mole % in both fiber compositions. Fibers were drawn from each composition at a variety of temperatures and draw speeds to provide a range of glass samples with varying

  15. {sup 11}B-NMR spectroscopic study on the interaction of epinephrine and p-BPA

    Energy Technology Data Exchange (ETDEWEB)

    Ichihara, K.; Yoshino, K. [Shinshu Univ., Department of Chemistry, Matsumoto, Nagano (Japan)

    2000-10-01

    It is studied that p-BPA (p-bronophenylalanine) which formed complex with catechol functional group has interaction with epinephrine by {sup 11}B-NMR. Two {sup 11}B-NMR resonance signals were observed at pH 7.0. The signal at 29.6 ppm is assigned to p-BPA and at 10.8 ppm is assigned to that of complex. We can determine complex formation constants (logK') in various pH. (author)

  16. THE P-31-NMR SPECTROSCOPIC DETERMINATION OF THE ENANTIOMERIC EXCESS OF UNPROTECTED AMINO-ACIDS

    NARCIS (Netherlands)

    HULST, R; DEVRIES, NK; FERINGA, BL

    1992-01-01

    No separation is needed! The enantiomeric excess of unprotected amino acids can be determined very reliable by P-31 NMR spectroscopy after derivatization as phosphonic amides 1. This rapid and simple analytical procedure, suitable for aqueous solutions. is also applicable for amino acid derivatives,

  17. NMR, FT-IR, FT-Raman, UV spectroscopic, HOMO-LUMO and NBO analysis of cumene by quantum computational methods

    Science.gov (United States)

    Sivaranjani, T.; Xavier, S.; Periandy, S.

    2015-03-01

    This work presents the investigation of cumene using the FT-IR, FT-Raman, NMR and UV spectra obtained through various spectroscopic techniques. The theoretical vibrational frequencies and optimized geometric parameters have been calculated by using HF and density functional theory with the hybrid methods B3LYP, B3PW91 and 6-311+G(d,p)/6-311++G(d,p) basis sets. The theoretical vibrational frequencies have been scaled and compared with the corresponding experimental data. 1H and 13C NMR spectra were recorded and chemical shifts of the molecule were compared to TMS by using the Gauge-Independent Atomic Orbital (GIAO) method. A study on the electronic and optical properties, absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, and potential energy surface (PES) is performed using HF and DFT methods. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. NLO properties related to polarizability and hyperpolarizability are also discussed.

  18. NMR methods for the investigation of structure and transport

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, Edme H. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Mechanische Verfahrenstechnik und Mechanik

    2012-07-01

    Extensive derivations of required fundamental relations for readers with engineering background New applications based on MRI, PGSE-NMR, and low-field NMR New concepts in quantitative data evaluation and image analysis Methods of nuclear magnetic resonance (NMR) are increasingly applied in engineering sciences. The book summarizes research in the field of chemical and process engineering performed at the Karlsruhe Institute of Technology (KIT). Fundamentals of the methods are exposed for readers with an engineering background. Applications cover the fields of mechanical process engineering (filtration, solid-liquid separation, powder mixing, rheometry), chemical process engineering (trickle-bed reactor, ceramic sponges), bioprocess engineering (biofilm growth), and food process engineering (microwave heating, emulsions). Magnetic Resonance Imaging (MRI) as well as low-field NMR are covered with notes on hardware. Emphasis is placed on quantitative data analysis and image processing. (orig.)

  19. UV/vis, 1H, and 13C NMR spectroscopic studies to determine mangiferin p Ka values

    Science.gov (United States)

    Gómez-Zaleta, Berenice; Ramírez-Silva, María Teresa; Gutiérrez, Atilano; González-Vergara, Enrique; Güizado-Rodríguez, Marisol; Rojas-Hernández, Alberto

    2006-07-01

    The acid constants of mangiferin (a natural xanthonoid) in aqueous solution were determined through an UV/vis spectroscopic study employing the SQUAD program as a computational tool. A NMR study complements the p Ka values assignment and evidences a H-bridge presence on 1-C. The chemical model used was consistent with the experimental data obtained. The p Ka values determined with this procedure were as follows: H 4(MGF) = H 3(MGF) - + H +, pK(6-H) = 6.52 ± 0.06; H 3(MGF) - = H 2(MGF) 2- + H +, pK(3-H) = 7.97 ± 0.06; H 2(MGF) 2- = H(MGF) 3- + H +, pK(7-H) = 9.44 ± 0.04; H(MGF) 3- = (MGF) 4- + H +, pK(1-H) = 12.10 ± 0.01; where it has been considered mangiferin C 19H 18O 11 as H 4(MGF). Mangiferin UV/vis spectral behavior, stability study in aqueous solution as well as NMR spectroscopy studies: one-dimensional 1H, 13C, 2D correlated 1H/ 13C performed by (g)-HSQC and (g)-HMBC methods; are also presented. p Ka values determination of H 4(MGF) in aqueous solution is a necessary contribution to subsequent pharmacokinetic study, and a step towards the understanding of its biological effects.

  20. ESR spectroscopic investigations of the radiation-grafting of fluoropolymers

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, G.; Roduner, E. [University of Stuttgart (Germany); Brack, H.P.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    ESR spectroscopic investigations have clarified the influence of several preparative parameters on the reaction rates and yields obtained in the radiation-grafting method used at PSI to prepare proton-conducting polymer membranes. At a given irradiation dose, a higher concentration of reactive radical sites was detected in ETFE films than in FEP films. This higher concentration explains the higher grafting levels and rates of the ETFE films found in our previous grafting experiments. Taken together, the in-situ ESR experiments and grafting experiments show that the rates of disappearance of radical species and grafting rates and final grafting levels depend strongly on the reaction temperature and the oxygen content of the system. Average grafted chain lengths were calculated to contain about 1,000 monomer units. (author) 2 figs., 4 refs.

  1. X-ray photoelectron spectroscopic investigation of conducting polymer blends.

    Science.gov (United States)

    Süzer, S; Toppare, L; Hallam, K R; Allen, G C

    1996-06-01

    Electrochemically prepared films of conducting polymers of polypyrrole and polythiophene and their blends with polyamide have been investigated by X-ray photoelectron spectroscopy. In the N1s region of the spectra of films containing polypyrrole the peak corresponding to N(+) at 402.0 eV is separated from that of neutral N. The intensity of the N(+) peak can be correlated with the electrical conductivity of the films and the spectroscopically derived ratio of F/N(+) is close to 4 indicating that one BF(-)(4) dopant ion is incorporated for every oxidized nitrogen center. In the spectra of films of polythiophene and its blends peaks corresponding to S and S(+) can not be resolved but again the F/C ratio correlates with the electrical conductivity.

  2. Spectroscopic investigation on porphyrins nano-assemblies onto gold nanorods

    Science.gov (United States)

    Trapani, Mariachiara; De Luca, Giovanna; Romeo, Andrea; Castriciano, Maria Angela; Scolaro, Luigi Monsù

    2017-02-01

    The interaction between gold nanorods (Au NRs), synthesized by a conventional seeded growth protocol, and the anionic tetrakis-(4-sulfonatophenyl)porphyrin (TPPS4) has been investigated through various spectroscopic techniques. At neutral pH, the formation of H-aggregates and the inclusion of porphyrin monomers in CTAB micelles covering the nanorods have been evidenced. Under mild acidic conditions (pH = 3) a nano-hybrid assembly of porphyrin J-aggregates and Au NRs has been revealed. For the sake of comparison, Cu(II) and Zn(II) metal porphyrin derivatives as well as a cationic porphyrin have been studied in the same experimental conditions, showing that: i) CuTPPS4 forms porphyrin H-dimers onto the Au NRs; ii) ZnTPPS4 undergoes to demetallation, followed by acidification of the central core and eventually aggregation onto Au NRs; iii) cationic porphyrin does not interact with Au NRs.

  3. Spectroscopic Investigations of the Photophysics of Cryptophyte Light-Harvesting

    Science.gov (United States)

    Dinshaw, Rayomond

    The biological significance of photosynthesis is indisputable as it is necessary for nearly all life on earth. Photosynthesis provides chemical energy for plants, algae, and bacteria, while heterotrophic organisms rely on these species as their ultimate food source. The initial step in photosynthesis requires the absorption of sunlight to create electronic excitations. Light-harvesting proteins play the functional role of capturing solar radiation and transferring the resulting excitation to the reaction centers where it is used to carry out the chemical reactions of photosynthesis. Despite the wide variety of light-harvesting protein structures and arrangements, most light-harvesting proteins are able to utilize the captured solar energy for charge separation with near perfect quantum efficiency.1 This thesis will focus on understanding the energy transfer dynamics and photophysics of a specific subset of light-harvesting antennae known as phycobiliproteins. These proteins are extracted from cryptophyte algae and are investigated using steady-state and ultrafast spectroscopic techniques.

  4. Infrared and MAS NMR Spectroscopic Studies of Al18B4O33

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The IR spectrum and 11B and 27Al MAS NMR spectra of Al18B4O33 are presented and discussed in relation to the possible existence of boron atoms substituting for aluminum atoms. TheIR spectrum shows that the strong vibrations of the BO3 groups are present in the 1 500~1 200em-1 region, and very weak bands of BO4 units are present in the region from 1 000 to 1 100cm-1. 11B MAS NMR spectrum indicates that the strong signal for BO3 units appears in the region from δ +5 to δ +20, and the very weak signal for BO4 units is at about δ-1, while 27AlMAS NMR spectrum shows five peaks at about δ +62, +42. 1, +14,-4.7 and-6.4, originating from AlO4, AlO4, A1O5, AlO6 and AlO6, respectively. These results reveal that there areminor BO4 units in Al18B4O33, indicating that a small amount of B atoms substitute for Al atomsin the 4-fold coordination.

  5. Evaluation of transformer insulating oil quality using NIR, fluorescence, and NMR spectroscopic data fusion.

    Science.gov (United States)

    Godinho, Mariana S; Blanco, Marcos R; Gambarra Neto, Francisco F; Lião, Luciano M; Sena, Marcelo M; Tauler, Romà; de Oliveira, Anselmo E

    2014-11-01

    Power transformers are essential components in electrical energy distribution. One of their most important parts is the insulation system, consisting of Kraft paper immersed in insulating oil. Interfacial tension and color are major parameters used for assessing oil quality and the system׳s degradation. This work proposes the use of near infrared (NIR), molecular fluorescence, and (1)H nuclear magnetic resonance (NMR) spectroscopy methods combined with chemometric multivariate calibration methods (Partial Least Squares - PLS) to predict interfacial tension and color in insulating mineral oil samples. Interfacial tension and color were also determined using tensiometry and colorimetry as standard reference methods, respectively. The best PLS model was obtained when NIR, fluorescence, and NMR data were combined (data fusion), demonstrating synergy among them. An optimal PLS model was calculated using the selected group of variables according to their importance on PLS projections (VIP). The root mean square errors of prediction (RMSEP) values of 2.9 mN m(-1) and 0.3 were estimated for interfacial tension and color, respectively. Mean relative standard deviations of 1.5% for interfacial tension and 6% for color were registered, meeting quality control requirements set by electrical energy companies. The methods proposed in this work are rapid and simple, showing great advantages over traditional approaches, which are slow and environmentally unfriendly due to chemical waste generation.

  6. Microscopic and spectroscopic investigation of an explanted opacified intraocular lens

    Energy Technology Data Exchange (ETDEWEB)

    Simon, V., E-mail: viosimon@phys.ubbcluj.ro [Babeş-Bolyai University, Faculty of Physics and Interdisciplinary Research Institute on Bio-Nano-Sciences, 400084 Cluj-Napoca (Romania); Radu, T.; Vulpoi, A. [Babeş-Bolyai University, Faculty of Physics and Interdisciplinary Research Institute on Bio-Nano-Sciences, 400084 Cluj-Napoca (Romania); Rosca, C. [Optilens Clinic of Ophthalmology, 400604 Cluj-Napoca (Romania); Eniu, D. [Iuliu Haţieganu University of Medicine and Pharmacy, Department of Molecular Sciences, 400349 Cluj-Napoca (Romania)

    2015-01-15

    Highlights: • Changes on intraocular lens (IOL) surface after implantation. • Partial opacification of IOL central area. • Elemental composition on IOL surface prior to and after implantation. • First XPS depth profiling examination of the opacifying deposits. • Cell-mediated hydroxyapatite structuring. - Abstract: The investigated polymethylmethacrylate intraocular lens explanted an year after implantation presented a fine granularity consisting of ring-like grains of about 15 μm in diameter. In order to evidence the changes occurred on intraocular lens relative to morphology, elemental composition and atomic environments, microscopic and spectroscopic analyses were carried out using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), energy-dispersive X-ray (EDS), and X-ray photoelectron (XPS) spectroscopies. The results revealed that the grains contain hydroxyapatite mineral phase. A protein layer covers the lens both in opacified and transparent zones. The amide II band is like in basal epithelial cells. The shape and size of the grains, and the XPS depth profiling results indicate the possibility of a cell-mediated process involving lens epithelial cells which fagocitated apoptotic epithelial cells, and in which the debris derived from cell necrosis were calcified. To the best of our knowledge, this is the first investigation on explanted intraocular lenses using XPS depth profiling in order to examine the inside of the opacifying deposits.

  7. Microscopic and spectroscopic investigation of an explanted opacified intraocular lens

    Science.gov (United States)

    Simon, V.; Radu, T.; Vulpoi, A.; Rosca, C.; Eniu, D.

    2015-01-01

    The investigated polymethylmethacrylate intraocular lens explanted an year after implantation presented a fine granularity consisting of ring-like grains of about 15 μm in diameter. In order to evidence the changes occurred on intraocular lens relative to morphology, elemental composition and atomic environments, microscopic and spectroscopic analyses were carried out using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), energy-dispersive X-ray (EDS), and X-ray photoelectron (XPS) spectroscopies. The results revealed that the grains contain hydroxyapatite mineral phase. A protein layer covers the lens both in opacified and transparent zones. The amide II band is like in basal epithelial cells. The shape and size of the grains, and the XPS depth profiling results indicate the possibility of a cell-mediated process involving lens epithelial cells which fagocitated apoptotic epithelial cells, and in which the debris derived from cell necrosis were calcified. To the best of our knowledge, this is the first investigation on explanted intraocular lenses using XPS depth profiling in order to examine the inside of the opacifying deposits.

  8. High Energy Solar Spectroscopic Imager (HESSI) Team Investigations

    Science.gov (United States)

    Emslie, A. Gordon

    1998-01-01

    This report covers activities on the above grant for the period through the end of September 1997. The work originally proposed to be performed under a three-year award was converted at that time to a two-year award for the remainder of the period, and is now funded under award NAGS-4027 through Goddard Space Flight Center. The P.I. is a co-investigator on the High Energy Solar Spectroscopic Imager (HESSI) team, selected as a Small-Class Explorer (SNMX) mission in 1997. He has also been a participant in the Space Physics Roadmap Planning Group. Our research has been strongly influenced by the NASA mission opportunities related to these activities. The report is subdivided into four sections, each dealing with a different aspect of our research within this guiding theme. Personnel involved in this research at UAH include the P.I. and graduate students Michele Montgomery and Amy Winebarger. Much of the work has been carried out in collaboration with investigators at other institutions, as detailed below. Attachment: Laser wakefield acceleration and astrophysical applications.

  9. Spectroscopic Investigation of Ce(3+) Doped Fluoride Crystals

    Science.gov (United States)

    Reinhart, Donald H.; Armagan, Guzin; Marsh, Waverly; Barnes, James; Chai, B. H. T.

    1995-01-01

    Doping of the trivalent rare-earth cerium ion into fluoride crystals is of interest in producing turnable ultra-violet solid state lasers. These lasers are desirable for many applications in medicine, industry, and scientific research, including remote sensing. High absorption and stimulated emission cross sections of the dipole allowed 4f-5d transitions show promise in cerium as a laser ion in crystals. Several research groups have already reported the observation of stimulated emission of cerium in LiYF4, LiSrAlF6, and LiCaAlF6. However, the color center formation in the crystals due to the excited state absorption of ultra-violet pump light adds difficulty to achieving laser action. We have investigated the spectroscopic properties of cerium such as absorption and emission spectra, and lifetimes in four different fluoride crystals, including LiCaAlF6, LiSrAlF6, KyF4 and LiYF4. We have derived the polarized absorption and stimulated emission cross sections from transmission and fluorescence emission measurements for each of the host crystals. we have measured the lifetime of the lowest 5d level; moreover, investigated the temperature dependence of this lifetime and color center formation. Our results on absorption and stimulated emission cross sections for LiCaAlF6 and LiSrAlF6 are similar to the results already published.

  10. NMR investigation of boron impurities in refined metallurgical grade silicon

    Energy Technology Data Exchange (ETDEWEB)

    Grafe, Hans-Joachim; Loeser, Wolfgang; Schmitz, Steffen; Sakaliyska, Miroslava [Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany); Wurmehl, Sabine [Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany); Institute for Solid State Physics, Technische Universitaet Dresden (Germany); Eisert, Stefan; Reichenbach, Birk; Mueller, Tim [Adensis GmbH, Dresden (Germany); Acker, Joerg; Rietig, Anja; Ducke, Jana [Department of Chemistry, Faculty for Natural Sciences, Brandenburg Technical University Cottbus-Senftenberg, Senftenberg (Germany)

    2015-09-15

    The nuclear magnetic resonance (NMR) method was applied for tracking boron impurities in the refining process of metallurgical grade (MG) silicon. From the NMR signal of the {sup 11}B isotope at an operating temperature 4.2 K, the boron concentration can be estimated down to the order of 1-10 wppm B. After melting and resolidification of MG-Si alloyed with Ca and Ti, a major fraction of B impurities remains in the Si solid solution as inferred from the characteristic NMR frequency. The alloying element Ti does not form substantial fractions of TiB{sub 2}. Acid leaching of crushed powders of MG-Si alloyed with Ca and Ti can diminish the initial impurity content of B suggesting its accumulation in the grain boundary phases. NMR signals of TiB{sub 2} at 4.2 K and room temperature (RT), and of poly-Si with different B doping at 4.2 K. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. PFG NMR investigations of TPA-TMA-silica mixtures.

    Science.gov (United States)

    Li, Xiang; Shantz, Daniel F

    2011-04-05

    Pulsed-field gradient (PFG) NMR studies of tetrapropylammonium (TPA)-tetramethylammonium (TMA)-silica mixtures are presented, and the effect of TMA as a foreign ion on the TPA-silica nanoparticle interactions before and after heating has been studied. Dynamic light scattering (DLS) results suggest that silica nanoparticles in these TPA-TMA systems grow via a ripening mechanism for the first 24 h of heating. PFG NMR of mixtures before heating show that TMA can effectively displace TPA from the nanoparticle surface. The binding isotherms of TPA at room temperature obtained via PFG NMR can be described by Langmuir isotherms, and indicate a decrease in the adsorbed amount of TPA upon addition of TMA. PFG NMR also shows a systematic increase in the self-diffusion coefficient of TPA in both the mixed TPA-TMA systems and pure TPA systems with heating time, indicating an increased amount of TPA in solution upon heating. By contrast, a much smaller amount of TMA is observed to desorb from the nanoparticles upon heating. These results point to the desorption of TPA from the nanoparticles being a kinetically controlled process. The apparent desorption rate constants were calculated from fitting the desorbed amount of TPA with time via a pseudosecond-order kinetic model. This analysis show the rate of TPA desorption in TPA-TMA mixtures increases with increasing TMA content, whereas for pure TPA mixtures the rate of TPA desorption is much less sensitive to the TPA concentration.

  12. 15N NMR Spectroscopic Study on Nitrogen Formsin1mmHumic Substances of Soils

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nitrogen forms of humic substances from a subalpine meadow soil, alateritic red soil and a weathered coal and the effect of acidhydrolysis on N structures of soil humic substances were studied byusing {15N cross-polarization magic angle spinning nuclearmagnetic resonance (CPMAS NMR) spectroscopy. Of the detectable15N-signal intensity in the spectra of soil humic substances71%79% may be attributed to amide groups, 10%18%to aromatic/aliphatic amines and 6%11% to indole- andpyrrole-like N. Whereas in the spectrum of the fulvic acid fromweathered coal 46%, at least, of the total 15N-signalintensity might be assigned to pyrrole-like N, 14% toaromatic/aliphatic amines, and the remaining intensities could not beassigned with certainty. Data on nonhydrolyzable residue ofprotein-sugar mixture and a 15N-labelled soil fulvic acidconfirm the formation of nonhydrolyzable heterocyclic N during acidhydrolysis.

  13. Spectroscopic and magnetic investigation of NiCo nanoferrites

    Energy Technology Data Exchange (ETDEWEB)

    Maqsood, Asghari, E-mail: tpl.qau@usa.net [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad (Pakistan); Khan, Kishwar, E-mail: kishwar.nust@gmail.com [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12, Islamabad (Pakistan); Anis-ur-Rehman, M.; Malik, M.A. [Applied Thermal Physics Laboratory, COMSATS Institute of Information Technology, Islamabad (Pakistan)

    2011-07-07

    Highlights: > Spinel ferrite is a special kind of cubic structure. > These ferrites are of great importance in electronics and communication industry. > These should be useful for high frequency applications. - Abstract: Spectroscopic and magnetic characterization of Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} (0.0 {<=} x {<=} 0.5) nanoparticles is presented. The infrared spectra are measured in the frequency range 700-350 cm{sup -1}. Two prominent bands are observed, low frequency band at about 400 cm{sup -1} and high frequency band at about 600 cm{sup -1} assigned to octahedral and tetrahedral sites, respectively. The force constants K{sub o} and K{sub t} corresponding to octahedral and tetrahedral sites, respectively are also calculated from FTIR spectra. The effect of co-concentration on the magnetic properties has been investigated using a vibrating sample magnetometer (VSM). After appropriate treatments, it is found that both magnetic saturation (M{sub s}) and coercivities (H{sub c}) increase with co-concentration.

  14. Radiation Effects on Polypropylene Carbon Nanofibers Composites: Spectroscopic Investigations

    Science.gov (United States)

    Hamilton, John; Mion, Thomas; Cristian Chipara, Alin; Ibrahim, Elamin I.; Lozano, Karen; Tidrow, Steven; Magdalena Chipara, Dorina; Chipara, Mircea

    2010-03-01

    Dispersion of carbon nanostructures within polymeric matrices affects their physical and chemical properties (increased Young modulus, improved thermal stability, faster crystallization rates, higher equilibrium degree of crystallinity, modified glass, melting, and crystallization temperatures, enhanced thermal and electrical conductivity). Nevertheless, little is known about the radiation stability of such nanocomposites. The research is focused on spectroscopic investigations of radiation-induced modifications in isotactic polypropylene (iPP)-vapor grown nanofiber (VGCNF) composites. VGCNF were dispersed within iPP by extrusion at 180^oC. Composites containing various amounts of VGCNFs ranging from 0 to 20 % wt. were prepared and subjected to gamma irradiation, at room temperature, at various integral doses (10 MGy, 20 MGy, and 30 MGy). Raman spectroscopy, ATR, and WAXS were used to assess the radiation-induced modifications in these nanocomposites. Acknowledgements: This research was supported by the Welch Foundation (Department of Chemistry at UTPA), by Air Force Research Laboratory (FA8650-07-2-5061) and by US Army Research Laboratory/Office (W911NF-08-1-0353).

  15. NMR methods for the investigation of structure and transport

    CERN Document Server

    Hardy, Edme H

    2011-01-01

    Methods of nuclear magnetic resonance (NMR) are increasingly applied in engineering sciences. The book summarizes research in the field of chemical and process engineering performed at the Karlsruhe Institute of Technology (KIT). Fundamentals of the methods are exposed for readers with an engineering background. Applications cover the fields of mechanical process engineering (filtration, solid-liquid separation, powder mixing, rheometry), chemical process engineering (trickle-bed reactor, ceramic sponges), bioprocess engineering (biofilm growth), and food process engineering (microwave heating

  16. Investigation of the energy barrier to the rotation of amide CN bonds in ACE inhibitors by NMR, dynamic HPLC and DFT.

    Science.gov (United States)

    Bouabdallah, S; Ben Dhia, M T; Driss, M R; Touil, S

    2016-09-01

    The isomerizations of Enalapril, Perindopril, Enalaprilat and Lisinopril have been investigated using NMR spectroscopic, dynamic chromatographic, unified equation and DFT theoretical calculations. The thermodynamic parameters (ΔH, ΔS and ΔG) were determined by varying the temperature in the NMR experiments. At the coalescence temperature, we can evaluate the isomerization barrier to the rotation (ΔG(≠)) around the amide bond. Using dynamics chromatography and an unified equation introduced by Trap, we can determine isomerization rate constants and Gibbs activation energies. Molecular mechanics calculations also provided evidence for the presence of low energy conformers for the ACE due to restricted amide rotation. With the value of barriers (ΔE) between them of the order of (20kJmol(-1)), which is in agreement with the dynamic NMR results and DFT calculations.

  17. 15N NMR Spectroscopic Study on Nitrogen Forms in Humic Substances of Soils

    Institute of Scientific and Technical Information of China (English)

    WENQIXAIO; ZHUOSUNENG; 等

    2001-01-01

    Nitrogen forms of humic substances from a subalpine meadow soil,a lateritic red soil and a weathered cola and the effect of acid hydrolysis on N structures of soil humic substances were studied by using 15N cross-polarization magic angle spinning nuclear magnetic resonance(CPMAS NMR) spectroscopy,Of the detectable 15N-signal intensity in the spectra of soil humic substances 71%-79% may be attributed to amide groups ,10%-18% to aromatic/aliphatic amines and 6%-11% to indole-and pyrrole-like N.Whereas in the spectrum of the fulvic acid from weathered coal 46%,at least,of the total 15N-signal intensity might be assigned to pyrrole-like N,14% to aromatic/aliphatic amines,and the reamining intensities could not be assigned with certainty,Data on nonhydrolyzable reside of protein-sugar mixture and a 15N-labelled soil fulvic acid confirm the formation of nonhydrolyzable heterocyclic N during acid hydrolysis.

  18. Spectroscopic characteristic (FT-IR, FT-Raman, UV, 1H and 13C NMR), theoretical calculations and biological activity of alkali metal homovanillates

    Science.gov (United States)

    Samsonowicz, M.; Kowczyk-Sadowy, M.; Piekut, J.; Regulska, E.; Lewandowski, W.

    2016-04-01

    The structural and vibrational properties of lithium, sodium, potassium, rubidium and cesium homovanillates were investigated in this paper. Supplementary molecular spectroscopic methods such as: FT-IR, FT-Raman in the solid phase, UV and NMR were applied. The geometrical parameters and energies were obtained from density functional theory (DFT) B3LYP method with 6-311++G** basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned. Geometric and magnetic aromaticity indices, atomic charges, dipole moments, HOMO and LUMO energies were also calculated. The microbial activity of investigated compounds was tested against Bacillus subtilis (BS), Pseudomonas aeruginosa (PA), Escherichia coli (EC), Staphylococcus aureus (SA) and Candida albicans (CA). The relationship between the molecular structure of tested compounds and their antimicrobial activity was studied. The principal component analysis (PCA) was applied in order to attempt to distinguish the biological activities of these compounds according to selected band wavenumbers. Obtained data show that the FT-IR spectra can be a rapid and reliable analytical tool and a good source of information for the quantitative analysis of the relationship between the molecular structure of the compound and its biological activity.

  19. Binding modes of environmental endocrine disruptors to human serum albumin: insights from STD-NMR, ITC, spectroscopic and molecular docking studies.

    Science.gov (United States)

    Yang, Hongqin; Huang, Yanmei; Liu, Jiuyang; Tang, Peixiao; Sun, Qiaomei; Xiong, Xinnuo; Tang, Bin; He, Jiawei; Li, Hui

    2017-09-11

    Given that bisphenols have an endocrine-disrupting effect on human bodies, thoroughly exposing their potential effects at the molecular level is important. Saturation transfer difference (STD) NMR-based binding studies were performed to investigate the binding potential of two bisphenol representatives, namely, bisphenol B (BPB) and bisphenol E (BPE), toward human serum albumin (HSA). The relative STD (%) suggested that BPB and BPE show similar binding modes and orientations, in which the phenolic rings were spatially close to HSA binding site. ITC analysis results showed that BPB and BPE were bound to HSA with moderately strong binding affinity through electrostatic interactions and hydrogen bonds. The order of binding affinity of HSA for two test bisphenols is as follows: BPE > BPB. The results of fluorescence competitive experiments using 5-dimethylaminonaphthalene-1-sulfonamide and dansylsarcosine as competitors, combined with molecular docking indicated that both bisphenols are prone to attach to the binding site II in HSA. Spectroscopic results (FT-IR, CD, synchronous and 3D fluorescence spectra) showed that BPB/BPE induces different degrees of microenvironmental and conformational changes to HSA.

  20. (17)O NMR and Raman Spectroscopies of Green Tea Infusion with Nanomaterial to Investigate Their Properties.

    Science.gov (United States)

    Zhou, Changyan; Zhang, Huiping; Yan, Ying; Zhang, Xinya

    2016-09-01

    (17)O NMR and Raman spectrograms of green tea infusions with nanomaterial were investigated. Different green tea infusions were prepared by steeping tea powder with different concentrations of nanomaterial aqueous solution. The tea infusions were tested with (17)O NMR and Raman spectroscopies. The (17)O NMR results showed that line width increased to 90 in the tea infusions after nanomaterial was added as a result of the effects of the self-association of Ca(2+) and tea polyphenol. The results of Raman spectroscopy showed that, in tea infusions, the enhancement of C─C and C─O stretching vibrations suggest an increase in the number of effective components in water.

  1. Characterization of Fen-Daqu Through Multivariate Statistical Analysis of H-1 NMR Spectroscopic Data

    NARCIS (Netherlands)

    Van-Diep, L.; Zheng, X.; Ma, K.; Chen, J.Y.; Han, B.Z.; Nout, M.J.R.

    2011-01-01

    J. Inst. Brew. 117(4), 516-522, 2011 Fen liquor is typical of Chinese light-flavour liquor (alcoholic spirit), which is fermented from sorghum with Fen-Daqu powder. Fen-Daqu is a saccharifying agent and fermentation starter in this fermentation process and in Fen traditional vinegar. To investigate

  2. Characterization of Fen-Daqu Through Multivariate Statistical Analysis of H-1 NMR Spectroscopic Data

    NARCIS (Netherlands)

    Van-Diep, L.; Zheng, X.; Ma, K.; Chen, J.Y.; Han, B.Z.; Nout, M.J.R.

    2011-01-01

    J. Inst. Brew. 117(4), 516-522, 2011 Fen liquor is typical of Chinese light-flavour liquor (alcoholic spirit), which is fermented from sorghum with Fen-Daqu powder. Fen-Daqu is a saccharifying agent and fermentation starter in this fermentation process and in Fen traditional vinegar. To investigate

  3. Investigating sorption on iron-oxyhydroxide soil minerals by solid-state NMR spectroscopy: a 6Li MAS NMR study of adsorption and absorption on goethite

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Paik, Younkee; Julmis, Keinia;

    2005-01-01

    High-resolution 2H MAS NMR spectra can be obtained for nanocrystalline particles of goethite (alpha-FeOOH, particle size approximately 4-10 nm) at room temperature, facilitating NMR studies of sorption under environmentally relevant conditions. Li sorption was investigated as a function of pH, th...

  4. Efficient ultrasound-assisted synthesis, spectroscopic, crystallographic and biological investigations of pyrazole-appended quinolinyl chalcones

    Science.gov (United States)

    Prasath, R.; Bhavana, P.; Sarveswari, S.; Ng, Seik Weng; Tiekink, Edward R. T.

    2015-02-01

    Two series of new quinolinyl chalcones containing a pyrazole group, 3a-f and 4a-r, have been synthesized by Claisen-Schmidt condensation of the derivatives of 2-methyl-3-acetylquinoline with either substituted 1,3-diphenyl-1H-pyrazole-4-carbaldehyde or 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde in 76-93% yield under ultrasonic method. The compounds were characterized using IR, 1H NMR and ESI-MS spectroscopic methods and, for representative compounds, by X-ray crystallography. An E-configuration about the Cdbnd C ethylene bond has been established via 1H NMR spectroscopy and X-ray crystallography. These compounds show promising anti-microbial properties, with 4a and 3e being the most potent against bacterial and fungal strains, respectively and the methoxy substituted compounds showed moderate anti-oxidant activity.

  5. Structure analysis and spectroscopic characterization of 2-Fluoro-3-Methylpyridine-5-Boronic Acid with experimental (FT-IR, Raman, NMR and XRD) techniques and quantum chemical calculations

    Science.gov (United States)

    Alver, Özgür; Dikmen, Gökhan

    2016-03-01

    Possible stable conformers, geometrical molecular structures, vibrational properties as well as band assignments, nuclear magnetic shielding tensors of 2-Fluoro-3-Methylpyridine-5-Boronic Acid (2F3MP5BA) were studied experimentally and theoretically using FT-IR, Raman, (CP/MAS) NMR and XRD spectroscopic methods. FT-IR and Raman spectra were evaluated in the region of 3500-400 cm-1, and 3200-400 cm-1, respectively. The optimized geometric structures, vibrational wavenumbers and nuclear magnetic shielding tensors were examined using Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. 1H, 13C NMR chemical shifts were calculated using the gauge invariant atomic orbital (GIAO) method. 1H, 13C, APT and HETCOR NMR experiments of title molecule were carried out in DMSO solution. 13C CP/MAS NMR measurement was done with 4 mm zirconium rotor and glycine was used as an external standard. Single crystal of 2F3MP5BA was also prepared for XRD measurements. Assignments of vibrational wavenumbers were also strengthened by calculating the total energy distribution (TED) values using scaled quantum mechanical (SQM) method.

  6. Confinement in single walled carbon nanotubes investigated by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Battie, Y., E-mail: yann.battie@univ-lorraine.fr [LCP-A2MC, Institut Jean Barriol, Université de Lorraine, 1 Bd Arago, 57070 Metz (France); Jamon, D. [Université de Lyon, Université Jean Monnet, EA 3523, Laboratoire Télécom Claude Chappe, 25 rue du Dr Rémy Annino, 42000 Saint Etienne (France); Lauret, J.S. [Laboratoire Aimé Cotton, UPR 3321, ENS Cachan, 94245 Cachan (France); Gu, Q.; Gicquel-Guézo, M. [FOTON, UMR 6082, INSA, Avenue des Buttes de Coësmes, 35043 Rennes (France); En Naciri, A. [LCP-A2MC, Institut Jean Barriol, Université de Lorraine, 1 Bd Arago, 57070 Metz (France); Loiseau, A. [Laboratoire d' étude des microstructures, ONERA-CNRS UMR 104, 29 Av. de la Division Leclerc, 92322 Chatillon (France)

    2014-11-28

    Thick films of single walled carbon nanotubes (SWCNTs) with different diameter and chirality distributions are characterized by combining transmission electron microscopy and spectroscopic ellipsometry. The dependence of the dielectric function with the increase of the SWCNT diameter occurs with a drastic redshift of the S{sub 11}, S{sub 22} and M{sub 11} transition energies. The transfer integral parameter γ{sub 0} of SWCNT is also evaluated and analyzed. We demonstrate that parts of the optical properties of SWCNTs are attributed to a one dimensional confinement effect. - Highlights: • Ellipsometric measurements are performed on carbon nanotube thick films. • The complex dielectric functions of conventional carbon nanotubes are given. • Confinement effects explain the variations of dielectric function of nanotubes.

  7. Stereochemical investigation of selegiline HCl with /sup 1/H and /sup 13/C NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Podanyi, B. (CHINOIN Gyogyszer- es Vegyeszeti Termekek Gyara, Budapest (Hungary))

    1982-12-01

    Selegiline HCl, the bioactive substance of the antiparkinsonic medicine, JUMEX was investigated by NMR spectroscopy. The dominant conformer was determined. Optically active shift-reagent was used for the determination of optical purity. The /sup 13/C spectrum was analyzed, and molecular dynamics was investigated at different temperatures.

  8. Spectroscopic ellipsometric and Raman spectroscopic investigations of pulsed laser treated glassy carbon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Csontos, J., E-mail: jcsontos@titan.physx.u-szeged.hu [University of Szeged, Department of Optics and Quantum Electronics, Dóm tér 9, H-6720 Szeged (Hungary); Pápa, Z.; Gárdián, A. [University of Szeged, Department of Optics and Quantum Electronics, Dóm tér 9, H-6720 Szeged (Hungary); Füle, M. [University of Szeged, Department of Experimental Physics, Dóm tér 9, H-6720 Szeged (Hungary); Budai, J. [University of Szeged, Department of Optics and Quantum Electronics, Dóm tér 9, H-6720 Szeged (Hungary); Toth, Z. [University of Szeged, Department of Optics and Quantum Electronics, Dóm tér 9, H-6720 Szeged (Hungary); University of Szeged, Department of Oral Biology and Experimental Dental Research, Tisza Lajos krt. 64, H-6720 Szeged (Hungary)

    2015-05-01

    Highlights: • Laser treatment modifies the top layer of glassy carbon as shown by ellipsometry. • Raman signal is composed from signals of the layer and the glassy carbon substrate. • Using volumetric fluence allows to compare the effects of different lasers. • Melting effects of glassy carbon was observed in case of Nd:YAG laser treatment. - Abstract: In this study spectroscopic ellipsometry (SE) and Raman spectroscopy are applied to study structural modification of glassy carbon, due to high intensity laser ablation. Two KrF lasers with different pulse durations (480 fs and 18 ns), an ArF (20 ns), and a frequency doubled Nd:YAG laser (8 ns) were applied to irradiate the surface of glassy carbon targets. The main characteristics of the different laser treatments are compared by introducing the volumetric fluence which takes into account the different absorption values at different wavelengths. SE showed the appearance of a modified layer on the ablated surfaces. In the case of the ns lasers the thickness of this layer was in the range of 10–60 nm, while in the case of fs laser it was less than 20 nm. In all cases the average refractive index (n) of the modified layers slightly decreased compared to the refractive index of glassy carbon. Increase in extinction coefficient (k) was observed in the cases of ArF and fs KrF laser treatment, while the k values decreased significantly in the cases of nanosecond pulse duration KrF and Nd:YAG laser treatments. In the Raman spectra of the ablated areas the characteristic D and G peaks were widened due to appearance of an amorphous phase. Both Raman spectroscopy and SE indicate that the irradiated areas show carbon nanoparticle formation in all cases.

  9. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, N.M.S.S.V.N. College, Madurai-625 019, Tamil Nadu (India)

    2016-05-06

    The pristine multi-walled carbon nanotubes (MWCNTs) were oxidized by the ultrasonication process. The oxidized MWCNTs were characterized by the X-ray diffraction (XRD), ultraviolet–visible (UV-Vis) and Fourier transform -Raman (FT-Raman) spectroscopic techniques. The XRD analysis confirms that the oxidized MWCNTs exist in a hexagonal structure and the sharp XRD peak corresponds to the (002) Bragg’s reflection plane, which indicates that the MWCNTs have higher crystalline nature. The UV-Vis analysis confirms that the MWCNTs functionalized with the carboxylic acid. The red shift was observed corresponds to the D band in the Raman spectrum, which reveals that the reduced disordered graphitic structure of oxidized MWCNTs. The strong Raman peak was observed at 2563 cm{sup -1} corresponds to the overtone of the D band, which is the characteristic vibrational mode of oxidized MWCNTs. The carboxylic acid functionalization of MWCNTs enhances the dispersibility, which paves the way for potential applications in the field of biosensors and targeted drug delivery.

  10. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    Science.gov (United States)

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    The pristine multi-walled carbon nanotubes (MWCNTs) were oxidized by the ultrasonication process. The oxidized MWCNTs were characterized by the X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) and Fourier transform -Raman (FT-Raman) spectroscopic techniques. The XRD analysis confirms that the oxidized MWCNTs exist in a hexagonal structure and the sharp XRD peak corresponds to the (002) Bragg's reflection plane, which indicates that the MWCNTs have higher crystalline nature. The UV-Vis analysis confirms that the MWCNTs functionalized with the carboxylic acid. The red shift was observed corresponds to the D band in the Raman spectrum, which reveals that the reduced disordered graphitic structure of oxidized MWCNTs. The strong Raman peak was observed at 2563 cm-1 corresponds to the overtone of the D band, which is the characteristic vibrational mode of oxidized MWCNTs. The carboxylic acid functionalization of MWCNTs enhances the dispersibility, which paves the way for potential applications in the field of biosensors and targeted drug delivery.

  11. Structural investigation of proapoptotic peptide by CD and NMR spectroscopy.

    Science.gov (United States)

    Pulsinelli, Emy; Vasile, Francesca; Vergani, Laura; Parodi, Silvio; Nicolini, Claudio

    2003-12-01

    We have performed a systematic investigation of the structural features of the peptides Int (a sequence able to cross cell membranes) and Int-H1(S6A,F8A) (which shows interesting antitumoral properties). After screening in aqueous solution at different ionic strength and pH values, we analyzed the structures of the peptides in different water/trifluoroethanol mixtures by Circular Dichroism and Nuclear Magnetic Resonance techniques.

  12. A Solid State NMR Investigation of Recent Marine Siliceous Sponge Spicules

    Directory of Open Access Journals (Sweden)

    Sylvie Masse

    2016-03-01

    Full Text Available The composition of four recent siliceous marine sponge spicules was studied and compared. In particular, multinuclear (29Si, 13C, 31P solid state nuclear magnetic resonance (NMR allowed the characterization of both the mineral and organic constituents in a non-destructive manner. The silica network condensation was similar for all samples. The organic matter showed a similar pattern but varied in abundance as a function of the sponge group (Hexactinellida or Demospongiae and sampling conditions (living or dead organisms. This indicates that the striking morphological differences observed at the macroscale for the various samples do not lead to significant fingerprints in the spectroscopic signatures of the mineral and organic constituents.

  13. Solid-phase enolate chemistry investigated using HR-MAS NMR spectroscopy.

    Science.gov (United States)

    Fruchart, Jean-Sébastien; Lippens, Guy; Kuhn, Cyrille; Gras-Masse, Hélène; Melnyk, Oleg

    2002-01-25

    Supported P4-t-Bu enolate chemistry of phenylacetyloxymethyl polystyrene (PS) resin was investigated using high-resolution magic angle spinning (HR-MAS) NMR spectroscopy. Direct analysis of the crude reaction suspensions through the use of a diffusion filter (DF) allowed a rapid selection of the optimal experimental conditions, but also the characterization of the enolate on the solid phase. Comparison with solution experiments and literature data allowed us to address partially the structure of the enolate. HR-MAS NMR spectra of the enolate revealed also a tight interaction of P4-t-Bu base with the polymer matrix.

  14. HPLC-SPE-NMR for combinatorial biosynthetic investigations – Expanding the landscape of diterpene structural diversity

    DEFF Research Database (Denmark)

    Kongstad, Kenneth Thermann; Andersen-Ranberg, Johan; Hamberger, Björn Robert;

    In this work, the analytical technique, HPLC-HRMS-SPE-NMR was used for the first time in combination with combinatorial biosynthetic investigations in N. benthamiana. This efficient setup allowed for identification of several diterpene synthase (diTPS) combinations responsible for stereospecific...

  15. {sup 17}O NMR investigation of oxidative degradation in polymers under gamma-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    ALAM,TODD M.; CELINA,MATHIAS C.; ASSINK,ROGER A.; CLOUGH,ROGER LEE; GILLEN,KENNETH T.

    2000-03-08

    The {gamma}-irradiated-oxidation of pentacontane (C{sub 50}H{sub 102}) and the polymer polyisoprene was investigated as a function of oxidation level using {sup 17}O nuclear magnetic resonance (NMR) spectroscopy. It is demonstrated that by using {sup 17}O labeled O{sub 2} gas during the {gamma}-irradiation process, details about the oxidative degradation mechanisms can be directly obtained from the analysis of the {sup 17}O NMR spectra. Production of carboxylic acids is the primary oxygen-containing functionality during the oxidation of pentacontane, while ethers and alcohols are the dominant oxidation product observed for polyisoprene. The formation of ester species during the oxidation process is very minor for both materials, with water also being produced in significant amounts during the radiolytic oxidation of polyisoprene. The ability to focus on the oxidative component of the degradation process using {sup 17}O NMR spectroscopy demonstrates the selectivity of this technique over more conventional approaches.

  16. Crystal structure, NMR and theoretical investigations on 2-( o-hydroxy-anilino)-1,4-napthoquinone

    Science.gov (United States)

    Feizi, Nourollah; Pinjari, Rahul V.; Gejji, Shridhar P.; Sayyed, Fareed B.; Gonnade, Rajesh; Rane, Sandhya Y.

    2010-03-01

    Crystal structure, 1H NMR and cyclic voltammetric investigations of 2-( o-hydroxy-anilino)-1,4-napthoquinone (HAN), resulting from coupling of aminophenol with 2-hydroxy-1,4-napthoquinone, have been carried out. X-ray structure reveals that the HAN ligand crystallizes in orthorhombic space group Pca2 1 with Z = 4, forming a chain via inter-molecular O2⋯H1A sbnd O1 and C15 sbnd H15⋯O3 interactions. Both 1H NMR and cyclic voltammetry experiments suggest the titled ligand is associated and exists as dimer in d6-DMSO while the monomer has been predicted in CDCl 3 solution. Density functional calculations can be utilized to gauge the strength of hydrogen-bonded interactions from the 1H chemical shifts in the NMR spectra. Self-consistent reaction field (SCRF) calculations further support the inferences drawn from cyclic voltammetry experiments.

  17. Intramolecular Hydrogen Bonding Involving Organic Fluorine: NMR Investigations Corroborated by DFT-Based Theoretical Calculations

    Directory of Open Access Journals (Sweden)

    Sandeep Kumar Mishra

    2017-03-01

    Full Text Available The combined utility of many one and two dimensional NMR methodologies and DFT-based theoretical calculations have been exploited to detect the intramolecular hydrogen bond (HB in number of different organic fluorine-containing derivatives of molecules, viz. benzanilides, hydrazides, imides, benzamides, and diphenyloxamides. The existence of two and three centered hydrogen bonds has been convincingly established in the investigated molecules. The NMR spectral parameters, viz., coupling mediated through hydrogen bond, one-bond NH scalar couplings, physical parameter dependent variation of chemical shifts of NH protons have paved the way for understanding the presence of hydrogen bond involving organic fluorine in all the investigated molecules. The experimental NMR findings are further corroborated by DFT-based theoretical calculations including NCI, QTAIM, MD simulations and NBO analysis. The monitoring of H/D exchange with NMR spectroscopy established the effect of intramolecular HB and the influence of electronegativity of various substituents on the chemical kinetics in the number of organic building blocks. The utility of DQ-SQ technique in determining the information about HB in various fluorine substituted molecules has been convincingly established.

  18. Molecular mobility in Medicago truncatula seed during early stage of germination: Neutron scattering and NMR investigations

    Energy Technology Data Exchange (ETDEWEB)

    Falourd, Xavier [UR1268 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes (France); Natali, Francesca [CNR-IOM-OGG, c/o Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Peters, Judith [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Université Joseph Fourier UFR PhITEM, BP 53, 38041 Grenoble Cedex 9 (France); Institut de Biologie Structurale, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1 (France); Foucat, Loïc, E-mail: Loic.Foucat@nantes.inra.fr [UR1268 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes (France)

    2014-01-15

    Highlights: • Neutron scattering and NMR approaches were used to characterize seed germination. • A parallel between macromolecular motions and water dynamics was established. • Freezing/thawing cycle revealed a hysteresis connected to the seed hydration level. - Abstract: First hours of Medicago truncatula (MT) seeds germination were investigated using elastic incoherent neutron scattering (EINS) and nuclear magnetic resonance (NMR), to follow respectively how macromolecular motions and water mobility evolve when water permeates into the seed. From EINS results, it was shown that there is an increase in macromolecular mobility with the water uptake. Changes in NMR relaxation parameters reflected microstructural changes associated with the recovery of the metabolic processes. The EINS investigation of the effect of temperature on macromolecular motions showed that there is a relationship between the amount of water in the seeds and the effect of freezing–thawing cycle. The NMR relaxometry results obtained at 253 K allowed establishing possible link between the freezing of water molecules tightly bound to macromolecules and their drastic motion restriction around 250 K, as observed with EINS at the highest water content.

  19. Raman and surface enhanced Raman spectroscopic investigation on Lamiaceae plants

    Science.gov (United States)

    Rösch, P.; Popp, J.; Kiefer, W.

    1999-05-01

    The essential oils of Thymus vulgaris and Origanum vulgaris are studied by means of micro-Raman spectroscopy. The containing monoterpenes can be identified by their Raman spectra. Further the essential oils are investigated in their natural environment, the so-called oil cells of these Lamiaceae plants, with surface enhanced Raman spectroscopy (SERS). This method has the advantage to enhance Raman signals and furthermore the SERS effect leads to fluorescence quenching.

  20. Investigation of the binding of roxatidine acetate hydrochloride with cyclomaltoheptaose (β-cyclodextrin) using IR and NMR spectroscopy.

    Science.gov (United States)

    Maheshwari, Arti; Sharma, Manisha; Sharma, Deepak

    2011-09-27

    NMR chemical shift changes of the cyclomaltoheptaose (β-cyclodextrin, β-CD) cavity protons as well as roxatidine acetate hydrochloride aromatic ring protons revealed the formation of a RAH-β-CD inclusion complex. Detailed FTIR and NMR spectroscopic ((1)H NMR, COSY, NOESY, ROESY) studies have been done. The stoichiometry of the complex was determined to be 1:1, and the overall binding constant was also determined by Scott's method. The NOESY spectrum confirmed the selective penetration of the aromatic ring of RAH into the β-CD cavity in comparison to that of the piperidine ring. The mode of penetration of the guest into the CD cavity and structure of the complex has been established.

  1. 2D NMR Investigation of Dynamic Equilibrium of Tautomers of Gossypol

    Institute of Scientific and Technical Information of China (English)

    SHEN Ying-lin; YANG Sheng-hua; YAN Xiao-hua; MA Xue-yi

    2004-01-01

    Gossypol was obtained as an yellow platelike crystal with m.p. 210-214 . In CDCl3 there were three tautomers of gossypol: Ⅰ aldehyde, Ⅱ lactol, Ⅲ ketal, in equilibrium .Their total 1H NMR spectra were assigned by means of 1D and 2D NMR techniques including 1H-1H cosy ,DEPT, HMQC (1H Detected Heteronuclear Multiple Quantum Coherence) and HMBC (1H Detected Heteronuclear Multiple Bond Connectivity) experiments.This paper first reported that we took use of the 2D NMR techniques to assign all of 1H NMR chemical shifts of each tautomer , through the assignments of each peaks we investigated the tautomerism of gossypol . We concluded that when gossypol ( Ⅰ ) was put into CDCl3 , it would tautomerized three tautomers, they stable existed and attained tautomeric equilibrium in a molar ratio of 6:2:1 according to peaks intensity ratios in CDCl3. The result listed in table 1.Table 1. The 1H spectroscopy chemical shifts (ppm) for gossypol (Ⅰ), (Ⅱ) and (Ⅲ)All spectra were recorded at room tempreture in CDCl3 using TMS as an internal standard reported in δ units,hydroxyl protons were identified by D2O exchange.

  2. Computational and Spectroscopic Investigations of the Molecular Scale Structure and Dynamics of Geologically Important Fluids and Mineral-Fluid Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    R. James Kirkpatrick; Andrey G. Kalinichev

    2008-11-25

    significantly larger systems. These calculations have allowed us, for the first time, to study the effects of metal cations with different charges and charge density on the NOM aggregation in aqueous solutions. Other computational work has looked at the longer-time-scale dynamical behavior of aqueous species at mineral-water interfaces investigated simultaneously by NMR spectroscopy. Our experimental NMR studies have focused on understanding the structure and dynamics of water and dissolved species at mineral-water interfaces and in two-dimensional nano-confinement within clay interlayers. Combined NMR and MD study of H2O, Na+, and Cl- interactions with the surface of quartz has direct implications regarding interpretation of sum frequency vibrational spectroscopic experiments for this phase and will be an important reference for future studies. We also used NMR to examine the behavior of K+ and H2O in the interlayer and at the surfaces of the clay minerals hectorite and illite-rich illite-smectite. This the first time K+ dynamics has been characterized spectroscopically in geochemical systems. Preliminary experiments were also performed to evaluate the potential of 75As NMR as a probe of arsenic geochemical behavior. The 75As NMR study used advanced signal enhancement methods, introduced a new data acquisition approach to minimize the time investment in ultra-wide-line NMR experiments, and provides the first evidence of a strong relationship between the chemical shift and structural parameters for this experimentally challenging nucleus. We have also initiated a series of inelastic and quasi-elastic neutron scattering measurements of water dynamics in the interlayers of clays and layered double hydroxides. The objective of these experiments is to probe the correlations of water molecular motions in confined spaces over the scale of times and distances most directly comparable to our MD simulations and on a time scale different than that probed by NMR. This work is being done

  3. Characterization of GaSb-based heterostructures by spectroscopic investigations

    Energy Technology Data Exchange (ETDEWEB)

    Imhof, Sebastian; Bueckers, Christina; Metzger, Bjoern; Thraenhardt, Angela; Chatterjee, Sangam; Koch, Stephan W. [Fachbereich Physik, Wissenschaftliches Zentrum fuer Materialwissenschaften, Philipps Universitaet Marburg, Renthof 5, 35032 Marburg (Germany)

    2008-07-01

    The material system (AlGaIn)(AsSb) is suitable for laser emission at 2 {mu}m or longer wavelength, which is interesting for various applications, e.g. material processing, gas detection, medical diagnostic and laser surgery. A wide range of material combinations is being considered for application, but there are still uncertainties with regards to their structural properties, such as band alignment, strain and general bandstructure parameters. In order to gain information on these structural properties, we investigate GaSb-based heterostructures by modulation spectroscopy using e.g. photomodulated reflection. The experimental data are compared to simulations based on a microscopic theory.

  4. Raman spectroscopic investigation of blood and related materials

    Science.gov (United States)

    Gnyba, M.; Jedrzejewska-Szczerska, M.; Wróbel, M. S.

    2015-03-01

    This paper reports preliminary studies on use of Raman spectroscopy for investigation of blood. High quality blood spectra were recorded in-vitro with excitation wavelengths of 830 nm. Because of complex composition of the blood as well as by light attenuation and scattering in the tissues, spectra set up from wide, low-intensive Raman bands and intensive optical background. To get information about origin of bands in Raman spectra it is necessary to create phantom, which would show influence of this parameter and can be used to calibrate the Raman measurement system. Spectra of phantoms of selected blood components were acquired and discussed.

  5. Vibrational Spectroscopic and Thermodynamic Investigation of Poly (vinyl butyral

    Directory of Open Access Journals (Sweden)

    Saiful Islam Ansari

    2016-03-01

    Full Text Available A detailed study was performed to investigate the normal modes of vibration and their dispersions in poly (vinyl butyral by using Urey-Bradley force field and Wilson’s GF matrix method as modified by Higgs. It provides detailed interpretation of FTIR. Characteristic feature of dispersion curves such as regions of high density–of–states, repulsion and character mixing of dispersion modes are discussed. Predictive values of heat capacity as a function of temperature between 0-350 K have been evaluated.

  6. In-vivo morphologic and spectroscopic investigation of Psoriasis

    Science.gov (United States)

    Kapsokalyvas, Dimitrios; Cicchi, Riccardo; Bruscino, Nicola; Alfieri, Domenico; Massi, Daniela; Lotti, Torello; Pavone, Francesco S.

    2011-07-01

    Psoriasis is an autoimmune disease of the skin characterized by hyperkeratosis, hyperproliferation of the epidermis, inflammatory cell accumulation and increased dilatation of dermal papillary blood vessels. Cases of psoriasis were investigated in vivo with optical means in order to evaluate the potential of in vivo optical biopsy. A Polarization Multispectral Dermoscope was employed for the macroscopic observation. Features such as the 'dotted' blood vessels pattern was observed with high contrast. High resolution image sections of the epidermis and the dermis were produced with a custom made Multiphoton Microscope. Imaging extended from the surface of the lesion down to the papillary dermis, at a depth of 200 μm. In the epidermis, a characteristic morphology of the stratum corneum found only in Psoriasis was revealed. Additionally, the cytoplasmic area of the cells in the stratum spinosum layer was found to be smaller than normal. In the dermis the morphological features were more pronounced, where the elongated dermal papillae dominated the papillary layer. Their length exceeds 100μm, which is a far greater value compared to that of healthy skin. These in vivo observations are consistent with the ex vivo histopathological observations, supporting both the applicability and potentiality of multispectral dermoscopy and multiphoton microscopy in the field of in vivo optical investigation and biopsy of skin.

  7. Spectroscopic investigation of interaction between mangiferin and bovine serum albumin

    Science.gov (United States)

    Lin, Hui; Lan, Jingfeng; Guan, Min; Sheng, Fenling; Zhang, Haixia

    2009-09-01

    The mechanism of interaction between mangiferin (MA) and bovine serum albumin (BSA) in aqueous solution was investigated by fluorescence spectra, synchronous fluorescence spectra, absorbance spectra and Fourier transform infrared (FT-IR) spectroscopy. The binding constants and binding sites of MA to BSA at different reaction times were calculated. And the distance between MA and BSA was estimated to be 5.20 nm based on Föster's theory. In addition, synchronous fluorescence and FT-IR measurements revealed that the secondary structures of the protein changed after the interaction of MA with BSA. As a conclusion, the interaction between the anti-diabetes Chinese medicine MA and BSA may provide some significant information for the mechanism of the traditional chinese medicine MA on the protein level to cure diabetes or other diseases.

  8. Infrared Spectroscopic Investigation on CH Bond Acidity in Cationic Alkanes

    Science.gov (United States)

    Matsuda, Yoshiyuki; Xie, Min; Fujii, Asuka

    2016-06-01

    We have demonstrated large enhancements of CH bond acidities in alcohol, ether, and amine cations through infrared predissociation spectroscopy based on the vacuum ultraviolet photoionization detection. In this study, we investigate for the cationic alkanes (pentane, hexane, and heptane) with different alkyl chain lengths. The σ electrons are ejected in the ionization of alkanes, while nonbonding electrons are ejected in ionization of alcohols, ethers, and amines. Nevertheless, the acidity enhancements of CH in these cationic alkanes have also been demonstrated by infrared spectroscopy. The correlations of their CH bond acidities with the alkyl chain lengths as well as the mechanisms of their acidity enhancements will be discussed by comparison of infrared spectra and theoretical calculations.

  9. A Spectroscopic Investigation on the Structural Evolution of Soy Based Polyurethane Foams

    Science.gov (United States)

    Puthanparambil, Deepa; Kimball, Casey; Hsu, Shaw L.

    2009-03-01

    Our current research deals with an economical and renewable soy based polyol for use in polyurethane foams. Infrared spectroscopic studies have revealed that the amount of polyurea segments formed and the kinetics of their formation in soy based polyurethane foam systems are considerably different from traditional systems employing ethylene oxide -- propylene oxide based polyols. The most crucial aspect of this research deals with the miscibility of water in the reactive mixtures involving extremely hydrophobic soy-based polyols. High Field Nuclear Magnetic Resonance Spectroscopy (NMR) with D2O as the probing agent was employed to determine the miscibility behavior at the molecular level. This technique was able to establish the structure and location of dispersed water, which can be extremely different based on the polyols used, thus affecting the morphology of the foam. The length and amount of polyureas directly impact the kinetics of the phase separation process to form the hard-segment rich domains and associated physical properties. The aggregation of these polyurea hard domains were characterized by the hydrogen bonds formed. This structural transformation as a function of reaction is also reflected in the segmental relaxation kinetics characterized by spin-spin diffusion, measured using a low field NMR instrument.

  10. Investigation of drug-excipient interactions in lapatinib amorphous solid dispersions using solid-state NMR spectroscopy.

    Science.gov (United States)

    Song, Yang; Yang, Xinghao; Chen, Xin; Nie, Haichen; Byrn, Stephen; Lubach, Joseph W

    2015-03-02

    This study investigated the presence of specific drug-excipient interactions in amorphous solid dispersions of lapatinib (LB) and four commonly used pharmaceutical polymers, including Soluplus, polyvinylpyrrolidone vinyl acetate (PVPVA), hydroxypropylmethylcellulose acetate succinate (HPMCAS), and hydroxypropylmethylcellulose phthalate (HPMCP). Based on predicted pKa differences, LB was hypothesized to exhibit a specific ionic interaction with HPMCP, and possibly with HPMCAS, while Soluplus and PVPVA were studied as controls without ionizable functionality. Thermal studies showed a single glass transition (Tg) for each dispersion, in close agreement with predicted values for Soluplus, PVPVA, and HPMCAS systems. However, the Tg values of LB-HPMCP solid dispersions were markedly higher than predicted values, indicating a strong intermolecular interaction between LB and HPMCP. (15)N solid-state NMR provided direct spectroscopic evidence for protonation of LB (i.e., salt formation) within the HPMCP solid dispersions. (1)H T1 and (1)H T1ρ relaxation studies of the dispersions supported the ionic interaction hypothesis, and indicated multiple phases in the cases of excess drug or polymer. In addition, the dissolution and stability behavior of each system was examined. Both acidic polymers, HPMCAS and HPMCP, effectively inhibited the crystallization of LB on accelerated stability, likely owing to beneficial strong intermolecular hydrogen and/or specific ionic bonds with the acidic polymers. Soluplus and PVPVA showed poor physical properties on stability and subsequently poor crystallization inhibition.

  11. Spectroscopic investigation of thermal conductivity in few-layer graphene

    Science.gov (United States)

    Denison, Joseph C., Jr.

    Carbon is an extremely versatile element due to the ability of its electronic structure to allow strong bonds with many elements including other carbon atoms. This allows for the formation of many types of large and complex architectures, such as fullerenes and carbon nanotubes, at the nanoscale. One of the most fascinating allotropes of carbon is graphene, a two-dimensional honeycomb lattice with carbon in sp2 hybridization, which building block for layered graphite and other nanocarbons.[1] Because of its unique structure, graphene displays several interesting properties including high thermal[2-4] and electrical mobility and conductivity[1,5]. The initial studies on graphene were performed on mechanically exfoliated samples, which were limited to few microns in size. In the recent years, large areas of single- and few-layer graphene (˜few cm x cm) are being produced by chemical vapor deposition technique for practical applications. However, chemical vapor deposition grown graphene is highly polycrystalline with interfaces such as edges, grain boundaries, dislocations, and point defects. This inevitable presence of defects in graphene influences its electrical and thermal transport. While many studies have previously focused on the influence of defects on electrical mobility and conductivity, there is little information on the influence of defects on the thermal properties of graphene. This study specifically investigates the effect of both intrinsic and extrinsic defects on the in-plane thermal properties of graphene using micro-Raman spectroscopy. The in-plane thermal conductivity of few-layered graphene (FLG) was measured using Raman spectroscopy, following the work of Balandin et al. [4]The thermal conductivity was estimated from a shift of the characteristic G-band of graphene as a function of the excitation laser power. The graphene samples were synthesized on nickel substrates using chemical vapor deposition, and transferred to copper TEM grids and

  12. Spectroscopic Investigation of a Repetitively-Pulsed Nanosecond Discharge

    Science.gov (United States)

    Yee, Benjamin T.

    This work reports on an investigation of a repetitively-pulsed nanosecond discharge (RPND) in helium over a range of 0.3-16.0 Torr. The discharge was studied experimentally via laser-absorption spectroscopy and opticals emission spectroscopy measurements. In concert with the experimental campaign, a global model of a helium plasma was developed with the aid of particle-in-cell simulations. The global model was then used to predict the population kinetics and emissions of the RPND. Synthesis of the results provided new data and insights on the development of the RPND. Among the results were direct measurements of the triplet metastable states during the excitation period. This period was found to be unexpectedly long at low pressures (less than or equal to 1.0 Torr), suggesting an excess in high-energy electrons as compared to an equilibrium distribution. Other phenomena such as a prominent return stroke and additional energy deposition by reflections in the transmission line were also identified. Estimates of the electric field and electron temperatures were obtained for several conditions. Furthermore, several optical methods for electron temperature measurement were evaluated for application to the discharge. Based on the global model simulations, the coronal model was found to apply to the line ratio of the 33S-23Po and 31S-2 1Po transitions, however further work is needed to ascertain its applicability to experimental discharges. These results provide new insight on the development of the repetitively-pulsed nanosecond discharge. Specifically, they reveal new information about the excited state dynamics within the discharge, the non-equilibrium nature of its electrons, and several avenues for future studies. This study extends the present understanding of repetitively-pulsed discharges, and advances the knowledge of energy coupling between electric fields and plasmas.

  13. NMR spectroscopic investigations on copper-catalyzed reactions and zintl anions

    OpenAIRE

    Koch, Carina

    2016-01-01

    The copper-catalyzed asymmetric conjugated 1,4-addition reaction of organozinc reagents to a,b-unsaturated compounds is a very effective and widely used method for the enantioselective carbon-carbon bond formation. By the use of phosphoramidite ligands it is possible to reach ee-values and conversion up to > 99 %. Furthermore, this outstanding reaction provides lower costs in comparison to other transition-metal catalyzed reactions and compatibility to many functional groups. Despite the grea...

  14. Development of a low resolution (1)H NMR spectroscopic technique for the study of matrix mobility in fresh and freeze-thawed hen egg yolk.

    Science.gov (United States)

    Au, Carmen; Wang, Tong; Acevedo, Nuria C

    2016-08-01

    Three experiments were conducted in developing a low resolution proton nuclear magnetic resonance ((1)H NMR) spectroscopic technique to study matrix mobility in fresh and freeze-thawed gelled yolk. The Carr-Purcell-Meiboom-Gill (CPMG) sequence was used to measure spin-spin relaxation times of proton pools representing major yolk constituents. A component identification test distinguished 3-4 pools. The least mobile pool was assigned to proteins, protein-lipid and protein-water interactions, and the most mobile to unbound water. The remaining pools were assigned to lipids, lipid-protein and lipid-water interactions. A stability test indicated that yolk had varied matrix mobility within the same sample across five days of refrigeration storage. A reproducibility test demonstrated high repeatability of fresh yolk measurements, but significant differences (p<0.05) were found within gelled yolk samples. This research determined that (1)H NMR spectroscopy, a non-destructive technique, can identify yolk components and detect changes in the matrix.

  15. Iodine-water-alkanol and potassium iodide-water-alkanol systems: Phase diagrams and regularities of association according to IR and NMR spectroscopic data

    Science.gov (United States)

    Monakhova, Yu. B.; Varlamova, T. M.; Rubtsova, E. M.; Mushtakova, S. P.

    2015-04-01

    The variation of the iodine and potassium iodide solubilities in water-monoatomic alcohol (ethanol, propanol, isopropanol) solvents is considered from the standpoint of IR spectroscopic and chemometric data on association in water-alkanol binary mixtures. The iodine and potassium iodide solubilities in the mixed solvents vary nonlinearly with solvent composition because of the formation of 1 : 1 and 1 : 3 water-alcohol heteroassociates and alcohol homoassociates. Different kinds of phase diagram are observed for the iodine-water-alcohol systems: the I2-H2O-1-C3H7OH and the I2-H2O-2-C3H7OH diagrams have a phase separation region, while the I2-H2O-C2H5OH diagram does not. This fact is explained in terms of the interaction between the components of the systems. The variation of the potassium iodide solubility in the mixed solvent is discussed: a decrease in the KI solubility is symbatic to an increase in the relative concentration of 1 : 1 associates in the water-alcohol solution. The run of the iodine and potassium iodide solubility curves at low alcohol concentrations is explained on the basis of NMR spectroscopic data on association in aqueous solutions of the monoatomic alcohols.

  16. 1H NMR spectroscopic analysis detects metabolic disturbances in rat urine on acute exposure to heavy metal tungsten alloy based metals salt.

    Science.gov (United States)

    Tyagi, Ritu; Rana, Poonam; Gupta, Mamta; Bhatnagar, Deepak; Srivastava, Shatakshi; Roy, Raja; Khushu, Subash

    2014-03-25

    Heavy metal tungsten alloys (HMTAs) have been found to be safer alternatives for making military munitions. Recently, some studies demonstrating the toxic potential of HMTAs have raised concern over the safety issues, and further propose that HMTAs exposure may lead to physiological disturbances as well. To look for the systemic effect of acute toxicity of HMTA based metals salt, (1)H nuclear magnetic resonance ((1)H NMR) spectroscopic profiling of rat urine was carried out. Male Sprague Dawley rats were administered (intraperitoneal) low and high dose of mixture of HMTA based metals salt and NMR spectroscopy was carried out in urine samples collected at 8, 24, 72 and 120 h post dosing (p.d.). Serum biochemical parameters and liver histopathology were also conducted. The (1)H NMR spectra were analysed using multivariate analysis techniques to show the time- and dose-dependent biochemical variations in post HMTA based metals salt exposure. Urine metabolomic analysis showed changes associated with energy metabolism, amino acids, N-methyl nicotinamide, membrane and gut flora metabolites. Multivariate analysis showed maximum variation with best classification of control and treated groups at 24h p.d. At the end of the study, for the low dose group most of the changes at metabolite level reverted to control except for the energy metabolites; whereas, in the high dose group some of the changes still persisted. The observations were well correlated with histopathological and serum biochemical parameters. Further, metabolic pathway analysis clarified that amongst all the metabolic pathways analysed, tricarboxylic acid cycle was most affected at all the time points indicating a switchover in energy metabolism from aerobic to anaerobic. These results suggest that exposure of rats to acute doses of HMTA based metals salt disrupts physiological metabolism with moderate injury to the liver, which might indirectly result from heavy metals induced oxidative stress.

  17. NMR Investigations of Structure and Dynamics in Polymers for Energy Storage Applications

    Science.gov (United States)

    Greenbaum, Steven

    Materials innovation is needed to realize major progress in energy storage capacity for lithium batteries and capacitors. Polymers hold considerable promise as ion conducting media in batteries and electrochemical capacitors and as dielectrics in thin film capacitors. Structural studies of materials utilized in lithium battery technology are hampered by the lack of long-range order found in well-defined crystalline phases. Powder x-ray diffraction yields structural parameters that have been averaged over hundreds of lattice sites, and is unable to provide structural information about amorphous phases. Our laboratory uses solid state nuclear magnetic resonance (NMR) methods to investigate structural and chemical aspects of lithium ion cathodes, anodes, electrolytes, interfaces and interphases. NMR is element- (nuclear-) specific and sensitive to small variations in the immediate environment of the ions being probed, for example Li+, and in most cases is a reliably quantitative spectroscopy in that the integrated intensity of a particular spectral component is directly proportional to the number of nuclei in the corresponding material phase. NMR is also a powerful tool for probing ionic and molecular motion in lithium battery electrolytes with a dynamic range spanning some ten orders of magnitude through spin-lattice relaxation and self-diffusion measurements. Broadband relaxometry based on Fast Field Cycling NMR (FFCNMR) methods can span three to four of these orders of magnitude in a single set of measurements. Results of several recent NMR investigations performed on our lab will be presented. We explore the ion transport mechanism in polyether-based and lithium polymer electrolytes and those based on other base polymers, in particular, the extent to which ionic motion is coupled to polymer segmental motion. Polycarbonates are being considered as a possible replacement for polypropylene in high power thin film capacitors due to their favorable dielectric

  18. Fluorine dynamics in BaF{sub 2} superionic conductors investigated by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Gumann, Patryk

    2008-07-01

    In this work the dynamics of fluorine in solid-state electrolytes having BaF{sub 2}-structure was investigated using three different NMR-methods: field cycling relaxometry, lineshape analysis, and static field gradient NMR. For this purpose a pure BaF{sub 2} crystal, as well as crystals doped with trivalent impurities (LaF{sub 3}), were studied as a function of temperature. Using MAS NMR it was possible to identify two lines in Ba{sub 0.9}La{sub 0.1}F{sub 2.1} having different chemical shift, and to refer them to the modified crystal structure. On this basis a model for the fluorine lineshape has been developed, taking into account three motional processes characterized by their correlation times. It includes jump diffusion of the fluorine ions among equivalent sites within two crystallographically distinct sublattices, and inter-lattice exchange processes. By measuring frequency and temperature-dependent spin lattice relaxation times, it was possible to gain information about fluorine dynamics on microscopic length scales. An attempt was also made to analyze the data for pure BaF{sub 2} and low admixture concentration samples with a non-exponential correlation function. (orig.)

  19. Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR.

    Science.gov (United States)

    Tres, Francesco; Coombes, Steven R; Phillips, Andrew R; Hughes, Leslie P; Wren, Stephen A C; Aylott, Jonathan W; Burley, Jonathan C

    2015-09-10

    We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide). A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR. Off-line 1H-NMR was used for the first time to simultaneously measure the dissolution profiles and rates of both the drug and the polymer from a solid dispersion. MRI and 1H-NMR data showed that the 5% drug loading compact erodes linearly, and that bicalutamide and Kollidon VA64 are released at approximately the same rate from the molecular dispersion. For the 30% extrudate, data indicated a slower water ingress into the compact which corresponds to a slower dissolution rate of both bicalutamide and Kollidon VA64.

  20. Two-dimensional NMR investigations of the dynamic conformations of phospholipids and liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Mei [Univ. of California, Berkeley, CA (United States). Applied Science and Technology

    1996-05-01

    Two-dimensional 13C, 1H, and 31P nuclear magnetic resonance (NMR) techniques are developed and used to study molecular structure and dynamics in liquid-crystalline systems, primarily phospholipids and nematic liquid crystals. NMR spectroscopy characterizes molecular conformation in terms of orientations and distances of molecular segments. In anisotropically mobile systems, this is achieved by measuring motionally-averaged nuclear dipolar couplings and chemical shift anisotropies. The short-range couplings yield useful bond order parameters, while the long-range interactions constrain the overall conformation. In this work, techniques for probing proton dipolar local fields are further developed to obtain highlyresolved dipolar couplings between protons and rare spins. By exploiting variable-angle sample spinning techniques, orientation-sensitive NMR spectra are resolved according to sitespecific isotropic chemical shifts. Moreover, the signs and magnitudes of various short-range dipolar couplings are obtained. They are used in novel theoretical analyses that provide information about segmental orientations and their distributions. Such information is obtained in a model-independent fashion or with physically reasonable assumptions. The structural investigation of phospholipids is focused on the dynam

  1. Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR

    Directory of Open Access Journals (Sweden)

    Francesco Tres

    2015-09-01

    Full Text Available We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide. A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR. Off-line 1H-NMR was used for the first time to simultaneously measure the dissolution profiles and rates of both the drug and the polymer from a solid dispersion. MRI and 1H-NMR data showed that the 5% drug loading compact erodes linearly, and that bicalutamide and Kollidon VA64 are released at approximately the same rate from the molecular dispersion. For the 30% extrudate, data indicated a slower water ingress into the compact which corresponds to a slower dissolution rate of both bicalutamide and Kollidon VA64.

  2. Investigation of Oxidative Degradation in Polymers Using (17)O NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd M.; Celina, Mathew; Assink, Roger A.; Clough, Roger L.; Gillen, Kenneth T.; Wheeler David R.

    1999-07-20

    The thermal oxidation of pentacontane (C{sub 50}H{sub 102}), and of the homopolymer polyisoprene, has been investigated using {sup 17}O NMR spectroscopy. By performing the oxidation using {sup 17}O labeled O{sub 2} gas, it is possible to easily identify degradation products, even at relatively low concentrations. It is demonstrated that details of the degradation mechanism can be obtained from analysis of the {sup 17}O NMR spectra as a function of total oxidation. Pentacontane reveals the widest variety of reaction products, and exhibits changes in the relative product distributions with increasing O{sub 2} consumption. At low levels of oxygen incorporation, peroxides are the major oxidation product, while at later stages of degradation these species are replaced by increasing concentrations of ketones, alcohols, carboxylic acids and esters. Analyzing the product distribution can help in identification of the different free-radical decomposition pathways of hydroperoxides, including recombination, proton abstraction and chain scission, as well as secondary reactions. The {sup 17}O NMR spectra of thermally oxidized polyisoprene reveal fewer degradation functionalities, but exhibit an increased complexity in the type of observed degradation species due to structural features such as unsaturation and methyl branching. Alcohols and ethers formed from hydrogen abstraction and free radical termination.

  3. Spectroscopic investigation of the constituent components effect on the biodegradable package characteristics

    Science.gov (United States)

    Coťa, C.; Cioica, N.; Filip, C.; Fechete, R.; Todica, M.; Nagy, E. M.; Cozar, O.

    2015-12-01

    The effect of the nature and the content of the plasticizers (water, glycerol) on the corn starch based biodegradable packages properties (crystalline-amorphous) and also on their degradation process after absorption of distilled water were investigated by 1H NMR relaxation and 13C CP/MAS NMR spectroscopies. For this goal, a set of 14 samples with various starch/glycerol/water (mass %) ratios were prepared and investigated after extrusion process in order to establish their crystalline or amorphous character. The composition having starch/glycerol/water 68/17/15 mass % ratio was found to have a dominant amorphous character and very similar features with a commercial specimen (USA) used for the package. It was also found that this best package is extremely degraded after just one day under water absorption. The most resistant package was that with a large content of starch (78/19.5/2.5).

  4. Spectroscopic investigation of the constituent components effect on the biodegradable package characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Coţa, C.; Cioica, N., E-mail: cioica@inma.ro; Nagy, E. M. [National Institute of Research-Development for Machines and Installations Designed to Agriculture and Food Industry – INMA Bucureşti – Cluj-Napoca Branch, 59, Al. Vaida-Voievod Str., RO-400458 Cluj-Napoca (Romania); Filip, C. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca (Romania); Fechete, R. [Technical University of Cluj-Napoca, Dept. of Physics, 25 G. Baritiu Str., RO-400020 Cluj-Napoca (Romania); Todica, M. [Babeş-Bolyai University, Faculty of Physics, 1 Kogalniceanu Str., RO-400084, Cluj-Napoca (Romania); Cozar, O. [National Institute of Research-Development for Machines and Installations Designed to Agriculture and Food Industry – INMA Bucureşti – Cluj-Napoca Branch, 59, Al. Vaida-Voievod Str., RO-400458 Cluj-Napoca (Romania); Academy of Romanian Scientists, 54 Splaiul Independentei, RO-050094, Bucharest (Romania)

    2015-12-23

    The effect of the nature and the content of the plasticizers (water, glycerol) on the corn starch based biodegradable packages properties (crystalline-amorphous) and also on their degradation process after absorption of distilled water were investigated by {sup 1}H NMR relaxation and {sup 13}C CP/MAS NMR spectroscopies. For this goal, a set of 14 samples with various starch/glycerol/water (mass %) ratios were prepared and investigated after extrusion process in order to establish their crystalline or amorphous character. The composition having starch/glycerol/water 68/17/15 mass % ratio was found to have a dominant amorphous character and very similar features with a commercial specimen (USA) used for the package. It was also found that this best package is extremely degraded after just one day under water absorption. The most resistant package was that with a large content of starch (78/19.5/2.5)

  5. UV-Raman and NMR spectroscopic studies on the crystallization of zeolite A and a new synthetic route.

    Science.gov (United States)

    Ren, Limin; Li, Caijin; Fan, Fengtao; Guo, Qiang; Liang, Desheng; Feng, Zhaochi; Li, Can; Li, Shougui; Xiao, Feng-Shou

    2011-05-23

    UV-Raman and NMR spectroscopy, combined with other techniques, have been used to characterize crystallization of zeolite A. In situ UV-Raman spectroscopy shows that the starting gel for crystallization of zeolite A contains a lot of four-ring (4R) building units and the appearance of six-ring (6R) building blocks is the signal for crystal formation. (29)Si NMR spectroscopy results suggest that the starting gel is double four-ring (D4R) rich and during crystallization of zeolite A both α and β cages appear. (27)Al NMR spectroscopy results indicate the absence of Al (2Si) species in the starting gel, suggesting the absence of single 4R building units in the starting gel. Furthermore, composition analysis of both solid and liquid samples shows that the solid rather than liquid phase predominates for the crystallization of zeolite A. Therefore, it is proposed that the crystallization of zeolite A mainly occurs in the solid phase by self-assembly or rearrangement starting from the zeolite building units mainly consisting of D4R. The essential role of D4R is directly confirmed by successful conversion from a solution of D4R to zeolite A in the presence of NaCl, and the importance of solid phase is reasonably demonstrated by the successful synthesis of zeolite A from a dry aluminosilicate gel. By considering that the solid phase has a major contribution to crystallization, a novel route was designed to synthesizing zeolite A from the raw materials water glass (Na(2)SiO(3) in aqueous solution) and NaAlO(2), without additional water and NaOH; this route not only simplifies synthetic procedures, but reduces water consumption. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Application of spectroscopic methods (FT-IR, Raman, ECD and NMR) in studies of identification and optical purity of radezolid

    Science.gov (United States)

    Michalska, Katarzyna; Gruba, Ewa; Mizera, Mikołaj; Lewandowska, Kornelia; Bednarek, Elżbieta; Bocian, Wojciech; Cielecka-Piontek, Judyta

    2017-08-01

    In the presented study, N-{[(5S)-3-(2-fluoro-4‧-{[(1H-1,2,3-triazol-5-ylmethyl)amino]methyl}biphenyl-4-yl)-2-oxo-1,3-oxazolidin-5-yl]methyl}acetamide (radezolid) was synthesized and characterized using FT-IR, Raman, ECD and NMR. The aim of this work was to assess the possibility of applying classical spectral methods such as FT-IR, Raman, ECD and NMR spectroscopy for studies on the identification and optical purity of radezolid. The experimental interpretation of FT-IR and Raman spectra of radezolid was conducted in combination with theoretical studies. Density functional theory (DFT) with the B3LYP hybrid functional was used for obtaining radezolid spectra. Full identification was carried out by COSY, 1H {13C} HSQC and 1H {13C} HMBC experiments. The experimental NMR chemical shifts and spin-spin coupling constants were compared with theoretical calculations using the DFT method and B3LYP functional employing the 6-311 ++G(d,p) basis set and the solvent polarizable continuum model (PCM). The experimental ECD spectra of synthesized radezolid were compared with experimental spectra of the reference standard of radezolid. Theoretical calculations enabled us to conduct HOMO and LUMO analysis and molecular electrostatic potential maps were used to determine the active sites of microbiologically active form of radezolid enantiomer. The relationship between results of ab initio calculations and knowledge about chemical-biological properties of S-radezolid and other oxazolidinone derivatives are also discussed.

  7. Lanthanide paramagnetic probes for NMR spectroscopic studies of fast molecular conformational dynamics and temperature control. Effective six-site proton exchange in 18-crown-6 by exchange spectroscopy.

    Science.gov (United States)

    Babailov, Sergey P

    2012-02-06

    (1)H and (13)C NMR measurements are reported for the CDCl(3) and CD(2)Cl(2) solutions of [La(18-crown-6)(NO(3))(3)] (I), [Pr(18-crown-6) (NO(3))(3)] (II), [Ce(18-crown-6)(NO(3))(3)] (III), and [Nd(18-crown-6)(NO(3))(3)] (IV) complexes. Temperature dependencies of the (1)H NMR spectra of paramagnetic II-IV have been analyzed using the dynamic NMR (DNMR) methods for six-site exchange. Two types of conformational dynamic processes were identified (the first one is conditioned by interconversion of complex enantiomeric forms and pseudorotation of a macrocycle molecule upon the C(2) symmetry axis; the second one is conditioned by macrocycle molecule inversion). Application of exchange spectroscopy (2D-EXSY) of DNMR for investigation of this dynamic system (II-IV) simplifies the assignment of the NMR signals and represents the first experimental study of multisite exchange. In the present work, the methodology of paramagnetic 4f (Ce, Pr, and Nd) probe applications for the study of free-energy, enthalpy, and entropy changes in chemical exchange processes, as well as the advantages of this method in a comparison with DNMR studies of diamagnetic substances, is discussed. In particular, as a result of paramagnetic chemical shifts in 4f complexes, the range of measurable rate constants expands considerably compared to the analogous range in diamagnetic compounds. Coordination compounds investigated in the paper represent new types of thermometric NMR sensors and lanthanide paramagnetic probes for in situ temperature control in solution.

  8. 1H and 13C HR-MAS NMR investigations on native and enzymatically digested bovine nasal cartilage.

    Science.gov (United States)

    Schiller, J; Naji, L; Huster, D; Kaufmann, J; Arnold, K

    2001-08-01

    Rheumatic diseases are accompanied by a progressive destruction of the cartilage layer of the joints. Despite the frequency of the disease, degradation mechanisms are not yet understood and methods for early diagnosis are not available. Although some information on pathogenesis could be obtained from the analysis of degradation products of cartilage supernatants, the most direct information on degradation processes would come from the native cartilage as such. We have used 1H as well as 13C HR-MAS (high resolution magic angle spinning) NMR spectroscopy to obtain suitable line-widths of NMR resonances of native cartilage. 1D and 2D NMR spectra of native cartilage were compared with those of enzymatically-treated (collagenase and papain) samples. In the 1H NMR spectra of native cartilage, resonances of polysaccharides, lipids and a few amino acids of collagen were detectable, whereas the 13C NMR spectra primarily indicated the presence of chondroitin sulfate. Treatment with papain resulted only in small changes in the 1H NMR spectrum, whereas a clear diminution of all resonances was detectable in the 13C NMR spectra. On the other hand, treatment with collagenase caused the formation of peptides with an amino acid composition typical for collagen (glycine, proline, hydroxyproline and lysine). It is concluded that the HR-MAS NMR spectra of cartilage may be of significance for the investigation of cartilage degradation since they allow the fast evaluation of cartilage composition and only very small amounts of sample are required.

  9. Characterization of a chiral stationary phase by HR/MAS NMR spectroscopy and investigation of enantioselective interaction with chiral ligates by transferred NOE.

    Science.gov (United States)

    Hellriegel, Christine; Skogsberg, Urban; Albert, Klaus; Lämmerhofer, Michael; Maier, Norbert M; Lindner, Wolfgang

    2004-03-31

    The surface chemistry of a chiral stationary phase (CSP) with a (tert-butyl carbamoyl) quinine selector immobilized on thiol-modified silica has been characterized by (1)H HR/MAS NMR and (29)Si CP/MAS NMR spectroscopy. The mostly well-resolved (1)H signals could be assigned to stem from the surface-bound selector and the latter suggested a bi- and trifunctional silane linkage. Suspended-state NMR spectroscopy thus proved a well-characterized surface chemistry as proposed. To study chiral recognition phenomena in the presence of the CSP, (1)H HR/MAS 2D transfer NOESY investigations in methanol-d(4) have been undertaken with various solutes including N-3,5-dinitrobenzoyl derivatives of leucine (DNB-Leu) and N-acetyl phenylalanine (Ac-Phe). Both (R)- and (S)-enantiomers of DNB-Leu and Ac-Phe interacted with the tBuCQN-CSP as indicated by negative cross-peaks in the trNOESY spectra, while the 2D NOESY of the dissolved solutes in absence of the chiral stationary phase showed positive cross-peaks. The intensities of the trNOE cross-peaks were much stronger for the (S)-enantiomers. This stereoselectivity paralleled the experimental chromatographic behavior, where the (S)-enantiomers revealed stronger binding and retention on the tBuCQN-CSP as well. Hence, we were able to correlate the retention behavior to the trNOE NMR spectroscopic data in a qualitative manner.

  10. 113Cd-NMR investigation of a cadmium-substituted copper, zinc-containing superoxide dismutase from yeast

    DEFF Research Database (Denmark)

    Kofod, Pauli; Bauer, Rogert; Danielsen, Eva

    1991-01-01

    113Cd nuclear magnetic resonance spectroscopy has been used to investigate the metal binding sites of cadmium-substituted copper,zinc-containing superoxide dismutase from baker's yeast. NMR signals were obtained for 113Cd(II) at the Cu site as well as for 113Cd(II) at the Zn site. The two subunits...... an explanation for the discrepancy in the literature regarding 113Cd-NMR investigations of bovine superoxide dismutase....

  11. NMR spectroscopic and bioinformatic analyses of the LTBP1 C-terminus reveal a highly dynamic domain organisation.

    Directory of Open Access Journals (Sweden)

    Ian B Robertson

    Full Text Available Proteins from the LTBP/fibrillin family perform key structural and functional roles in connective tissues. LTBP1 forms the large latent complex with TGFβ and its propeptide LAP, and sequesters the latent growth factor to the extracellular matrix. Bioinformatics studies suggest the main structural features of the LTBP1 C-terminus are conserved through evolution. NMR studies were carried out on three overlapping C-terminal fragments of LTBP1, comprising four domains with characterised homologues, cbEGF14, TB3, EGF3 and cbEGF15, and three regions with no homology to known structures. The NMR data reveal that the four domains adopt canonical folds, but largely lack the interdomain interactions observed with homologous fibrillin domains; the exception is the EGF3-cbEGF15 domain pair which has a well-defined interdomain interface. (15N relaxation studies further demonstrate that the three interdomain regions act as flexible linkers, allowing a wide range of motion between the well-structured domains. This work is consistent with the LTBP1 C-terminus adopting a flexible "knotted rope" structure, which may facilitate cell matrix interactions, and the accessibility to proteases or other factors that could contribute to TGFβ activation.

  12. Specific binding of a dihydropyrimidinone derivative with DNA: Spectroscopic, calorimetric and modeling investigations

    Energy Technology Data Exchange (ETDEWEB)

    Wang Gongke, E-mail: wanggongke@126.com [School of Chemistry and Environmental Science, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007 (China); Yan Changling; Wang Dongchao; Li Dan [School of Chemistry and Environmental Science, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007 (China); Lu Yan, E-mail: yanlu2001@sohu.com [School of Chemistry and Environmental Science, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007 (China)

    2012-07-15

    One of the dihydropyrimidinone derivative 5-(ethoxycarbonyl)-6-methyl-4-(4-methoxyphenyl) -3,4-dihydropyrimidin-2(1H)-one (EMMD) was synthesized, and its binding properties with calf-thymus DNA (ctDNA) were investigated using spectroscopic, viscometric, isothermal titration calorimetric (ITC) and molecular modeling techniques. Fluorescence spectra suggested that the fluorescence enhancement of the binding interaction of EMMD to ctDNA was a static process with ground state complex formation. The binding constant determined with spectroscopic titration and ITC was found to be in the same order of 10{sup 4} M{sup -1}. According to the results of the viscosity analysis, fluorescence competitive binding experiment, fluorescence quenching studies, absorption spectral and ITC investigations, it can be concluded that EMMD is intercalative binding to ctDNA. Furthermore, the results of molecular modeling confirmed those obtained from spectroscopic, viscosimetric and ITC investigations. Additionally, ITC studies also indicated that the binding interaction is predominantly enthalpy driven. - Highlights: Black-Right-Pointing-Pointer Medically important dihydropyrimidinones derivative EMMD is synthesized. Black-Right-Pointing-Pointer EMMD is intercalative binding into ctDNA helix. Black-Right-Pointing-Pointer Hydrogen bonding may play an essential role in the binding of EMCD with ctDNA. Black-Right-Pointing-Pointer This binding interaction is predominantly enthalpy driven.

  13. NMR investigations of surfaces and interfaces using spin-polarized xenon

    Energy Technology Data Exchange (ETDEWEB)

    Gaede, Holly Caroline [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1995-07-01

    129Xe NMR is potentially useful for the investigation of material surfaces, but has been limited to high surface area samples in which sufficient xenon can be loaded to achieve acceptable signal to noise ratios. In Chapter 2 conventional 129Xe NMR is used to study a high surface area polymer, a catalyst, and a confined liquid crystal to determine the topology of these systems. Further information about the spatial proximity of different sites of the catalyst and liquid crystal systems is determined through two dimensional exchange NMR in Chapter 3. Lower surface area systems may be investigated with spin-polarized xenon, which may be achieved through optical pumping and spin exchange. Optically polarized xenon can be up to 105times more sensitive than thermally polarized xenon. In Chapter 4 highly polarized xenon is used to examine the surface of poly(acrylonitrile) and the formation of xenon clathrate hydrates. An attractive use of polarized xenon is as a magnetization source in cross polarization experiments. Cross polarization from adsorbed polarized xenon may allow detection of surface nuclei with drastic enhancements. A non-selective low field thermal mixing technique is used to enhance the 13C signal of CO2 of xenon occluded in solid CO2 by a factor of 200. High-field cross polarization from xenon to proton on the surface of high surface area polymers has enabled signal enhancements of ~1,000. These studies, together with investigations of the efficiency of the cross polarization process from polarized xenon, are discussed in Chapter 5. Another use of polarized xenon is as an imaging contrast agent in systems that are not compatible with traditional contrast agents. The resolution attainable with this method is determined through images of structured phantoms in Chapter 6.

  14. Barbiturate bearing aroylhydrazine derivatives: Synthesis, NMR investigations, single crystal X-ray studies and biological activity

    Science.gov (United States)

    Giziroglu, Emrah; Sarikurkcu, Cengiz; Aygün, Muhittin; Basbulbul, Gamze; Soyleyici, H. Can; Firinci, Erkan; Kirkan, Bulent; Alkis, Ayse; Saylica, Tayfur; Biyik, Halil

    2016-03-01

    A series of barbituric acid aroylhydrazine derivatives have been prepared from their corresponding 1,3-dimethyl-5-acetyl barbituric acid and aroylhydrazines. All compounds have been fully characterized by using FT-IR, multinuclear NMR (1H, 13C) and Mass (MS) spectrometry. We also describe the X-ray crystal structure of 3a, which crystallizes in the monoclinic P21/n space group. The crystal structure is stabilized with infinite linear chains of dimeric units. Furthermore, all compounds were investigated for their tyrosinase inhibition, antioxidative and antimicrobial activies. The results from biological activity assays have shown that all of compounds have excellent antioxidant, significant tyrosinase inhibition and moderate antimicrobial activity.

  15. NMR investigation of non-brominated and brominated epoxy ester prepolymers

    Science.gov (United States)

    Žigon, M.; Osredkar, U.; Šebenik, A.

    1992-03-01

    1H, 13C and two-dimensional NMR spectroscopy has been used to investigate the structure of epoxy ester prepolymers, based on non-brominated DGEBA-type or brominated DGETBBA-type epoxy resins, and on an oligomeric carboxylic acid. In the presence of a quaternary phosphonium salt, besides diglycidylether of bisphenol A (DGEBA) or diglycidylether of tetrabromobisphenol A (DGETBBA) and their higher oligomers, monoesters with characteristic R-CH 2-CH(OH)-CH 2-OCOR' groups were detected in prevailing quantities. In dependence of the epoxy-carboxy ratio, isomeric monoesters with hydroxymethyl groups, diesters and diols might also be present.

  16. Molecular structure activity on pharmaceutical applications of Phenacetin using spectroscopic investigation

    Science.gov (United States)

    Madanagopal, A.; Periandy, S.; Gayathri, P.; Ramalingam, S.; Xavier, S.

    2017-01-01

    The pharmaceutical compound; Phenacetin was investigated by analyzing FT-IR, FT-Raman and 1H &13C NMR spectra. The hybrid efficient computational calculations performed for computing physical and chemical parameters. The cause of pharmaceutical activity due to the substitutions; carboxylic, methyl and amine groups in appropriate positions on the pedestal compound was deeply investigated. Moreover, 13C NMR and 1H NMR chemical shifts correlated with TMS standard to explain the truth of compositional ratio of base and ligand groups. The bathochromic shift due to chromophores over the energy levels in UV-Visible region was strongly emphasized the Anti-inflammatory chemical properties. The chemical stability was pronounced by the strong kubo gap which showed the occurring of charge transformation within the molecule. The occurrence of the chemical reaction was feasibly interpreted by Gibbs free energy profile. The standard vibrational analysis stressed the active participation of composed ligand groups for the existence of the analgesic as well as antipyretic properties of the Phenacetin compound. The strong dipole interaction energy utilization for the transition among non-vanishing donor and acceptor for composition of the molecular structure was interpreted.

  17. Further NMR-spectroscopic studies of interaction of phospholipid liposomes with methacryloyloxydecyl dihydrogen phosphate (MDP) in dental adhesives.

    Science.gov (United States)

    Fujisawa, S; Komoda, Y

    1993-06-01

    To determine how MDP interacts with liposomes, the chemical shifts of dipalmitoylphosphatidylcholine (DPPC)/MDP and dilauroylphosphatidylethanolamine (DLEA)/cholesterol (CS)/MDP liposomes were studied by NMR spectroscopy using a D2O buffer solution at pH 7.0 as a model for biological membranes. Proton chemical shifts of MDP enhanced shielding in DPPC liposomes together with an increase in the mobility of DPPC. However, MDP signals were not observed in DLEA/CS liposomes due to saturation. It is known that an ionized chemical does not lead to increased permeability of cell membranes composed of a lipid bilayer. However, MDP, which is ionized at pH 7.0, had a large interaction with the liposome systems. This appeared to arise from hydrophobic interaction between deca methylene groups of MDP and acyl chains of phospholipid.

  18. Microscopic and Spectroscopic Investigation of Poly(3-hexylthiophene Interaction with Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Maurizio De Crescenzi

    2011-08-01

    Full Text Available The inclusion of carbon nanotubes in polymer matrix has been proposed to enhance the polymer’s physical and electrical properties. In this study, microscopic and spectroscopic techniques are used to investigate the interaction between poly(3-hexylthiophene (P3HT and nanotubes and the reciprocal modification of physical properties. The presence of P3HT-covered nanotubes dispersed in the polymer matrix has been observed by atomic force microscopy and transmission electron microscopy. Then, the modification of P3HT optical properties due to nanotube inclusion has been evidenced with spectroscopic techniques like absorption and Raman spectroscopy. The study is completed with detailed nanoscale analysis by scanning probe techniques. The ordered self assembly of polymer adhering on the nanotube is unveiled by showing an example of helical wrapping of P3HT. Scanning tunneling spectroscopy study provides information on the electronic structure of nanotube-polymer assembly, revealing the charge transfer from P3HT to the nanotube.

  19. Solution 1H, 15N NMR spectroscopic characterization of substrate-bound, cyanide-inhibited human heme oxygenase: water occupation of the distal cavity.

    Science.gov (United States)

    Li, Yiming; Syvitski, Ray T; Auclair, Karine; Ortiz de Montellano, Paul; La Mar, Gerd N

    2003-11-05

    A solution NMR spectroscopic study of the cyanide-inhibited, substrate-bound complex of uniformly (15)N-labeled human heme oxygenase, hHO, has led to characterization of the active site with respect to the nature and identity of strong hydrogen bonds and the occupation of ordered water molecules within both the hydrogen bonding network and an aromatic cluster on the distal side. [(1)H-(15)N]-HSQC spectra confirm the functionalities of several key donors in particularly robust H-bonds, and [(1)H-(15)N]HSQC-NOESY spectra lead to the identification of three additional robust H-bonds, as well as the detection of two more relatively strong H-bonds whose identities could not be established. The 3D NMR experiments provided only a modest, but important, extension of assignments because of the loss of key TOCSY cross-peaks due to the line broadening from a dynamic heterogeneity in the active site. Steady-state NOEs upon saturating the water signal locate nine ordered water molecules in the immediate vicinity of the H-bond donors, six of which are readily identified in the crystal structure. The additional three are positioned in available spaces to account for the observed NOEs. (15)N-filtered steady-state NOEs upon saturating the water resonances and (15)N-filtered NOESY spectra demonstrate significant negative NOEs between water molecules and the protons of five aromatic rings. Many of the NOEs can be rationalized by water molecules located in the crystal structure, but strong water NOEs, particularly to the rings of Phe47 and Trp96, demand the presence of at least an additional two immobilized water molecules near these rings. The H-bond network appears to function to order water molecules to provide stabilization for the hydroperoxy intermediate and to serve as a conduit to the active site for the nine protons required per HO turnover.

  20. Investigating lanthanide dopant distributions in Yttrium Aluminum Garnet (YAG) using solid state paramagnetic NMR.

    Science.gov (United States)

    McCarty, Ryan J; Stebbins, Jonathan F

    2016-10-01

    This paper demonstrates the approach of using paramagnetic effects observed in NMR spectra to investigate the distribution of lanthanide dopant cations in YAG (yttrium aluminum garnet, Y3Al5O12) optical materials, as a complimentary technique to optical spectroscopy and other standard methods of characterization. We investigate the effects of Ce(3+), Nd(3+), Yb(3+), Tm(3+), and Tm(3+)-Cr(3+) on (27)Al and (89)Y NMR spectra. We note shifted resonances for both AlO4 and AlO6 sites. In some cases, multiple shifted peaks are observable, and some of these can be empirically assigned to dopant cations in known configurations to the observed nuclides. In many cases, AlO6 peaks shifted by more than one magnetic neighbor can be detected. In general, we observe that the measured intensities of shifted resonances, when spinning sidebands are included, are consistent with predictions from models with dopant cations that are randomly distributed throughout the lattice. In at least one set of (27)Al spectra, we identify two sub-peaks possibly resulting from two paramagnetic cations with magnetically coupled spin states neighboring the observed nucleus. We identify systematic changes in the spectra related to known parameters describing the magnetic effects of lanthanide cations, such as larger shift distances when the expectation value of electron spins is greater. We lastly comment on the promise of this technique in future analyses of laser and other crystalline oxide materials. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Vibrational spectroscopic, 1H NMR and quantum chemical computational study of 4-hydroxy-2-oxo-1,2-dihydroquinoline-8-carboxylic acid.

    Science.gov (United States)

    Ulahannan, Rajeev T; Panicker, C Yohannan; Varghese, Hema Tresa; Van Alsenoy, C; Musiol, Robert; Jampilek, Josef; Anto, P L

    2014-01-01

    FT-IR, FT-Raman and (1)H NMR spectra of 4-hydroxy-2-oxo-1,2-dihydroquinoline-8-carboxylic acid were recorded and obtained data were confronted with the computed using Gaussian09 software package. DFT/B3LYP, B3PW91 calculations have been done using 6-31G* and SDD basis sets, to investigate the vibrational frequencies and geometrical parameters. The assignments of the normal modes are done by potential energy distribution (PED) calculations. The calculated first hyperpolarizability is comparable with the reported values of similar quinoline derivatives and is an attractive object for future studies of non-linear optics. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using NBO analysis. MEP predicts the most reactive part in the molecule. The calculated (1)H NMR results are in good agreement with experimental data.

  2. Spectroscopic quantification of soil phosphorus forms by {sup 31}P-NMR after nine years of organic or mineral fertilization

    Energy Technology Data Exchange (ETDEWEB)

    Gatiboni, Luciano Colpo, E-mail: gatiboni@cav.udesc.br [Universidade Estadual de Santa Catarina (UDESC), Lages, SC (Brazil); Brunetto, Gustavo; Rheinheimer, Danilo dos Santos; Kaminski, Joao; Flores, Alex Fabiani Claro; Lima, Maria Angelica Silveira; Girotto, Eduardo; Copetti, Andre Carlos Cruz, E-mail: danilo.rheinheimer@pq.cnpq.br, E-mail: joao.kaminski@gmail.com, E-mail: acflores@quimica.ufsm.br, E-mail: masl32003@gmail.com, E-mail: girottosolos@gmail.com, E-mail: andrecopetti@yahoo.com.br [Universidade Federal de Santa Maria (UFSM), RS (Brazil); Pandolfo, Carla Maria; Veiga, Milton, E-mail: pandolfo@epagri.sc.gov.br, E-mail: milveiga@epagri.sc.gov.br [Empresa de Pesquisa Agropecuaria e Extensao Rural de Santa Catarina (EPAGRI), Campos Novos, SC (Brazil)

    2013-05-15

    Long-standing applications of mineral fertilizers or types of organic wastes such as manure can cause phosphorus (P) accumulation and changes in the accumulated P forms in the soil. The objective of this research was to evaluate the forms of P accumulated in soils treated with mineral fertilizer or different types of manure in a long-term experiment. Soil was sampled from the 0-5 cm layer of plots fertilized with five different nutrient sources for nine years: 1) control without fertilizer; 2) mineral fertilizer at recommended rates for local conditions; 3) 5 t ha{sup -1} year{sup -1} of moist poultry litter; 4) 60 m{sup 3} ha{sup -1} year{sup -1} of liquid cattle manure and 5) 40 m{sup 3} ha{sup -1} year{sup -1} of liquid swine manure. The {sup 31}P-NMR spectra of soil extracts detected the following P compounds: orthophosphate, pyrophosphate, inositol phosphate, glycerophosphate, and DNA. The use of organic or mineral fertilizer over nine years did not change the soil P forms but influenced their concentration. Fertilization with mineral or organic fertilizers stimulated P accumulation in inorganic forms. Highest inositol phosphate levels were observed after fertilization with any kind of manure and highest organic P concentration in glycerophosphate form in after mineral or no fertilization. (author)

  3. Spectroscopic quantification of soil phosphorus forms by 31p-nmr after nine years of organic or mineral fertilization

    Directory of Open Access Journals (Sweden)

    Luciano Colpo Gatiboni

    2013-06-01

    Full Text Available Long-standing applications of mineral fertilizers or types of organic wastes such as manure can cause phosphorus (P accumulation and changes in the accumulated P forms in the soil. The objective of this research was to evaluate the forms of P accumulated in soils treated with mineral fertilizer or different types of manure in a long-term experiment. Soil was sampled from the 0-5 cm layer of plots fertilized with five different nutrient sources for nine years: 1 control without fertilizer; 2 mineral fertilizer at recommended rates for local conditions; 3 5 t ha-1 year-1 of moist poultry litter; 4 60 m³ ha-1 year-1 of liquid cattle manure and 5 40 m³ ha-1 year-1 of liquid swine manure. The 31P-NMR spectra of soil extracts detected the following P compounds: orthophosphate, pyrophosphate, inositol phosphate, glycerophosphate, and DNA. The use of organic or mineral fertilizer over nine years did not change the soil P forms but influenced their concentration. Fertilization with mineral or organic fertilizers stimulated P accumulation in inorganic forms. Highest inositol phosphate levels were observed after fertilization with any kind of manure and highest organic P concentration in glycerophosphate form in after mineral or no fertilization.

  4. Design of ET(B) receptor agonists: NMR spectroscopic and conformational studies of ET7-21[Leu7, Aib11, Cys(Acm)15].

    Science.gov (United States)

    Hewage, Chandralal M; Jiang, Lu; Parkinson, John A; Ramage, Robert; Sadler, Ian H

    2002-03-01

    In a previous report we have shown that the endothelin-B receptor-selective linear endothelin peptide, ET-1[Cys (Acm)1,15, Ala3, Leu7, Aib11], folds into an alpha-helical conformation in a methanol-d3/water co-solvent [Hewage et al. (1998) FEBS Lett., 425, 234-238]. To study the requirements for the structure-activity relationships, truncated analogues of this peptide were subjected to further studies. Here we report the solution conformation of ET7-21[Leu7, Aib11, Cys(Acm)15], in a methanol-d3/water co-solvent at pH 3.6, by NMR spectroscopic and molecular modelling studies. Further truncation of this short peptide results in it displaying poor agonist activity. The modelled structure shows that the peptide folds into an alpha-helical conformation between residues Lys9-His16, whereas the C-terminus prefers no fixed conformation. This truncated linear endothelin analogue is pivotal for designing endothelin-B receptor agonists.

  5. Divergent Urinary Metabolic Phenotypes between Major Depressive Disorder and Bipolar Disorder Identified by a Combined GC-MS and NMR Spectroscopic Metabonomic Approach.

    Science.gov (United States)

    Chen, Jian-Jun; Zhou, Chan-Juan; Liu, Zhao; Fu, Yu-Ying; Zheng, Peng; Yang, De-Yu; Li, Qi; Mu, Jun; Wei, You-Dong; Zhou, Jing-Jing; Huang, Hua; Xie, Peng

    2015-08-07

    Bipolar disorder (BD) is a complex debilitating mental disorder that is often misdiagnosed as major depressive disorder (MDD). Therefore, a large percentage of BD subjects are incorrectly treated with antidepressants in clinical practice. To address this challenge, objective laboratory-based tests are needed to discriminate BD from MDD patients. Here, a combined gas chromatography-mass spectrometry (GC-MS)-based and nuclear magnetic resonance (NMR) spectroscopic-based metabonomic approach was performed to profile urine samples from 76 MDD and 43 BD subjects (training set) to identify the differential metabolites. Samples from 126 healthy controls were included as metabolic controls. A candidate biomarker panel was identified by further analyzing these differential metabolites. A testing set of, 50 MDD and 28 BD subjects was then used to independently validate the diagnostic efficacy of the identified panel using an area under the receiver operating characteristic curve (AUC). A total of 20 differential metabolites responsible for the discrimination between MDD and BD subjects were identified. A panel consisting of six candidate urinary metabolite biomarkers (propionate, formate, (R*,S*)2,3-dihydroxybutanoic acid, 2,4-dihydroxypyrimidine, phenylalanine, and β-alanine) was identified. This panel could distinguish BD from MDD subjects with an AUC of 0.913 and 0.896 in the training and testing sets, respectively. These results reveal divergent urinary metabolic phenotypes between MDD and BD. The identified urinary biomarkers can aid in the future development of an objective laboratory-based diagnostic test for distinguishing BD from MDD patients.

  6. Bio-important antipyrine derived Schiff bases and their transition metal complexes: Synthesis, spectroscopic characterization, antimicrobial, anthelmintic and DNA cleavage investigation

    Science.gov (United States)

    Manjunath, M.; Kulkarni, Ajaykumar D.; Bagihalli, Gangadhar B.; Malladi, Shridhar; Patil, Sangamesh A.

    2017-01-01

    Spectroscopic (IR, NMR, UV-vis, ESR, ESI-mass), magnetic and TGA studies suggests octahedral geometry for all the CoII, NiII and CuII complexes of the Schiff bases, derived from 4-aminoantipyrine and 8-formyl-7-Hydroxy-4-methylcoumarin/5-formyl-6-hydroxycoumarin, coordinated through ONO donor sites. Antibacterial (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi), antifungal (Aspergillus niger, Aspergillus flavus and Cladosporium) and DNA cleavage properties of the metal complexes are investigated. The results suggested that some of the synthesized compounds are potential antimicrobials. The synthesized compounds tested for their anthelmintic activities and it was found that CoII and NiII complexes exhibited good anthelmintic properties.

  7. γ‐ and δ-Lactams through Palladium-Catalyzed Intramolecular Allylic Alkylation: Enantioselective Synthesis, NMR Investigation, and DFT Rationalization

    DEFF Research Database (Denmark)

    Bantreil, Xavier; Prestat, Guillaume; Moreno, Aitor;

    2011-01-01

    the cyclization reactions to take place in up to 94:6 enantiomeric ratio. A model Pd-allyl complex has been prepared and studied through NMR spectroscopic analysis, which provided insight into the processes responsible for the observed enantiomeric ratios. DFT studies were used to characterize the diastereomeric...

  8. Solid state NMR investigation of silica aerogel supported Fischer-Tropsch catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhiru; Dunn, Brian C.; Turpin, Gregory C.; Eyring, Edward M.; Ernst, Richard D.; Pugmire, Ronald J. [Department of Chemistry, University of Utah, Salt Lake City, UT 84112 (United States)

    2007-01-15

    The Fischer-Tropsch (F-T) catalyst is the critical component for the F-T synthesis of a variety of hydrocarbons from syngas. Fischer-Tropsch cobalt, iron and ruthenium catalysts supported on silica aerogel have been prepared using a combination of sol-gel chemistry and vapor phase deposition methods. Solid state NMR spectroscopy, a very powerful technique for analyzing the structure and dynamics of various materials, was employed in the study of these F-T catalyst systems. The silica aerogel supported F-T catalysts have been investigated using both solid state {sup 29}Si and {sup 13}C NMR methods. The silica aerogel's tetrahedral sub-unit structure and the influence of the loaded metal compounds have been observed. Three types of Si(O{sub 1/2}){sub 4} tetrahedral unit structure (Q{sub 2}, Q{sub 3} and Q{sub 4}) are clearly resolved in the silica aerogel samples. The calcining process and the loading of metal compounds produce line broadening in the {sup 29}Si spectra sufficient to prevent clear resolution of the three distinct Q{sub n} spectral lines, but the broadened spectra indicate that the three Q sub-unit structures are still present. The ferrocene and ruthenocene molecules used in the vapor phase deposition method exhibit a rapid exchange within the silica aerogel support similar to what one would expect in the gas or liquid state. (author)

  9. The structure of polycaprolactone-clay nanocomposites investigated by 1H NMR relaxometry.

    Science.gov (United States)

    Monteiro, Mariana S S B; Rodrigues, Claudia Lopes; Neto, Roberto P C; Tavares, Maria Inês Bruno

    2012-09-01

    Nanocomposites based on polycaprolactone (PCL), containing concentrations of 1, 3 and 5 wt% of sodium montmorillonite (NT-25) and organo-modified montmorillonite clay, with three different salts (Viscogel B7, Viscogel S4 and Viscogel B8), were prepared employing the solution intercalation method using chloroform. The PCL nanocomposites were characterized by relaxometry, through determination of the hydrogen spin-lattice relaxation times using low-field nuclear magnetic resonance (NMR). Conventional X-ray diffraction (XDR) was also used to measure the basal space of the nanoclay. The proton spin-lattice relaxation parameters showed that hybrid nanocomposites were formed, containing different parts of intercalated and exfoliated organoclay. The proton T1rhoH also indicated changes in the microstructure, organization and the molecular mobility of the hybrid materials. NMR relaxometry is a good way to evaluate nanomaterials because it provides complementary information, since it is measured in a different time scale. Furthermore, differential scanning calorimetry and thermogravimetric analysis were also used to investigate the crystallization and thermal behavior of the nanocomposites, respectively. All materials had low crystallization temperature (Tc) and the melting temperature (Tm) were very close to that of the PCL matrix, but the degree of crystallinity of the nanocomposites decreased. TGA analysis demonstrated that montmorillonite accelerates PCL's decomposition while unmodified montmorillonite has the opposite effect.

  10. Spectroscopic (FT-IR, FT-Raman, 1H- and 13C-NMR, Theoretical and Microbiological Study of trans o-Coumaric Acid and Alkali Metal o-Coumarates

    Directory of Open Access Journals (Sweden)

    Małgorzata Kowczyk-Sadowy

    2015-02-01

    Full Text Available This work is a continuation of research on a correlation between the molecular structure and electronic charge distribution of phenolic compounds and their biological activity. The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of trans o-coumaric (2-hydroxy-cinnamic acid was studied. We investigated the relationship between the molecular structure of the tested compounds and their antimicrobial activity. Complementary molecular spectroscopic techniques such as infrared (FT-IR, Raman (FT-Raman, ultraviolet-visible (UV-VIS and nuclear magnetic resonance (1H- and 13C-NMR were applied. Structures of the molecules were optimized and their structural characteristics were calculated by the density functional theory (DFT using the B3LYP method with 6-311++G** as a basis set. Geometric and magnetic aromaticity indices, atomic charges, dipole moments and energies were also calculated. Theoretical parameters were compared to the experimental characteristics of investigated compounds. Correlations between certain vibrational bands and some metal parameters, such as electronegativity, ionization energy, atomic and ionic radius, were found. The microbial activity of studied compounds was tested against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris and Candida albicans.

  11. Synthesis, X-ray crystallography, thermal studies, spectroscopic and electrochemistry investigations of uranyl Schiff base complexes.

    Science.gov (United States)

    Asadi, Zahra; Shorkaei, Mohammad Ranjkesh

    2013-03-15

    Some tetradentate salen type Schiff bases and their uranyl complexes were synthesized and characterized by UV-Vis, NMR, IR, TG, C.H.N. and X-ray crystallographic studies. From these investigations it is confirmed that a solvent molecule occupied the fifth position of the equatorial plane of the distorted pentagonal bipyramidal structure. Also, the kinetics of complex decomposition by using thermo gravimetric methods (TG) was studied. The thermal decomposition reactions are first order for the studied complexes. To examine the properties of uranyl complexes according to the substitutional groups, we have carried out the electrochemical studies. The electrochemical reactions of uranyl Schiff base complexes in acetonitrile were reversible.

  12. Raman spectroscopic investigation of thorium dioxide-uranium dioxide (ThO₂-UO₂) fuel materials.

    Science.gov (United States)

    Rao, Rekha; Bhagat, R K; Salke, Nilesh P; Kumar, Arun

    2014-01-01

    Raman spectroscopic investigations were carried out on proposed nuclear fuel thorium dioxide-uranium dioxide (ThO2-UO2) solid solutions and simulated fuels based on ThO2-UO2. Raman spectra of ThO2-UO2 solid solutions exhibited two-mode behavior in the entire composition range. Variations in mode frequencies and relative intensities of Raman modes enabled estimation of composition, defects, and oxygen stoichiometry in these compounds that are essential for their application. The present study shows that Raman spectroscopy is a simple, promising analytical tool for nondestructive characterization of this important class of nuclear fuel materials.

  13. Electron spectroscopic investigation of metal-insulator transition in Ce1-SrTiO3

    Indian Academy of Sciences (India)

    U Manju; S R Krishnakumar; Sugata Ray; S Raj; M Onoda; C Carbone; D D Sarma

    2003-10-01

    We have carried out detailed electron spectroscopic investigation of Ce1-SrTiO3 exhibiting insulator-metal transition with . Core level X-ray photoelectron spectra of Ce 3 as well as resonant photoemission spectra obtained at the Ce 4 → 4 resonant absorption threshold establish Ce as being in the trivalent state throughout the series. Using the `off-resonance’ condition for Ce 4 states, we obtain the Ti 3 dominated spectral features close to , exhibiting clear signatures of coherent and incoherent peaks. We discuss the implications of our findings in relation to the metal-insulator transition observed in this series of compounds.

  14. Investigation of multiaxial molecular dynamics by 2H MAS NMR spectroscopy.

    Science.gov (United States)

    Kristensen, J H; Hoatson, G L; Vold, R L

    1998-11-01

    The technique of 2H MAS NMR spectroscopy is presented for the investigation of multiaxial molecular dynamics. To evaluate the effects of discrete random reorientation a Lie algebraic formalism based on the stochastic Liouville-von Neumann equation is developed. The solution to the stochastic Liouville-von Neumann equation is obtained both in the presence and absence of rf irradiation. This allows effects of molecular dynamics to be evaluated during rf pulses and extends the applicability of the formalism to arbitrary multiple pulse experiments. Theoretical methods are presented for the description of multiaxial dynamics with particular emphasis on the application of vector parameters to represent molecular rotations. Numerical time and powder integration algorithms are presented that are both efficient and easy to implement computationally. The applicability of 2H MAS NMR spectroscopy for investigating molecular dynamics is evaluated from theoretical spectra. To demonstrate the potential of the technique the dynamics of thiourea-2H4 is investigated experimentally. From a series of variable temperature MAS and quadrupole echo spectra it has been found that the dynamics can be described by composite rotation about the CS and CN bonds. Both experiments are sensitive to the fast CS rotation which is shown to be described by the Arrhenius parameters E(CS) = 46.4 +/- 2.3 kJ mol(-1) and ln(A(CS))= 32.6 +/- 0.9. The MAS experiment represents a significant improvement by simultaneously allowing the dynamics of the slow CN rotation to be fully characterized in terms of E(CN) = 56.3 +/- 3.4 kJ mol(-1) and ln(A(CN)) = 25.3 +/- 1.1.

  15. Dynamic Nuclear Polarization NMR as a new tool to investigate the nature of organic compounds occluded in plant silica particles.

    Science.gov (United States)

    Masion, Armand; Alexandre, Anne; Ziarelli, Fabio; Viel, Stéphane; Santos, Guaciara M

    2017-06-13

    The determination of the chemical nature of the organic matter associated with phytoliths remains a challenge. This difficulty mainly stems from amounts of organic carbon (C) that are often well below the detection limit of traditional spectroscopic tools. Conventional solid-state (13)C Nuclear Magnetic Resonance (NMR) is widely used to examine the nature and structure of organic molecules, but its inherent low sensitivity prohibits the observation of diluted samples. The recent advent of commercial microwave source in the terahertz range triggered a renewed interest in the Dynamic Nuclear Polarization (DNP) technique to improve the signal to noise ratio of solid-state NMR experiments. With this technique, the (13)C spectrum of a phytolith sample containing 0.1% w/w C was obtained overnight with sufficient quality to permit a semi-quantitative analysis of the organic matter, showing the presence of peptides and carbohydrates as predominant compounds. Considering the natural abundance of the (13)C isotope, this experiment demonstrates that DNP NMR is sufficiently sensitive to observe spin systems present in amounts as low as a few tens of ppm.

  16. Spectral investigations of 2,5-difluoroaniline by using mass, electronic absorption, NMR, and vibrational spectra

    Science.gov (United States)

    Kose, Etem; Karabacak, Mehmet; Bardak, Fehmi; Atac, Ahmet

    2016-11-01

    One of the most significant aromatic amines is aniline, a primary aromatic amine replacing one hydrogen atom of a benzene molecule with an amino group (NH2). This study reports experimental and theoretical investigation of 2,5-difluoroaniline molecule (2,5-DFA) by using mass, ultraviolet-visible (UV-vis), 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared and Raman (FT-IR and FT-Raman) spectra, and supported with theoretical calculations. Mass spectrum (MS) of 2,5-DFA is presented with their stabilities. The UV-vis spectra of the molecule are recorded in the range of 190-400 nm in water and ethanol solvents. The 1H and 13C NMR chemical shifts are recorded in CDCl3 solution. The vibrational spectra are recorded in the region 4000-400 cm-1 (FT-IR) and 4000-10 cm-1 (FT-Raman), respectively. Theoretical studies are underpinned the experimental results as described below; 2,5-DFA molecule is optimized by using B3LYP/6-311++G(d,p) basis set. The mass spectrum is evaluated and possible fragmentations are proposed based on the stable structure. The electronic properties, such as excitation energies, oscillator strengths, wavelengths, frontier molecular orbitals (FMO), HOMO and LUMO energies, are determined by time-dependent density functional theory (TD-DFT). The electrostatic potential surface (ESPs), density of state (DOS) diagrams are also prepared and evaluated. In addition to these, reduced density gradient (RDG) analysis is performed, and thermodynamic features are carried out theoretically. The NMR spectra (1H and 13C) are calculated by using the gauge-invariant atomic orbital (GIAO) method. The vibrational spectra of 2,5-DFA molecule are obtained by using DFT/B3LYP method with 6-311++G(d,p) basis set. Fundamental vibrations are assigned based on the potential energy distribution (PED) of the vibrational modes. The nonlinear optical properties (NLO) are also investigated. The theoretical and experimental results give a detailed description of

  17. Chromate adsorption on selected soil minerals: Surface complexation modeling coupled with spectroscopic investigation

    Energy Technology Data Exchange (ETDEWEB)

    Veselská, Veronika, E-mail: veselskav@fzp.czu.cz [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Fajgar, Radek [Department of Analytical and Material Chemistry, Institute of Chemical Process Fundamentals of the CAS, v.v.i., Rozvojová 135/1, CZ-16502, Prague (Czech Republic); Číhalová, Sylva [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic); Bolanz, Ralph M. [Institute of Geosciences, Friedrich-Schiller-University Jena, Carl-Zeiss-Promenade 10, DE-07745, Jena (Germany); Göttlicher, Jörg; Steininger, Ralph [ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, DE-76344, Eggenstein-Leopoldshafen (Germany); Siddique, Jamal A.; Komárek, Michael [Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcka 129, CZ-16521, Prague (Czech Republic)

    2016-11-15

    Highlights: • Study of Cr(VI) adsorption on soil minerals over a large range of conditions. • Combined surface complexation modeling and spectroscopic techniques. • Diffuse-layer and triple-layer models used to obtain fits to experimental data. • Speciation of Cr(VI) and Cr(III) was assessed. - Abstract: This study investigates the mechanisms of Cr(VI) adsorption on natural clay (illite and kaolinite) and synthetic (birnessite and ferrihydrite) minerals, including its speciation changes, and combining quantitative thermodynamically based mechanistic surface complexation models (SCMs) with spectroscopic measurements. Series of adsorption experiments have been performed at different pH values (3–10), ionic strengths (0.001–0.1 M KNO{sub 3}), sorbate concentrations (10{sup −4}, 10{sup −5}, and 10{sup −6} M Cr(VI)), and sorbate/sorbent ratios (50–500). Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy were used to determine the surface complexes, including surface reactions. Adsorption of Cr(VI) is strongly ionic strength dependent. For ferrihydrite at pH <7, a simple diffuse-layer model provides a reasonable prediction of adsorption. For birnessite, bidentate inner-sphere complexes of chromate and dichromate resulted in a better diffuse-layer model fit. For kaolinite, outer-sphere complexation prevails mainly at lower Cr(VI) loadings. Dissolution of solid phases needs to be considered for better SCMs fits. The coupled SCM and spectroscopic approach is thus useful for investigating individual minerals responsible for Cr(VI) retention in soils, and improving the handling and remediation processes.

  18. Investigating the interaction between peptides of the amphipathic helix of Hcf106 and the phospholipid bilayer by solid-state NMR spectroscopy

    Science.gov (United States)

    Zhang, Lei; Liu, Lishan; Maltsev, Sergey; Lorigan, Gary A.; Dabney-Smith, Carole

    2013-01-01

    The chloroplast twin arginine translocation (cpTat) system transports highly folded precursor proteins into the thylakoid lumen using the protonmotive force as its only energy source. Hcf106, as one of the core components of the cpTat system, is part of the precursor receptor complex and functions in the initial precursor-binding step. Hcf106 is predicted to contain a single amino terminal transmembrane domain followed by a Pro-Gly hinge, a predicted amphipathic α-helix (APH), and a loosely structured carboxy terminus. Hcf106 has been shown biochemically to insert spontaneously into thylakoid membranes. To better understand the membrane active capabilities of Hcf106, we used solid-state NMR spectroscopy to investigate those properties of the APH. In this study, synthesized peptides of the predicted Hcf106 APH (amino acids 28–65) were incorporated at increasing mol% into 1-palmitoyl-2-oleoyl-sn-glycero-phosphocholine (POPC) and POPC/MGDG (monogalactosyldiacylglycerol; mole ratio 85:15) multilamellar vesicles (MLVs) to probe the peptide-lipid interaction. Solid-state 31P NMR and 2H NMR spectroscopic experiments revealed that the peptide perturbs the headgroup and the acyl chain regions of phospholipids as indicated by changes in spectral lineshape, chemical shift anisotropy (CSA) line width, and 2H order SCD parameters. In addition, the comparison between POPC MLVs and POPC/MGDG MLVs indicated that the lipid bilayer composition affected peptide perturbation of the lipids, and such perturbation appeared to be more intense in a system more closely mimicking a thylakoid membrane. PMID:24144541

  19. Investigation of the conformation of aspartic acid by the NMR method

    Energy Technology Data Exchange (ETDEWEB)

    Tananaeva, N.N.; Gorokhovatskaya, M.Ya.; Tikhonova, R.V.; Kostromina, N.A.

    1986-01-01

    The conformations of aspartic acid were investigated in relation to the pH value by /sup 1/H and /sup 13/C NMR methods. It was shown that the form of the spectra becomes simpler in the transition from the alkaline to the acidic region and changes from an ABX to an A/sub 2/X system. The order of protonation of the donating groups was established. The spin-spin coupling constants at various pH values were calculated, and the conformational transitions were examined on the basis of their variation. The possibility of the closure of a six-membered ring in the molecule in the alkaline region and the opening of this ring in the acidic region was demonstrated.

  20. DOSY-NMR and raman investigations on the self-aggregation and cyclodextrin complexation of vanillin.

    Science.gov (United States)

    Ferrazza, Ruggero; Rossi, Barbara; Guella, Graziano

    2014-06-26

    Vanillin (4-hydroxy-3-methoxybenzaldehyde) is a phenolic aldehyde with limited solubility in water; in this work, we investigate its self-aggregation, as well as its complexation equilibria with β-cyclodextrin by using nuclear magnetic resonance (NMR) and vibrational spectroscopy. In particular, diffusion-ordered NMR (DOSY) measurements allowing to detect diffusional changes caused by aggregation/inclusion phenomena lead to a reliable estimate of the equilibrium constants of these processes, while Raman spectroscopy was used to further characterize some structural details of vanillin self-aggregates and inclusion complexes. Although the self-association binding constant of vanillin in water was found to be low (K(a) ∼10), dimeric species are not negligible within the investigated range of concentration (3-65 mM); on the other hand, formation of β-cyclodextrin self-aggregates was not detected by DOSY measurements on aqueous solutions of β-cyclodextrin at different concentrations (2-12 mM). Finally, the binding of vanillin with β-cyclodextrin, as measured by the DOSY technique within a narrow range of concentrations (2-15 mM) by assuming the existence of only the monomeric 1:1 vanillin/β-CD complex, was about an order of magnitude higher (K(c) ∼ 90) than self-aggregation. However, the value of the equilibrium constant for this complexation was found to be significantly affected by the analytical concentrations of the host and guest system, thus indicating that K(c) is an "apparent" equilibrium constant.

  1. Pr(Ⅲ) and Nd(Ⅲ) Absorption Spectroscopic Probe to Investigate Interaction with Lysozyme (HEW)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Pr(Ⅲ) and Nd(Ⅲ) can be utilized as absorption spectroscopic probes to investigate the interaction of biomolecules like Lysozyme (HEW) with Ca(Ⅱ) in-vitro; the most abundant metal ion in the human body system. The spectroscopic techniques involving comparative absorption, absorption difference, and quantitative intensity analysis using 4f-4f transitions are utilized for changes in the inner sphere coordination pattern of Pr(Ⅲ) and Nd(Ⅲ) in solution as well as in solid state. The present study deals with an important biomolecule in human metabolism, that is, Lysozyme (HEW). The absorption spectral parameters such as the oscillator strength (P), the Judd-Ofelt (Tλ) intensity parameters, and the Slater-Condon inter electronic parameters are calculated using chi square methods. The obtained results are used to determine the probable geometry of the complex in the solution, the nature of the bond between Pr(Ⅲ)/Nd(Ⅲ) with lysozyme, and the inner sphere coordination environment of f-f transitions. The results obtained from various experimental conditions are utilized to investigate the coordination changes in the Pr(Ⅲ)/Nd(Ⅲ) complexes caused by different coordinating sites of lysozyme, normalized bite, denticity, the solvent nature, the coordination number, the nature of bond and other parameters to mimic the interaction of the Ca(Ⅱ) ion with such biomolecule.

  2. Spectroscopic investigations on thin adhesive layers in multi-material laminates.

    Science.gov (United States)

    Voronko, Yuliya; Chernev, Boril S; Eder, Gabriele C

    2014-01-01

    Three different spectroscopic approaches, Raman linescans, Raman imaging, and attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) imaging were evaluated for the visualization of the thin adhesive layers (3-6 μm) present in polymeric photovoltaic backsheets. The cross-sections of the multilayer laminates in the original, weathered, and artificially aged samples were investigated spectroscopically in order to describe the impact of the environmental factors on the evenness and thickness of the adhesive layers. All three methods were found to be suitable tools to detect and visualize these thin layers within the original and aged polymeric laminates. However, as the adhesive layer is not very uniform in thickness and partly disintegrates upon weathering and/or artificial aging, Raman linescans yield only qualitative information and do not allow for an estimation of the layer thickness. Upon increasing the measuring area by moving from one-dimensional linescans to two-dimensional Raman images, a much better result could be achieved. Even though a longer measuring time has to be taken into account, the information on the uniformity and evenness of the adhesive layer obtainable using the imaging technique is much more comprehensive. Although Raman spectroscopy is known to have the superior lateral resolution as compared with ATR FT-IR spectroscopy, the adhesive layers of the samples used within this study (layer thickness 3-6 μm) could also be detected and visualized by applying the ATR FT-IR spectroscopic imaging method. However, the analysis of the images was quite a demanding task, as the thickness of the adhesive layer was in the region of the resolution limit of this method. The information obtained for the impact of artificial aging and weathering on the adhesive layer obtained using Raman imaging and ATR FT-IR imaging was in good accordance.

  3. Spectroscopic investigation on the inclusion complex formation between amisulpride and γ-cyclodextrin.

    Science.gov (United States)

    Negi, Jeetendra Singh; Singh, Shivpal

    2013-02-15

    The purpose of this research was to investigate inclusion complex formation between poorly soluble drug amisulpride (AMI) and γ-cyclodextrin (γ-CD). The solubility of AMI was enhanced by formation of inclusion complex of AMI with nano-hydrophobic cavity of γ-CD. The stoichiometry of inclusion complex was studied by continuous variation Job's plot method and found 1:1. The binding constant was found 1166.65 M(-1) by Benesi-Hildebrand plot. The molecular docking of AMI and γ-CD was done to investigate complexation. The inclusion complex formation was further confirmed by (1)H NMR and FT-IR, DSC and XRD analysis. The solubility of AMI was increased 3.74 times after inclusion complex formation with γ-CD.

  4. NMR as a tool in the investigation of fundamental problems in ordered liquids

    NARCIS (Netherlands)

    Burnell, E.E.; Lange, de C.A.

    2005-01-01

    An overview is presented of modern NMR techniques and a variety of experimental and theoretical tools employed in the study of solutes dissolved in liquid crystals. The NMR techniques involve multiple quantum and spectral subtraction methods, In addition, various experimental and theoretical tools a

  5. Structural and spectroscopic investigation of lanthanum-substituted strontium-oxybritholites

    Indian Academy of Sciences (India)

    K Boughzala; S Nasr; E Ben Salem; F Kooli; K Bouzouita

    2009-05-01

    Lanthanum-substituted strontium-oxybritholites, Sr10-La(PO4)6-(SiO4)O with = 0, 2 and 4, prepared by solid state reaction were investigated by chemical analysis, powder X-ray diffraction, Raman and 29Si MAS NMR spectroscopies. The refinements of powder XRD patterns of the substituted compounds by the Rietveld method showed that the lanthanum occupied the two metal sites, i.e. (4f) and (6h) sites into the apatite structure, with a clear preference for the (6h) sites. A progressive shift of the free oxygen O(4) towards the centre of the triangles formed by the metal-atoms in the (6h) positions was observed when the lanthanum content increased. It led to the formation of a Sr/La(2)-O(4) strong bond, which might have increased the stability of these compounds. The bands of Raman spectra were assigned to the vibration modes of PO4 and SiO4 groups. The comparison of the results of 29Si MAS NMR analysis with those obtained with the 31P previously reported, suggested that both species occupied the same crystallographic sites.

  6. Spectroscopic investigation of the vibrational quasi-continuum arising from internal rotation of a methyl group

    Energy Technology Data Exchange (ETDEWEB)

    Hougen, J.T. [NIST, Gaithersburg, MD (United States)

    1993-12-01

    The goal of this project is to use spectroscopic techniques to investigate in detail phenomena involving the vibrational quasi-continuum in a simple physical system. Acetaldehyde was chosen for the study because: (i) methyl groups have been suggested to be important promotors of intramolecular vibrational relaxation, (ii) the internal rotation of a methyl group is an easily describle large-amplitude motion, which should retain its simple character even at high levels of excitation, and (iii) the aldehyde carbonyl group offers the possibility of both vibrational and electronic probing. The present investigation of the ground electronic state has three parts: (1) understanding the {open_quotes}isolated{close_quotes} internal-rotation motion below, at, and above the top of the torsional barrier, (2) understanding in detail traditional (bond stretching and bending) vibrational fundamental and overtone states, and (3) understanding interactions involving states with multiquantum excitations of at least one of these two kinds of motion.

  7. Structural and mechanical properties of cellulose acetate/graphene hybrid nanofibers: Spectroscopic investigations

    Directory of Open Access Journals (Sweden)

    B. S. Kim

    2013-06-01

    Full Text Available Cellulose acetate/graphene (CA/graphene and cellulose acetate/graphene-COOH (CA/graphene-COOH hybrid nanofibers were fabricated via electrospinning technique, and their morphologies, crystallinity and mechanical properties were investigated. The added amounts of graphene and graphene-COOH were varied from 0.5 to 5.0 wt%. The crystal structures and morphologies of the resultant hybrid nanofibers were investigated by wide angle X-ray diffraction (WAXD, scanning electron microscopy (SEM and transmission electron microscopy (TEM, respectively. Graphene-COOH incorporated CA nanofiber mats showed higher Young’s modulus of about 910 MPa among than those of CA/graphene nanofibers, which is due to molecular interactions between –COOH groups in acid-treated graphene and C=O groups in CA via hydrogen bonding. This specific interaction was demonstrated by spectroscopic studies (Raman and Fourier transform infrared (FT-IR spectroscopies.

  8. NMR investigation of imidazolium-based ionic liquids and their aqueous mixtures.

    Science.gov (United States)

    Cesare Marincola, Flaminia; Piras, Cristina; Russina, Olga; Gontrani, Lorenzo; Saba, Giuseppe; Lai, Adolfo

    2012-04-10

    (1)H and (13)C NMR spectroscopy is employed to investigate the interaction of water with two imidazolium-based ionic liquids (ILs), 1-hexyl-3-methylimidazolium bromide ([C(6)mim]Br) and 1-octyl-3-methylimidazolium bromide ([C(8)mim]Br), at IL concentrations well above the critical aggregation concentration (CAC). The results are compared with those of the neat samples. To this aim, a detailed analysis of the changes in the (1)H chemical shifts, (13)C relaxation parameters, and 2D ROESY data due to the presence of water is performed. The results for both neat ILs are consistent with a packed structure where head-to-head, head-to-tail, and tail-to-tail contacts occur and where the site of maximal mobility restriction is at the polar head. At the lowest investigated water content, the presence of water influences mainly the environment around the IL polar head, slowing down the motional dynamics of the aromatic ring with respect to the alkyl chain. At higher water contents this difference diminishes, the motional freedom of the whole molecule increasing. The presence of ROESY cross-peaks between protons in the polar and apolar IL regions, as well as between protons in non-neighboring alkyl groups, at all investigated water contents suggests that the alkyl tails are not fully segregated in hydrophobic domains, as expected for micelle-like structures.

  9. Synthesis and spectroscopic investigation of nanostructured europium oxalate: A potential red emitting phosphor

    Science.gov (United States)

    Vimal, G.; Mani, K. P.; Biju, P. R.; Joseph, C.; Unnikrishnan, N. V.; Ittyachen, M. A.

    2015-10-01

    Nanostructured europium oxalate was successfully synthesized for the first time by microwave assisted co-precipitation method. Structure and nanocrystalline nature of the synthesized europium oxalate was analyzed using X-ray diffraction and the results were confirmed by transmission electron microscopy. Fourier transform infrared spectroscopy was employed to identify the different functional groups present in the nanostructured europium oxalate. Detailed spectroscopic investigations were carried out using Judd-Ofelt theory to find out the spectroscopic parameters of europium oxalate. Nature of the metal-ligand bond and symmetry of the environment around Eu3+ ions, which strongly influences the luminescence characteristics of the material, were analyzed. Photoluminescence emission spectrum of the material confirmed the strong red emission predicted by the JO theoretical analysis which is further ascertained by CIE chromaticity diagram. Further analysis on the luminescence parameters such as life time, quantum efficiency and color purity of nanostructured europium oxalate revealed the suitability of this material as a potential phosphor for red emission.

  10. Spectroscopic Parameter and Molecular Constant Investigations on Low-Lying States of BeF Radical

    Directory of Open Access Journals (Sweden)

    Jin Feng Sun

    2012-02-01

    Full Text Available The potential energy curves (PECs of X2Σ+, A2Πr and B2Σ+ states of BeF radical have been investigated using the complete active space self-consistent-field (CASSCF method, followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI approach at the correlation-consistent basis sets, cc-pV5Z for Be and aug-cc-pV6Z for F. Based on the PECs of X2Σ+, A2Πr and B2Σ+ states, the spectroscopic parameters (De, Re, ωe, ωeχe, αe and Be have also been determined in the present work. With the PECs determined at the present level of theory, vibrational states have been predicted for each state when the rotational quantum number J equals zero (J = 0. The vibrational levels, inertial rotation and centrifugal distortion constants are determined for the three states, and the classical turning points are also calculated for the X2Σ+ state. Compared with the available experiments and other theories, it can be seen that the present spectroscopic parameter and molecular constant results are more fully in agreement with the experimental findings.

  11. Crystallographic, spectroscopic (FTIR and NMR) and quantum computational calculation studies on bis(2-methoxy-4-((E)-prop-1-enyl)phenyl)oxalate

    Science.gov (United States)

    Ersanli, Cem Cüneyt; Kaya Kantar, Günay; Şaşmaz, Selami

    2017-09-01

    In this paper, we report first, a new synthesis of bis(2-methoxy-4-((E)-prop-1-enyl)phenyl)oxalate, namely, C22H22O6, (I). Then, we present detailed FTIR, 1H NMR, 13C NMR spectroscopies and single-crystal X-ray diffraction techniques, Hartree-Fock (HF) and Density Functional Theory (DFT) molecular orbital calculation study of the title compound. Compound (I) crystallizes in the monoclinic space group P21/c, with Z = 2 in cells with a = 6.3440(5)Å, b = 10.1098(9)Å, c = 16.1899(15)Å, V = 1035.65(16)Å3 and displays weak C-H⋯O intermolecular interaction which contributes to crystal packing. The molecular geometry was also calculated using the Gaussian03W software, and structure was optimized using the HF and DFT/B3LYP methods with the 6-31G(d,p) basis set at the ground state. The harmonic vibrational frequencies, 1H and 13C NMR chemical shifts of I were calculated using the same method with the 6-31G(d,p) basis set. The calculated results show that the predicted geometry can well reproduce structural parameters. The energetic behaviors of the title compound in solvent media were examined using the DFT/B3LYP method with the 6-31G(d,p) basis set applying the Polarizable Continuum Model (PCM). Besides, the frontier molecular orbitals (FMOs), Mulliken population method, natural population analysis (NPA), molecular electrostatic potential (MEP) map of the title compound were investigated by theoretical calculations. Based on vibrational analyses, the thermodynamic properties of I at different temperatures have been calculated, and corresponding relations between the properties and temperature have also been obtained.

  12. Spectroscopic [FT-IR and FT-Raman] and theoretical [UV-Visible and NMR] analysis on α-Methylstyrene by DFT calculations.

    Science.gov (United States)

    Karthikeyan, N; Joseph Prince, J; Ramalingam, S; Periandy, S

    2015-05-15

    In the present research work, the FT-IR, FT-Raman and (13)C and (1)H NMR spectra of the α-Methylstyrene were recorded. The observed fundamental frequencies in finger print as well as functional group regions were assigned according to their uniqueness region. The Gaussian computational calculations are carried out by HF and DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The impact of the presence of vinyl group in phenyl structure of the compound is investigated. The modified vibrational pattern of the molecule associated vinyl group was analyzed. Moreover, (13)C NMR and (1)H NMR were calculated by using the gauge independent atomic orbital (GIAO) method with B3LYP methods and the 6-311++G(d,p) basis set and their spectra were simulated and the chemical shifts linked to TMS were compared. A study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies were carried out. The kubo gap of the present compound was calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. The NLO properties related to Polarizability and hyperpolarizability based on the finite-field approach were also discussed. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

  13. Investigation of zinc alkali pyrophosphate glasses. Part II: Local and medium range orders analysed by 1D/2D NMR

    Energy Technology Data Exchange (ETDEWEB)

    Rajbhandari, P. [UCCS UMR-CNRS 8181, Université de Lille1, Villeneuve d' Ascq (France); Chen, Y. [LASIR UMR-CNRS 8516, Université de Lille1, Villeneuve d' Ascq (France); Doumert, B. [IMMCL CNRS-FR2638, Université de Lille1, Villeneuve d' Ascq (France); Montagne, L. [UCCS UMR-CNRS 8181, Université de Lille1, Villeneuve d' Ascq (France); Tricot, G., E-mail: gregory.tricot@univ-lille1.fr [UCCS UMR-CNRS 8181, Université de Lille1, Villeneuve d' Ascq (France); LASIR UMR-CNRS 8516, Université de Lille1, Villeneuve d' Ascq (France)

    2015-04-01

    The structure of the (66-x)ZnO-xNa{sub 2}O-33.4P{sub 2}O{sub 5} composition line, selected for the development of low-Tg and stable glasses, has been investigated by 1D/2D NMR spectroscopy. If standard 1D {sup 31}P MAS-NMR experiments give access to the Q{sup n} speciation and show the presence of Q{sup 0}, Q{sup 1} and Q{sup 2} sites within the glass structure, application of the homonuclear through-space correlation technique ({sup 31}P DQ-SQ) allows for a more accurate description of the phosphate units. Clear distinction between the Q{sup 1} sites involved in dimmers or in longer chains has been derived from 2D NMR correlation maps and leads to the re-assignment of Q{sup 1} into Q{sup 1,1} and Q{sup 1,2} species. {sup 23}Na and {sup 23}Na({sup 31}P) REDOR MAS-NMR experiments have been used to analyse the Na{sup +} ions distribution and its interaction with the phosphate network. {sup 67}Zn static NMR experiments, performed at very high field, were carried out and suggest a constant Zn{sup 2+} coordination state all along the composition line. The results have been used to discuss the impact of the Zn{sup 2+}/Na{sup +} ratio on the extent of disorder within the glass network expressed in terms of Q{sup n} dismutation equilibrium constant and phosphate chain length distribution. - Highlights: • Structure of zinc alkali pyrophosphate glasses have been analysed by 1D/2D NMR. • 2D {sup 31}P experiments allow to separate Q{sup 1,1} and Q{sup 1,2} species. • {sup 67}Zn static NMR shows a constant signal all along the composition line.

  14. A new combined nuclear magnetic resonance and Raman spectroscopic probe applied to in situ investigations of catalysts and catalytic processes

    Energy Technology Data Exchange (ETDEWEB)

    Camp, Jules C. J.; Mantle, Michael D. [Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA (United Kingdom); York, Andrew P. E. [Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading RG4 9NH (United Kingdom); McGregor, James, E-mail: james.mcgregor@sheffield.ac.uk [Department of Chemical and Biological Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2014-06-15

    Both Raman and nuclear magnetic resonance (NMR) spectroscopies are valuable analytical techniques capable of providing mechanistic information and thereby providing insights into chemical processes, including catalytic reactions. Since both techniques are chemically sensitive, they yield not only structural information but also quantitative analysis. In this work, for the first time, the combination of the two techniques in a single experimental apparatus is reported. This entailed the design of a new experimental probe capable of recording simultaneous measurements on the same sample and/or system of interest. The individual datasets acquired by each spectroscopic method are compared to their unmodified, stand-alone equivalents on a single sample as a means to benchmark this novel piece of equipment. The application towards monitoring reaction progress is demonstrated through the evolution of the homogeneous catalysed metathesis of 1‑hexene, with both experimental techniques able to detect reactant consumption and product evolution. This is extended by inclusion of magic angle spinning (MAS) NMR capabilities with a custom made MAS 7 mm rotor capable of spinning speeds up to 1600 Hz, quantified by analysis of the spinning sidebands of a sample of KBr. The value of this is demonstrated through an application involving heterogeneous catalysis, namely the metathesis of 2-pentene and ethene. This provides the added benefit of being able to monitor both the reaction progress (by NMR spectroscopy) and also the structure of the catalyst (by Raman spectroscopy) on the very same sample, facilitating the development of structure-performance relationships.

  15. (1)H NMR spectroscopic elucidation in solution of the kinetics and thermodynamics of spin crossover for an exceptionally robust Fe(2+) complex.

    Science.gov (United States)

    Petzold, Holm; Djomgoue, Paul; Hörner, Gerald; Speck, J Matthäus; Rüffer, Tobias; Schaarschmidt, Dieter

    2016-09-21

    A series of Fe(2+) spin crossover (SCO) complexes [Fe(5/6)](2+) employing hexadentate ligands (5/6) with cis/trans-1,2-diamino cyclohexanes (4) as central building blocks were synthesised. The ligands were obtained by reductive amination of 4 with 2,2'-bipyridyl-6-carbaldehyde or 1,10-phenanthroline-2-carbaldehyde 3. The chelating effect and the rigid structure of the ligands 5/6 lead to exceptionally robust Fe(2+) and Zn(2+) complexes conserving their structure even in coordinating solvents like dmso at high temperatures. Their solution behavior was investigated using variable temperature (VT) (1)H NMR spectroscopy and VT Vis spectroscopy. SCO behavior was found for all Fe(2+) complexes in this series centred around and far above room temperature. For the first time we have demonstrated that the thermodynamics as well as kinetics for SCO can be deduced by using VT (1)H NMR spectroscopy. An alternative scheme using a linear correction term C(1) to model chemical shifts for Fe(2+) SCO complexes is presented. The rate constant for the SCO of [Fe(rac-trans-5)](2+) obtained by VT (1)H NMR was validated by Laser Flash Photolysis (LFP), with excellent agreement (1/(kHL + kLH) = 33.7/35.8 ns for NMR/LFP). The solvent dependence of the transition temperature T1/2 and the solvatochromism of complex [Fe(rac-trans-5)](2+) were ascribed to hydrogen bond formation of the secondary amine to the solvent. Enantiomerically pure complexes can be prepared starting with R,R- or S,S-1,2-diaminocyclohexane (R,R-trans-4 or S,S-trans-4). The high robustness of the complexes reduces a possible ligand scrambling and allows preparation of quasiracemic crystals of [Zn(R,R-5)][Fe(S,S-5)](ClO4)4·(CH3CN) composed of a 1 : 1 mixture of the Zn and Fe complexes with inverse chirality.

  16. Investigation of material properties by NMR in low and high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Rata, D.G.

    2006-07-10

    In this work the experiments have been performed at both low and high field. The experiments cover various domains from simple relaxation experiments in low field to diffusion and spin-diffusion in high field. The applications of low-field investigations are: - quality control of chemical products. - water content determination inside of the walls of buildings. - determination of multilayer polymer coatings on a concrete. In high-field NMR several alkane molecules swollen at equilibrium in cross-linked natural rubber samples have been investigated and analyzed based on the assumptions of the Vrentras theory. A small diffusion anisotropy of the order of 10% has been discovered because of a deformation of free volume under compression. The anisotropy increases with the cross-link density and the compression ratio. The results presented in this study show that the solvent size influences the anisotropy of the diffusion process through the size parameter. The spin-diffusion measurements have been performed on Stanyl samples with different aged samples, at controlled temperature conditions. (orig.)

  17. X-ray and 1H-NMR spectroscopic studies of the structures and conformations of the new nootropic agents RU-35929, RU-47010 and RU-35965

    Science.gov (United States)

    Amato, Maria E.; Bandoli, Giuliano; Casellato, Umberto; Pappalardo, Giuseppe C.; Toja, Emilio

    1990-10-01

    The crystal and molecular structures of the nootropics (±)1-benzenesulphonyl-2-oxo-5-ethoxypyrrolidine ( 1), (±)1-(3-pyridinylsulphonyl)-2-oxo-5-ethoxypyrrolidine ( 2) and (±)1-benzenesulphonyl-2-oxo-5-isopropyloxypyrrolidine ( 3) have been determined by X-ray analysis. The solution conformation of 1, 2 and 3 has been investigated by 1H NMR spectroscopy. In the solid state, the main feature consists of the similar structural parameters and conformations, with the exception of the conformation adopted by the 5-ethoxy moiety which changes on passing from 1 to 2. The solid state overall enveloped conformation of the 2-pyrrolidinone ring for the three nootropics is found to be retained in solution on the basis of NMR evidence. Comparison between calculated and experimental coupling constant values shows that one of the two possible puckered opposite conformational isomers (half-chair shapes) occurs in solution. The relative pharmacological potencies of 1, 2 and 3 cannot therefore be interpreted in terms of the different conformation features presently detectable by available experimental methods.

  18. Combined experimental and quantum chemical studies on spectroscopic (FT-IR, FT-Raman, UV-Vis, and NMR) and structural characteristics of quinoline-5-carboxaldehyde

    Science.gov (United States)

    Kumru, Mustafa; Altun, Ahmet; Kocademir, Mustafa; Küçük, Vesile; Bardakçı, Tayyibe; Şaşmaz, İbrahim

    2016-12-01

    Comparative experimental and theoretical studies have been performed on the structure and spectral (FT-IR, FT-Raman, UV-Vis and NMR) features of quinoline-5-carboxaldehyde. Quantum chemical calculations have been carried out at Hartree-Fock and density functional B3LYP levels with the triple-zeta 6-311++G** basis set. Two stable conformers of quinoline-5-carboxaldehyde arising from the orientation of the carboxaldehyde moiety have been located at the room temperature. The energetic separation of these conformers is as small as 2.5 kcal/mol with a low transition barrier (around 9 kcal/mol). Therefore, these conformers are expected to coexist at the room temperature. Several molecular characteristics of quinoline-5-carboxaldehyde obtained through B3LYP and time-dependent B3LYP calculations, such as conformational stability, key geometry parameters, vibrational frequencies, IR and Raman intensities, UV-Vis vertical excitation energies and the corresponding oscillator strengths have been analyzed. The 1H and 13C NMR chemical shifts of quinoline-5-carboxaldehyde were also investigated.

  19. Domain-specific interactions between MLN8237 and human serum albumin estimated by STD and WaterLOGSY NMR, ITC, spectroscopic, and docking techniques

    Science.gov (United States)

    Yang, Hongqin; Liu, Jiuyang; Huang, Yanmei; Gao, Rui; Tang, Bin; Li, Shanshan; He, Jiawei; Li, Hui

    2017-03-01

    Alisertib (MLN8237) is an orally administered inhibitor of Aurora A kinase. This small-molecule inhibitor is under clinical or pre-clinical phase for the treatment of advanced malignancies. The present study provides a detailed characterization of the interaction of MLN8237 with a drug transport protein called human serum albumin (HSA). STD and WaterLOGSY nuclear magnetic resonance (NMR)-binding studies were conducted first to confirm the binding of MLN8237 to HSA. In the ligand orientation assay, the binding sites of MLN8237 were validated through two site-specific spy molecules (warfarin sodium and ibuprofen, which are two known site-selective probes) by using STD and WaterLOGSY NMR competition techniques. These competition experiments demonstrate that both spy molecules do not compete with MLN8237 for the specific binding site. The AutoDock-based blind docking study recognizes the hydrophobic subdomain IB of the protein as the probable binding site for MLN8237. Thermodynamic investigations by isothermal titration calorimetry (ITC) reveal that the non-covalent interaction between MLN8237 and HSA (binding constant was approximately 105 M-1) is driven mainly by favorable entropy and unfavorable enthalpy. In addition, synchronous fluorescence, circular dichroism (CD), and 3D fluorescence spectroscopy suggest that MLN8237 may induce conformational changes in HSA.

  20. Investigation of a polymer-dispersed liquid crystal system by NMR diffusometry and relaxometry

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Mingxue

    2013-02-26

    Polymer-dispersed liquid crystals (PDLCs) are polymer composites containing a dispersion of liquid crystal droplets in polymer networks. PDLCs have attracted much attention due to their unique properties and potential usage. The properties of PDLCs depend on the degree of phase separation and the size of liquid crystal droplets. To investigate the structure will help us to better understand and optimize PDLCs.The main aim of this PhD thesis was to investigate PDLCs by NMR techniques. Diffusion constants and spin-lattice relaxation times in the laboratory (T{sub 1}) and rotating frame (T{sub 1{rho}}) were measured for PDLCs as well as precursor mixtures based on the trifunctional monomer trimethylolpropane triacrylate (TMPTA) and the commercial nematic mixture E7. The variation of the main dipolar splitting of {sup 1}H spectra with increasing temperature was analyzed to obtain the nematic-to-isotropic phase transition temperature and the nematic order parameter of E7 and, for comparison, the nematic liquid crystal 5CB.Diffusion constants in TMPTA/E7 mixtures, measured by pulsed-field gradient NMR, increase for both E7 and TMPTA as the mass fraction of E7 increases, due to the lower viscosity of E7. E7 in the PDLC diffuses more slowly than in the bulk because of the hindrance by the polymer matrix. T{sub 1} and T{sub 1{rho}} relaxation times in the liquid or liquid-crystalline phases of TMPTA and bulk E7 are higher than in the PDLC and the pure polymer, due to the lower mobility in the polymer samples. T{sub 1{rho}} in the PDLC is even shorter than in the pure polymer, indicating an anti-softening effect caused by E7 molecules. In bulk E7, the well-ordered rod-like molecules exhibit a unique H-C dipolar coupling, which leads to oscillations in the cross-polarization curve. However, in the PDLC, the anchoring effect at the boundary between the polymer and LC droplets disturbs the molecular order resulting in a smooth cross polarization curve.

  1. A DFT investigation of structure, spectroscopic properties and tautomerism of the anticonvulsant drug Lyrica

    Science.gov (United States)

    Sadeghzade, Zohre; Beyramabadi, S. Ali; Morsali, Ali

    2015-03-01

    The Lyrica (Pregabalin) is a novel anticonvulsant and neuropathic pain drug, which could exist as four possible conformers. Herein, employing density functional theory (DFT), and handling the solvent effects with the PCM model, the structural parameters, energetic behavior, natural bond orbital analysis (NBO), as well as tautomerism mechanization of the Lyrica are investigated. The L1 (-OH form) is the most stable conformer of the Lyrica, which can be tautomerized to the L5 (-NH form) tautomer. The tautomerism reaction includes an intramolecular-proton transfer, which affects considerably the structural parameters and atomic charges of the L1. The DFT-computed NMR chemical shifts and IR vibrational frequencies are good in agreement with the experimental values, confirming suitability of the optimized geometry for the Lyrica.

  2. Structural Investigations of Portland Cement Components, Hydration, and Effects of Admixtures by Solid-State NMR Spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen Bengaard; Andersen, Morten D.; Jakobsen, Hans Jørgen

    2006-01-01

    Solid-state, magic-angle spinning (MAS) NMR spectroscopy represents a valuable tool for structural investigations on the nanoscale of the most important phases in anhydrous and hydrated Portland cements and of various admixtures. This is primarily due to the fact that the method reflects the first...... in the cement phases. The role of flouride ions is of special interest for mineralized Portland cements and it demonstrated that the location of these anions in anhydrous and hydrated Portland cements can be clarified using 19F MAS or 29Si{19F} CP/MAS NMR despite these cements contain only about 0.2 wt...

  3. Interactions between {beta}-carboline alkaloids and bovine serum albumin: Investigation by spectroscopic approach

    Energy Technology Data Exchange (ETDEWEB)

    Nafisi, Shohreh, E-mail: drshnafisi@gmail.com [Department of Chemistry, Islamic Azad University, Central Tehran Branch (IAUCTB), Tehran (Iran, Islamic Republic of); Panahyab, Ataollah [Department of Chemistry, Islamic Azad University, Central Tehran Branch (IAUCTB), Tehran (Iran, Islamic Republic of); Bagheri Sadeghi, Golshan [Department of Biology, Islamic Azad University, Science and Research Branch, Tehran (Iran, Islamic Republic of)

    2012-09-15

    {beta}-Carboline alkaloids are present in medicinal plants such as Peganum harmala L. that have been used as folk medicine in anticancer therapy. BSA is the major soluble protein constituent of the circulatory system, and has many physiological functions including the transport of a variety of compounds. This study is the first attempt to investigate the binding of {beta}-carboline alkaloids to BSA by using a constant protein concentration and varying drug concentrations at pH 7.2. FTIR and UV-Vis spectroscopic methods were used to analyze the binding modes of {beta}-carboline alkaloids, the binding constants and the effects of drug complexation on BSA stability and conformation. Spectroscopic evidence showed that {beta}-carboline alkaloids bind BSA via hydrophobic interaction and van der Waals contacts along with H-bonding with the -NH groups, with overall binding constants of K{sub harmine-BSA}=2.04 Multiplication-Sign 10{sup 4} M{sup -1}, K{sub tryptoline-BSA}=1.2 Multiplication-Sign 10{sup 4} M{sup -1}, K{sub harmaline-BSA}=5.04 Multiplication-Sign 10{sup 3} M{sup -1}, K{sub harmane-BSA}=1.41 Multiplication-Sign 10{sup 3} M{sup -1} and K{sub harmalol-BSA}=1.01 Multiplication-Sign 10{sup 3} M{sup -1}, assuming that there is one drug molecule per protein. The BSA secondary structure was altered with a major decrease of {alpha}-helix from 64% (free protein) to 59% (BSA-harmane), 56% (BSA-harmaline and BSA-harmine), 55% (BSA-tryptoline), 54% (BSA-harmalol) and {beta}-sheet from 15% (free protein) to 6-8% upon {beta}-carboline alkaloids complexation, inducing a partial protein destabilization. - Highlights: Black-Right-Pointing-Pointer We model the binding of {beta}-carboline alkaloids to BSA by using the spectroscopic methods. Black-Right-Pointing-Pointer We investigate the effects of drug complexation on BSA stability and conformation. Black-Right-Pointing-Pointer A partial protein destabilization occurred at high alkaloids concentration. Black

  4. Authenticity study of Phyllanthus species by NMR and FT-IR techniques coupled with chemometric methods

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Maiara S.; Pereira-Filho, Edenir R.; Ferreira, Antonio G. [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica; Boffo, Elisangela F. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Quimica; Figueira, Glyn M., E-mail: maiarassantos@yahoo.com.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Centro Pluridisciplinar de Pesquisas Quimicas, Biologicas e Agricolas

    2012-07-01

    The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as 'quebra-pedras' in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, {sup 1}H HR-MAS NMR and {sup 1}H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques. (author)

  5. Authenticity study of Phyllanthus species by NMR and FT-IR Techniques coupled with chemometric methods

    Directory of Open Access Journals (Sweden)

    Maiara S. Santos

    2012-01-01

    Full Text Available The importance of medicinal plants and their use in industrial applications is increasing worldwide, especially in Brazil. Phyllanthus species, popularly known as "quebra-pedras" in Brazil, are used in folk medicine for treating urinary infections and renal calculus. This paper reports an authenticity study, based on herbal drugs from Phyllanthus species, involving commercial and authentic samples using spectroscopic techniques: FT-IR, ¹H HR-MAS NMR and ¹H NMR in solution, combined with chemometric analysis. The spectroscopic techniques evaluated, coupled with chemometric methods, have great potential in the investigation of complex matrices. Furthermore, several metabolites were identified by the NMR techniques.

  6. Spectroscopic investigation of asteroids belonging to the Themis and Beagle families

    Science.gov (United States)

    Fornasier, S.; Perna, D.; Barucci, M. A.; Merlin, F.; Dotto, E.

    2012-09-01

    24 Themis is the largest body of the Themis family. Within this big family a cluster of very young asteroids (age Beagle sub-family, has been identified. Recently water ice and organics were detected on 24 Themis indicating that the Themis family may be an important reservoir of ice. Moreover, the main belt comets 133P, 238P, and 176P may be related with the Themis family because of orbital proximities and spectral properties analogies. The aim of this work is to spectroscopically investigate some asteroids belonging to the Themis family and to the young Beagle sub-family in order to look for absorption bands related to water ice, hydrated silicates and organics.

  7. 15N and 1H Solid-State NMR Investigation of a Canonical Low-Barrier Hydrogen-Bond Compound: 1,8-bis(dimethylamino) naphthalene

    OpenAIRE

    White, Paul B.; Hong, Mei

    2015-01-01

    Strong or low-barrier hydrogen bonds have been often proposed in proteins to explain enzyme catalysis and proton transfer reactions. So far 1H chemical shifts and scalar couplings have been used as the main NMR spectroscopic signatures for strong H-bonds. In this work, we report simultaneous measurements of 15N and 1H chemical shifts and N-H bond lengths by solid-state NMR in 15N-labeled 1,8-bis(dimethylamino) naphthalene (DMAN), which contains a well known strong NHN H-bond. We complexed DMA...

  8. Influence of Zn-Cd substitution: spectroscopic and theoretical investigation of 8-hydroxyquinoline complexes.

    Science.gov (United States)

    Ramalho, Teodorico C; Martins, Tales L C; Borges, Luiz E Pizarro; de Pinho, Marcos Henrique; de Avillez, Roberto Ribeiro; da Cunha, Elaine F F

    2009-05-01

    It is now well known that zinc is crucial for the synthesis of nucleic acids and, consequently, for cellular division. However, (67)Zn, the NMR-detectable isotope, is one of the isotopes most poorly studied by NMR. The strategy used for NMR studies is the substitution of Zn by (113)Cd. In this work, we employed (13)C, (113)Cd NMR (CPMAS), X-ray and DFT calculation in order to evaluate the Zn-Cd substitution using 8-hydroxyquinoline like prototype compound. Our results show that there are strong structural and electronics effects are involved in the substitution.

  9. Push-through Direction Injectin NMR Automation

    Science.gov (United States)

    Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the two major spectroscopic techniques successfully used in metabolomics studies. The non-invasive, quantitative and reproducible characteristics make NMR spectroscopy an excellent technique for detection of endogeno...

  10. Push-through Direction Injectin NMR Automation

    Science.gov (United States)

    Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the two major spectroscopic techniques successfully used in metabolomics studies. The non-invasive, quantitative and reproducible characteristics make NMR spectroscopy an excellent technique for detection of endogeno...

  11. Solid state NMR investigation of a novel Li ion ceramic electrolyte. Li doped BPO sub 4

    CERN Document Server

    Dodd, A J

    2002-01-01

    Over the last decade lithium ion conducting batteries have emerged as the leading technology in battery materials. Their performance, however, is limited to applications below around 50 deg C by the liquid nature of the electrolytes used. In the quest for a solid state electrolyte for use in high temperature applications the nano-crystalline ceramic lithium doped boron phosphate material was developed. Solid state nuclear magnetic resonance (NMR) has been employed to investigate some of the fundamental properties of this material including ionic mobility, defect structure, sample purity and ionic distribution. The findings of this work show that when synthesised at a reaction temperature above 600 deg C the loss of boron from the structure results in the incorporation of vacancy sites about which the Li ions gather in small clusters. Multiple-pulse multiple-quantum spin counting techniques are employed in an effort to count the number of quadrupolar sup 7 Li nuclei interacting in a cluster though it is ultima...

  12. A review on the applications of the nuclear magnetic resonance (NMR) technology for investigating fractures

    Science.gov (United States)

    Golsanami, Naser; Sun, Jianmeng; Zhang, Zhiying

    2016-10-01

    This review focuses on the recent applications of nuclear magnetic resonance (NMR) technology for characterizing fractures. The paper aims to help researchers in extending the existing reservoir characterization methods (which are commonly used in conventional hydrocarbon reservoirs) for appropriate usage in unconventional resources. This is because some techniques for quantifying and qualifying fractures have been investigated in conventional sandstone and carbonate reservoirs, but the reality for unconventional resources is that such techniques are still poorly developed. Fractures are necessary for economical production of petroleum from many low-permeability reservoirs. The characterization of fractures by well logging technology is of great interest in the petroleum industry. The main purpose of this study is to review the characterization techniques that are developed either for identifying fractures or distinguishing fracture porosity from matrix porosity. This concept plays a leading role in providing availability of an optimized well completion program. The results of this study indicated that in terms of both sandstone and carbonate tight reservoirs, there have not been many steps taken toward the aforementioned goal up to now. Nevertheless, these steps are valuable enough to be counted on and could serve a meaningful function in treating hydrocarbon reservoirs. Because of the ongoing changes in today's petroleum industry, development of a comprehensive methodology will create greater economic benefits in unconventional reservoirs than in the conventional ones.

  13. Investigation of Rhodopsin Dynamics in its Signaling State by Solid-State Deuterium NMR Spectroscopy

    Science.gov (United States)

    Struts, Andrey V.; Chawla, Udeep; Perera, Suchithranga M.D.C.; Brown, Michael F.

    2017-01-01

    Site-directed deuterium NMR spectroscopy is a valuable tool to study the structural dynamics of biomolecules in cases where solution NMR is inapplicable. Solid-state 2H NMR spectral studies of aligned membrane samples of rhodopsin with selectively labeled retinal provide information on structural changes of the chromophore in different protein states. In addition, solid-state 2H NMR relaxation time measurements allow one to study the dynamics of the ligand during the transition from the inactive to the active state. Here we describe the methodological aspects of solid-state 2H NMR spectroscopy for functional studies of rhodopsin, with an emphasis on the dynamics of the retinal cofactor. We provide complete protocols for the preparation of NMR samples of rhodopsin with 11-cis-retinal selectively deuterated at the methyl groups in aligned membranes. In addition, we review optimized conditions for trapping the rhodopsin photointermediates; and lastly we address the challenging problem of trapping the signaling state of rhodopsin in aligned membrane films. PMID:25697522

  14. New organic single crystal of (benzylthio)acetic acid: Synthesis, crystal structure, spectroscopic (ATR-FTIR, 1H and 13C NMR) and thermal characterization

    Science.gov (United States)

    Sienkiewicz-Gromiuk, Justyna; Tarasiuk, Bogdan; Mazur, Liliana

    2016-04-01

    (Benzylthio)acetic acid (Hbta) was synthesized with 78% yield from benzyl chloride and thiourea as substrates. Well-shaped crystals of Hbta were grown by slow solvent evaporation technique from pure methanol. The compound was investigated by single-crystal X-ray and powder diffraction techniques and was also characterized by other analytical methods, like ATR-FTIR, 1H and 13C NMR and TG/DSC. The acid molecule adopts bent conformation in the solid state. The crystal structure of Hbta is stabilized by numerous intermolecular interactions, including O-H···O, C-H···O, C-H···S and C-H···π contacts. Thermal decomposition of the obtained material takes place above 150 °C.

  15. Accurate molecular structure and spectroscopic properties for nucleobases: A combined computational - microwave investigation of 2-thiouracil as a case study

    Science.gov (United States)

    Puzzarini, Cristina; Biczysko, Malgorzata; Barone, Vincenzo; Peña, Isabel; Cabezas, Carlos; Alonso, José L.

    2015-01-01

    The computational composite scheme purposely set up for accurately describing the electronic structure and spectroscopic properties of small biomolecules has been applied to the first study of the rotational spectrum of 2-thiouracil. The experimental investigation was made possible thanks to the combination of the laser ablation technique with Fourier Transform Microwave spectrometers. The joint experimental – computational study allowed us to determine accurate molecular structure and spectroscopic properties for the title molecule, but more important, it demonstrates a reliable approach for the accurate investigation of isolated small biomolecules. PMID:24002739

  16. Spectroscopic investigation of the interactions of carbofuran and amitrol herbicides with human serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Tunç, Sibel, E-mail: stunc@akdeniz.edu.tr; Duman, Osman, E-mail: osmanduman@akdeniz.edu.tr; Soylu, İnanç; Kancı Bozoğlan, Bahar

    2014-07-01

    In this study, various spectroscopic techniques including UV absorption, fluorescence and synchronous fluorescence spectroscopy were used to examine the interactions of carbofuran (CF) and amitrol (AMT) herbicides with human serum albumin (HSA). The results of spectroscopic experiments illustrated that CF was bound by HSA, on the other hand there was no interaction between HSA and AMT molecules. In HSA–CF system, static quenching mechanism was responsible for the fluorescence quenching of HSA. The Stern–Volmer constant and binding constant decreased with increasing temperature. This means that an increase in temperature reduces the stability of HSA–CF complex. In HSA–CF system, the number of binding site on protein was found to be one. From the thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) were calculated as −22.30 kJ mol{sup −1} and −10.70 J mol{sup −1} K{sup −1}, respectively, which indicated that the interaction forces between HSA and CF molecules were mainly hydrogen bonding and van der Waals forces. The conformational change in the protein structure was investigated by synchronous fluorescence spectroscopy. According to the results of synchronous fluorescence analysis, there was a change in the protein structure owing to the interaction of CF with HSA. - Highlights: • UV absorption, fluorescence and synchronous fluorescence measurements confirm the formation of HSA–CF complex. • The formation of HSA–CF complex involves both hydrogen bonding and van der Waals forces. • There is no interaction between HSA and AMT molecules. • Binding constants, numbers of binding sites and thermodynamic parameters have been calculated. • The binding of CF to HSA changes the conformational structure of protein.

  17. Investigation of neohesperidin dihydrochalcone binding to human serum albumin by spectroscopic methods

    Energy Technology Data Exchange (ETDEWEB)

    Bozoğlan, Bahar Kancı; Tunç, Sibel, E-mail: stunc@akdeniz.edu.tr; Duman, Osman, E-mail: osmanduman@akdeniz.edu.tr

    2014-11-15

    In this study, the interaction of human serum albumin (HSA) with neohesperidin dihydrochalcone (NHD) was investigated by UV, fluorescence, synchronous fluorescence and circular dichroism spectroscopic methods. Experimental results confirmed the complex formation between HSA and NHD molecules under physiological conditions. NHD quenched the intrinsic fluorescence spectrum of HSA by static quenching mechanism. The binding constant of this system was calculated as 2.79×10{sup 4} M{sup −1} at 298.15 K. The stability of HSA–NHD complex illustrated a decrease with increasing temperature. The number of binding sites was found to be 1. Thermodynamic parameter values were calculated by using van’t Hoff equation. According to sign and magnitude of thermodynamic parameters (ΔH=−29.22 kJ mol{sup −1} and ΔS=−12.91 J mol{sup −1} K{sup −1}), hydrogen bonding and van der Waals forces were found as the effective interaction forces between HSA and NHD molecules. Synchronous fluorescence and circular dichroism spectroscopic methods proved the alteration of secondary structure of HSA in the presence of NHD. Site marker competitive experiments indicated that the binding of NHD to HSA took place in subdomain IIA region of protein. - Highlights: • Static quenching mechanism is effective in the interaction of HSA with NHD. • Hydrogen bonding and van der Waals forces play an important role in the binding process. • NHD causes a slight change in the conformational structure of HSA. • The binding site of NHD takes place in subdomain IIA region of HSA.

  18. 13C-NMR spectroscopic evaluation of the citric acid cycle flux in conditions of high aspartate transaminase activity in glucose-perfused rat hearts.

    Science.gov (United States)

    Tran-Dinh, S; Hoerter, J A; Mateo, P; Gyppaz, F; Herve, M

    1998-12-01

    A new mathematical model, based on the observation of 13C-NMR spectra of two principal metabolites (glutamate and aspartate), was constructed to determine the citric acid cycle flux in the case of high aspartate transaminase activity leading to the formation of large amounts of labeled aspartate and glutamate. In this model, the labeling of glutamate and aspartate carbons by chemical and isotopic exchange with the citric acid cycle are considered to be interdependent. With [U-13C]Glc or [1,2-(13)C]acetate as a substrate, all glutamate and aspartate carbons can be labeled. The isotopic transformations of 32 glutamate isotopomers into 16 aspartate isotopomers or vice versa were studied using matrix operations; the results were compiled in two matrices. We showed how the flux constants of the citric acid cycle and the 13C-enrichment of acetyl-CoA can be deduced from 13C-NMR spectra of glutamate and/or aspartate. The citric acid cycle flux in beating Wistar rat hearts, aerobically perfused with [U-13C]glucose in the absence of insulin, was investigated by 13C-NMR spectroscopy. Surprisingly, aspartate instead of glutamate was found to be the most abundantly-labeled metabolite, indicating that aspartate transaminase (which catalyses the reversible reaction: (glutamate + oxaloacetate 2-oxoglutarate + aspartate) is highly active in the absence of insulin. The amount of aspartate was about two times larger than glutamate. The quantities of glutamate (G0) or aspartate (A0) were approximately the same for all hearts and remained constant during perfusion: G0 = (0.74 +/- 0.03) micromol/g; A0 = (1.49 +/- 0.05) micromol/g. The flux constants, i.e., the fraction of glutamate and aspartate in exchange with the citric acid cycle, were about 1.45 min(-1) and 0.72 min(-1), respectively; the flux of this cycle is about (1.07 +/- 0.02) micromol min(-1) g(-1). Excellent agreement between the computed and experimental data was obtained, showing that: i) in the absence of insulin, only 41

  19. Molecular structure, spectroscopic characterization (FT-IR, FT-Raman, UV and NMR), HOMO and LUMO analysis of 3-ethynylthiophene with DFT quantum chemical calculations

    Science.gov (United States)

    Karabacak, Mehmet; Bilgili, Sibel; Mavis, Tugba; Eskici, Mustafa; Atac, Ahmet

    2013-11-01

    In this work, FT-IR, FT-Raman, UV and NMR spectra of 3-ethynylthiophene (3-ETP, C6H4S) were carried out by using density functional theory DFT/B3LYP method with the 6-311++G(d,p), 6-311+G(d,p), 6-311G(d,p), 6-31++G(d,p), 6-31+G(d,p), 6-31G(d,p) basis sets. FT-IR and FT-Raman spectra were recorded in the regions of 3500-400 cm-1 and 3500-50 cm-1, respectively. The geometrical parameters, energies and wavenumbers were obtained and the complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The 1H, 13C and HMQC (1H-13C correlation) NMR spectra in chloroform (CDCl3) were recorded and calculated. The UV spectrum of investigated compound were recorded in the region of 200-400 nm in ethanol solution. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies were performed by DFT/B3LYP approach and the results were compared with experimental observations. The thermodynamic properties such zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment of the studied compound were calculated. As a result, the calculated results were compared with the observed data and found to be in good agreement.

  20. Theoretical and experimental investigation of the 1H NMR spectrum of putrescine

    Science.gov (United States)

    Allouche, A. R.; Graveron-Demilly, D.; Fauvelle, F.; Aubert-Frécon, M.

    2008-12-01

    Chemical shifts δ and spin-spin coupling constants J have been calculated for the putrescine molecule, a polyamine present in prostate tissue, through a DFT/B3LYP/6-311++G(d,p)/PCM/(GIAO) approach, which has been shown to be accurate in previous work. From δ and J values, calculated for the first time for the isolated and the solvated putrescine, the 1H NMR spectra have been simulated. Comparisons between the calculated and the experimental NMR spectra at 400 MHz show a good agreement and allow to propose reliable values for the NMR spin Hamiltonian parameters of putrescine to be used as good starting values for further quantitation methods of metabolites in prostate tissue.

  1. Bis(pentamethylcyclopentadienyl)ytterbium: An investigation of weak interactions in solution using multinuclear NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, D.J.

    1995-07-01

    NMR spectroscopy is ideal for studying weak interactions (formation enthalpy {le}20 kcal/mol) in solution. The metallocene bis(pentamethylcyclopentadienyl)ytterbium, Cp*{sub 2}Yb, is ideal for this purpose. cis-P{sub 2}PtH{sub 2}complexes (P = phosphine) were used to produce slow-exchange Cp*{sub 2}YbL adducts for NMR study. Reversible formation of (P{sub 2}PtH){sub 2} complexes from cis-P{sub 2}PtH{sub 2} complexes were also studied, followed by interactions of Cp*{sub 2}Yb with phosphines, R{sub 3}PX complexes. A NMR study was done on the interactions of Cp*{sub 2}Yb with H{sub 2}, CH{sub 4}, Xe, CO, silanes, stannanes, C{sub 6}H{sub 6}, and toluene.

  2. Molecular dynamics of spider dragline silk fiber investigated by 2H MAS NMR.

    Science.gov (United States)

    Shi, Xiangyan; Holland, Gregory P; Yarger, Jeffery L

    2015-03-09

    The molecular dynamics of the proteins that comprise spider dragline silk were investigated with solid-state (2)H magic angle spinning (MAS) NMR line shape and spin-lattice relaxation time (T1) analysis. The experiments were performed on (2)H/(13)C/(15)N-enriched N. clavipes dragline silk fibers. The silk protein side-chain and backbone dynamics were probed for Ala-rich regions (β-sheet and 31-helical domains) in both native (dry) and supercontracted (wet) spider silk. In native (dry) silk fibers, the side chains in all Ala containing regions undergo similar fast methyl rotations (>10(9) s(-1)), while the backbone remains essentially static (silk is wet and supercontracted, the presence of water initiates fast side-chain and backbone motions for a fraction of the β-sheet region and 31-helicies. β-Sheet subregion 1 ascribed to the poly(Ala) core exhibits slower dynamics, while β-sheet subregion 2 present in the interfacial, primarily poly(Gly-Ala) region that links the β-sheets to disordered 31-helical motifs, exhibits faster motions when the silk is supercontracted. Particularly notable is the observation of microsecond backbone motions for β-sheet subregion 2 and 31-helicies. It is proposed that these microsecond backbone motions lead to hydrogen-bond disruption in β-sheet subregion 2 and helps to explain the decrease in silk stiffness when the silk is wet and supercontracted. In addition, water mobilizes and softens 31-helical motifs, contributing to the increased extensibility observed when the silk is in a supercontracted state. The present study provides critical insight into the supercontraction mechanism and corresponding changes in mechanical properties observed for spider dragline silks.

  3. Spectroscopic and structural investigation of undoped and Er{sup 3+} doped hafnium silicate layers

    Energy Technology Data Exchange (ETDEWEB)

    Khomenkova, L., E-mail: khomen@ukr.net [CIMAP CEA/CNRS/ENSICAEN/UCBN, 6 Blvd. Maréchal Juin, 14050 Caen Cedex 4 (France); V. Lashkaryov Institute of Semiconductor Physics at NASU, 41 Pr. Nauky, Kyiv 03028 (Ukraine); An, Y.-T. [CIMAP CEA/CNRS/ENSICAEN/UCBN, 6 Blvd. Maréchal Juin, 14050 Caen Cedex 4 (France); Khomenkov, D. [Taras Shevchenko National University of Kyiv, Faculty of Physics, 4 Pr. Hlushkov, Kyiv 03022 (Ukraine); Portier, X.; Labbé, C.; Gourbilleau, F. [CIMAP CEA/CNRS/ENSICAEN/UCBN, 6 Blvd. Maréchal Juin, 14050 Caen Cedex 4 (France)

    2014-11-15

    This paper demonstrates the functionality of radio-frequency magnetron sputtering for the fabrication of undoped and Er-doped Si-rich-HfO{sub 2} films with specific structural and spectroscopic properties. The effect of post-deposition treatment on film properties was investigated by means of Fourier-transform infrared spectroscopy, Raman scattering and photoluminescence methods, as well as Transmission Electron microscopy. It was observed that annealing treatment at 850–1000 °C causes phase separation process and the formation of HfO{sub 2}, SiO{sub 2} and pure Si phases. This process stimulates also an intense light emission in the 700–950-nm spectral range under broad band excitation. The phase separation mechanism as well as the nature of radiative transitions were discussed. Photoluminescence was ascribed to carrier recombination in silicon clusters and host defects. The appearance of silicon clusters was also confirmed by the comparison of luminescent properties of pure HfO{sub 2}, SiO{sub 2}, Si-rich-HfO{sub 2} and Si-rich-SiO{sub 2} films. Additional argument for Si clusters’ formation was obtained under investigation of Er-doped Si-rich HfO{sub 2} films. These latter demonstrated 1.54-µm Er{sup 3+} luminescence under non-resonant excitation originating from an energy transfer from Si clusters towards Er{sup 3+} ions.

  4. Spectroscopic investigation of zinc tellurite glasses doped with Yb3 + and Er3 + ions

    Science.gov (United States)

    Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

    2016-08-01

    This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80 - x - y) TeO2 + (0.20) ZnO + xEr2O3 + yYb2O3 (x = 0, y = 0; x = 0.004, y = 0; x = 0, y = 0.05 and x = 0.004, y = 0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er3 + glasses as erbium doped fiber amplifiers at 1.55 μm in infrared emission region.

  5. In situ spectroscopic investigation of the cobalt-catalyzed oxidation of lignin model compounds in ionic liquids

    NARCIS (Netherlands)

    Zakzeski, J.; Bruijnincx, P.C.A.; Weckhuysen, B.M.

    2011-01-01

    The cobalt-catalyzed oxidation of lignin and lignin model compounds using molecular oxygen in ionic liquids proceeds readily under mild conditions, but mechanistic insight and evidence for the species involved in the catalytic cycle is lacking. In this study, a spectroscopic investigation of the com

  6. Spectroscopic and structural investigation on intermediates species structurally associated to the tricyclic bisguanidine compound and to the toxic agent, saxitoxin

    Science.gov (United States)

    Romani, Davide; Tsuchiya, Shigeki; Yotsu-Yamashita, Mari; Brandán, Silvia Antonia

    2016-09-01

    In the present work, we have studied the structural, topological and spectroscopic properties of five cyclic and of open chain species derived from tricyclic bisguanidine compound in gas and aqueous phases combining the DFT calculations with the experimental infrared and 1H NMR, 13C NMR and UV-visible spectra. These species are members of the saxitoxin family and they were recently synthesized by Tsuchiya et al. (Chemistry. A European Journal, 21 (2015) 7835-7840). Here, the self consistent reaction force (SCRF) calculations were employed in aqueous medium to study the solvation energies by using the polarized continuum (PCM) and solvation (SM) models. All the calculations were performed with the 6-31G* and 6-311++G** basis sets. The atomic charges, electrostatic potentials, bond order, stabilization energy, topological properties suggest the structural connection between the cyclic cationic and saxitoxin species while the electrophilicity and nucleophilicity indexes could be one of the explanations for the Nav blocking activities of these species. The complete vibrational assignments for all the species are reported. The predicted spectra present a reasonable concordance with the corresponding experimental ones.

  7. NMR investigation of field-induced magnetic order in barium manganese oxide

    Science.gov (United States)

    Suh, Steve

    the triangular Mn5+ magnetic lattice of Ba3Mn2O8 coupled with interdimer interaction is predicted to result in incommensurate spin structure when the symmetry axis of Ba3Mn2O8 is aligned parallel to the field. Because of single ion anisotropy of the system, Ba3Mn 2O8 has phase diagram that depends on its alignment with respect to the external field[5]. This means that the microscopic spin structure is different depending on whether the material's symmetry axis is aligned parallel or perpendicular to the field. Also, since we are dealing with S = 1, we have potential to investigate spin-gap closure due to singlet and triplet states as well as triplet and quintet states if we are able to access high enough fields (15T to 30T). Measurements at National High Magnetic Field Laboratory (NHMFL), gives us a superficial taste of what it is like to be in the phase created by triplet and quintet gap closure. The temperature range allowed by the Oxford dilution refrigerator system at Brown Lab, UCLA is from 1K down to 30mK. The magnetic field range allowed by the superconducting magnet at Brown Lab, UCLA is from 0T up to 12T. This combination of temperature and field range allows us to investigate the first quantum critical point (Hc1) in detail with various NMR measurements. Normal state frequency shift as a function of temperature near Hc1 reveals behavior consistent with dilute hardcore bose gas. Analysis of the lineshapes of NMR spectra going into spin order BEC phase as a function of field, we directly observe incommensurate nature of spin order and deduce development of order parameter consistent with mean-field theory. Finally, we verify that the language of dilute 3D Bosons also applies to Ba3Mn2O8 through T1 measurements. From critical behavior inferred in T1 measurements, we complete phase boundary diagram at low temperatures and apply general concept of softening in Goldstone mode near Hc1 to describe our T 1 dependence as a function of temperature.

  8. Structural investigation of bistrifluron using x-ray crystallography, NMR spectroscopy, and molecular modeling

    CERN Document Server

    Moon, J K; Rhee, S K; Kim, G B; Yun, H S; Chung, B J; Lee, S S; Lim, Y H

    2002-01-01

    A new insecticide, bistrifluron acts as an inhibitor of insect development and interferes with the cuticle formation of insects. Since it shows low acute oral and dermal toxicities, it can be one of potent insecticides. Based on X-ray crystallography, NMR spectroscopy and molecular modeling, the structural studies of bistrifluron have been carried out.

  9. USING HIGH-RESOLUTION SOLUTION-STATE NMR SPECTROSCOPY TO INVESTIGATE PMDI REACTIONS WITH WOOD

    Science.gov (United States)

    Solution-state NMR spectroscopy provides a powerful tool for understanding the formation of chemical bonds between wood components and adhesives. Finely ground cell wall (CW) material fully dissolves in a solvent system containing dimethylsulfoxide (DMSO-d6) and N-methyl¬imidazole (NMI-d6), keeping ...

  10. Synergistic effect of the simultaneous chemometric analysis of {sup 1}H NMR spectroscopic and stable isotope (SNIF-NMR, {sup 18}O, {sup 13}C) data: Application to wine analysis

    Energy Technology Data Exchange (ETDEWEB)

    Monakhova, Yulia B., E-mail: yul-monakhova@mail.ru [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Bruker Biospin GmbH, Silberstreifen, Rheinstetten 76287 (Germany); Department of Chemistry, Saratov State University, Astrakhanskaya Street 83, Saratov 410012 (Russian Federation); Godelmann, Rolf [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Hermann, Armin [Landesuntersuchungsamt -Institut für Lebensmittelchemie und Arzneimittelprüfung, Emy-Roeder-Straße 1, Mainz 55129 (Germany); Kuballa, Thomas [Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, Karlsruhe 76187 (Germany); Cannet, Claire; Schäfer, Hartmut; Spraul, Manfred [Bruker Biospin GmbH, Silberstreifen, Rheinstetten 76287 (Germany); Rutledge, Douglas N. [AgroParisTech, UMR 1145, Ingénierie Procédés Aliments, 16 rue Claude Bernard, Paris F-75005 (France)

    2014-06-23

    Highlights: • {sup 1}H NMR profilings of 718 wines were fused with stable isotope analysis data (SNIF-NMR, {sup 18}O, {sup 13}C). • The best improvement was obtained for prediction of the geographical origin of wine. • Certain enhancement was also obtained for the year of vintage (from 88 to 97% for {sup 1}H NMR to 99% for the fused data). • Independent component analysis was used as an alternative chemometric tool for classification. - Abstract: It is known that {sup 1}H NMR spectroscopy represents a good tool for predicting the grape variety, the geographical origin, and the year of vintage of wine. In the present study we have shown that classification models can be improved when {sup 1}H NMR profiles are fused with stable isotope (SNIF-NMR, {sup 18}O, {sup 13}C) data. Variable selection based on clustering of latent variables was performed on {sup 1}H NMR data. Afterwards, the combined data of 718 wine samples from Germany were analyzed using linear discriminant analysis (LDA), partial least squares-discriminant analysis (PLS-DA), factorial discriminant analysis (FDA) and independent components analysis (ICA). Moreover, several specialized multiblock methods (common components and specific weights analysis (ComDim), consensus PCA and consensus PLS-DA) were applied to the data. The best improvement in comparison with {sup 1}H NMR data was obtained for prediction of the geographical origin (up to 100% for the fused data, whereas stable isotope data resulted only in 60–70% correct prediction and {sup 1}H NMR data alone in 82–89% respectively). Certain enhancement was obtained also for the year of vintage (from 88 to 97% for {sup 1}H NMR to 99% for the fused data), whereas in case of grape varieties improved models were not obtained. The combination of {sup 1}H NMR data with stable isotope data improves efficiency of classification models for geographical origin and vintage of wine and can be potentially used for other food products as well.

  11. Synthesis and spectroscopic DNA binding investigations of dibutyltin N-(5-chlorosalicylidene)-leucinate

    Science.gov (United States)

    Zhang, Shufang; Yuan, Hongyu; Tian, Laijin

    2017-02-01

    A new dibutyltin N-(5-Chlorosalicylidene)-leucinate (DNCL) was synthesized by the reaction of dibutyltin dichloride with in situ formed potassium N-(5-chlorosalicylidene)-L-isoleucinate 3 characterized by elemental analysis, IR, 1H NMR (1H, 13C and 119Sn) spectra. The interaction between DNCL and calf thymus deoxyribonucleic acid (ctDNA) in a pH 7.4 Tris-HCl buffer solution was investigated by UV-Vis spectroscopy, fluorescence spectroscopy, and viscosity measurements. It was found that DNCL molecules could intercalate into the base pairs of DNA, forming a DNCL-DNA complex with a binding constant of Kf = 5.75 × 105 L mol-1 (310 K). The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) and Gibbs free energy (ΔG) were calculated to be 1.16 × 105 J mol-1, 486.5 J K-1 mol -1 and -3.48 × 104 J mol-1 at 310 K, respectively. Hydrophobic interaction was the predominant intermolecular force in stabilizing the DNCL-DNA complex.

  12. Multi-spectroscopic investigation of the binding interaction of fosfomycin with bovine serum albumin☆

    Institute of Scientific and Technical Information of China (English)

    Manjunath D. Meti; Sharanappa T. Nandibewoor; Shrinivas D. Joshi; Uttam A. More; Shivamurti A. Chimatadar

    2015-01-01

    The interaction between fosfomycin (FOS) and bovine serum albumin (BSA) has been investigated effectively by multi-spectroscopic techniques under physiological pH 7.4. FOS quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites n and observed binding constant KA were measured by the fluorescence quenching method. The thermodynamic parameters △G0, △H0 and △S0 were calculated at different temperatures according to the van't Hoff equation. The site of binding of FOS in the protein was proposed to be Sudlow's site I based on displacement experiments using site markers viz. warfarin, ibuprofen and digitoxin. The distance r between the donor (BSA) and acceptor (FOS) molecules was obtained according to the F?rster theory. The effect of FOS on the conformation of BSA was analyzed using synchronous fluorescence spectra (SFS), circular dichroism (CD) and 3D fluorescence spectra. A molecular modeling study further confirmed the binding mode obtained by the experimental studies.

  13. Electrochemical and Spectroscopic Study of Mononuclear Ruthenium Water Oxidation Catalysts: A Combined Experimental and Theoretical Investigation

    KAUST Repository

    de Ruiter, J. M.

    2016-09-20

    One of the key challenges in designing light-driven artificial photosynthesis devices is the optimization of the catalytic water oxidation process. For this optimization it is crucial to establish the catalytic mechanism and the intermediates of the catalytic cycle, yet a full description is often difficult to obtain using only experimental data. Here we consider a series of mononuclear ruthenium water oxidation catalysts of the form [Ru(cy)(L)(H2O)](2+) (cy = p-cymene, L = 2,2\\'-bipyridine and its derivatives). The proposed catalytic cycle and intermediates are examined using density functional theory (DFT), radiation chemistry, spectroscopic techniques, and electrochemistry to establish the water oxidation mechanism. The stability of the catalyst is investigated using online electrochemical mass spectrometry (OLEMS). The comparison between the calculated absorption spectra of the proposed intermediates with experimental spectra, as well as free energy calculations with electrochemical data, provides strong evidence for the proposed pathway: a water oxidation catalytic cycle involving four proton-coupled electron transfer (PCET) steps. The thermodynamic bottleneck is identified as the third PCET step, which involves O-O bond formation. The good agreement between the optical and thermodynamic data and DFT predictions further confirms the general applicability of this methodology as a powerful tool in the characterization of water oxidation catalysts and for the interpretation of experimental observables.

  14. Corrosion investigation of fire-gilded bronze involving high surface resolution spectroscopic imaging

    Science.gov (United States)

    Masi, G.; Chiavari, C.; Avila, J.; Esvan, J.; Raffo, S.; Bignozzi, M. C.; Asensio, M. C.; Robbiola, L.; Martini, C.

    2016-03-01

    Gilded bronzes are often affected by severe corrosion, due to defects in the Au layer and Au/Cu alloy galvanic coupling, stimulated by large cathodic area of the gilded layer. Galvanic corrosion, triggered by gilding defects, leads to products growth at the Au/bronze interface, inducing blistering or break-up of the Au layer. In this context, fire-gilded bronze replicas prepared by ancient methods (use of spreadable Au-Hg paste) was specifically characterised by compiling complementary spectroscopic and imaging information before/after accelerated ageing with synthetic rain. Fire-gilded bronze samples were chemically imaged in cross-section at nano-metric scale (XPS). We have found a net surface enrichment in Zn and Sn after fire-gilding and presence of metallic Hg, Pb and Cu within the Au layer. Moreover, the composition distribution of the elements together with their oxidation has been determined. It was also revealed that metallic phases including Hg and Pb remain in the gilding after corrosion. Moreover, selective dissolution of Zn and Cu occurs in the crater due to galvanic coupling, which locally induces relative Sn species enrichment (decuprification). The feasibility advantages and disadvantages of chemical imaging using HR-SRPES to study artworks have been investigated on representative replicas.

  15. A spectroscopic investigation into the reaction of sodium tetrathionate with cysteine

    Science.gov (United States)

    Church, J. S.; Evans, D. J.

    2008-01-01

    A spectroscopic investigation into the reaction of sodium tetrathionate with cysteine at pH 5 both at the boil and at room temperature has been carried out. The Raman and infrared spectra of the model compounds cysteine, cysteine- S-sulfonate, cysteine- S-thiosulfonate, sodium thiosulfate and sodium sulfite were also obtained and vibrations involving the sulfur atoms were analyzed in detail. These results were utilized in the interpretation of the spectra obtained from tetrathionate-cysteine reaction mixtures. The reaction supernatants were analyzed by high performance thin layer chromatography while the precipitates were analyzed gravimetrically. It was found that during the reaction, the thiol groups of cysteine are oxidised to give predominantly cysteine- S-sulfonate. Cystine was also detected but was determined gravimetrically to be a minor reaction product. No significant amounts of cysteine- S-thiosulfonate were detected. The reaction is accompanied by the formation of elemental sulfur and a small amount of sulfite. Major reaction pathways are put forth that are consistent with the experimental data.

  16. Investigation of laser-tissue interaction in medicine by means of laser spectroscopic measurements

    Science.gov (United States)

    Lademann, Juergen; Weigmann, Hans-Juergen

    1995-01-01

    Toxic and carcinogenic substances were produced during laser application in medicine for the cutting and evaporation of tissue. The laser smoke presents a danger potential for the medical staff and the patients. The laser tissue interaction process was investigated by means of laser spectroscopic measurements which give the possibility of measuring metastable molecular states directly as a prerequisite to understand and to influence fundamental laser tissue interaction processes in order to reduce the amount of harmful chemicals. Highly excited atomic and molecular states and free radicals (CN, OH, C2, CH, CH2) have been detected applying spontaneous and laser induced fluorescence methods. It was found that the formation of harmful substances in the laser plumes can be reduced significantly by optimization of the surrounding gas atmosphere. A high content of oxygen or water in the interaction zone has been found, in agreement with the results of classical and analytical methods, as a suitable way to decrease pollutant emission. The experimental methods and the principal results are applicable not only in laser medicine but in laser material treatment generally.

  17. Spectroscopic investigation on the interaction of salidroside with bovine serum albumin

    Science.gov (United States)

    Cheng, Zhengjun; Zhang, Yuntao

    2008-10-01

    This study is designed to examine the interaction of salidroside with bovine serum albumin (BSA) under physiological conditions with drug concentrations in the range of 1.67-20.0 μM. Spectroscopic analysis of the emission quenching at different temperatures has revealed that the quenching mechanism of salidroside with BSA is static quenching mechanism. The calculated distance r between salidroside and the protein is evaluated according to the theory of Forster energy transfer. The results of FTIR, CD, synchronous fluorescence spectra and UV-vis absorption spectra experiment show that the secondary structures of the protein has been changed in the presence of salidroside. The thermodynamic parameters, enthalpy change (Δ H0) and entropy change (Δ S0) are calculated to be -50.50 kJ mol -1 and -59.13 J mol -1 K -1according to van't Hoff equation, which indicate that the hydrogen bonds and van der Waals forces are the intermolecular force stabilizing the complex. The effects of common ions on the binding constants of BSA-salidroside complexes were also investigated.

  18. Assignments of 1H and 13C NMR Signals of Mogroside IVa

    Institute of Scientific and Technical Information of China (English)

    ZHANGJian-ye; YANGXiu-wei

    2003-01-01

    Aim To investigate the structure of mogroside IVa isolated from traditional Chinese medicine fructus momordicae [fruits of Siraitia grosvenori (Swingle) C. Jeffery] and summarize the NMR characteristics of the structure. Methods Cormnon extraction, separafion and purification methods were used. Various NMR techniques including 1H NMR,13C NMR, DEPT, 1H-1H COSY, HSQC, HMBC, NOESY and molecular model simulated by comtmter were used to elucidate the structure. Results 1H and 13C NMR signals of mogroside IVa were assigned, and spectroscopic basis was obtained for identification of such type of compounds. Conclusion 1D and 2D NMR techniques including 1H-1H COSY, HSQC, HMBC, NOESY spectra are powerful tools for structure analysis. The structure determined by NMR methods is identical with energy minimized conformation simulated by computer.

  19. The acquisition of multidimensional NMR spectra within a single scan

    Science.gov (United States)

    Frydman, Lucio; Scherf, Tali; Lupulescu, Adonis

    2002-01-01

    A scheme enabling the complete sampling of multidimensional NMR domains within a single continuous acquisition is introduced and exemplified. Provided that an analyte's signal is sufficiently strong, the acquisition time of multidimensional NMR experiments can thus be shortened by orders of magnitude. This could enable the characterization of transient events such as proteins folding, 2D NMR experiments on samples being chromatographed, bring the duration of higher dimensional experiments (e.g., 4D NMR) into the lifetime of most proteins under physiological conditions, and facilitate the incorporation of spectroscopic 2D sequences into in vivo imaging investigations. The protocol is compatible with existing multidimensional pulse sequences and can be implemented by using conventional hardware; its performance is exemplified here with a variety of homonuclear 2D NMR acquisitions. PMID:12461169

  20. Spectroscopic investigation of new water soluble Mn(II)(2) and Mg(II)(2) complexes for the substrate binding models of xylose/glucose isomerases.

    Science.gov (United States)

    Patra, Ayan; Bera, Manindranath

    2014-01-30

    In methanol, the reaction of stoichiometric amounts of Mn(OAc)(2)·4H(2)O and the ligand H(3)hpnbpda [H(3)hpnbpda=N,N'-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N'-diacetic acid] in the presence of NaOH, afforded a new water soluble dinuclear manganese(II) complex, [Mn2(hpnbpda)(μ-OAc)] (1). Similarly, the reaction of Mg(OAc)(2)·4H(2)O and the ligand H3hpnbpda in the presence of NaOH, in methanol, yielded a new water soluble dinuclear magnesium(II) complex, [Mg2(hpnbpda)(μ-OAc)(H2O)2] (2). DFT calculations have been performed for the structural optimization of complexes 1 and 2. The DFT optimized structure of complex 1 shows that two manganese(II) centers are in a distorted square pyramidal geometry, whereas the DFT optimized structure of complex 2 reveals that two magnesium(II) centers adopt a six-coordinate distorted octahedral geometry. To understand the mode of substrate binding and the mechanistic details of the active site metals in xylose/glucose isomerases (XGI), we have investigated the binding interactions of biologically important monosaccharides d-glucose and d-xylose with complexes 1 and 2, in aqueous alkaline solution by a combined approach of FTIR, UV-vis, fluorescence, and (13)C NMR spectroscopic techniques. Fluorescence spectra show the binding-induced gradual decrease in emission of complexes 1 and 2 accompanied by a significant blue shift upon increasing the concentration of sugar substrates. The binding modes of d-glucose and d-xylose with complex 2 are indicated by their characteristic coordination induced shift (CIS) values in (13)C NMR spectra for C1 and C2 carbon atoms.

  1. Spectroscopic investigations of novel pharmaceuticals: Stability and resonant interaction with laser beam

    Science.gov (United States)

    Smarandache, Adriana; Boni, Mihai; Andrei, Ionut Relu; Handzlik, Jadwiga; Kiec-Kononowicz, Katarzyna; Staicu, Angela; Pascu, Mihail-Lucian

    2017-09-01

    This paper presents data about photophysics of two novel thio-hydantoins that exhibit promising pharmaceutical properties in multidrug resistance control. Time stability studies are necessary to establish the proper use of these compounds in different applications. As for their administration as drugs, it is imperative to know their shelf life, as well as storage conditions. At the same time, laser induced modified properties of the two new compounds are valuable to further investigate their specific interactions with other materials, including biological targets. The two new thio-hydantoins under generic names SZ-2 and SZ-7 were prepared as solutions in dimethyl sulfoxide at different concentrations, as well as in deionised water. For the stability assay they were kept in various light/temperature conditions up to 60 days. The stability was estimates based on UV-vis absorption measurements. The samples in bulk shape were exposed different time intervals to laser radiation emitted at 266 nm as the fourth harmonic of a Nd:YAG laser. The resonant interaction of the studied compounds with laser beams was analysed through spectroscopic methods UV-vis and FTIR absorption, as well as laser induced fluorescence spectroscopy. As for stability assay, only solutions kept in dark at 4 °C have preserved the absorption characteristics, considering the cumulated measuring errors, less than one week. The vibrational changes that occur in their FTIR and modified fluorescence spectra upon laser beam exposure are also discussed. A result of the experimental analysis is that modifications are induced in molecular structures of the investigated compounds by resonant interaction with laser radiation. This fact evidences that the molecules are photoreactive and their characteristics might be shaped through controlled laser radiation exposure using appropriate protocols. This conclusion opens many opportunities both in the biomedical field, but also in other industrial activities

  2. Hyperpolarized 89Y NMR spectroscopic detection of yttrium ion and DOTA macrocyclic ligand complexation: pH dependence and Y-DOTA intermediates

    Science.gov (United States)

    Ferguson, Sarah; Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Kovacs, Zoltan; Lumata, Lloyd

    Dissolution dynamic nuclear polarization (DNP) is a rapidly emerging physics technique used to enhance the signal strength in nuclear magnetic resonance (NMR) and imaging (MRI) experiments for nuclear spins such as yttrium-89 by >10,000-fold. One of the most common and stable MRI contrast agents used in the clinic is Gd-DOTA. In this work, we have investigated the binding of the yttrium and DOTA ligand as a model for complexation of Gd ion and DOTA ligand. The macrocyclic ligand DOTA is special because its complexation with lanthanide ions such as Gd3+ or Y3+ is highly pH dependent. Using this physics technology, we have tracked the complexation kinetics of hyperpolarized Y-triflate and DOTA ligand in real-time and detected the Y-DOTA intermediates. Different kinds of buffers were used (lactate, acetate, citrate, oxalate) and the pseudo-first order complexation kinetic calculations will be discussed. The authors would like to acknowledge the support by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  3. Synthesis, spectroscopic (FT-IR, FT-Raman, NMR, UV-Visible), first order hyperpolarizability, NBO and molecular docking study of (E)-1-(4-bromobenzylidene)semicarbazide

    Science.gov (United States)

    Raja, M.; Muhamed, R. Raj; Muthu, S.; Suresh, M.

    2017-01-01

    The compound (E)-1-(4-bromobenzylidene)semicarbazide(4BSC) was synthesized and characterized by FT-IR, FT-Raman, UV-Visible, 1HNMR and 13CNMR spectra. The optimized molecular geometry(bond length, bond angle), the complete vibrational frequency, the infrared intensities and the Raman scattering activities were calculated by using density functional theory(DFT) B3LYP method with the help of 6-311++G(d,p) basis set. From the recorded UV-Visible spectrum, the electronic properties such as excitation energies, wavelength, band gap and oscillator strength are evaluated by TD-DFT in DMSO solution and gas phase methods using 6-311++G(d,p) basis set. The calculated HOMO - LUMO band gap energies confirm that charge transfer occurs within the molecule. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the gauge-independent atomic orbital (GIAO) method and compared with experimental results. The hyperconjugative interaction energy E(2) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. Besides NLO and MEP were also calculated and interpreted. To study the biological activity of the investigation molecule, molecular docking was done to identify the hydrogen bond lengths and binding energy with different antimicrobial protein. Thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations the heat capacity (C), entropy (S) and enthalpy changes (H) and temperatures.

  4. {sup 103}Rh NMR investigation of the superconductor Rh{sub 17}S{sub 15}

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, T., E-mail: t-koyama@sci.u-hyogo.ac.j [Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297 (Japan); Kanda, K.; Motoyama, G.; Ueda, K.; Mito, T.; Kohara, T. [Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297 (Japan); Nakamura, H. [Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501 (Japan)

    2010-12-15

    We present {sup 103}Rh NMR studies for the superconductor Rh{sub 17}S{sub 15} (T{sub c} 5.4 K). We have identified the observed NMR lines corresponding to four different Rh sites in the cubic unit cell and deduced the temperature (T) dependence of the Knight shift components in Rh 24m site whose point symmetry is not axial. The isotropic part of the Knight shift K decreases with T in the normal state, indicating the negative hyperfine coupling and the enhancement of the spin susceptibility at lower T. The sudden change of K below T{sub c} is an indication of the spin-singlet Cooper paring.

  5. From NMR chemical shifts to amino acid types: Investigation of the predictive power carried by nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Marin, Antoine; Malliavin, Therese E. [Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Theorique, CNRS UPR 9080 (France)], E-mail: therese.malliavin@ibpc.fr; Nicolas, Pierre; Delsuc, Marc-Andre [INRA - Domaine de Vilvert, Unite Mathematique Informatique et Genome (France)

    2004-09-15

    An approach to automatic prediction of the amino acid type from NMR chemical shift values of its nuclei is presented here, in the frame of a model to calculate the probability of an amino acid type given the set of chemical shifts. The method relies on systematic use of all chemical shift values contained in the BioMagResBank (BMRB). Two programs were designed, one (BMRB stats) for extracting statistical chemical shift parameters from the BMRB and another one (RESCUE2) for computing the probabilities of each amino acid type, given a set of chemical shifts. The Bayesian prediction scheme presented here is compared to other methods already proposed: PROTYP (Grzesiek and Bax, J. Biomol. NMR, 3, 185-204, 1993) RESCUE (Pons and Delsuc, J. Biomol. NMR, 15, 15-26, 1999) and PLATON (Labudde et al., J. Biomol. NMR, 25, 41-53, 2003) and is found to be more sensitive and more specific. Using this scheme, we tested various sets of nuclei. The two nuclei carrying the most information are C{sub {beta}} and H{sub {beta}}, in agreement with observations made in Grzesiek and Bax, 1993. Based on four nuclei: H{sub {beta}}, C{sub {beta}}, C{sub {alpha}} and C', it is possible to increase correct predictions to a rate of more than 75%. Taking into account the correlations between the nuclei chemical shifts has only a slight impact on the percentage of correct predictions: indeed, the largest correlation coefficients display similar features on all amino acids.

  6. Bis(pentamethylcyclopentadienyl)ytterbium: An investigation of weak interactions in solution using multinuclear NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, David Joel [Univ. of California, Berkeley, CA (United States)

    1995-07-01

    NMR spectroscopy is ideal for studying weak interactions (formation enthalpy ≤20 kcal/mol) in solution. The metallocene bis(pentamethylcyclopentadienyl)ytterbium, Cp*2Yb, is ideal for this purpose. cis-P2PtH2complexes (P = phosphine) were used to produce slow-exchange Cp*2YbL adducts for NMR study. Reversible formation of (P2PtH)2 complexes from cis-P2PtH2 complexes were also studied, followed by interactions of Cp*2Yb with phosphines, R3PX complexes. A NMR study was done on the interactions of Cp*2Yb with H2, CH4, Xe, CO, silanes, stannanes, C6H6, and toluene.

  7. 17O-Dynamic NMR and DFT Investigation of Bis(acyloxyiodoarenes

    Directory of Open Access Journals (Sweden)

    Giovanni Cerioni

    2012-10-01

    Full Text Available Bis(acetoxyiodobenzene and related acyloxy derivatives of hypervalent I(III were studied by variable temperature solution-state 17O-NMR and DFT calculations. The 17O-NMR spectra reveal a dynamic process that interchanges the oxygen atoms of the acyloxy groups. For the first time, coalescence events could be detected for such compounds, allowing the determination of activation free energy data which are found to range between 44 and 47 kJ/mol. The analysis of the 17O linewidth measured for bis(acetoxyiodobenzene indicates that the activation entropy is negligible. DFT calculations show that the oxygen atom exchange arises as a consequence of the [1,3]-sigmatropic shift of iodine. The calculated activation barriers are in excellent agreement with the experimental results. Both the 17O-NMR and DFT studies show that the solvent and chemical alterations, such as modification of the acyl groups or para- substitution of the benzene ring, hardly affect the energetics of the dynamic process. The low I-O Wiberg bond index (0.41–0.42 indicates a possible explanation of the invariance of both the energy barrier and the 17O chemical shift with para-substitution.

  8. Raman and photoelectron spectroscopic investigation of high-purity niobium materials: Oxides, hydrides, and hydrocarbons

    Science.gov (United States)

    Singh, Nageshwar; Deo, M. N.; Nand, Mangla; Jha, S. N.; Roy, S. B.

    2016-09-01

    We present investigations of the presence of oxides, hydrides, and hydrocarbons in high-purity (residual resistivity ratio, ˜300) niobium (Nb) materials used in fabrication of superconducting radio frequency (SRF) cavities for particle accelerators. Raman spectroscopy of Nb materials (as-received from the vendor as well as after surface chemical- and thermal processing) revealed numerous peaks, which evidently show the presence of oxides (550 cm-1), hydrides (1277 and 1385 cm-1: ˜80 K temperature), and groups of hydrocarbons (1096, 2330, 2710, 2830, 2868, and 3080 cm-1). The present work provides direct spectroscopic evidence of hydrides in the electropolished Nb materials typically used in SRF cavities. Raman spectroscopy thus can provide vital information about the near-surface chemical species in niobium materials and will help in identifying the cause for the performance degradation of SRF cavities. Furthermore, photoelectron spectroscopy was performed on the Nb samples to complement the Raman spectroscopy study. This study reveals the presence of C and O in the Nb samples. Core level spectra of Nb (doublet 3d5/2 and 3d3/2) show peaks near 206.6 and 209.4 eV, which can be attributed to the Nb5+ oxidation state. The core level spectra of C 1 s of the samples are dominated by graphitic carbon (binding energy, 284.6 eV), while the spectra of O 1 s are asymmetrically peaked near binding energy of ˜529 eV, and that indicates the presence of metal-oxide Nb2O5. The valence-band spectra of the Nb samples are dominated by a broad peak similar to O 2p states, but after sputtering (for 10 min) a peak appears at ˜1 eV, which is a feature of the elemental Nb atom.

  9. Spectroscopic investigation on europium doped heavy metal borate glasses for red luminescent application

    Energy Technology Data Exchange (ETDEWEB)

    Hegde, Vinod; Wagh, Akshatha; Kamath, Sudha D. [Manipal University, Department of Physics, Manipal Institute of Technology, Manipal (India); Hegde, Hemanth [Manipal University, Department of Chemistry, Manipal Institute of Technology, Manipal (India); Vishwanath, C.S.D. [Sri Venkateswara University, Department of Physics, Tirupati (India)

    2017-05-15

    The present study explores a new borate family glasses based on 10ZnO-5Na{sub 2}O-10Bi{sub 2}O{sub 3}-(75 - x) B{sub 2}O{sub 3}-xEu{sub 2}O{sub 3} (x = 0, 0.1, 0.5, 1, 1.5, 2, 3 mol%) composition, synthesized by rapid melt quench technique. Prepared glasses were subjected to the density and refractive index measurements and their values were used to calculate other physical properties of the glass matrix as a function of Eu{sup 3+} concentration. XRD confirmed amorphous nature of the glasses. FTIR spectra in the absorption mode were recorded in the 400-4000 cm{sup -1} region to identify different functional groups in the glass matrix. Deconvoluted FTIR spectra showed increase in BO{sub 4} units with rise in europium content which confirmed the 'network strengthener' role of europium ions by creating bridging oxygens (BOs). Optical properties were investigated for their luminescence behavior through various spectroscopic techniques such as UV-Vis-NIR absorption, excitation, emission, decay profiles, and color measurements at room temperature. Lasing properties of the glasses like total radiative life time, branching ratio, emission cross section, and optical gain were obtained from the calculated Judd-Ofelt (Ω{sub 2},Ω{sub 4}) intensity parameters. From the measured values of emission, cross sections, branching ratios, life times, strong photoluminescence features, and CIE chromaticity coordinates, 0.5 mol% of Eu{sup 3+} ions doped ZnNaBiB glasses showed optimum performance and are potential candidate for red light generation at 613 nm. (orig.)

  10. Effect of paramagnetic doping on an inorganic polymer triaquadipotassiumbis(malonato)zincate: spectroscopic investigation

    Science.gov (United States)

    Boobalan, S.; Sambasiva Rao, P.

    2011-01-01

    Spectroscopic investigations on Mn(II)-doped triaquadipotassiumbis(malonato)zincate [K2(H2O)3] [Zn(mal)2], an inorganic polymer, have been carried out at room temperature using single crystal electron paramagnetic resonance (EPR), ultraviolet-visible, FT-IR and powder XRD techniques. Single crystal rotations along the three orthogonal axes show more than 30 lines of patterns in EPR spectra, indicating the presence of two sites, one with a large D value and the other with a smaller D value. The calculated spin-Hamiltonian parameters are as follows. Site 1: g xx =2.099, g yy =2.092, g zz =1.988, A xx =9.77, A yy =9.71, A zz =8.96 mT, D xx =-29.09, D yy =-11.90, D zz =40.99 mT; Site 2: g xx =2.040, g yy =1.995, g zz =1.924, A xx =9.51, A yy =9.09, A zz =8.80 mT, D xx =-11.94, D yy =-7.51 and D zz =19.45 mT. The direction cosines of g/A/D do not match with the direction cosines of Zn-O bonds in the host lattice for either site, suggesting that both the Mn(II) sites entered the lattice interstitially. Optical results indicate a strong covalent bonding between the metal ion and ligands, with site symmetry being primarily octahedral. The FT-IR and powder XRD data confirm the retention of the crystal structure, even after incorporating a paramagnetic probe. Various admixture coefficients, bonding and optical parameters have also been calculated.

  11. Spectroscopic investigation on europium doped heavy metal borate glasses for red luminescent application

    Science.gov (United States)

    Hegde, Vinod; Wagh, Akshatha; Hegde, Hemanth; Vishwanath, C. S. Dwaraka; Kamath, Sudha D.

    2017-05-01

    The present study explores a new borate family glasses based on 10ZnO-5Na2O-10Bi2O3-(75 - x) B2O3- xEu2O3 ( x = 0, 0.1, 0.5, 1, 1.5, 2, 3 mol%) composition, synthesized by rapid melt quench technique. Prepared glasses were subjected to the density and refractive index measurements and their values were used to calculate other physical properties of the glass matrix as a function of Eu3+ concentration. XRD confirmed amorphous nature of the glasses. FTIR spectra in the absorption mode were recorded in the 400-4000 cm-1 region to identify different functional groups in the glass matrix. Deconvoluted FTIR spectra showed increase in BO4 units with rise in europium content which confirmed the `network strengthener' role of europium ions by creating bridging oxygens (BOs). Optical properties were investigated for their luminescence behavior through various spectroscopic techniques such as UV-Vis-NIR absorption, excitation, emission, decay profiles, and color measurements at room temperature. Lasing properties of the glasses like total radiative life time, branching ratio, emission cross section, and optical gain were obtained from the calculated Judd-Ofelt (Ω2,Ω4) intensity parameters. From the measured values of emission, cross sections, branching ratios, life times, strong photoluminescence features, and CIE chromaticity coordinates, 0.5 mol% of Eu3+ ions doped ZnNaBiB glasses showed optimum performance and are potential candidate for red light generation at 613 nm.

  12. Synthesis of quinoline derivatives containing pyrazole group and investigation of their crystal structure and spectroscopic properties in relation to acidity and alkalinity of mediums

    Science.gov (United States)

    Ren, Tiegang; Wang, Jie; Li, Guihui; Cheng, Hongbin; Li, Yongzhe

    2014-08-01

    Two series of quinoline derivatives containing pyrazole group were synthesized and characterized by means of 1H NMR, FT-IR, MS, elemental analysis and X-ray single crystal diffraction, and their UV-vis absorption behavior and fluorescence properties were also measured. Moreover, the effects of acetic acid and triethylamine on the spectroscopic properties of synthesized products were examined with compounds 3a and 5a as examples. It has been found that all synthesized quinoline derivatives show maximum absorption peak at 303 nm and emission peaks around 445 nm. Besides, both acetic acid and triethylamine can change the acidity of the medium, thereby influencing the UV-vis absorption spectra and fluorescence spectra of synthesized products. Moreover, theoretical investigations indicate that the integration of H+ and N atom of quinoline ring favors the formation of a new product in the presence of acetic acid, and the product obtained in this case shows a new UV-vis absorption peak at 400 nm.

  13. Spectroscopic Investigations of Highly Charged Tungsten Ions - Atomic Spectroscopy and Fusion Plasma Diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Clementson, Joel [Lund Univ. (Sweden)

    2010-05-01

    The spectra of highly charged tungsten ions have been investigated using x-ray and extreme ultraviolet spectroscopy. These heavy ions are of interest in relativistic atomic structure theory, where high-precision wavelength measurements benchmark theoretical approaches, and in magnetic fusion research, where the ions may serve to diagnose high-temperature plasmas. The work details spectroscopic investigations of highly charged tungsten ions measured at the Livermore electron beam ion trap (EBIT) facility. Here, the EBIT-I and SuperEBIT electron beam ion traps have been employed to create, trap, and excite tungsten ions of M- and L-shell charge states. The emitted spectra have been studied in high resolution using crystal, grating, and x-ray calorimeter spectrometers. In particular, wavelengths of n = 0 M-shell transitions in K-like W55+ through Ne-like W64+, and intershell transitions in Zn-like W44+ through Co-like W47+ have been measured. Special attention is given to the Ni-like W46+ ion, which has two strong electric-dipole forbidden transitions that are of interest for plasma diagnostics. The EBIT measurements are complemented by spectral modeling using the Flexible Atomic Code (FAC), and predictions for tokamak spectra are presented. The L-shell tungsten ions have been studied at electron-beam energies of up to 122 keV and transition energies measured in Ne-like W64+ through Li-like W71+. These spectra constitute the physics basis in the design of the ion-temperature crystal spectrometer for the ITER tokamak. Tungsten particles have furthermore been introduced into the Sustained Spheromak Physics Experiment (SSPX) spheromak in Livermore in order to investigate diagnostic possibilities of extreme ultraviolet tungsten spectra for the ITER divertor. The spheromak measurement and spectral modeling using FAC suggest that tungsten ions in charge states around Er-like W6+ could be useful for

  14. Tautomerism in o-hydroxyanilino-1,4-naphthoquinone derivatives: Structure, NMR, HPLC and density functional theoretic investigations

    Science.gov (United States)

    Bhand, Sujit; Patil, Rishikesh; Shinde, Yogesh; Lande, Dipali N.; Rao, Soniya S.; Kathawate, Laxmi; Gejji, Shridhar P.; Weyhermüller, Thomas; Salunke-Gawali, Sunita

    2016-11-01

    Structure and spectral characteristics of 'Ortho' ((E)-4-hydroxy-2-(2‧-(4‧-R)-hydroxyphenyl)-imino)-naphthalen-1(2H)-one) and 'para' (2-(2‧-(4‧-R)-hydroxyphenyl)-amino)-1,4-naphthoquinone) tautomers of o-hydroxyanilino-1,4-naphthoquinone derivatives (Rdbnd H, 1A; sbnd CH3, 2A; and -Cl, 3A) are investigated using the 1H, 13C, DEPT, gDQCOSY, gHSQCAD NMR, HPLC, cyclic voltammetry techniques combined with the density functional theory. The compound 2A crystallizes in monoclinic space group P21/c. wherein the polymer chain is facilitated via Osbnd H⋯O and Csbnd H⋯O intermolecular hydrogen bonding. Marginal variations in bond distances in quinonoid and aminophenol moieties render structural flexibility to these compounds those in solution exist as exist in 'ortho - para' tautomers. 1H and 13C NMR spectra in DMSO-d6 showed two sets of peaks in all compounds; whereas only the para tautomer of for 1A and 2A, the para tautomer is predominant in CD3CN solution. Further the ortho-para interconversion is accompanied by a large up-field signals for C(3)sbnd H(3) in their 1H and 13C NMR spectra. These inferences are corroborated by the density functional theoretic calculations.

  15. {sup 1}H NMR investigation of self-association of vanillin in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Bogdan, Mircea; Floare, Calin G; PIrnau, Adrian, E-mail: mircea.bogdan@itim-cj.r [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)

    2009-08-01

    A self-association of vanillin have been studied by {sup 1}H NMR spectroscopy using the analysis of proton chemical shifts changes in aqueous solution as a function of concentration. The experimental results have been analysed using indefinite non-cooperative and cooperative models of molecular self-association, enabling the determination of equilibrium constants, parameters of cooperativity and the limiting values of vanillin proton chemical shifts in the complex. It was found that the dimer formation creates energetically favourable conditions for subsequent molecular association.

  16. 1H NMR investigation of self-association of vanillin in aqueous solution

    Science.gov (United States)

    Bogdan, Mircea; Floare, Calin G.; Pîrnau, Adrian

    2009-08-01

    A self-association of vanillin have been studied by 1H NMR spectroscopy using the analysis of proton chemical shifts changes in aqueous solution as a function of concentration. The experimental results have been analysed using indefinite non-cooperative and cooperative models of molecular self-association, enabling the determination of equilibrium constants, parameters of cooperativity and the limiting values of vanillin proton chemical shifts in the complex. It was found that the dimer formation creates energetically favourable conditions for subsequent molecular association.

  17. Stereochemical investigations on the diketopiperazine derivatives of enalapril and lisinopril by NMR spectroscopy

    Science.gov (United States)

    Demeter, Ádám; Fodor, Tamás; Fischer, János

    1998-11-01

    Stereochemical analysis of epimeric diketopiperazine (DKP) derivatives of enalapril and lisinopril has been performed by NMR spectroscopy. The present study focuses on the configurational assignment and conformational characteristics of the epimeric DKPs obtained from cyclization and subsequent base-catalyzed hydrolysis. We report full 1H and 13C assignments as obtained by a concerted use of 1D and 2D methods. The configuration of the respective stereogenic centres and the main conformational features were derived from the measured scalar and NOE connections. One conspicuous conformational feature of the sidechain is its tendency to bend over the piperazinedione ring.

  18. Investigations of the structure and "interfacial" surface chemistry of Bioglass (RTM) materials by solid-state multinuclear NMR spectroscopy

    Science.gov (United States)

    Sarkar, Gautam

    formation of surface silica species and follow the formation of phosphate species, respectively, while cross-polarization magic-angle spinning (CP/MAS) 29Si and 31P NMR have provided information about low intensity NMR peaks due to various silicon- and phosphorus-species present in the vicinity of associated protons on the surface of in vitro reacted BioglassRTM materials. The solid-state NMR investigations of the "interfacial" surface reactions of BioglassRTM materials are discussed in the context of the structure of these materials and the influence of this structure on the kinetics and the mechanism of their "interfacial" surface chemistry. (Abstract shortened by UMI.) BioglassRTM, trademark, University of Florida, Gainesville, FL, 32611.

  19. Magnetic and NMR investigation of RRh3B2 (R=La to Gd) compounds

    Science.gov (United States)

    Malik, S. K.; Dhar, S. K.; Vijayaraghavan, R.; Wallace, W. E.

    1982-11-01

    Magnetization (4.2 to 300 K) and 11B paramagnetic NMR (77 to 300 K) studies have been carried out on ternary borides RRh3B2 (R=La to Gd). These compounds crystallize in the CeCo3B2-type structure. From cell volume considerations Ce is in a mixed valent/quadrivalent state while the rest of the rare earth ions are in a trivalent state. With the exception of La and Pr compounds, all other compounds are found to order magnetically. From the high values of the ratio of paramagnetic moment to ordered state moment, the magnetic ordering is inferred to be the itinerant type in CeRh3B2 and EuRh3B2. In Nd and Gd compounds, magnetization data reveal that magnetic ordering is associated with the rare earth sublattice. A complex behavior of magnetization is observed in SmRh3B2. A first order quadrupole split 11B NMR spectrum is observed in Ce, Pr, Nd, and Sm compounds. The boron Knight shift in all these compounds is small and, within the limits of experimental error, scales linearly with susceptibility in Pr and Nd compounds. A temperature independent Knight shift is observed in SmRh3B2, indicating the influence of strong crystal fields.

  20. Spin state and orbital ordering in CuCr2O4 investigated by NMR

    Science.gov (United States)

    Jo, Euna; Kang, Byeongki; Kim, Changsoo; Kwon, Sangil; Lee, Soonchil

    2013-09-01

    63,65Cu and 53Cr nuclear magnetic resonance spectra for CuCr2O4 were measured at various magnetic fields and temperatures. The microscopic evidence of orbital ordering in CuCr2O4 was obtained from a dipolar hyperfine field, NQR, and magnetic anisotropy analysis of the linewidth broadening of the Cu and Cr NMR spectra measured in the external magnetic field. The energy gap in the dispersion relation of the spin wave excitation was measured from the temperature dependence of the resonance frequency of Cu and Cr ions in CuCr2O4. The energy gap of the Cu ions is about 10 K (± 5 K), and that of the Cr ions is about 40 K (± 5 K). These values imply that the spin-orbit coupling of Cr ions is stronger than that of Cu ions related to the orbital ordering in CuCr2O4. The magnetic field dependence of the Cr NMR frequency shows that the angle between the Cr3+ magnetic moment and the Cu2+ magnetic moment is about 98∘ (± 2∘).

  1. Structural Investigations of Portland Cement Components, Hydration, and Effects of Admixtures by Solid-State NMR Spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen Bengaard; Andersen, Morten D.; Jakobsen, Hans Jørgen

    2006-01-01

    Solid-state, magic-angle spinning (MAS) NMR spectroscopy represents a valuable tool for structural investigations on the nanoscale of the most important phases in anhydrous and hydrated Portland cements and of various admixtures. This is primarily due to the fact that the method reflects the firs.......% flourine. Finally, the detection and quantification of strätlingite (2CaO·Al2O3·SiO2·8H2O) in Portland cement mixtures containing metakaolin will be demonstrated....

  2. Investigation on silver complexes of novel 1,2,3-triazole linked crown ethers by NMR analysis

    Indian Academy of Sciences (India)

    Piotr Seliger; Natalia Gutowska; Monika Stefaniak; Jarosław Romański

    2015-10-01

    The novel derivatives of 1,2,3-triazole linked crown ethers were investigated towards silver(I) ion coordination. The NMR measurements in deuterated methanol in different ratios of ligand and silver cation were studied. The experiments were performed in order to examine the way of binding Ag(I) ion by the selected ligands. The results are presented for complexes with the Ag:L stoichiometry 0.5:1, 1:1 and 2:1, respectively. Depending on the type of crown ether moiety incorporated into the macrocyclic skeleton, interesting differences in the mode of stepwise coordination of the ion were noticed.

  3. Investigation of the interaction of naringin palmitate with bovine serum albumin: spectroscopic analysis and molecular docking.

    Directory of Open Access Journals (Sweden)

    Xia Zhang

    Full Text Available BACKGROUND: Bovine serum albumin (BSA contains high affinity binding sites for several endogenous and exogenous compounds and has been used to replace human serum albumin (HSA, as these two compounds share a similar structure. Naringin palmitate is a modified product of naringin that is produced by an acylation reaction with palmitic acid, which is considered to be an effective substance for enhancing naringin lipophilicity. In this study, the interaction of naringin palmitate with BSA was characterised by spectroscopic and molecular docking techniques. METHODOLOGY/PRINCIPAL FINDINGS: The goal of this study was to investigate the interactions between naringin palmitate and BSA under physiological conditions, and differences in naringin and naringin palmitate affinities for BSA were further compared and analysed. The formation of naringin palmitate-BSA was revealed by fluorescence quenching, and the Stern-Volmer quenching constant (KSV was found to decrease with increasing temperature, suggesting that a static quenching mechanism was involved. The changes in enthalpy (ΔH and entropy (ΔS for the interaction were detected at -4.11 ± 0.18 kJ·mol(-1 and -76.59 ± 0.32 J·mol(-1·K(-1, respectively, which indicated that the naringin palmitate-BSA interaction occurred mainly through van der Waals forces and hydrogen bond formation. The negative free energy change (ΔG values of naringin palmitate at different temperatures suggested a spontaneous interaction. Circular dichroism studies revealed that the α-helical content of BSA decreased after interacting with naringin palmitate. Displacement studies suggested that naringin palmitate was partially bound to site I (subdomain IIA of the BSA, which was also substantiated by the molecular docking studies. CONCLUSIONS/SIGNIFICANCE: In conclusion, naringin palmitate was transported by BSA and was easily removed afterwards. As a consequence, an extension of naringin applications for use in food, cosmetic

  4. Corrosion investigation of fire-gilded bronze involving high surface resolution spectroscopic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Masi, G., E-mail: giulia.masi5@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); Chiavari, C., E-mail: cristina.chiavari@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); C.I.R.I. (Centro Interdipartimentale Ricerca Industriale) Meccanica Avanzata e Materiali, Università di Bologna, Bologna, via Terracini 28, 40131 Bologna (Italy); Avila, J., E-mail: jose.avila@synchrotron-soleil.fr [Synchrotron SOLEIL, L’Orme des Merisiers, 91190 Saint-Aubin (France); Esvan, J., E-mail: jerome.esvan@ensiacet.fr [Centre Interuniversitaire de Recherche et d’Ingénierie des Matériaux, Université de Toulouse, 4 allée Emile Monso, 31030 Toulouse (France); Raffo, S., E-mail: simona.raffo2@unibo.it [Dipartimento di Chimica Industriale “Toso Montanari”, Università di Bologna, viale Risorgimento 4, 40136 Bologna (Italy); Bignozzi, M.C., E-mail: maria.bignozzi@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); Asensio, M.C., E-mail: maria-carmen.asensio@synchrotron-soleil.fr [Synchrotron SOLEIL, L’Orme des Merisiers, 91190 Saint-Aubin (France); Robbiola, L., E-mail: robbiola@univ-tlse2.fr [TRACES Lab (CNRS UMR5608), Université Toulouse Jean-Jaurès, 5, allées Antonio-Machado, 31058 Toulouse (France); and others

    2016-03-15

    Graphical abstract: - Highlights: • Fire-gilded bronze prepared by ancient methods (Au–Hg layer on Cu–Sn–Zn–Pb–Sb). • Heating during gilding induces Sn and Znenrichment in the top part of the gilded layer. • SR-HRPES mapping of corrosion craters (cross-section) after accelerated ageing. • Selective dissolution of Cu and Zn in the craters induces Sn species enrichment. • The main species in the craters are related to hydroxi-oxide compounds. - Abstract: Gilded bronzes are often affected by severe corrosion, due to defects in the Au layer and Au/Cu alloy galvanic coupling, stimulated by large cathodic area of the gilded layer. Galvanic corrosion, triggered by gilding defects, leads to products growth at the Au/bronze interface, inducing blistering or break-up of the Au layer. In this context, fire-gilded bronze replicas prepared by ancient methods (use of spreadable Au–Hg paste) was specifically characterised by compiling complementary spectroscopic and imaging information before/after accelerated ageing with synthetic rain. Fire-gilded bronze samples were chemically imaged in cross-section at nano-metric scale (<200 nm) using high energy and lateral resolution synchrotron radiation photoemission (HR-SRPES) of core levels and valence band after conventional characterisation of the samples by Glow Discharge optical Emission Spectroscopy (GD-OES) and conventional X-ray photoelectron spectroscopy (XPS). We have found a net surface enrichment in Zn and Sn after fire-gilding and presence of metallic Hg, Pb and Cu within the Au layer. Moreover, the composition distribution of the elements together with their oxidation has been determined. It was also revealed that metallic phases including Hg and Pb remain in the gilding after corrosion. Moreover, selective dissolution of Zn and Cu occurs in the crater due to galvanic coupling, which locally induces relative Sn species enrichment (decuprification). The feasibility advantages and disadvantages of

  5. Quality of sour cherry juice of different clones and cultivars (Prunus cerasus L.) determined by a combined sensory and NMR spectroscopic approach

    DEFF Research Database (Denmark)

    Clausen, Morten Rahr; Pedersen, Bjarne Hjelmsted; Bertram, Hanne Christine S.

    2011-01-01

    Juice was manufactured from seven different sour cherry clones/cultivars and evaluated by quantitative descriptive sensory analysis and 1H NMR spectroscopy. The sensory evaluation showed a large variation in several sensory attributes between the sour cherry clones/cultivars, which could be divid...

  6. Investigating Functional Extension of Optical Coherence Tomography for Spectroscopic Analysis of Blood Oxygen Saturation

    Science.gov (United States)

    Chen, Siyu

    Over the past two decades, optical coherence tomography (OCT) has been successfully applied to various fields of biomedical researching and clinical studies, including cardiology, urology, dermatology, dentistry, oncology, and most successfully, ophthalmology. This dissertation seeks to extend the current OCT practice, which is still largely morphology-based, into a new dimension, functional analysis of metabolic activities in vivo. More specifically, the investigation is focused on retrieving blood oxygen saturation (sO2) using intrinsic hemoglobin optical absorption contrast. Most mammalian cells rely on aerobic respiration to support cellular function, which means they consume oxygen to create adenosine triphosphate (ATP). Metabolic rate of oxygen (MRO2), a key hemodynamic parameter, characterizes how much oxygen is consumed during a given period of time, reflecting the metabolic activity of the target tissue. For example, retinal neurons are highly active and almost entirely rely on the moment-to-moment oxygen supply from retinal circulations. Thus, variation in MRO2 reveals the instantaneous activity of these neurons, shedding light on the physiological and pathophysiological change of cellular functions. Eventually, measuring MRO2 can potentially provide a biomarker for early-stage disease diagnosis, and serve as one benchmark for evaluating effectiveness of medical intervention during disease management. Essential in calculating MRO2, blood sO2 measurements using spectroscopic OCT analysis has been attempted as early as 2003. OCT is intrinsically sensitive to the blood optical absorption spectrum due to its wide-band illumination and detection scheme relying on back-scattered photon. However, accurate retrieval of blood sO2 using conventional near infrared (NIR) OCT systems in vivo has remained challenging. It was not until the development of OCT systems using visible light illumination (vis-OCT) when accurate measurement of blood sO2 was reported in live

  7. Employment of different spectroscopic tools for the investigation of chromium(VI) oxidation of acetaldehyde in aqueous micellar medium

    Indian Academy of Sciences (India)

    SUSANTA MALIK; ANIRUDDHA GHOSH; PINTU SAR; MONOHAR HOSSAIN MONDAL; KALACHAND MAHALI; BIDYUT SAHA

    2017-05-01

    Different spectroscopic methods have been applied to investigate the chromic acid oxidation of acetaldehyde in aqueous media, catalysed by surfactants. Three representative heteroaromatic nitrogen base promoters, 2-picolinic acid (PA), 2,2’-bipyridine (bpy) and 1,10-phenanthroline (phen), have been associated along with surfactants as promoters to the kinetic study. Comparative studies of unpromoted and promoted reactions invoked that 2,2’-bipyridine produced maximum rate enhancement. The mechanism of the reaction path has been proposed with the help of kinetic results and spectroscopic studies. The observed net enhancementof rate effects has been explained with scientific manipulations and data obtained. The combination of TX-100 and1,10-phenanthroline is found to be most effective for acetaldehyde oxidation.

  8. Spectroscopic (FT-IR, FT-Raman, 1H, 13C NMR, UV/VIS), thermogravimetric and antimicrobial studies of Ca(II), Mn(II), Cu(II), Zn(II) and Cd(II) complexes of ferulic acid

    Science.gov (United States)

    Kalinowska, M.; Piekut, J.; Bruss, A.; Follet, C.; Sienkiewicz-Gromiuk, J.; Świsłocka, R.; Rzączyńska, Z.; Lewandowski, W.

    2014-03-01

    The molecular structure of Mn(II), Cu(II), Zn(II), Cd(II) and Ca(II) ferulates (4-hydroxy-3-methoxycinnamates) was studied. The selected metal ferulates were synthesized. Their composition was established by means of elementary and thermogravimetric analysis. The following spectroscopic methods were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (13C, 1H NMR) and ultraviolet-visible (UV/VIS). On the basis of obtained results the electronic charge distribution in studied metal complexes in comparison with ferulic acid molecule was discussed. The microbiological study of ferulic acid and ferulates toward Escherichia coli, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris was done.

  9. Structural diversity of metal phytate compounds: a solid state C-13 NMR and FT-IR spectroscopic investigation

    Science.gov (United States)

    Phytate (myo-inositol-1,2,3,4,5,6-hexakisphosphate) is the major organic phosphorus component in the environment. Phytate contains a 6-carbon ring with 1 hydrogen and 1 phosphate attached to each carbon. Each of the 6 phosphate groups is attached in an ester linkage. Phytate exists in aqueous soluti...

  10. Solid state 1D and 2D NMR spectroscopic investigations of conformational changes of metal phytate compounds

    Science.gov (United States)

    Phytate (myo-inositol-1,2,3,4,5,6-hexakisphosphate) (IP6) is the major organic phosphorus component in ceral grains, legumes and seeds high in oil. The high chelating ability of phytate decreases the nutritional availabilty of dietary metal ions (e.g., Ca2+, Fe3+ and Zn2+). Phytate could also decrea...

  11. Investigation of Ti-doped NaAlH4 by solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R; Majzoub, E; Herberg, J

    2003-11-24

    In recent years, the development of Ti-doped NaAlH{sub 4} as a hydrogen storage material has gained attention because of its large weight percentage of hydrogen ({approx}5%) compared to traditional interstitial hydrides. The addition of transition-metal dopants, in the form of Ti-halides, such as TiCl{sub 3}, dramatically improves the kinetics of the absorption and desorption of hydrogen from NaAlH{sub 4}. However, the role that Ti plays in enhancing the absorption and desorption of H{sub 2} is still unknown. In the present study, {sup 27}Al, {sup 23}Na, and {sup 1}H MAS (Magic Angle Spinning) NMR (Nuclear Magnetic Resonance) has been performed to understand the titanium speciation in Ti-doped NaAlH{sub 4}. All experiments were performed on a sample of crushed single crystals exposed to Ti during growth, a sample of solvent-mixed 4TiCl{sub 3} + 112NaAlH{sub 4}, a reacted sample of solvent-mixed TiCl{sub 3} + {sup 3}NaAlH{sub 4} with THF, and a reacted sample of ball-milled TiCl3 + 3NaAlH{sub 4}. The {sup 27}Al MAS NMR has shown differences in compound formation between solvent-mixed TiCl{sub 3} + 3NaAlH{sub 4} with THF and the mechanically ball-milled TiCl{sub 3} + 3NaAlH{sub 4}. {sup 27}Al MAS NMR of the mechanically ball-milled mixture of fully-reacted TiCl{sub 3} + 3NaAlH{sub 4} showed spectral signatures of TiAl{sub 3} while, the solvent-mixed 4TiCl{sub 3} + 112NaAlH{sub 4}, which is totally reacted, does not show the presences of TiAl{sub 3}, but shows the existence of Al{sub 2}O{sub 3}.

  12. Spectroscopic investigation of native defect induced electron-phonon coupling in GaN nanowires

    Science.gov (United States)

    Parida, Santanu; Patsha, Avinash; Bera, Santanu; Dhara, Sandip

    2017-07-01

    The integration of advanced optoelectronic properties in nanoscale devices of group III nitride can be realized by understanding the coupling of charge carriers with optical excitations in these nanostructures. The native defect induced electron-phonon coupling in GaN nanowires are reported using various spectroscopic studies. The GaN nanowires having different native defects are grown in an atmospheric pressure chemical vapor deposition technique. X-ray photoelectron spectroscopic analysis revealed the variation of Ga/N ratios in nanowires having possible native defects, with respect to their growth parameters. The analysis of the characteristic features of electron-phonon coupling in the Raman spectra show the variations in carrier density and mobility, with respect to the native defects in unintentionally doped GaN nanowires. The radiative recombination of donor acceptor pair transitions and the corresponding LO phonon replicas observed in photoluminescence studies further emphasize the role of native defects in electron-phonon coupling.

  13. A spectroscopic investigations of anticancer drugs binding to bovine serum albumin

    Science.gov (United States)

    Bakkialakshmi, S.; Chandrakala, D.

    2012-03-01

    The binding of anticancer drugs (i) Uracil (U), (ii) 5-Fluorouracil (5FU) and (iii) 5-Chlorouracil (5ClU), to bovine serum albumin (BSA) at two levels of temperature was studied by the fluorescence of quenching method. UV/Vis, time-resolved fluorescence, Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and scanning electron microscope (SEM) analyses were also made. Binding constants (Ka) and binding sites (n) at various levels of temperature were calculated. The obtained binding sites were found to be equal to one for all the three quenchers (U, 5FU and 5ClU) at two different temperature levels. Thermodynamic parameters ΔH, ΔG and ΔS have been calculated and were presented in tables. Change in FTIR absorption intensity shows strong binding of anticancer drugs to BSA. Changes in chemical shifts of NMR and fluorescence lifetimes of the drugs indicate the presence of interaction and binding of BSA to anticancer drugs. 1H NMR spectra and SEM photographs also conform this binding.

  14. Nuclear magnetic resonance spectroscopic investigation of anode exhaust of direct methanol fuel cells without isotope enrichment

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Young Seok; Hwang, Reo Yun; Han, Ochee [Western Seoul Center, Korea Basic Science Institute, Seoul (Korea, Republic of)

    2016-12-15

    Fuel cells are devices that electrochemically convert the chemical energy of fuels such as natural gas, gasoline, and methanol, into electricity. Fuel cells more efficiently use energy than internal combustion engines and do not produce undesirable pollutants, such as NO{sub x} ,SO{sub x} and particulates. Fuel cells can be distinguished from one another by their electrolytes. Among the various direct alcohol fuel cells, direct methanol fuel cells (DMFCs) have been developed most. However, DMFCs have several practical problems such as methanol crossove r from an anode to a cathode and slow methanol oxidation reaction rates. Therefore, understanding the electrochemical reaction mechanisms of DMFCs may provide clues to solve these problems, and various analytical methods have been employed to examine these mechanisms. We demonstrated that {sup 1}H and {sup 13}C NMR spectroscopy can be used for analyzing anode exhausts of DMFCs operated with methanol without any isotope enrichment. However, the low sensitivity of NMR spectroscopy hindered our efforts to detect minor reaction intermediates. Therefore, sensitivity enhancement techniques such as dynamic nuclear polarization (DNP) NMR methods and/or presaturation methods to increase the dynamic range of the proton spectra by pre-saturating large water signals, are expected to be useful to detect low-concentration species.

  15. A subzero 1H NMR relaxation investigation of water dynamics in tomato pericarp.

    Science.gov (United States)

    Foucat, Loïc; Lahaye, Marc

    2014-09-01

    (1)H NMR relaxation times (T1 and T2) were measured at low field (0.47 T) in pericarp tissues of three tomato genotypes (Ferum, LA0147 and Levovil) at subzero temperature (-20 °C) and two ripening stages (mature green and red). The unfrozen water dynamics was characterised by two T1 and three T2 components. The relaxation time values and their associated relative populations allowed differentiating the ripening stage of only LA0147 and Levovil lines. But the three genotypes were unequivocally discriminated at the red ripe stage. The unfrozen water distribution was discussed in terms of specific interactions, especially with sugars, in relation with their osmoprotectant effects.

  16. Investigating the mechanisms of amylolysis of starch granules by solution-state NMR.

    Science.gov (United States)

    Baldwin, Andrew J; Egan, Danielle L; Warren, Fredrick J; Barker, Paul D; Dobson, Christopher M; Butterworth, Peter J; Ellis, Peter R

    2015-05-11

    Starch is a prominent component of the human diet and is hydrolyzed by α-amylase post-ingestion. Probing the mechanism of this process has proven challenging, due to the intrinsic heterogeneity of individual starch granules. By means of solution-state NMR, we demonstrate that flexible polysaccharide chains protruding from the solvent-exposed surfaces of waxy rice starch granules are highly mobile and that during hydrothermal treatment, when the granules swell, the number of flexible residues on the exposed surfaces increases by a factor of 15. Moreover, we show that these flexible chains are the primary substrates for α-amylase, being cleaved in the initial stages of hydrolysis. These findings allow us to conclude that the quantity of flexible α-glucan chains protruding from the granule surface will greatly influence the rate of energy acquisition from digestion of starch.

  17. Theoretical investigation of nano zirconium carbide sheet: A study of NMR, NBO, EPR and Polar

    Directory of Open Access Journals (Sweden)

    Roya Rouhani

    2015-09-01

    Full Text Available In this work, we have focused on the zirconium carbide (ZrC sheet. The result exhibited that ZrC exhibits various outstanding physical and chemical properties, such as high hardness (25 Gpa, high melting point (3420°C, high corrosion and wear resistance, solid-state phase stability as well as chemical stability. Hence, ZrC has been considered a good potential material for ultra-high temperature applications. Applications range from cutting tools, grinding wheels and abrasives for mechanical as well as structural components in chemical and electronic industries. Abinitio calculation was carried out for Zirconium carbide sheet (ZrC using Gaussian 09 program for the first time (Fig 1. We choose B3LYP for calculating natural bond orbital (NBO, Nuclear magnetic resonance (NMR, Electron paramagnetic resonance (EPR and polar.

  18. Conformational and stereoeletronic investigations of muscarinic agonists of acetylcholine by NMR and theoretical calculations

    Science.gov (United States)

    da Silva, Julio Cesar A.; Ducati, Lucas C.; Rittner, Roberto

    2012-05-01

    NMR solvent effects and theoretical calculations showed muscarinic agonists present a large stability for their near synclinal conformations, indicating the presence of significant stabilization factors. Analysis of the results clearly indicated that this stability is not determined by the dihedral around the substituted C-C ethane bond, as stated by some authors, but a consequence of the geometry adopted in order to maximize N+/O interactions in this type of molecules. It can be assumed that acetylcholine and its muscarinic agonists exhibit their biologic activity when the positively charged nitrogen and the oxygen atoms are in the same side of the molecule within an interatomic distance ranging from 3.0 to 6.0 Å.

  19. A solid state NMR investigation of char forming processes in polymer degradation

    CERN Document Server

    Dick, C M

    2002-01-01

    A detailed knowledge of the condensed phase chemistry occurring in polymers exposed to elevated temperatures is crucial to understanding the behaviour of polymers exposed to fire. This is particularly true when trying to reduce polymer flammability by means of promoting char-forming reactions. Until recently, however, structural information on highly crosslinked chars and their precursors has been difficult to obtain, and as a consequence many degradation workers have merely labelled degradation residues as 'intractable'. However, the application of solid state NMR techniques developed in our laboratories for the structural characterisation of coals has provided a considerable insight into the structure and chemistry of polymer chars formed under both oxidative and non-oxidative conditions. A series of polymers including poly(vinyl chloride), poly(vinyl acetate), polyurethanes, polychloropene, cis and trans polyisoprene have been studied. These polymers have been used to describe the application of quantitati...

  20. Thiol-thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV-vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule.

    Science.gov (United States)

    Gökce, Halil; Öztürk, Nuri; Ceylan, Ümit; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

    2016-06-15

    In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Thiol-thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV-vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule

    Science.gov (United States)

    Gökce, Halil; Öztürk, Nuri; Ceylan, Ümit; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

    2016-06-01

    In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311 ++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data.

  2. 4-Cyano-α-methyl-l-phenylalanine as a spectroscopic marker for the investigation of peptaibiotic-membrane interactions.

    Science.gov (United States)

    De Zotti, Marta; Bobone, Sara; Bortolotti, Annalisa; Longo, Edoardo; Biondi, Barbara; Peggion, Cristina; Formaggio, Fernando; Toniolo, Claudio; Dalla Bona, Andrea; Kaptein, Bernard; Stella, Lorenzo

    2015-04-01

    Two analogs of the ten-amino acid residue, membrane-active lipopeptaibiotic trichogin GA IV, mono-labeled with 4-cyano-α-methyl-L-phenylalanine, a potentially useful fluorescence and IR absorption probe of the local microenvironment, were synthesized by the solid-phase methodology and conformationally characterized. The single modification was incorporated either at the N-terminus (position 1) or near the C-terminus (position 8) of the peptide main chain. In both cases, the replaced amino acid was the equally helicogenic α-aminoisobutyric acid (Aib) residue. We performed a solution conformational analysis by use of FT-IR absorption, CD, and 2D-NMR spectroscopies. The results indicate that both labeled analogs essentially maintain the overall helical propensity of the naturally occurring lipopeptaibiotic. Peptide-membrane interactions were assessed by fluorescence and ATR-IR absorption techniques. Analogies and differences between the two peptides were highlighted. Taken together, our data confirm literature results that some of the spectroscopic parameters of the 4-cyanobenzyl chromophore are sensitive markers of the local microenvironment.

  3. [Application of Raman spectroscopic technique to the identification and investigation of Chinese ancient jades and jade artifacts].

    Science.gov (United States)

    Zhao, Hong-Xia; Gan, Fu-Xi

    2009-11-01

    Laser Raman spectroscopic technique is one of the essential methods in scientific archaeological research, which belongs to the nondestructive analysis. As a very good nondestructive analysis approach, it has not been widely applied in the research of the Chinese ancient jade artifacts. First of all in the present paper the fundamentals of laser Raman spectroscopic technique and the new research progress in this field were reviewed. Secondly, the Raman spectra of five familiar jades including nephrite (mainly composed of tremolite), Xiuyan Jade (mainly composed of serpentine), Dushan Jade (mainly composed of anorthite and Zoisite), turquoise and lapis lazuli were summarized respectively. As for an example, the Raman spectra of the four Chinese ancient jade artifacts excavated from Liangzhu Site of Zhejiang Province and Yinxu Site of Anyang in Henan Province were compared with that of the nephrite sample in Hetian of Xinjiang Province. It was shown that the Raman spectroscopic technique is a good nondestructive approach to the identification and investigation of the structures and mineral composition of Chinese ancient jade artifacts. Finally, the limitations and the foreground of this technique were discussed.

  4. Segmental motions of poly(ethylene glycol) chains adsorbed on Laponite platelets in clay-based hydrogels: a NMR investigation.

    Science.gov (United States)

    Lorthioir, Cédric; Khalil, Mouhamad; Wintgens, Véronique; Amiel, Catherine

    2012-05-22

    The segmental dynamics of poly(ethylene glycol) (PEG) chains adsorbed on the clay platelets within nanocomposite PEG/Laponite hydrogels was investigated over the tens of microseconds time scale, using combined solution and solid-state NMR approaches. In a first step, the time evolution of the molecular mobility displayed by the PEG chains following the addition to a Laponite aqueous dispersion was monitored during the aggregation of the clay disks and the hydrogel formation, by means of (1)H solution-state NMR. Part of the PEG repeat units were found to get strongly constrained during the gelation process. Comparisons between this time evolution of the PEG local dynamics in the PEG/Laponite/water systems and the increase of the macroscopic storage shear modulus, mainly governed by the assembling of the Laponite disks, indicate that the slowing down of the segmental motions arises from adsorbed PEG repeat units or chain portions strongly constrained between aggregated clay layers. In a second step, after completion of the gelation process, the molecular motions of the adsorbed PEG chains were probed by (1)H solid-state NMR spectroscopy. (1)H double-quantum experiments indicate that the adsorbed PEG repeat units, though reported to be frozen over a few tens of nanoseconds, still display significant reorientational motions over the tens of microseconds time scale. Using a comparison with a model system of amorphized PEG chains, the characteristic frequency of these segmental motions was found to range between 78.0 kHz and 100.7 MHz at 300 K. Interestingly, at this temperature, the level of reorientational motions detected for these adsorbed PEG chain portions was found to be as restricted as the one of bulk amorphous PEG chains, cooled at a slightly lower temperature (about 290 K).

  5. In Situ 13C NMR at Elevated-Pressures and -Temperatures Investigating the Conversion of CO2 to Magnesium and Calcium Carbonate Minerals

    Science.gov (United States)

    Surface, J. A.; Conradi, M. S.; Skemer, P. A.; Hayes, S. E.

    2013-12-01

    We have constructed specialized NMR hardware to conduct in situ elevated-pressure, elevated-temperature 13C NMR studies of unmixed heterogeneous mixtures of solids, liquids, gases, and supercritical fluids. Specifically, our aim is to monitor CO2 uptake in both ultramafic rocks and in more porous geological materials to understand the mechanisms of chemisorption as a function of temperature, pressure and pH. In this in situ NMR probe, we are able to simulate processes at geologically relevant fluid pressures and temperatures, monitoring the kinetics of CO2 conversion to carbonates. The in situ NMR experiments consist of heterogeneous mixtures of rock, salty brine solution, and moderate pressure CO2 gas at elevated temperatures. The purpose of studying these reactions is to determine efficacy of carbonate formation in various geological reservoirs. Via 13C NMR, we have spectroscopically characterized and quantified the conversion of CO2 to magnesium carbonate and calcium carbonate minerals. When CO2 reacts with the calcium or magnesium in a mineral or rock sample, the 13C chemical shift, linewidth, lineshape, and relaxation times change dramatically. This change can be monitored in situ and provide instantaneous and continuous characterization that maps the chemistry that is taking place. For example, on the pathway to MgCO3 formation, there are a number of phases of Mg(OH)x(H2O)y(CO3)z that are apparent via NMR spectroscopy. We will demonstrate that NMR can be used for quantitative characterization of multiple metastable mineral phases in pure forms and in mixtures. Results are confirmed via powder XRD and Raman spectroscopy of aquo- hydro- carbonato- magnesium species and calcium carbonate species. We also have monitored the 13C spectroscopy to analyze the phase of CO2 (liquid, supercritical, or gas) and its conversion into other forms, such as bicarbonate and carbonate species, providing a "window" into the in situ pH of the reacting system. Reference: 'In Situ

  6. DNA induced sequestration of a bioactive cationic fluorophore from the lipid environment: A spectroscopic investigation.

    Science.gov (United States)

    Ghosh, Saptarshi; Kundu, Pronab; Chattopadhyay, Nitin

    2016-01-01

    The effect of calf-thymus DNA (ctDNA) on the lipid bound probe, formed by the cationic phenazinium dye phenosafranin (PSF) and the anionic lipid dimyristoyl-L-α-phosphatidylglycerol (DMPG), has been unearthed exploiting various spectroscopic techniques. Steady state and time-resolved fluorometric studies and measurements of circular dichroism and DNA helix melting temperature reveal that in the presence of DNA the probe is dislodged from the lipid environment and gets intercalated within the DNA helix. The work qualitatively illustrates that the anionic lipid can be used as a potential nanocarrier for delivering the cationic drugs to the most relevant biomacromolecular target, DNA.

  7. Ab initio study, investigation of NMR shielding tensors, NBO and vibrational frequency of catechol thioethers

    Directory of Open Access Journals (Sweden)

    A. Bagheri Gh

    2010-08-01

    Full Text Available The electrochemical oxidation of dopamine and 3,4-dihydroxymethamphetamine (HHMA has been studied in the presence of GSH and cysteine as a nucleophile. In order to determine the optimized geometries, energies, dipole moments, atomic charges, thermochemical analysis and other properties, we performed quantum chemical ab initio and density functional calculations at B3LYP level with 6-31G* basis set. The structural and vibrational properties of 5-S-glutathionyldopamine, 5-S-cysteinyldopamine and 5-S-N-acetylcysteinyldopamine are studied. The chemical shifts of anisotropy and Δδ are calculated. The gauge-invariant atomic orbital (GIAO method was employed to calculate isotropic atomic shielding of compounds. These calculations yield molecular geometries in good agreement with available experimental data. The bond lengths, bond angles, dipole moment, electron affinity, ionization potential, electronegativy, absolute hardness, highest occupied molecular orbital (HOMO and the energy of the lowest unoccupied molecular orbital (LUMO of the studied compounds were calculated in gas phase and water. NMR analysis of dopamine-o-quinone-glutathione conjugate revealed that the addition of glutathione was at C-5 to form glutathionyl-dopamine.

  8. Molecular mobility in dense protein systems: an investigation through 1H NMR relaxometry and diffusometry.

    Science.gov (United States)

    Bouchoux, Antoine; Schorr, Diane; Daffé, Awa; Cambert, Mireille; Gésan-Guiziou, Geneviève; Mariette, François

    2012-09-27

    Understanding how proteins behave in highly concentrated systems is a major issue in many fields of research, including biology, biophysics, and chemical engineering. In this paper, we provide a comprehensive (1)H NMR study of molecular mobility in dilute to highly concentrated dispersions of the exact same protein (casein) but organized in two distinct supramolecular forms: spongelike casein micelles or soft casein aggregates. Both relaxometry and diffusometry experiments were performed, so that three different parameters are reported: spin-spin relaxation rates of non-water protons (1/T(2,ne)), spin-spin relaxation rates of water protons (1/T(2,e+w)), and water self-diffusion coefficients (D(w)). The results are discussed in an effort to understand the respective effects of protein crowding and protein supramolecular organization on each mobility indicator. We also examine if connections exist between the observed changes in molecular mobility and the already documented changes in rheological and osmotic properties of casein dispersions as concentration is increased.

  9. Does aluminium bind to histidine? An NMR investigation of amyloid β12 and amyloid β16 fragments.

    Science.gov (United States)

    Narayan, Priya; Krishnarjuna, Bankala; Vishwanathan, Vinaya; Jagadeesh Kumar, Dasappa; Babu, Sudhir; Ramanathan, Krishna Venkatachala; Easwaran, Kalpathy Ramaier Katchap; Nagendra, Holenarasipur Gundurao; Raghothama, Srinivasarao

    2013-07-01

    Aluminium and zinc are known to be the major triggering agents for aggregation of amyloid peptides leading to plaque formation in Alzheimer's disease. While zinc binding to histidine in Aβ (amyloid β) fragments has been implicated as responsible for aggregation, not much information is available on the interaction of aluminium with histidine. In the NMR study of the N-terminal Aβ fragments, DAEFRHDSGYEV (Aβ12) and DAEFRHDSGYEVHHQK (Aβ16) presented here, the interactions of the fragments with aluminium have been investigated. Significant chemical shifts were observed for few residues near the C-terminus when aluminium chloride was titrated with Aβ12 and Aβ16 peptides. Surprisingly, it is nonhistidine residues which seem to be involved in aluminium binding. Based on NMR constrained structure obtained by molecular modelling, aluminium-binding pockets in Aβ12 were around charged residues such as Asp, Glu. The results are discussed in terms of native structure propagation, and the relevance of histidine residues in the sequences for metal-binding interactions. We expect that the study of such short amyloid peptide fragments will not only provide clues for plaque formation in aggregated conditions but also facilitate design of potential drugs for these targets. © 2013 John Wiley & Sons A/S.

  10. Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

    Directory of Open Access Journals (Sweden)

    Cesar Garcias-Morales

    2015-10-01

    Full Text Available This paper reports the synthesis of a series of piperidones 1–8 by the Mannich reaction and analysis of their structures and conformations in solution by NMR and mass spectrometry. The six-membered rings in 2,4,6,8-tetraphenyl-3,7-diazabicyclo[3.3.1]nonan-9-ones, compounds 1 and 2, adopt a chair–boat conformation, while those in 2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ones, compounds 3–8, adopt a chair–chair conformation because of stereoelectronic effects. These stereoelectronic effects were analyzed by the 1JC–H coupling constants, which were measured in the 13C satellites of the 1H NMR spectra obtained with the hetero-dqf pulse sequence. In the solid state, these stereoelectronic effects were investigated by measurement of X-ray diffraction data, the molecular geometry (torsional bond angles and bond distances, and inter- and intramolecular interactions, and by natural bond orbital analysis, which was performed using density functional theory at the ωB97XD/6311++G(d,p level. We found that one of the main factors influencing the conformational stability of 3–8 is the interaction between the lone-pair electrons of nitrogen and the antibonding sigma orbital of C(7–Heq (nN→σ*C–H(7eq, a type of hyperconjugative interaction.

  11. Spectroscopic ellipsometry investigations of the optical properties of manganese doped bismuth vanadate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, Neelam; Krupanidhi, S.B. [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); Varma, K.B.R., E-mail: kbrvarma@mrc.iisc.ernet.in [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

    2010-04-15

    The optical properties of Bi{sub 2}V{sub 1-x}Mn{sub x}O{sub 5.5-x} {l_brace}x = 0.05, 0.1, 0.15 and 0.2 at.%{r_brace} thin films fabricated by pulsed laser deposition on platinized silicon substrates were studied in UV-visible spectral region (1.51-4.17 eV) using spectroscopic ellipsometry. The optical constants and thicknesses of these films have been obtained by fitting the ellipsometric data ({Psi} and {Delta}) using a multilayer four-phase model system and a relaxed Lorentz oscillator dispersion relation. The surface roughness and film thickness obtained by spectroscopic ellipsometry were found to be consistent with the results obtained by atomic force and scanning electron microscopy. The refractive index measured at 650 nm does not show any marginal increase with Mn content. Further, the extinction coefficient does not show much decrease with increasing Mn content. An increase in optical band gap energy from 2.52 to 2.77 eV with increasing Mn content from x = 0.05 to 0.15 was attributed to the increase in oxygen ion vacancy disorder.

  12. Enhanced efficiency of solid-state NMR investigations of energy materials using an external automatic tuning/matching (eATM) robot

    Science.gov (United States)

    Pecher, Oliver; Halat, David M.; Lee, Jeongjae; Liu, Zigeng; Griffith, Kent J.; Braun, Marco; Grey, Clare P.

    2017-02-01

    suited to collect. These new developments in automation of NMR experiments are likely to advance the application of in and ex situ NMR investigations to an ever-increasing range of energy storage materials and systems.

  13. Metal Carbonation of Forsterite in Supercritical CO2 and H2O Using Solid State 29Si, 13C NMR Spectroscop

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Hu, Jian Z.; Hoyt, David W.; Sears, Jesse A.; Wang, Chong M.; Rosso, Kevin M.; Felmy, Andrew R.

    2010-03-11

    Ex situ solid state NMR was used for the first time to study fundamental mineral carbonation processes and reaction extent relevant to geologic carbon sequestration (GCS) using a model silicate mineral forsterite (Mg2SiO4)+supercriticalCO2 with and without H2O. Run conditions were 80 C and 96 atm. 29Si NMR clearly shows that in the absence of CO2, the role of H2O is to hydrolyze surface Mg-O-Si bonds to produce dissolved Mg2+, and mono- and oligomeric hydroxylated silica species. Surface hydrolysis products contain only Q0 (Si(OH)4) and Q1(Si(OH)3OSi) species. An equilibrium between Q0, Q1 and Mg2+ with a saturated concentration equivalent to less than 3.2% of the Mg2SiO4 conversion is obtained at a reaction time of up to 7 days. Using scCO2 without H2O, no reaction is observed within 7 days. Using both scCO2 and H2O, the surface reaction products for silica are mainly Q3 (SiOH(OSi)3) species accompanied by a lesser amount of Q2 (Si(OH)2(OSi)2) and Q4 (Si(OSi)4). However, no Q0 and Q1 were detected, indicating the carbonic acid formation/deprotonation and magnesite (MgCO3) precipitation reactions are faster than the forsterite hydrolysis process. Thus it can be concluded that the Mg2SiO4 hydrolysis process is the rate limiting step of the overall mineral carbonation process. 29Si NMR combined with XRD, TEM, SAED and EDX further reveal that the reaction is a surface reaction with the Mg2SiO4 crystallite in the core and with condensed Q2-Q4 species forming amorphous surface layers. 13C MAS NMR identified a possible reaction intermediate as (MgCO3)4-Mg(OH)2-5H2O. However, at long reaction times only crystallite magnesite MgCO3 products are observed.

  14. Spectroscopic investigations of dispersion-shifted fiber with thin active Bi-doped ring and high nonlinear refractive index

    Science.gov (United States)

    Zlenko, A. S.; Akhmetshin, U. G.; Bogatyrjov, V. A.; Bulatov, L. I.; Dvoyrin, V. V.; Firstov, S. V.; Dianov, E. M.

    2009-10-01

    A germanium-doped silica-core fiber with an active region in the form of a thin ring of silica doped with bismuth ions was fabricated. Bismuth doping in the ring surrounding the core allows to stabilize bismuth in silica glass, and it does not impose any restrictions on the composition of the core. The bismuth concentration in the ring is less than 0.2 wt.%. The GeO2 concentration in the core is more than 15 mol.%. A high germanium concentration in the core allows to shift the zero dispersion wavelength to 1860 nm and to obtain a high nonlinear refractive index (n2 more than 3,2*10-20 m2/W). Spectroscopic investigations were carried out in the visible and near infrared (800-1700 nm) spectral range. Despite the small concentration of bismuth, we observed the absorption and luminescence characteristic bands, confirming the presence of bismuth active centers in silica glass. Upon pumping at 1350 nm the on/off gain spectrum was measured on a 20-m fiber. The gain was observed throughout investigated range of 1430-1530 nm. The maximal gain of ~9.5 dB was obtained near 1430 nm. The results of the spectroscopic investigations of the fiber with a thin active Bi-doped ring showed prospects of the creation and application of such fiber type for laser and nonlinear optics.

  15. Flavonoids from Curcuma longa leaves and their NMR assignments.

    Science.gov (United States)

    Jiang, Chia-Ling; Tsai, Sheng-Fa; Lee, Shoei-Sheng

    2015-01-01

    Chemical investigation of the n-BuOH-soluble fraction of the EtOH extract of the aerial part of Curcuma longa led to the isolation of 11 flavonol glycosides and one dihydroflavonol glucoside (1) via chromatography over Sephadex LH-20 and Lobar RP-18 columns. Although they are known, the 1H and 13C NMR data recorded in CD3OD rather than the common DMSO-d6 are doubly checked via extensive 2D NMR spectroscopic analyses, leading to some revisions of the reported data, especially for the glycon part.

  16. Mg-doped hydroxyapatite nanoplates for biomedical applications: A surfactant assisted microwave synthesis and spectroscopic investigations

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Vijay Kumar [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India); Bhattacharjee, Birendra Nath; Parkash, Om [Department of Ceramic Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Kumar, Devendra, E-mail: devendra.cer@iitbhu.ac.in [Department of Ceramic Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Rai, Shyam Bahadur, E-mail: sbrai49@yahoo.co.in [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India)

    2014-11-25

    Highlights: • Microwave irradiation technique: employed for the synthesis of Mg-HAp nanoplates. • Surfactant (EDTA) assisted synthesis of Mg-HAp. • FT-IR and Raman analysis of functional groups of Mg-HAp. - Abstract: Nanoplates of Mg doped hydroxyapatite (Mg-HAp) were derived successfully and rapidly via microwave irradiation technique. Hydroxyapatite (HAp) is the hard tissues and main inorganic component in mammals. Different nanostructures of HAp exist in different parts of human bone but nanorods are very common due to its intrinsic nature to grow in rode-like structure under physiological as well as under applied ambient conditions in laboratory. On the addition of Mg at very low level (0.06 mol%) in pure HAp results the formation of 2-D plate-like nanostructures rather than rod-like which is the matter of interest. In this attempt our efforts have been focused on the study of effect of Mg incorporation on structural and spectroscopic properties of HAp prepared via microwave irradiation technique. This technique is preferred due to several advantages viz. very fast as well as homogeneous heating, time/energy saving and eco-friendliness. The calcium nitrate tetrahydrate (Ca(NO{sub 3}){sub 2}⋅4H{sub 2}O)) as a source of calcium, magnesium nitrate hexahydrate (Mg(NO{sub 3}){sub 2}⋅6H{sub 2}O) as a source of magnesium, disodium hydrogen phosphate dihydrate (NaH{sub 2}PO{sub 4}⋅2H{sub 2}O) as a source of phosphorous and sodium ethylene diamine tetra acetate (NaEDTA) as a surfactant were used as starting reagents. Sodium hydroxide (NaOH) pellets were employed to adjust the pH value of final solution. The solution of fixed pH value was kept into the microwave oven generating waves of frequency 2.45 GHz (water absorption frequency) and power 750 W for 8 min. The precipitate thus obtained was washed, centrifuged and then dried at 100 °C for 2 h. Dried powder was then calcined at 700 °C for 2 h. The bright white powder thus obtained was characterized

  17. Crystalline perfection, spectroscopic investigations and transport properties of trisglycine zinc chloride NLO single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sugandhi, K.; Dinakaran, S.; Jose, M.; Uthrakumar, R. [Department of Physics, Loyola College, Chennai 600 034 (India); Jeya Rejendran, A. [Department of Chemistry, Loyola College, Chennai 600 034 (India); Bhagvannarayana, G. [CGC section, National Physical Laboratory, New Delhi 110 012 (India); Joseph, V. [Department of Physics, Loyola College, Chennai 600 034 (India); Jerome Das, S., E-mail: sjeromedas2004@yahoo.co [Department of Physics, Loyola College, Chennai 600 034 (India)

    2010-09-15

    Bulk single crystals of trisglycine zinc chloride have been grown from aqueous solution by slow cooling technique. Single crystal and powder XRD analyses confirmed orthorhombic crystal structure with non-centrosymmetric space group Pbn2{sub 1.} High resolution X-ray diffraction results have established that the quality of the grown crystal is quite good for device fabrication. The crystal was characterized by FTIR and NMR spectral analyses. Optical absorption studies show that the material has very low absorption in the wavelength range 240-2000 nm. The analysis of absorption coefficient in the absorption region reveals a direct band gap of 4.21 eV. The crystal possesses remarkable thermal stability up to 229 {sup o}C. Photoconductivity studies of the grown crystal revealed the positive photoconducting nature. The grown crystal exhibited considerable hardness anisotropy with Vicker's hardness tester. Dielectric constant and dielectric loss were calculated by varying frequencies at different temperatures.

  18. A novel solid-state NMR method for the investigation of trivalent lanthanide sorption on amorphous silica at low surface loadings.

    Science.gov (United States)

    Mason, H E; Begg, J D; Maxwell, R S; Kersting, A B; Zavarin, M

    2016-07-13

    The modelling of radionuclide transport in the subsurface depends on a comprehensive understanding of their interactions with mineral surfaces. Spectroscopic techniques provide important insight into these processes directly, but at high concentrations are sometimes hindered by safety concerns and limited solubilities of many radionuclides, especially the actinides. Here we use Eu(iii) as a surrogate for trivalent actinide species, and study Eu(iii) sorption on the silica surface at pH 5 where sorption is fairly limited. We have applied a novel, surface selective solid-state nuclear magnetic resonance (NMR) technique to provide information about Eu binding at the silica surface at estimated surface loadings ranging from 0.1 to 3 nmol m(-2) (<0.1% surface loading). The NMR results show that inner sphere Eu(iii) complexes are evenly distributed across the silica surface at all concentrations, but that at the highest surface loadings there are indications that precipitates may form. These results illustrate that this NMR technique may be applied in solubility-limited systems to differentiate between adsorption and precipitation to better understand the interactions of radionuclides at solid surfaces.

  19. Investigating the Spectroscopic Variability and Magnetic Activity of Photometrically Variable M Dwarfs in SDSS

    Science.gov (United States)

    Ventura, Jean-Paul; Cid, Aurora; Schmidt, Sarah J.; Rice, Emily L.; Cruz, Kelle L.

    2017-01-01

    Magnetic activity, a wide range of observable phenomena produced in the outer atmospheres of stars, is currently not well understood for M dwarfs. In higher mass stars, magnetic activity is powered by a dynamo process involving the differential rotation of a star’s inner regions. This process generates a magnetic field, heats up regions in the atmosphere, and produces emission line radiation (H-alpha) from collisional excitation. Using the Sloan Digital Sky Survey’s (SDSS) Time Domain Spectroscopic Survey (TDSS), we will compare the H-alpha emission line strengths for a sample of 12,000 known photometrically variable M dwarfs observed in the PAN-STARRS1 survey with those of a known non-variable sample. This will be done in order to test whether photometric variability of the sample correlate with chromospheric H-alpha emission features and if not, explore the alternate reasons for that photometric variability, like binarity.

  20. Electrochemical and spectroscopic investigations of immobilized de novo designed heme proteins on metal electrodes

    DEFF Research Database (Denmark)

    Albrecht, Tim; Li, WW; Ulstrup, Jens;

    2005-01-01

    On the basis of rational design principles, template-assisted four-helix-bundle proteins that include two histidines for coordinative binding of a heme were synthesized. Spectroscopic and thermodynamic characterization of the proteins in solution reveals the expected bis-histidine coordinated heme...... methods. For all proteins, immobilization causes a decrease in protein stability and a loosening of the helix packing, as reflected by a partial dissociation of a histidine ligand in the ferrous state and very low redox potentials. For the covalently attached MOP-C, the overall interfacial redox process...... involves the coupling of electron transfer and heme ligand dissociation, which was analyzed by time-resolved SERR spectroscopy. Electron transfer was found to be significantly slower for the mono-histidine-coordinated than for the bis-histidine-coordinated heme. For the latter, the formal heterogeneous...

  1. Investigation of effect of annealing on thermally evaporated ZnSe thin films through spectroscopic techniques

    Science.gov (United States)

    Mahesha, M. G.; Rashmitha; Meghana, N.; Padiyar, Meghavarsha

    2017-09-01

    ZnSe thin films have been grown on clean glass substrates by thermal evaporation technique and deposited films have been annealed at 473 K. William-Hall method has been adopted to extract information on crystallite size and internal strain in the film from X-ray diffractogram. Effect of annealing on ZnSe films has been analyzed by spectroscopic techniques which include optical absorption, Raman, and photoluminescence spectroscopy. From optical absorption, band gap has been estimated along with other optical parameters like refractive index and extinction coefficient. Also, Urbach tail, which originates near bad edge due to structural disorders, has been characterized. Raman spectra have been analyzed to get the information on the influence of crystallite size and strain effect on peak position, intensity and width. Photoluminescence spectra have been recorded and analyzed to get an insight on defect levels induced due to vacancies, interstadials, and impurity complexes.

  2. Raman and terahertz spectroscopical investigation of cocrystal formation process of piracetam and 3-hydroxybenzoic acid

    Science.gov (United States)

    Du, Yong; Zhang, Huili; Xue, Jiadan; Fang, Hongxia; Zhang, Qi; Xia, Yi; Li, Yafang; Hong, Zhi

    2015-03-01

    Cocrystallization can improve physical and chemical properties of active pharmaceutical ingredient, and this feature has great potential in pharmaceutical development. In this study, the cocrystal of piracetam and 3-hydroxybenzoic acid under grinding condition has been characterized by Raman and terahertz spectroscopical techniques. The major vibrational modes of individual starting components and cocrystal are obtained and assigned. Spectral results show that the vibrational modes of the cocrystal are different from those of the corresponding parent materials. The dynamic process of such pharmaceutical cocrystal formation has also been monitored directly with Raman and THz spectra. The formation rate is pretty fast in first several 20 min grinding time, and then it becomes slow. After ∼35 min, such process has been almost completed. These results offer us the unique means and benchmark for characterizing the cocrystal conformation from molecule-level and also provide us rich information about the reaction dynamic during cocrystal formation process in pharmaceutical fields.

  3. Self-Association of N-Methylacetamide Examined by Infrared and NMR Spectroscopies

    Science.gov (United States)

    Schenck, Heather L.; Hui, KaWai

    2011-01-01

    These spectroscopic experiments investigate polarity and concentration effects on self-association behavior in N-methylacetamide. Inquiry can be limited to the concentration dependence of hydrogen bonding and estimation of dimerization constant (NMR studies) or to the effect of solvent polarity on extent of hydrogen bonding (IR studies). The…

  4. Self-Association of N-Methylacetamide Examined by Infrared and NMR Spectroscopies

    Science.gov (United States)

    Schenck, Heather L.; Hui, KaWai

    2011-01-01

    These spectroscopic experiments investigate polarity and concentration effects on self-association behavior in N-methylacetamide. Inquiry can be limited to the concentration dependence of hydrogen bonding and estimation of dimerization constant (NMR studies) or to the effect of solvent polarity on extent of hydrogen bonding (IR studies). The…

  5. Spectroscopic investigation on the interaction of maslinic acid with bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Molina-Bolívar, J.A., E-mail: jmb@uma.es [Department of Applied Physics II, Engineering School, University of Málaga, 29071 Málaga (Spain); Galisteo-González, F. [Department of Applied Physics, University of Granada, 18071 Granada (Spain); Carnero Ruiz, C. [Department of Applied Physics II, Engineering School, University of Málaga, 29071 Málaga (Spain); Medina-O' Donnell, M.; Parra, A. [Department of Organic Chemistry, University of Granada, 18071 Granada (Spain)

    2014-12-15

    Ultraviolet–visible (UV–vis), steady-state and time-resolved fluorescence, and Fourier transform-infrared (FT-IR) spectroscopy were used to study the interaction between maslinic acid (MA) and bovine serum albumin (BSA). Binding constants were determined at three different temperatures (298, 304, and 310 K). Spectroscopic analysis revealed that the fluorescence-quenching mechanism between MA and BSA was a static quenching procedure. MA specifically binds to one site of the BSA molecule forming a stable complex with a binding constant of (5.4±0.4)×10{sup 4} M{sup −1} at pH 7.4 and 298 K. From the thermodynamic parameters of the binding process (ΔG{sup 0}, ΔH{sup 0} and ΔS{sup 0}) it can be inferred that hydrogen bonds and van der Waals interactions are the predominant intermolecular forces responsible for the stabilization of the complex. Anisotropy studies revealed that tryptophan residues of BSA undergo motion restrictions as a result of the interaction with MA. The distance between MA and the fluorophore residue of BSA was evaluated according to the theory of Föster for fluorescence resonance energy transfer (FRET). Observations from FT-IR spectra and three-dimensional fluorescence indicated changes in the conformation of BSA upon ligand binding. - Highlights: • The interaction between MA and BSA was examined with spectroscopic techniques. • The interaction between MA and BSA was studied at different temperatures. • Fluorescence spectroscopy studies suggest that quenching mechanism is static. • The hydrogen bonds and van der Waals interactions are predominant forces. • Conformational changes of the protein upon binding of MA were observed.

  6. Production of stable isotope labelled lipase Lip2 from Yarrowia lipolytica for NMR: investigation of several expression systems.

    Science.gov (United States)

    Nars, G; Saurel, O; Bordes, F; Saves, I; Remaud-Siméon, M; André, I; Milon, A; Marty, A

    2014-09-01

    Extracellular lipase Lip2 from Yarrowia lipolytica is a promising biocatalyst with unusual structural features, as indicated by X-ray crystallography. These features comprise a mobile domain called the lid that controls access to the catalytic site. Conformational rearrangements of the lid have been suggested to regulate lipase enzymatic activities. We used nuclear magnetic resonance to investigate the dynamics of Lip2 by exploring four expression systems, Escherichia coli, cell-free, Pichia pastoris and Y. lipolytica to produce uniformly labelled enzyme. The expression of Lip2 was assessed by determining its specific activity and measuring (15)N-(1)H HSQC spectra. Y. lipolytica turned out to be the most efficient expression system. Here, we report the first use of Y. lipolytica as an expression host for the production of uniform stable isotopic labelled protein for further structural and dynamics studies using NMR.

  7. Interactions of acetylcholinesterase with salvianolic acid B and rosmarinic acid from Salvia miltiorhiza water extract investigated by NMR relaxation rate

    Institute of Scientific and Technical Information of China (English)

    Guo Wei Yin; Yi Ming Li; Wei Wei; Shan Hao Jiang; Da Yuan Zhu; Wei Hong Du

    2008-01-01

    In order to understand whether the ameliorating effect on old ages memory disorder by the root of Salvia miltiorhiza is related to the acetylcholinesterase (AChE) inhibition, two main ingredients, salvianolic acid B (1) and rosmarinic acid (2), which were isolated from S. Miltiorhiza water extract, were investigated in vitro by NMR relaxation rate in this work. The results showed that the proton selective relaxation rates and the molecular rotational correlation time of proton pairs for compounds 1 and 2 increased significantly by adding of AChE in mixing solution. The study reveals that the two compounds might bind to the enzyme and have AChE inhibitory effect, which could contribute to the ameliorating effect at some extent on old ages memory disorder.

  8. Study of a Conformational Equilibrium of Lisinopril by HPLC, NMR, and DFT

    Science.gov (United States)

    Bouabdallah, Sondes; Ben Dhia, Med Thaieb; Driss, Med Rida

    2014-01-01

    The isomerization of lisinopril has been investigated using chromatographic, NMR spectroscopic, and theoretical calculations. The NMR data, particularly the NOEDIFF experiments, show that the major species that was eluted first is the trans form. The proportion was 77% and 23% for the trans and cis, respectively. The thermodynamic parameters (ΔH, ΔS, and ΔG) were determined by varying the temperature in the NMR experiments. The interpretations of the experimental data were further supported by DFT/B3LYP calculations. PMID:24707291

  9. Study of a Conformational Equilibrium of Lisinopril by HPLC, NMR, and DFT

    Directory of Open Access Journals (Sweden)

    Sondes Bouabdallah

    2014-01-01

    Full Text Available The isomerization of lisinopril has been investigated using chromatographic, NMR spectroscopic, and theoretical calculations. The NMR data, particularly the NOEDIFF experiments, show that the major species that was eluted first is the trans form. The proportion was 77% and 23% for the trans and cis, respectively. The thermodynamic parameters (ΔH, ΔS, and ΔG were determined by varying the temperature in the NMR experiments. The interpretations of the experimental data were further supported by DFT/B3LYP calculations.

  10. Design of a helix-bundle cross-link: NMR and UV-visible spectroscopic analyses and molecular modeling of ring-oxidized retinals.

    Science.gov (United States)

    Williams, T C; Mani, V

    1991-03-19

    In order to generate potential chemical cross-links for studying the chromophore binding site of bacteriorhodopsin and related helix-bundle proteins, MnO2 was used to oxidize all-trans-retinal's ring moiety. The structures and solution conformations of three ring-oxidized retinal analogues have been determined by using UV-visible absorption and 1H and 13C NMR spectroscopies, primarily with regard to (i) the introduction of a functional group at the ring end of the chromophore, (ii) the retention of the all-trans geometry of the polyenal side chain, and (iii) the torsional angle of the ring-polyenal bond. Analyses of their UV-visible absorption spectral parameters (lambda max, epsilon max, and vibrational fine structure) and NMR spectral parameters (1H-1H coupling constants, 1H and 13C NMR chemical shifts, and 1H homonuclear Overhauser effects) indicated the 4-oxo and the 2,3-dehydro-4-oxo derivatives both possess the twisted 6-s-cis conformation adopted by most six-membered ring analogues of retinal in solution or crystal. However, the alpha-dioxocyclopentenyl analogue exists in solution predominantly (70-80%) as the planar 6-s-trans conformer, similar to violerythrine chromophore analogues. In order to identify the minor solution forms, molecular modeling and geometry optimizations using the semiempirical molecular orbital method AM1 defined two additional symmetry-related minima at +/- 30-40 degrees in its C6-C7 torsional energy profile. Because the chromophores of bacterio- and halorhodopsins and sensory rhodopsins are bound as the 6-s-trans conformer [Harbison, G.S., Smith, S.O., Pardoen, J.A., Courtin, J.M.L., Lugtenburg, J., Herzfeld, J., Mathies, R.A., & Griffin, R.G. (1985) Biochemistry 24, 6955-6962; Baselt, D.R., Fodor, S.P.A., van der Steen, R., Lugtenburg, J., Bogomolni, R.A., & Mathies, R.A. (1989) Biophys. J. 55, 193-196], we suggest that the cyclopentenyl analogue's alpha-diketo function may be favorably positioned within the binding pocket and

  11. Spectroscopic and quantum chemical investigations of substituent effects on the azo-hydrazone tautomerism and acid-base properties of arylazo pyridone dyes.

    Science.gov (United States)

    Dostanić, J; Mijin, D; Ušćumlić, G; Jovanović, D M; Zlatar, M; Lončarević, D

    2014-04-05

    A series of 5-(4-substituted arylazo)-6-hydroxy-4-methyl-3-cyano-2-pyridone dyes was synthesized and the structure of the dyes was confirmed by UV-Vis, FT-IR, (1)H NMR and (13)C NMR spectroscopic techniques. The azo-hydrazone tautomeric equilibrium was found to depend on the substituents as well as on the acidity and basicity of the media. Ionization constant, pKa, of the dyes was determined by UV-Vis spectroscopy and correlated with the Hammett substituent constants, σp and σI. The interpretation of the effect of different substituent in phenyl ring of arylazo pyridone dyes on their spectroscopic and structural properties was based on quantum chemical calculations performed by the density functional theory (DFT/M06-2X) method. The DFT calculations confirmed the existence of two forms in water solution: hydrazone form in acidic and neutral media and anionic form in basic media. The different contribution of azo and hydrazone canonical forms of anionic form is observed for dyes with electron-donating and dyes with electron-withdrawing groups. The dependence of absorption spectra and determined pKa values to the substituent type seems to be mostly due to azo/hydrazone canonical structure ratio in their anionic form. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. (1)H and (13)C NMR spectroscopic studies of hexane-extractable lipids from soils under shelterbelts of different age and composition of plants.

    Science.gov (United States)

    Szajdak, Lech Wojciech; Maryganova, Victoria; Skakovskii, Eugene; Tychinskaya, Ludmila

    2015-01-01

    Comparative study of the composition of lipids extracted with n-hexane from soils under shelterbelts of different age and composition of plants and adjoining cultivated fields in agrolandscape has been carried out with the application of (1)Н and (13)С NMR spectroscopy. The lipid content correlates with the organic carbon content in soils and is the highest in the soil under the 200-years old shelterbelt. The data received indicate that hexane-extractable lipids from the soil under the 200-years old shelterbelt have undergone the most significant biochemical and chemical transformations (oxidation, hydrolysis, polymerization) with the accumulation of resistant compounds and destruction of esters of o-phthalic acid as anthropogenic contaminants compared to the lipids from the soil under the 14-years old shelterbelt and soils of adjoining arable fields.

  13. FTIR, FTRaman, UV-Visible and NMR spectroscopic studies on 3,3‧,4,4‧-tetrachloroazoxybenzene, an azoxybenzene derivative with toxic effects

    Science.gov (United States)

    Castillo, María V.; Pergomet, Jorgelina L.; Carnavale, Gustavo A.; Davies, Lilian; Zinczuk, Juan; Brandán, Silvia Antonia

    2017-08-01

    We have synthesized 3,3‧,4,4‧ Tetrachloroazoxybenzene (TCAOB) and, later, characterized it by using infrared, Raman, 1H, 13C NMR and UV-visible spectroscopies. The structural, topological and vibrational properties of four Cis and three Trans isomers were theoretically predicted by using the hybrid B3LYP together with the 6-31G* and 6-311++G** basis sets. The 69 normal modes of vibration for all TCAOB isomers were assigned by using the scaled quantum mechanical force field (SQMFF) procedure and their experimental vibrational spectra and normal internal coordinates. The high stabilities of all Cis and Trans isomers are supported by the π→π*, n→σ*, n→π* and π*→π* electronic transitions calculated by NBO studies while the AIM analyses reveal for the Trans forms the existence of intra-molecular Csbnd H⋯O hydrogen bonds, as suggested by the broad IR band observed in the higher wavenumbers region. The low gap energy for the Trans I isomer supports their higher reactivity probably due to the repulsion of the more electronegative Cl and O atoms as a consequence of their proximities. In addition, the force constants for all Cis and Trans isomers were calculated by using both levels of theory. Here, the comparisons of the predicted IR, Raman, NMR and ultraviolet-visible spectra with the corresponding experimental ones demonstrate good concordances. The existence of the Ndbnd O groups in all TCAOB isomers support the differences in their properties, as compared with those reported for TCAB.

  14. Structural and spectroscopic (UV-Vis, IR, Raman, and NMR) characteristics of anisaldehydes that are flavoring food additives: A density functional study in comparison with experiments

    Science.gov (United States)

    Altun, Ahmet; Swesi, O. A. A.; Alhatab, B. S. S.

    2017-01-01

    The molecular structures, vibrational spectra (IR and Raman), electronic spectra (UV-Vis and DOS), and NMR spectra (13C and 1H) of p-anisaldehyde, m-anisaldehyde, and o-anisaldehyde have been studied by using the B3LYP density functional and the 6-311++G** basis set. While p-anisaldehyde has been found to contain two stable conformers at room temperature, m-anisaldehyde and o-anisaldehyde contain four stable conformers. In agreement with the calculated ground-state energetics and small transition barriers, the comparison of the experimental and calculated spectra of the anisaldehydes indicates equilibrium between all conformers at room temperature. However, the two conformers of o-anisaldehyde, in which the methoxy group lies out of the ring plane, are too rare at the equilibrium. The equilibrium conditions of the conformers of the anisaldehyde isomers have been shown readily accessible through UV-Vis and 13C NMR spectral studies but requiring very detailed vibrational analyses. The effect of the solvent has been found to red-shift the electronic absorption bands and to make the anisaldehydes more reactive and soft. Molecular electrostatic potential maps of the anisaldehydes show that their oxygen atoms are the sites for nucleophilic reactivity. Compared with the most sophisticated NBO method, ESP charges have been found mostly reliable while Mulliken charges fail badly with the present large 6-311++G** basis set. The present calculations reproduce not only the experimental spectral characteristics of the anisaldehydes but also reveal their several structural features.

  15. A spectroscopic study of nicotine analogue 2-phenylpyrrolidine (PPD) using resonant two-photon ionization (R2PI), microwave, and 2D NMR techniques.

    Science.gov (United States)

    Martin, Danielle E; Robertson, Evan G; MacLellan, Jonathan G; Godfrey, Peter D; Thompson, Christopher D; Morrison, Richard J S

    2009-02-25

    Conformational preferences of the nicotine analogue 2-phenylpyrrolidine (PPD) have been studied in both gaseous and solution phases. Theoretical calculations at the MP2 and B3LYP levels point to 5-6 stable conformers which differ in three degrees of conformational freedom; torsion between the two rings, inversion at the pyrrolidine (PY) amine, and PY ring puckering, characterized using the Cremer-Pople definition for pseudorotation. Only one conformer has a trans arrangement between the amino hydrogen and the phenyl substituent. It is 6-8 kJ mol(-1) more stable than the cis conformers, has a perpendicular ring arrangement, and puckers at the nitrogen atom--similar to structures reported for nicotine. Resonant two-photon ionization (R2PI) data, including hole burn spectra, indicate only one conformer is present in the free jet expansion, and band contour analysis suggests assignment to the trans conformer. Confirmation was provided by microwave spectroscopy. Fifty-seven lines measured in the 48-72 GHz region were assigned to 206 b-type transitions and fitted to yield rotational constants within 2 MHz of MP2 values predicted for the trans conformer. The solution-phase conformers of PPD were studied using 1D and 2D (1)H NMR spectroscopy and solvent-based theoretical calculations. In marked contrast to the gas phase, NMR data reveals only cis conformers present in solution. Calculations confirm increased stability for these conformers when placed in simulated chloroform or water environments. Solvent molecules are believed to disrupt a crucial N...H(ortho) stabilizing interaction present within the trans conformer.

  16. Structural Basis for Asymmetric Conductance of the Influenza M2 Proton Channel Investigated by Solid-State NMR Spectroscopy.

    Science.gov (United States)

    Mandala, Venkata S; Liao, Shu-Yu; Kwon, Byungsu; Hong, Mei

    2017-07-07

    The influenza M2 protein forms an acid-activated proton channel that is essential for virus replication. The transmembrane H37 selects for protons under low external pH while W41 ensures proton conduction only from the N terminus to the C terminus and prevents reverse current under low internal pH. Here, we address the molecular basis for this asymmetric conduction by investigating the structure and dynamics of a mutant channel, W41F, which permits reverse current under low internal pH. Solid-state NMR experiments show that W41F M2 retains the pH-dependent α-helical conformations and tetrameric structure of the wild-type (WT) channel but has significantly altered protonation and tautomeric equilibria at H37. At high pH, the H37 structure is shifted toward the π tautomer and less cationic tetrads, consistent with faster forward deprotonation to the C terminus. At low pH, the mutant channel contains more cationic tetrads than the WT channel, consistent with faster reverse protonation from the C terminus. (15)N NMR spectra allow the extraction of four H37 pKas and show that the pKas are more clustered in the mutant channel compared to WT M2. Moreover, binding of the antiviral drug, amantadine, at the N-terminal pore at low pH did not convert all histidines to the neutral state, as seen in WT M2, but left half of all histidines cationic, unambiguously demonstrating C-terminal protonation of H37 in the mutant. These results indicate that asymmetric conduction in WT M2 is due to W41 inhibition of C-terminal acid activation by H37. When Trp is replaced by Phe, protons can be transferred to H37 bidirectionally with distinct rate constants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. An NMR metabolomics investigation of perturbations after treatment with Chinese herbal medicine formula in an experimental model of sepsis.

    Science.gov (United States)

    Li, Yunzhi; Liu, Hongbin; Wu, Xianzhong; Li, Donghua; Huang, Jing

    2013-05-01

    Sepsis is a leading cause of morbidity and mortality in critically ill patients. OMICS and systems pharmacology approaches offer the promise of new therapeutic candidates for the treatment of patients with sepsis. Qin-Re-Jie-Du (QRJD) and Liang-Xue-Huo-Xue (LXHX) are two traditional Chinese herbal medicine (CHM) formulas with putative effects in sepsis treatment. The present study aimed to assess their efficacy in an experimental model of sepsis in rats (cecal ligation and punctures) and investigate their mechanism of action using a 1H-NMR metabolomics approach. Rats were randomly divided into four groups (i.e., model group, sham control group, and two CHM treatment groups). Water extracts of QRJD and LXHX were orally administered to the two CHM treatment groups at a dose of 24 g/kg of body weight, once daily for 3 consecutive days. The same volume of 0.9% saline solution was orally administered to the model and sham surgery groups. Plasma samples were collected and measured using 600 MHz 1H-NMR spectroscopy. As a result, 18 potential metabolite biomarkers involved in multiple metabolic pathways, including increased energy metabolism, fat mobilization, and disrupted amino acid metabolism, were identified in septic rats. The principal component analysis (PCA) and partial least squares discriminant (PLS-DA) plots of the metabolic state correlated well with the mortality and clinical biochemistry results. An analysis of potential biomarkers verified the holistic effects of the two CHM formulas. The Cori cycle was positively regulated in the QRJD-treated formulas treatment group but also inhibited in the LXHX-treated group, which demonstrates the different efficacies of these solutions in septic rats.

  18. Spectroscopic and mechanistic investigations into oxidation of aspartame by diperiodatocuprate(III in aqueous alkaline medium

    Directory of Open Access Journals (Sweden)

    Jayant I. Gowda

    2015-12-01

    Full Text Available The oxidation of aspartame (ASP by diperiodatocuprate(III (DPC in aqueous alkaline medium at 298 K and a constant ionic strength of 0.30 mol dm−3 was studied spectrophotometrically. The reaction between aspartame and diperiodatocuprate(III in alkaline medium exhibits 1:6 stoichiometry in the reaction. The order of the reaction with respect to [diperiodatocuprate(III] was unity, while the apparent order with respect to [aspartame] was less than unity over the concentration range studied. The rate of the reaction increased with increase in [OH−] whereas the rate decreased with increase in [$ {\\text{IO}}^-_4 $]. Increasing the ionic strength of the medium increased the rate. The main products were identified by FT-IR, NMR, and LC-MS spectral studies. The probable mechanism was proposed. The activation parameters with respect to slow step of the mechanism were computed and discussed. Thermodynamic quantities were also calculated. Kinetic studies suggest that [Cu(H2IO6(H2O2] is the reactive species of Cu(III.

  19. Lanthanide complexes derived from hexadentate macrocyclic ligand: synthesis, spectroscopic and thermal investigation.

    Science.gov (United States)

    Chandra, Sulekh; Tyagi, Monika; Rani, Soni; Kumar, Sumit

    2010-02-01

    The lanthanide complexes derived from (3,5,13,15-tetramethyl 2,6,12,16,21-22-hexaazatricyclo[15.3.I(1-17)I(7-11)]cosa-1(21),2,5,7,9,11(22),12,15,17,19-decane) were synthesized. The complexes were found to have general composition [Ln(L)X(2).H(2)O]X, where Ln=La(3+), Ce(3+), Nd(3+), Sm(3+) and Eu(3+) and X=NO(3)(-) and Cl(-). The ligand was characterized by elemental analyses, IR, Mass, and (1)H NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral techniques and thermal studies. The ligand acts as a hexadentate and coordinates through four nitrogen atoms of azomethine groups and two nitrogen of pyridine ring. The lanthanum complexes are diamagnetic while the other Ln(III) complexes are paramagnetic. The spectral parameters i.e. nephelauxetic ratio (beta), covalency factor (b(1/2)), Sinha parameter (delta%) and covalency angular overlap parameter (eta) have been calculated from absorption spectra of Nd(III) and Sm(III) complexes. These parameters suggest the metal-ligand covalent bonding. In the present study, the complexes were found to have coordination number nine.

  20. Spectroscopic Investigation and Photophysics of a D-π-A-π-D Type Styryl Pyrazine Derivative.

    Science.gov (United States)

    El-Daly, Samy A; Alamry, Khalid A

    2016-01-01

    E,E-2,5-bis(3,4-dimethoxystyryl)pyrazine (BDSP)has been prepared by aldol condensation between 2,5-dimethypyrazine and 3,4-dimthoxybenzaldehyde and characterized by IR, 1HNMR, 13C NMR and X-ray crystallography.The electronic absorption and emission properties of BDSP were studied in different solvents. BDSP displays a strong solvatochromic effect of the emission spectrum that is reflected by large red shifts of its fluorescence emission maximum on increasing the solvent polarity, indicating a large change in dipole moment of BDSP upon excitation due to photoinduced intramolecular charge transfer (PICT). Excited state intermolecular hydrogen bonding affects the energy of emission spectrum and fluorescence quantum yield of BDSP dye. The dye solutions (1×10(-4) M) in DMSO, DMF, CH3CN and dioxane give laser emission in green region upon excitation by a 337.1 nm nitrogen pulse (λ=337 nm). The tuning range, gain coefficient (α), emission cross – section (σe) and half-life energy (E1/2) has been determined. Ground and electronic excited states geometric optimization were performed using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. A DFT natural bond analysis complemented the ICT. BDSP dye displays fluorescence quenching by colloidal silver nanoparticles(AgNPs). The fluorescence data reveal that radiative and non-radiative energy transfer play a major role in the fluorescence quenching mechanism.

  1. DFT simulation, quantum chemical electronic structure, spectroscopic and structure-activity investigations of 2-benzothiazole acetonitrile

    Science.gov (United States)

    Arjunan, V.; Thillai Govindaraja, S.; Jose, Sujin P.; Mohan, S.

    2014-07-01

    The Fourier transform infrared and FT-Raman spectra of 2-benzothiazole acetonitrile (BTAN) have been recorded in the range 4000-450 and 4000-100 cm-1 respectively. The conformational analysis of the compound has been carried out to obtain the stable geometry of the compound. The complete vibrational assignment and analysis of the fundamental modes of the compound are carried out using the experimental FTIR and FT-Raman data and quantum chemical studies. The experimental vibrational frequencies are compared with the wavenumbers derived theoretically by B3LYP gradient calculations employing the standard 6-31G**, high level 6-311++G** and cc-pVTZ basis sets. The structural parameters, thermodynamic properties and vibrational frequencies of the normal modes obtained from the B3LYP methods are in good agreement with the experimental data. The 1H (400 MHz; CDCl3) and 13C (100 MHz; CDCl3) nuclear magnetic resonance (NMR) spectra are also recorded. The electronic properties, the energies of the highest occupied and lowest unoccupied molecular orbitals are measured by DFT approach. The kinetic stability of the molecule has been determined from the frontier molecular orbital energy gap. The charges of the atoms and the structure-chemical reactivity relations of the compound are determined by its chemical potential, global hardness, global softness, electronegativity, electrophilicity and local reactivity descriptors by conceptual DFT methods. The non-linear optical properties of the compound have been discussed by measuring the polarisability and hyperpolarisability tensors.

  2. Real time spectroscopic ellipsometry investigation of homoepitaxial GaN grown by plasma assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tong-Ho; Choi, Soojeong; Wu, Pae; Brown, April [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States); Losurdo, Maria; Giangregorio, Maria M.; Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM UdR Bari, via Orabona, 4, 70126 Bari (Italy); Moto, Akihiro [Innovation Core SEI, Inc., 3235 Kifer Road, Santa Clara, CA 95051 (United States)

    2006-06-15

    The growth of GaN by plasma assisted molecular beam epitaxy on GaN template substrates (GaN on sapphire) is investigated with in-situ multi-channel spectroscopic ellipsometry. Growth is performed under various Ga/N flux ratios at growth temperatures in the range 710-780 C. The thermal roughening of the GaN template caused by decomposition of the surface is investigated through the temporal variation of the GaN pseudodielectric function over the temperature range of 650 C to 850 C. The structural, morphological, and optical properties are also discussed. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Dipodal quinoline-tethered fluorescent probe synthesis and investigation of spectroscopic properties

    Science.gov (United States)

    Obalı, Aslıhan Yılmaz; Yilmaz, Menzeher Serkan; Uçan, Halil İsmet

    2017-10-01

    Novel quinoline-tethered fluorescent probe was designed and synthesized as multidentate ligand. Their sensing actions were confirmed by UV-Vis absorbance and emission spectroscopic studies in presence of perchlorate salts of Co2+, Li+, Fe2+, K+, Pb2+, Cu2+, Zn2+, Ni2+, Hg2+, Ag+ cations in acetonitrile (1 × 10-5 M for absorption studies, 1 × 10-7 M for fluorescence studies). It was found that the dipodal compounds can selectively bind to Cu2+ and Ag+ metal ions with a significant quenching in their emissions. The capture of Cu2+ and Ag+ by the probe resulted in deprotonation of the secondary amine conjugated to the quinoline-tethered probe, so that the electron-donation ability of the 'N' atom would be greatly enhanced and the probe (2) showed blue-shift in emission and exhibited an on-off fluorescent response. The binding study was explored by using fluorescence spectroscopy with Job plot method.

  4. Investigation of the interaction between berberine and nucleosomes in solution: Spectroscopic and equilibrium dialysis approach

    Science.gov (United States)

    Rabbani-Chadegani, Azra; Mollaei, Hossein; Sargolzaei, Javad

    2017-02-01

    Berberine is a natural plant alkaloid with high pharmacological potential. Although its interaction with free DNA has been the subject of several reports, to date there is no work concerning the effect of berberine on nucleoprotein structure of DNA, the nucleosomes. The present study focuses on the binding affinity of berberine to nucleosomes and histone H1 employing various spectroscopic techniques, fluorescence, circular dichroism, thermal denaturation as well as equilibrium dialysis. The results showed that the binding of berberine to nucleosomes is positive cooperative with Ka = 5.57 × 103 M- 1. Berberine quenched with the chromophores of protein moiety of nucleosomes and reduced fluorescence emission intensity at 335 nm with Ksv value of 0.135. Binding of berberine to nucleosomes decreased the absorbance at 210 and 260 nm, produced hypochromicity in thermal denaturation profiles and its affinity to nucleoprotein structure of nucleosomes was much higher than to free DNA. Berberine also exhibited high affinity to histone H1 in solution and the binding was positive cooperative with. Ka = 3.61 × 103 M- 1. Moreover berberine decreased fluorescence emission intensity of H1 by quenching with tyrosine residue in its globular core domain. The circular dichroism profiles demonstrated that the binding of drug induced secondary structural changes in both DNA stacking and histone H1. It is concluded that berberine is genotoxic drug, interacts with nucleosomes and in this process histone H1 is involved to exert its anticancer activity.

  5. Spectroscopic investigation and direct comparison of the reactivities of iron pyridyl oxidation catalysts

    Science.gov (United States)

    Song, Yang; Mayes, Howard G.; Queensen, Matthew J.; Bauer, Eike B.; Dupureur, Cynthia M.

    2017-03-01

    The growing interest in green chemistry has fueled attention to the development and characterization of effective iron complex oxidation catalysts. A number of iron complexes are known to catalyze the oxidation of organic substrates utilizing peroxides as the oxidant. Their development is complicated by a lack of direct comparison of the reactivities of the iron complexes. To begin to correlate reactivity with structural elements, we compare the reactivities of a series of iron pyridyl complexes toward a single dye substrate, malachite green (MG), for which colorless oxidation products are established. Complexes with tetradentate, nitrogen-based ligands with cis open coordination sites were found to be the most reactive. While some complexes reflect sensitivity to different peroxides, others are similarly reactive with either H2O2 or tBuOOH, which suggests some mechanistic distinctions. [Fe(S,S-PDP)(CH3CN)2](SbF6)2 and [Fe(OTf)2(tpa)] transition under the oxidative reaction conditions to a single intermediate at a rate that exceeds dye degradation (PDP = bis(pyridin-2-ylmethyl) bipyrrolidine; tpa = tris(2-pyridylmethyl)amine). For the less reactive [Fe(OTf)2(dpa)] (dpa = dipicolylamine), this reaction occurs on a timescale similar to that of MG oxidation. Thus, the spectroscopic method presented herein provides information about the efficiency and mechanism of iron catalyzed oxidation reactions as well as about potential oxidative catalyst decomposition and chemical changes of the catalyst before or during the oxidation reaction.

  6. Investigating the spectroscopic, magnetic and circumstellar variability of the O9 subgiant star HD 57682

    CERN Document Server

    Grunhut, J H; Sundqvist, J O; ud-Doula, A; Neiner, C; Ignace, R; Marcolino, W L F; Rivinius, Th; Fullerton, A; Kaper, L; Mauclaire, B; Buil, C; Garrel, T; Ribeiro, J; Ubaud, S

    2012-01-01

    The O9IV star HD 57682, discovered to be magnetic within the context of the MiMeS survey in 2009, is one of only eight convincingly detected magnetic O-type stars. Among this select group, it stands out due to its sharp-lined photospheric spectrum. Since its discovery, the MiMeS Collaboration has continued to obtain spectroscopic and magnetic observations in order to refine our knowledge of its magnetic field strength and geometry, rotational period, and spectral properties and variability. In this paper we report new ESPaDOnS spectropolarimetric observations of HD 57682, which are combined with previously published ESPaDOnS data and archival H{\\alpha} spectroscopy. This dataset is used to determine the rotational period (63.5708 \\pm 0.0057 d), refine the longitudinal magnetic field variation and magnetic geometry (dipole surface field strength of 880\\pm50 G and magnetic obliquity of 79\\pm4\\circ as measured from the magnetic longitudinal field variations, assuming an inclination of 60\\circ), and examine the p...

  7. IR spectroscopic investigation of the inhibition of the glycation process by acetylsalicylic acid

    Science.gov (United States)

    Otero de Joshi, Virginia; Gil, Herminia; Contreras, Silvia; Velasquez, William; Joshi, Narahari V.

    2000-05-01

    An IR spectroscopic study was carried out at room temperature for Human Serum albumin (HSA) glycated with fructose and glucose and inhibited with acetylsalicylic acid. The glycation process was carried out in our laboratory by a conventional method to confirm earlier reported observation of the effect of glycation on the intensity variation of the IR spectra, particularly, in the range 1500 cm-1 to 1700 cm-1 and around 3300 cm-1. IR spectra reveal that the effects of glycation of HSA by fructose are more intense than with glucose, which is the expected. Bovine serum albumin was also glycated using Glucose-6-phosphate disodium salt, and gamma-globulin was glycate with glucose, As expected, the glycation process was more intense with glucose-t-phosphate disodium salt. Acetyl salicylic acid was also used and its inhibitor effects could be observed in both cases, with glucose and with glucose-6-phosphate disodium salt even though, to a smaller extent with the latter. This is consistent with the earlier data and is explained on the basis of the attachment of macromolecules to (epsilon) -NH2 groups of lysines. The experimental results confirm that acetylsalicylic acid, indeed, acts as an inhibitor by acetylation of the (epsilon) -NG2 group where the sugars are supposed to be attached.

  8. Qualitative and quantitative changes in phospholipids and proteins investigated by spectroscopic techniques in animal depression model

    Science.gov (United States)

    Depciuch, J.; Sowa-Kucma, M.; Nowak, G.; Papp, M.; Gruca, P.; Misztak, P.; Parlinska-Wojtan, M.

    2017-04-01

    Depression becomes nowadays a high mortality civilization disease with one of the major causes being chronic stress. Raman, Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-vis) spectroscopies were used to determine the changes in the quantity and structure of phospholipids and proteins in the blood serum of rats subjected to chronic mild stress, which is a common animal depression model. Moreover, the efficiency of the imipramine treatment was evaluated. It was found that chronic mild stress not only damages the structure of the phospholipids and proteins, but also decreases their level in the blood serum. A 5 weeks imipramine treatment did increase slightly the quantity of proteins, leaving the damaged phospholipids unchanged. Structural information from phospholipids and proteins was obtained by UV-vis spectroscopy combined with the second derivative of the FTIR spectra. Indeed, the structure of proteins in blood serum of stressed rats was normalized after imipramine therapy, while the impaired structure of phospholipids remained unaffected. These findings strongly suggest that the depression factor, which is chronic mild stress, may induce permanent (irreversible) damages into the phospholipid structure identified as shortened carbon chains. This study shows a possible new application of spectroscopic techniques in the diagnosis and therapy monitoring of depression.

  9. HPLC-SPE-NMR for combinatorial biosynthetic investigations – expanding the landscape of diterpene structural diversity

    DEFF Research Database (Denmark)

    Kongstad, Kenneth Thermann; Andersen-Ranberg, Johan; Hamberger, Björn Robert

    In this work, the analytical technique, HPLC-HRMS-SPE-NMR was used for the first time in combination with combinatorial biosynthetic investigations in N. benthamiana. This efficient setup allowed for identification of several diterpene synthase (diTPS) combinations responsible for stereospecific ......In this work, the analytical technique, HPLC-HRMS-SPE-NMR was used for the first time in combination with combinatorial biosynthetic investigations in N. benthamiana. This efficient setup allowed for identification of several diterpene synthase (diTPS) combinations responsible for...

  10. NMR analysis of compositional heterogeneity in polysaccharides

    Science.gov (United States)

    Many copolysaccharides are compositionally heterogeneous, and the composition determined by the usual analytical or spectroscopic methods provides only an average value. For some polysaccharides, the NMR data contain copolymer sequence information, such as diad, triad, and tetrad sequence intensiti...

  11. Spectroscopic investigation of europium benzoate in acetonitrile: Luminescence enhancement and complexation studies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Satendra; Maji, S. [Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Joseph, M. [Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Sankaran, K., E-mail: ksran@igcar.gov.in [Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2015-05-15

    Luminescence from Eu{sup 3+} complexed with benzoic acid (BA) has been studied using acetonitrile (MeCN) as solvent. More than two orders luminescence enhancement is found as compared to Eu{sup 3+}–BA complex in aqueous medium. The lifetime of Eu{sup 3+} in this complex is 900 μs which is much higher as compared to 118 μs in aqueous medium, suggesting the luminescence enhancement is a result of reduction in non-radiative decay channels in MeCN medium. Luminescence spectroscopy along with UV–vis spectroscopy is used to study the complexation behavior of Eu{sup 3+}–BA in this medium. In contrary to aqueous medium where Eu{sup 3+}–BA forms ML and ML{sub 2} type species, spectroscopic data reveal formation of only ML{sub 3} complex with composition Eu(BA){sub 3}(MeCN){sub 6} in MeCN medium. Absorbance, luminescence lifetimes and the ratio of areas of 615–592 nm peaks are used in HypSpec computation program to determine the log β for the ML{sub 3} complex. - Highlights: • Luminescence and complexation of Eu{sup 3+}–BA have been studied in MeCN. • The luminescence intensity of Eu{sup 3+}–BA is 320 times more in MeCN compared to aqueous medium. • Luminescence enhancement is a result of sensitization and reduction in non-radiative decay channels in MeCN. • Eu{sup 3+} forms only ML{sub 3} type complex with BA in MeCN contrary to aqueous medium where it forms ML and ML{sub 2} type species.

  12. Investigation of optical and spectroscopic properties of Sm3+ ions in CaBAl glasses

    Science.gov (United States)

    Brito, D. R. N.; Queiroz, M. N.; Barboza, M. J.; Steimacher, A.; Pedrochi, F.

    2017-02-01

    Samples of CaBAl glass with composition of (25-x)CaO-50B2O3-15Al2O3-10CaF2-xSm2O3, with Sm2O3 concentration varying from 0.5 to 7 wt%, were prepared by using melt-quenching method in air atmosphere. The samples were prepared with different concentrations of Sm2O3, aiming to understand how the dopant changes the optical and spectroscopic properties of the glass. The doped CaBAl glasses were studied by means of volumetric density measurements, refractive index, optical absorption, luminescence at room temperature, luminescence as function of the temperature and radiative lifetime. All results were discussed in function of Sm2O3 concentration. The measured volumetric density and polarizability showed an increase with Sm2O3 doping. The refractive index showed a small increase due to RE doping, although within the errors. The absorption bands were attributed to Sm3+ transitions from the ground state 6H5/2 to the various excited states. The luminescence spectra present emission bands assigned to the appropriate electronic f-f transitions of Sm3+ ions; there are four emission bands at 565, 602, 649 and 710 nm. The luminescence quenching was observed up to 2 wt% of Sm2O3. The O/R ratio as function of the Sm2O3 concentration showed changes in the symmetry site with addition of Sm2O3. The CIE 1931 diagram presented a reddish-orange shift color with Sm2O3 doping. The luminescence intensity presents a decrease with temperature increase for all studied samples. The experimental lifetime decreases with the increase of Sm2O3, mainly due to ion-ion interaction.

  13. Microstructure and spectroscopic investigations of calcium zinc bismuth phosphate glass ceramics doped with manganese ions

    Science.gov (United States)

    Suneel Kumar, A.; Sambasiva Rao, M. V.; Chinna Ram, G.; Krishna Rao, D.

    2017-07-01

    Multi-component 10CaF2-20ZnO-(15 - x)Bi2O3-55P2O5:xMnO (0 ≤ x ≤ 2.5) glass ceramics were synthesised by melt quenching technique and heat treatment. The prepared glass ceramics were characterised by XRD, DTA, EDS and SEM. Spectroscopic studies such as optical absorption, EPR, FTIR and Raman were also carried out on these glass ceramics. The XRD and SEM studies have indicated that ceramic samples contain well defined and randomly distributed grains of different crystalline phases. The observed increase of enthalpy from DTA patterns up to 1 mol% of MnO indicates that the crystallisation starts initially from the surface of the material then gradually it is extended to the volume of the material and this influence is meagre at higher concentrations of MnO. The absorption spectra of manganese doped glass ceramics have exhibited two types of conventional bands; one due to Mn2+ ions and other due to Mn3+ ions. The EPR spectra of MnO doped glass ceramics showed a resonance signal around g2 = 2.023 with a six line hyperfine structure and another signal at about g1 = 4.314. The relative intensity and half-width of these two signals are observed to increase with the increase in the concentration of manganese ions up to 1 mol% beyond this concentration it is found to decrease. Such observation indicates the conversion of part of Mn2+ ions into Mn3+ ions in the glass ceramic matrix. The observed increase in the intensity of symmetrical structural units at the expense of asymmetrical structural units from the FTIR and Raman spectra at higher concentration of MnO indicating that Mn2+ ions occupy the network forming positions in the glass ceramic structure.

  14. Chemical and nanometer-scale structure of kerogen and its change during thermal maturation investigated by advanced solid-state 13C NMR spectroscopy

    Science.gov (United States)

    Mao, J.; Fang, X.; Lan, Y.; Schimmelmann, A.; Mastalerz, Maria; Xu, L.; Schmidt-Rohr, K.

    2010-01-01

    We have used advanced and quantitative solid-state nuclear magnetic resonance (NMR) techniques to investigate structural changes in a series of type II kerogen samples from the New Albany Shale across a range of maturity (vitrinite reflectance R0 from 0.29% to 1.27%). Specific functional groups such as CH3, CH2, alkyl CH, aromatic CH, aromatic C-O, and other nonprotonated aromatics, as well as "oil prone" and "gas prone" carbons, have been quantified by 13C NMR; atomic H/C and O/C ratios calculated from the NMR data agree with elemental analysis. Relationships between NMR structural parameters and vitrinite reflectance, a proxy for thermal maturity, were evaluated. The aromatic cluster size is probed in terms of the fraction of aromatic carbons that are protonated (???30%) and the average distance of aromatic C from the nearest protons in long-range H-C dephasing, both of which do not increase much with maturation, in spite of a great increase in aromaticity. The aromatic clusters in the most mature sample consist of ???30 carbons, and of ???20 carbons in the least mature samples. Proof of many links between alkyl chains and aromatic rings is provided by short-range and long-range 1H-13C correlation NMR. The alkyl segments provide most H in the samples; even at a carbon aromaticity of 83%, the fraction of aromatic H is only 38%. While aromaticity increases with thermal maturity, most other NMR structural parameters, including the aromatic C-O fractions, decrease. Aromaticity is confirmed as an excellent NMR structural parameter for assessing thermal maturity. In this series of samples, thermal maturation mostly increases aromaticity by reducing the length of the alkyl chains attached to the aromatic cores, not by pronounced growth of the size of the fused aromatic ring clusters. ?? 2010 Elsevier Ltd. All rights reserved.

  15. Preparation and characterizations of SnO2 nanopowder and spectroscopic (FT-IR, FT-Raman, UV-Visible and NMR) analysis using HF and DFT calculations.

    Science.gov (United States)

    Ayeshamariam, A; Ramalingam, S; Bououdina, M; Jayachandran, M

    2014-01-24

    In this work, pure and singe phase SnO2 Nano powder is successfully prepared by simple sol-gel combustion route. The photo luminescence and XRD measurements are made and compared the geometrical parameters with calculated values. The FT-IR and FT-Raman spectra are recorded and the fundamental frequencies are assigned. The optimized parameters and the frequencies are calculated using HF and DFT (LSDA, B3LYP and B3PW91) theory in bulk phase of SnO2 and are compared with its Nano phase. The vibrational frequency pattern in nano phase gets realigned and the frequencies are shifted up to higher region of spectra when compared with bulk phase. The NMR and UV-Visible spectra are simulated and analyzed. Transmittance studies showed that the HOMO-LUMO band gap (Kubo gap) is reduced from 3.47 eV to 3.04 eV while it is heated up to 800°C. The Photoluminescence spectra of SnO2 powder showed a peak shift towards lower energy side with the change of Kubo gap from 3.73 eV to 3.229 eV for as-prepared and heated up to 800°C. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

  16. Thermal, conductivity, NMR, and Raman spectroscopic measurements and phase diagram of the Cs2S2O7-CsHSO4 system

    DEFF Research Database (Denmark)

    Rasmussen, Søren Birk; Hama, Hind; Lapina, Olga;

    2003-01-01

    The conductivity of the binary system CS2S2O7-CsHSO4 has been measured at 20 different molten compositions in the full composition range and in the temperature range 430-750 K. From the obtained liquidus-solidus phase transition temperatures, the phase diagram has been constructed. It is of the s......The conductivity of the binary system CS2S2O7-CsHSO4 has been measured at 20 different molten compositions in the full composition range and in the temperature range 430-750 K. From the obtained liquidus-solidus phase transition temperatures, the phase diagram has been constructed...... from the NMR measurements on CsHSO4, CS2S2O7, and Cs2S2O7-CsHSO4 mixtures. For 11 selected compositions covering the entire composition range of the CS2S2O7-CsHSO4 binary system, the conductivity of the molten state has been expressed by equations of the form k(X) = A(X) + B(X)(T - T-m) + C(X)(T - T...

  17. (19) F NMR Spectroscopic Analysis of the Binding Modes in Triple-Helical Peptide Nucleic Acid (PNA)/MicroRNA Complexes.

    Science.gov (United States)

    Tähtinen, Ville; Granqvist, Lotta; Murtola, Merita; Strömberg, Roger; Virta, Pasi

    2017-05-23

    Triplex-forming peptide nucleic acids (TFPNAs) were targeted to double-helical regions of (19) F-labeled RNA hairpin models (a UA-rich duplex with a hexaethylene glycol (heg) loop and a microRNA model, miR-215). In addition to conventional UV- and circular dichroism (CD)-based detection, binding was monitored by (19) F NMR spectroscopy. Detailed information on the stoichiometry and transition between the triple-helical peptide nucleic acid (PNA)/RNA and (PNA)2 /RNA binding modes could be obtained. γ-(R)-Hydroxymethyl-modified thymine-1-yl- and 2-aminopyridin-3-yl-acetyl derivatives of TFPNAs were additionally synthesized, which were targeted to the same RNA models, and the effect of the γ-(R)-hydroxymethyl group on binding was studied. An appropriate pattern of γ-(R)-hydroxymethyl modifications reduced the stability of the ternary complex and preferred stoichiometric binding to the miR-215 model. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Synthesis, spectroscopic and X-ray characterization of a copper(II) complex with the Schiff base derived from pyridoxal and aminoguanidine: NMR spectral studies of the ligand.

    Science.gov (United States)

    Leovac, Vukadin M; Joksović, Milan D; Divjaković, Vladimir; Jovanović, Ljiljana S; Saranović, Zana; Pevec, Andrej

    2007-07-01

    A copper(II) complex with the pyridoxal-aminoguanidine (PL-AG) Schiff base adduct, as an organic compound of the very potent biological activity and promising pharmacological importance in the treatment of diabetic complications, has been prepared and characterized. The X-ray structural analysis of the [CuCl2(PL-AG)] complex showed that it has a distorted pseudo-square-pyramidal (4+1) structure with the tridentate ONN Schiff base in the equatorial plane, with the Cu-O(1), Cu-N(1) and Cu-N(3) bond lengths of 1.917(2)A, 1.930(2)A and 1.984(2)A, respectively. The bond length of the equatorial Cu-Cl(1) is 2.279(1)A, while that of the apical Cu-Cl(2) is 2.792(1)A. Pyridoxal fragment is coordinated in its zwitterionic form. In addition to the X-ray structural analysis, the complex was characterized by IR spectrometric, conductometric and magnetic techniques, and the ligand itself by IR, 1H and 13C NMR spectra.

  19. Quantum mechanical, spectroscopic studies (FT-IR, FT-Raman, NMR, UV) and normal coordinates analysis on 3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide

    Science.gov (United States)

    Muthu, S.; Uma Maheswari, J.; Sundius, Tom

    2013-05-01

    Famotidine (3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide) is a histamine H2-receptor antagonist that inhibits stomach acid production, and it is commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD/GORD). Quantum chemical calculations of the equilibrium geometry of famotidine in the ground state were carried out using density functional theory (DFT/B3LYP) with the 6-311G(d,p) basis set. In addition, harmonic vibrational frequencies, infrared intensities and Raman activities were calculated at the same level of theory. A detailed interpretation of the infrared and Raman spectrum of the drug is also reported. Theoretical simulations of the FT-IR, and FT-Raman spectra of the title compound have been calculated. Good correlations between the experimental 1H and 13C NMR chemical shifts and calculated GIAO shielding tensors were found. The results of the energy and oscillator strength calculations by time-dependent density functional theory (TD-DFT) supplement the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis were presented. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The linear polarizability and first order hyperpolarizabilities of the studied molecule indicate that the compound is a good candidate for nonlinear optical materials.

  20. Structural, spectroscopic (FT-IR, NMR, UV-visible), nonlinear optical (NLO), cytotoxic and molecular docking studies of 4-nitro-isonitrosoacetophenone (ninapH) by DFT method

    Science.gov (United States)

    Kucuk, Ilhan; Kaya, Yunus; Kaya, A. Asli

    2017-07-01

    (4-Nitro-phenyl)-oxo-acetaldehyde oxime (ninapH) is a type of oxime, which has a oxime and α-carbonyl groups. This molecule has been synthesized from literature procedure. The structural properties and conformational behaviors were examined using the density functional theory (DFT) with the B3LYP method combined with the 6-311++G(d,p) basis set. As a result of the conformational studies, the most stable conformer was determined, and then this molecule was optimized with the same basis set. Comprehensive theoretical and experimental structural studies on the molecule have been carried out by FT-IR, NMR and UV-vis spectrometry. The calculated HOMO and LUMO energies show that charge transfer within the molecule. The first order hyperpolarizability and molecular electrostatic potential (MEP) were also performed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the ninapH have been calculated at different temperatures, 100-1000 K. In addition, the molecular docking studies have been performed with DNA and protein structures (downloaded from Protein Data Bank).

  1. Communication: Proton NMR dipolar-correlation effect as a method for investigating segmental diffusion in polymer melts

    Science.gov (United States)

    Lozovoi, A.; Mattea, C.; Herrmann, A.; Rössler, E. A.; Stapf, S.; Fatkullin, N.

    2016-06-01

    A simple and fast method for the investigation of segmental diffusion in high molar mass polymer melts is presented. The method is based on a special function, called proton dipolar-correlation build-up function, which is constructed from Hahn Echo signals measured at times t and t/2. The initial rise of this function contains additive contributions from both inter- and intramolecular magnetic dipole-dipole interactions. The intermolecular contribution depends on the relative mean squared displacements (MSDs) of polymer segments from different macromolecules, while the intramolecular part reflects segmental reorientations. Separation of both contributions via isotope dilution provides access to segmental displacements in polymer melts at millisecond range, which is hardly accessible by other methods. The feasibility of the method is illustrated by investigating protonated and deuterated polybutadiene melts with molecular mass 196 000 g/mol at different temperatures. The observed exponent of the power law of the segmental MSD is close to 0.32 ± 0.03 at times when the root MSD is in between 45 Å and 75 Å, and the intermolecular proton dipole-dipole contribution to the total proton Hahn Echo NMR signal is larger than 50% and increases with time.

  2. NMR Investigation of the complexation of (S-2-isopropyl- 1-(o-nitrophenylsulfonylaziridine with -cyclodextrin

    Directory of Open Access Journals (Sweden)

    Mohamed Z. Sliman

    2014-07-01

    Full Text Available Aziridines are known to undergo hydrolysis in the presence of cyclodextrins, whereas the latter are largely investigated as potential vectors of biologically active compounds. Despite this easy cyclodextrin-induced cleavage of aziridines in aqueous medium, it was of interest to find out a model aziridine derivative that would be sufficiently water-stable and form a stable complex with b-cyclodextrin in aqueous medium, so that it could be used as a reference in future formulations or vectorization work. Among compounds we have investigated, we found out that only (S-2-isopropyl-1-(o-nitrophenylsulfonylaziridine complied with the above-mentioned solubility and stability requirements. NMR studies of the inclusion complex of this derivative with b-cyclodextrin provided useful parameters related to the stoichiometry of the complex and the association constant Ka. The geometry of the complex was assessed by 2D-ROESY experiments, suggesting a deep insertion of the aziridine into the cavity of b-cyclodextrin.

  3. Theoretical (DFT) and experimental (FT-IR, FT-Raman, FT-NMR) investigations on 7-Acetoxy-4-(bromomethyl)coumarin

    Science.gov (United States)

    Erdogdu, Y.; Saglam, S.; Dereli, Ö.

    2015-09-01

    An analysis of the results of the structural and spectroscopic studies of 7-Acetoxy-4-(bromomethyl) coumarin (7A4BMC) molecule were performed by FT-IR, FT-Raman, FT-NMR and quantum chemical calculations. The FT-IR and FT-Raman spectra of 7A4BMC were recorded in the 400-4000 and 50-3500 cm-1 region, respectively. The molecular conformations of 7A4BMC were computed at the B3LYP/6-311++G(d,p) level of theory. Molecular structure and spectral calculations were calculated by means of B3LYP with 6-311++G(d,p), cc-pVDZ and cc-pVTZ basis sets. The whole vibrational characteristics of the 7A4BMC molecule are given.

  4. Investigation of temperature dependent dielectric constant of a sputtered TiN thin film by spectroscopic ellipsometry

    Science.gov (United States)

    Tripura Sundari, S.; Ramaseshan, R.; Jose, Feby; Dash, S.; Tyagi, A. K.

    2014-01-01

    The temperature dependence of optical constants of titanium nitride thin film is investigated using Spectroscopic Ellipsometry (SE) between 1.4 and 5 eV in the temperature range of 300 K to 650 K in steps of 50 K. The real and imaginary parts of the dielectric functions ɛ1(E) and ɛ2(E) marginally increase with increase in temperature. A Drude Lorentz dielectric analysis based on free electron and oscillator model are carried out to describe the temperature behavior. With increase in temperature, the unscreened plasma frequency and broadening marginally decreased and increased, respectively. The parameters of the Lorentz oscillator model also showed that the relaxation time decreased with temperature while the oscillator energies increased. This study shows that owing to the marginal change in the refractive index with temperature, titanium nitride can be employed for surface plasmon sensor applications even in environments where rise in temperature is imminent.

  5. Systematic NMR/NQR investigation of the local charge environment in iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Graefe, Uwe; Bruening, Eva-Maria; Lang, Guillaume; Veyrat, Louis; Baek, Seung-Ho; Grafe, Hans-Joachim; Hammerath, Franziska; Manthey, Katarina; Behr, Guenther; Werner, Jochen; Wurmehl, Sabine; Buechner, Bernd [IFW Dresden, Institute for Solid State Research, P.O. Box 270116, D-01171 Dresden (Germany); Paar, Dalibor [IFW Dresden, Institute for Solid State Research, P.O. Box 270116, D-01171 Dresden (Germany); Dept. of Physics, Faculty of Science, Univ. of Zagreb, P.O. Box 331, HR-10002 Zagreb (Croatia)

    2012-07-01

    As iron-based superconductors are a striking example of a system featuring unconventional superconductivity close to a region of static magnetism in the phase diagram, much attention has been devoted to the study of ground-state coexistence and/or competition. In this regard, a more general question is the existence and the role played by electronic inhomogeneities, whether in ordered states or in the paramagnetic state. A powerful tool to investigate these issues is Nuclear Magnetic/Quadrupole Resonance, which allows to probe locally the electric charge environment and the spin fluctuations. Here, we present a summary of recent results and on-going studies at the As site of 1111 iron pnictides.

  6. Extra-framework aluminium species in hydrated faujasite zeolite as investigated by two-dimensional solid-state NMR spectroscopy and theoretical calculations.

    Science.gov (United States)

    Li, Shenhui; Zheng, Anmin; Su, Yongchao; Fang, Hanjun; Shen, Wanling; Yu, Zhiwu; Chen, Lei; Deng, Feng

    2010-04-21

    Extra-framework aluminium (EFAL) species in hydrated dealuminated HY zeolite were thoroughly investigated by various two-dimensional solid-state NMR techniques as well as density functional theoretical calculations. (27)Al MQ MAS NMR experiments demonstrated that five-coordinated and four-coordinated extra-framework aluminium subsequently disappeared with the increase of water loading, and the quadrupole interaction of each aluminium species decreased gradually during the hydration process. (1)H double quantum MAS NMR revealed that the EFAL species in the hydrated zeolite consisted of three components: a hydroxyl AlOH group, and two types of water molecule (rigid and mobile water). (1)H-(27)Al LG-CP HETCOR experiments indicated that both the extra-framework and the framework Al atoms were in close proximity to the rigid water in the fully rehydrated zeolite. The experimental results were further confirmed by DFT theoretical calculations. Moreover, theoretical calculation results further demonstrated that the EFAL species in the hydrated zeolite consisted of the three components and the calculated (1)H NMR chemical shift for each component agreed well with our NMR observations. It is the rigid water that connects the extra-framework aluminium with the four-coordinated framework aluminium through strong hydrogen bonds.

  7. The influence of membrane electrode assembly water content on the performance of a polymer electrolyte membrane fuel cell as investigated by 1H NMR microscopy.

    Science.gov (United States)

    Feindel, Kirk W; Bergens, Steven H; Wasylishen, Roderick E

    2007-04-21

    The relation between the performance of a self-humidifying H(2)/O(2) polymer electrolyte membrane fuel cell and the amount and distribution of water as observed using (1)H NMR microscopy was investigated. The integrated (1)H NMR image signal intensity (proportional to water content) from the region of the polymer electrolyte membrane between the catalyst layers was found to correlate well with the power output of the fuel cell. Several examples are provided which demonstrate the sensitivity of the (1)H NMR image intensity to the operating conditions of the fuel cell. Changes in the O(2)(g) flow rate cause predictable trends in both the power density and the image intensity. Higher power densities, achieved by decreasing the resistance of the external circuit, were found to increase the water in the PEM. An observed plateau of both the power density and the integrated (1)H NMR image signal intensity from the membrane electrode assembly and subsequent decline of the power density is postulated to result from the accumulation of H(2)O(l) in the gas diffusion layer and cathode flow field. The potential of using (1)H NMR microscopy to obtain the absolute water content of the polymer electrolyte membrane is discussed and several recommendations for future research are provided.

  8. Investigation of luminescence and spectroscopic properties of Nd3+ions in cadmium alkali borate glasses

    Science.gov (United States)

    Mohan, Shaweta; Thind, Kulwant Singh

    2016-07-01

    Neodymium doped cadmium alkali borate glasses having composition 20CdOsbnd 20R2Osbnd 59.5H3BO3sbnd 0.5Nd2O3; (R = Li, Na and K) were prepared by conventional melt-quenching technique. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. The physical properties such as density, refractive index, molar volume, rare earth ion concentration etc. were determined. Optical absorption and fluorescence spectra were recorded. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. These parameters were in turn used to predict the radiative properties such as the radiative transition probability (A), radiative lifetime (τR) and branching ratio (βR) for the fluorescent levels of Nd3+ ion in the present glass series. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω4/Ω6), the value of which is in the range of 0.2-1.5, typical for Nd3+ in different laser hosts. The variation of Ω2 with the change in alkali oxide has been attributed to the changes in the asymmetry of the ligand field at the rare earth ion site. The shift of the hypersensitive bands, study of the oscillator strengths and the variation of the spectral profile of the transition 4I9/2 → 4F7/2 + 4S3/2 indicate a maximum covalency of Ndsbnd O bond for glass with potassium ions. From the fluorescence spectra, peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σp) have been obtained for the three transitions 4F3/2 → 4I9/2,4F3/2 → 4I11/2 and4F3/2 → 4I13/2 of Nd3+ ion. The relatively high values of σp obtained for Nd3+ in present glass system suggest that these materials can be considered as suitable candidates for laser applications. The glass with potassium ions shows the highest value of the stimulated emission cross-section.

  9. Time resolved spectroscopic investigation of SiD2 + D2: kinetic study

    Science.gov (United States)

    Al-Rubaiey, Najem A.; Walsh, Robin

    2017-03-01

    Silylenes (silanediyls) have made an important impact on organosilicon chemistry even if it is of more recent foundation than carbenes in organic chemistry and much less complete. These species are highly reactive intermediates. They play a central role in the chemical vapour deposition (CVD) of various silicon-containing thin films which have a technological importance in microelectronics as well as in the dry etching processes of silicon wafers. Spectroscopic methods have been developed to observe these species, a necessary pre-requisite to their direct monitoring. In this work, deuterated phenylsilane precursor, PhSiD3 was chosen for SiD2 because its analogue phenylsilane, PhSiH3 proved to be a good precursor for SiH2 and the high quality decay signals observed revealed that SiD2 be readily detected from PhSiD3 and that if other decomposition pathways (e.g. PhSiD + D2) are occurring, they do not effect measurements of the rate constants for SiD2. The absorption spectrum of SiD2 formed from the flash photolysis of a mixture of PhSiD3 and SF6 at 193nm were found in the region 17384-17391 cm-1 with strong band at 17387.07 cm-1. This single rotational line of pQ1 was chosen to monitor SiD2 removal. Time-resolved studies of SiD2 have been carried out to obtain rate constants for its bimolecular reactions with D2. The reactions were studied over the pressure range 5-100 Torr (in SF6 bath gas) at four temperatures in the range 298-498K. Single decay from 10 photolysis laser shots were averaged and found to give reasonable first-order kinetics fits. Second order kinetics were obtained by pressure dependence of the pseudo first order decay constants and substance D2 pressures within experimental error. The reaction was found to be weakly pressure dependent at all temperatures, consistent with a third-body mediated association process. In addition, SiH2+ H2 reaction is approximately ca. 60% faster than SiD2+D2 reaction. Theoretical extrapolations (using Lindemann

  10. Time resolved spectroscopic investigation of SiD2 + D2: kinetic study

    Directory of Open Access Journals (Sweden)

    Al-Rubaiey Najem A.

    2017-01-01

    Full Text Available Silylenes (silanediyls have made an important impact on organosilicon chemistry even if it is of more recent foundation than carbenes in organic chemistry and much less complete. These species are highly reactive intermediates. They play a central role in the chemical vapour deposition (CVD of various silicon-containing thin films which have a technological importance in microelectronics as well as in the dry etching processes of silicon wafers. Spectroscopic methods have been developed to observe these species, a necessary pre-requisite to their direct monitoring. In this work, deuterated phenylsilane precursor, PhSiD3 was chosen for SiD2 because its analogue phenylsilane, PhSiH3 proved to be a good precursor for SiH2 and the high quality decay signals observed revealed that SiD2 be readily detected from PhSiD3 and that if other decomposition pathways (e.g. PhSiD + D2 are occurring, they do not effect measurements of the rate constants for SiD2. The absorption spectrum of SiD2 formed from the flash photolysis of a mixture of PhSiD3 and SF6 at 193nm were found in the region 17384-17391 cm-1 with strong band at 17387.07 cm-1. This single rotational line of pQ1 was chosen to monitor SiD2 removal. Time-resolved studies of SiD2 have been carried out to obtain rate constants for its bimolecular reactions with D2. The reactions were studied over the pressure range 5-100 Torr (in SF6 bath gas at four temperatures in the range 298-498K. Single decay from 10 photolysis laser shots were averaged and found to give reasonable first-order kinetics fits. Second order kinetics were obtained by pressure dependence of the pseudo first order decay constants and substance D2 pressures within experimental error. The reaction was found to be weakly pressure dependent at all temperatures, consistent with a third-body mediated association process. In addition, SiH2+ H2 reaction is approximately ca. 60% faster than SiD2+D2 reaction. Theoretical extrapolations (using

  11. Automatic Tuning Matching Cycler (ATMC) In Situ NMR Spectroscopy as a Novel Approach for Real-Time Investigations of Li- and Na-Ion Batteries

    OpenAIRE

    2016-01-01

    This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.jmr.2016.02.008 We have developed and explored the use of a new Automatic Tuning Matching Cycler (ATMC) in situ NMR probe system to track the formation of intermediate phases and investigate electrolyte decomposition during electrochemical cycling of Li- and Na-ion batteries (LIBs and NIBs). The new approach addresses many of the issues arising during in situ NMR, e.g., sign...

  12. One-Pot Synthesis, X-Ray Diffraction and MAS NMR Spectroscopic Study of Gallosilicate Nitrate Cancrinite Na8[GaSiO4]6(NO34(H2O6

    Directory of Open Access Journals (Sweden)

    Ashok V. Borhade

    2010-01-01

    Full Text Available One-pot synthetic gallosilicate nitrate cancrinite (CAN framework topology have been synthesized under hydrothermal conditions at 100 °C. The synthesized product was characterized by, X-ray powder diffraction, IR, Raman and 29Si, 23Na MAS NMR spectroscopy, SEM and thermogravimetry. The crystal structure refinement of pure nitrate cancrinite has been carried out from X-ray data using Rietveld refinement method. Gallosilicate cancrinite Na8[GaSiO4]6(NO34(H2O6 crystalline hexagonal with space group P63 and a = 12.77981 Å (2, c = 5.20217 Å (1, (Rwp = 0.0696 Rp = 0.0527. The results by MAS NMR spectroscopy confirmed the alternating Si, Ga ordering of the gallosilicate framework for a Si/Ga ratio of 1.0. A distribution of the quadrupolar interaction of the sodium cations caused by the enclatherated water molecules and motional effects can be suggested from the 23Na MAS NMR. Thermogravimetric investigation shows the extent of nitrate entrapment, stability within the cancrinite cage and decomposition properties. SEM clearly shows the hexagonal needle shaped crystals of nitrate cancrinite.

  13. Investigating organic multilayers by spectroscopic ellipsometry: specific and non-specific interactions of polyhistidine with NTA self-assembled monolayers

    Directory of Open Access Journals (Sweden)

    Ilaria Solano

    2016-04-01

    Full Text Available Background: A versatile strategy for protein–surface coupling in biochips exploits the affinity for polyhistidine of the nitrilotriacetic acid (NTA group loaded with Ni(II. Methods based on optical reflectivity measurements such as spectroscopic ellipsometry (SE allow for label-free, non-invasive monitoring of molecule adsorption/desorption at surfaces.Results: This paper describes a SE study about the interaction of hexahistidine (His6 on gold substrates functionalized with a thiolate self-assembled monolayer bearing the NTA end group. By systematically applying the difference spectra method, which emphasizes the small changes of the ellipsometry spectral response upon the nanoscale thickening/thinning of the molecular film, we characterized different steps of the process such as the NTA-functionalization of Au, the adsorption of the His6 layer and its eventual displacement after reaction with competitive ligands. The films were investigated in liquid, and ex situ in ambient air. The SE investigation has been complemented by AFM measurements based on nanolithography methods (nanografting mode.Conclusion: Our approach to the SE data, exploiting the full spectroscopic potential of the method and basic optical models, was able to provide a picture of the variation of the film thickness along the process. The combination of δΔi+1,i(λ, δΨi+1,i(λ (layer-addition mode and δΔ†i',i+1(λ, δΨ†i',i+1(λ (layer-removal mode difference spectra allowed us to clearly disentangle the adsorption of His6 on the Ni-free NTA layer, due to non specific interactions, from the formation of a neatly thicker His6 film induced by the Ni(II-loading of the NTA SAM.

  14. Sm{sup 3+}-doped Sc{sub 2}O{sub 3} polycrystalline ceramics: Spectroscopic investigation

    Energy Technology Data Exchange (ETDEWEB)

    Gheorghe, Cristina, E-mail: cristina_gheorghe2002@yahoo.com [National Institute for Laser, Plasma and Radiation Physics, ECS Laboratory, 077125 Magurele-Bucharest (Romania); Lupei, Aurelia; Voicu, Flavius [National Institute for Laser, Plasma and Radiation Physics, ECS Laboratory, 077125 Magurele-Bucharest (Romania); Enculescu, Monica [National Institute of Materials Physics Optics and Spectroscopy Laboratory, PO Box MG-7, 77125 Magurele-Bucharest (Romania)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Investigation of Sm{sup 3+}: Sc{sub 2}O{sub 3} ceramics in order to evaluate its potential for visible emission. Black-Right-Pointing-Pointer The optical spectra in the UV-IR at 10 and 300 K range of Sm{sup 3+} Sc{sub 2}O{sub 3} ceramics, were performed. Black-Right-Pointing-Pointer Spectroscopic parameters were evaluated in the frame of the Judd-Ofelt theory. - Abstract: Sm{sup 3+}-doped Sc{sub 2}O{sub 3} translucent polycrystalline ceramics were fabricated by solid-state reaction method in order to evaluate its potential for visible emission. The optical spectra in the UV-IR range of Sm{sup 3+} in these samples, at different temperatures (10-300 K), were performed. A series of data on Sm: Sc{sub 2}O{sub 3} system not investigated previously were obtained from the analysis of the absorption and visible emission spectra as well as the emission kinetics: an extended energy level scheme, absorption cross sections for different bands, lifetimes, etc. Additional spectroscopic parameters were evaluated in the frame of the Judd-Ofelt (J-O) theory: J-O intensity parameters, oscillator strengths, radiative transitions probabilities, radiative lifetimes, branching ratios, and the cross sections (by Fuechtbauer-Ladenburg) of the main three visible emissions: {sup 4}G{sub 5/2} {yields} {sup 6}H{sub 5/2} (yellow), {sup 4}G{sub 5/2} {yields} {sup 6}H{sub 7/2} (orange) and {sup 4}G{sub 5/2} {yields} {sup 6}H{sub 9/2} (red).

  15. 1H NMR and FT-IR dataset based structural investigation of poly(amic acids and polyimides from 4,4′-diaminostilbene

    Directory of Open Access Journals (Sweden)

    Amit Kumar

    2016-06-01

    Full Text Available Structural investigation of polymers by various available analytical methods is important in order to correlate the structure with polymer properties for which understanding of polymer structure is very important factor. The data presented here in this article shows the 1H NMR spectra used for the characterization of prepared poly(amic acids (PAAs. It is often difficult to assigns the peak in NMR of polymers due to its complexity. Data presented here helps in assigning the proton peak in complex NMR of PAAs prepared from aromatic diamines. Further functionality in polymer chains can be confirmed by FT-IR spectra. Change in functionality during some reaction or process can be monitored by disappearance or appearance of peaks in FT-IR. The complete imidization of PAAs to Polyimides (PIs is difficult to analyze because of the chemical stability i.e. insolubility of PIs in most of the solvent therefore the completion of imidization process was confirmed using FTIR.

  16. Molecular structure and spectroscopic investigations combined with hypoglycemic/anticancer and docking studies of a new barbituric acid derivative

    Science.gov (United States)

    Barakat, Assem; Soliman, Saied M.; Elshaier, Yaseen A. M. M.; Ali, M.; Al-Majid, Abdullah Mohammed; Ghabbour, Hazem A.

    2017-04-01

    The one-pot synthesis reaction of barbituric acid derivative, 1,3-cyclohexandione, and 4-fluorobenzaldehyde in water mediated by NHEt2 as base afforded 4 with excellent yield. The synthesized compound was characterized by spectrophotometric tools as well as X-ray single crystal diffraction technique. The stability of the nine possible isomers of the synthesized compound was studied using the B3LYP method and 6-31G(d,p) basis set. The electronic and spectroscopic properties of the most stable isomer were predicted. The UV-Vis absorption spectrum displayed two bands at 203 and 257 nm in the solvent chloroform. The latter was calculated at 235.6 nm (f = 0.1995) in the gas phase due to H-2→L (42%) and H-1→L+2 (14%) excitations. In solution, using chloroform as a solvent, a slight bathochromic shift to 237.6 nm with an increase in the absorption intensity (f = 0.2898) was predicted. The molecular orbital energy level diagram of this transition band was characterized mainly by π-π* transitions. The 13C and 1H NMR chemical shifts correlated well with the experimental data. The correlations had higher correlation coefficients (R2) when solvent effects were considered. The atomic charges were calculated using natural population analysis and the charged regions were presented using a molecular electrostatic potential (MEP) map. The synthesized compound was examined as a hypoglycemic agent via inhibition of α-glucosidase and β-glucuronidase enzymes. Its inhibitory activity against α-glucosidase was 10 times greater than the inhibitory activity of the standard drug acarbose (IC50 77.9 ± 0.3 μM and 840 ± 1.73 μM, respectively). Moreover, the target compound was evaluated for anticancer activity against MCF-7, H460, 3T3, and Hela cell lines. It demonstrated inhibitory activity against the MCF-7 and H460 cell lines with IC50 5.80 ± 0.12 and 19.6 ± 0.5 μM, respectively, in comparison to doxorubicin. The docking study was performed using the OpenEye program.

  17. Investigations on Synperiplanar and Antiperiplanar Isomers of Losartan: Theoretical and Experimental NMR Studies.

    Science.gov (United States)

    Kujawski, Jacek; Czaja, Kornelia; Ratajczak, Tomasz; Jodłowska, Elżbieta; Chmielewski, Marcin K

    2015-06-29

    Losartan inhibits the renin-angiotensin-aldosterone system by blocking the angiotensin II receptor. It is commonly used in cardiovascular diseases, such as hypertension. Several publications applied the ab initio and density functional theory methods to investigate the molecule of losartan. Only in one of them were the nuclear magnetic resonance spectra calculations carried out, and their results were correlated with the experimental values. The authors focused their attention on calculations of the anion form of losartan, taking into consideration both its synperiplanar and antiperiplanar configurations. Coefficients of determination and mean absolute deviation parameters were calculated for the experimental and calculated chemical shifts for every used basis set. They showed a noticeably stronger correlation for the anti-isomers than for the syn-isomers. Moreover, the solvation model increased the value of this parameter. The results of calculations confirmed that an anti-conformation of the analyte seems to be the preferred one, and such an orientation might be most potent within the receptor cavity, which is in agreement with the results of previous studies.

  18. Investigations on Synperiplanar and Antiperiplanar Isomers of Losartan: Theoretical and Experimental NMR Studies

    Directory of Open Access Journals (Sweden)

    Jacek Kujawski

    2015-06-01

    Full Text Available Losartan inhibits the renin-angiotensin-aldosterone system by blocking the angiotensin II receptor. It is commonly used in cardiovascular diseases, such as hypertension. Several publications applied the ab initio and density functional theory methods to investigate the molecule of losartan. Only in one of them were the nuclear magnetic resonance spectra calculations carried out, and their results were correlated with the experimental values. The authors focused their attention on calculations of the anion form of losartan, taking into consideration both its synperiplanar and antiperiplanar configurations. Coefficients of determination and mean absolute deviation parameters were calculated for the experimental and calculated chemical shifts for every used basis set. They showed a noticeably stronger correlation for the anti-isomers than for the syn-isomers. Moreover, the solvation model increased the value of this parameter. The results of calculations confirmed that an anti-conformation of the analyte seems to be the preferred one, and such an orientation might be most potent within the receptor cavity, which is in agreement with the results of previous studies.

  19. NMR spectroscopic study of the carbon and nitrogen dynamics of grass-derived pyrogenic organic material during 2.3 years of incubation in soil

    Science.gov (United States)

    Hilscher, André; Knicker, Heike

    2010-05-01

    Incomplete combustion of vegetation results in pyrogenic organic material (PyOM) which occurs ubiquitously in soils and sediments. To understand the C sequestration potential of PyOM in environmental systems knowledge is required about the respective degradation and humification mechanisms and the stability of the different chemical PyOM structures. The present study focuses on the microbial recalcitrance of PyOM on molecular scale. Therefore, microcosms incubation experiments were performed using PyOM produced from highly isotopically enriched 13C and 15N rye grass (Lolium perenne) at 350°C under oxic conditions for one (1M) and four minutes (4M). Solid-state CPMAS 13C and 15N NMR studies were accomplished to obtain insights into the involved humification mechanisms at different stages the PyOM degradation. In total up to 38% of the bulk PyOM C was mineralised during the 28 months of incubation. The O/N-alkyl C and alkyl C residues which survived the charring process were effectively decomposed. At the end of the incubation up to 73% and 57% of the initial O/N-alkyl C and alkyl C amount were mineralised or converted to other C groups, respectively. The total aryl C group recovery of the PyOM decreased significantly during the 28 months of incubation (P ≤ 0.001). After 20 months of incubation between 26% and 40% of the initial aryl C amount was lost. For this group, relative short half time periods in the range of 3.0 and 3.8 years were obtained. The observed loss of aromatic C structures may be attributed to two simultaneous processes, the mineralisation to CO2 and the conversion to other C groups by partial oxidation. The presence of a readily decomposable co-substrate showed no significant changes in the degradation pattern of the different PyOM, possibly because decomposable sources were already available in the starting PyOM. Most of the organic bound N of the fresh PyOM was assignable to heterocyclic aromatic compounds such as pyrrole and indole

  20. FTIR, FT-Raman, FT-NMR, UV-visible and quantum chemical investigations of 2-amino-4-methylbenzothiazole.

    Science.gov (United States)

    Arjunan, V; Sakiladevi, S; Rani, T; Mythili, C V; Mohan, S

    2012-03-01

    The FT-IR (4000-400 cm(-1)) and FT-Raman (4000-100 cm(-1)) spectral measurements and complete assignments of the observed spectra of 2-amino-4-methylbenzothiazole (2A4MBT) have been proposed. Ab initio and DFT calculations have been performed and the structural parameters of the compound were determined from the optimised geometry with 6-31G(d,p), 6-311++G(d,p) and cc-pVDZ basis sets and giving energies, harmonic vibrational frequencies, depolarisation ratios, IR intensities and Raman activities. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO, LUMO and band gap energies were measured by time-dependent DFT (TD-DFT) approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman activities chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule. The influences of methyl and amino groups on the skeletal modes and on the proton chemical shifts have been investigated. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. NIR fluorescence spectroscopic investigations of Er{sup 3+}-ions doped borate based tellurium calcium zinc niobium oxide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, O. [Department of Instrumentation, Sri Venkateswara University, Tirupati 517502 (India); Dhoble, S.J. [Department of Physics, RTM Nagpur University, Nagpur 440033 (India); Ramesh, B.; Devarajulu, G. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Reddy, C. Madhukar [Department of Physics, AP Model School, Yerravaripalem 517194 (India); Linganna, K. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Reddy, G. Rajasekhar [Department of Instrumentation, Sri Venkateswara University, Tirupati 517502 (India); Raju, B. Deva Prasad, E-mail: drdevaprasadraju@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Department of Future Studies, Sri Venkateswara University, Tirupati 517502 (India)

    2015-08-15

    A series of Er{sup 3+} ions doped tellurium calcium zinc niobium borate glasses were prepared by the melt quenching technique. The prepared samples were investigated by optical absorption and near infrared fluorescence spectroscopic studies. The obtained Judd–Ofelt intensity parameters Ω{sub λ} (λ=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from absorption spectra and their results are studied and compared with reported literature. The stark-level energies of {sup 4}I{sub 13/2} excited and {sup 4}I{sub 15/2} ground states were evaluated by using both the absorption and emission measurements. The effect of Er{sup 3+} ion concentration on the emission intensity of {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} transition was discussed. Intense and broad 1.53 µm infrared fluorescence is observed at 980 nm diode laser excitation. Photoluminescence (PL) and its decay behavior studies were carried out for the transition {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} at 1.53 µm emission. The broad emission together with higher values of the bandwidth (81 nm), stimulated emission cross-section (32.25×10{sup −22} cm{sup 2}) and lifetime (530 µs for 1.0 mol% of Er{sup 3+}) of level {sup 4}I{sub 13/2} make these glasses attractive for broadband amplifiers. From the analysis of spectroscopic data, the present glass is a prospective photonic material for practical applications in the visible and NIR region. - Highlights: • In this study we prepared TCZNB glasses doped with Er{sup 3+} ions. • Glasses are characterized with absorption, emission and lifetime analysis. • Judd–Ofelt theory is used to calculate radiative properties. • TCZNB glasses could be used as NIR lasers.

  2. Spectroscopic investigation on the interaction of copper porphyrazines and phthalocyanine with human telomeric G-quadruplex DNA.

    Science.gov (United States)

    Hassani, Leila; Hakimian, Fatemeh; Safaei, Elham

    2014-01-01

    The G-quadruplex DNA is a novel target for anticancer drug discovery and many scientific groups are investigating interaction of small molecules with G-quadruplex DNA to discover therapeutic agents for cancer. Here, interaction of a phthalocyanine (Cu(PcTs)) and two tetrapyridinoporphyrazines ([Cu(2,3-tmtppa)](4+) and [Cu(3,4-tmtppa)](4+)) with Na(+) and K(+) forms of human telomeric G-quadruplex DNA has been investigated by spectroscopic techniques. The results indicated that interaction of the cationic porphyrazines is remarkably stronger than the anionic phthalocyanine and they presumably bind to the G-quadruplex DNA through end-stacking. Fluorescent intercalator displacement assay implied the displacement ability of the complexes with thiazole orange. In addition, circular dichroism spectra of both quadruplex forms converge to the Na(+) isoform after binding to the porphyrazines. In conclusion, the porphyrazines as the complexes that bind to the G-quadruplex DNA, could be suitable candidates for further investigations about inhibition of telomerase enzyme. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Technical and technological investigation of cultural heritage: experience in applications of spectroscopic methods

    Science.gov (United States)

    Grigorieva, I. A.; Chugunova, K. S.; Kadikova, I. F.; Khavrin, S. V.; Pisareva, S. A.

    2016-12-01

    Physical and chemical methods of analysis are indispensable for restoration, study of painting techniques, examination and attribution of works of art. Development of new directions of investigations as well as improvements in sample preparation allow applying non-destructive analysis methods, minimizing amount of matter used to obtain informative spectra, preventing alteration and destruction of samples in the course of investigation. This paper observes the examples of applying optical and spectral methods, including molecular spectral analysis and electron microscopy, for study of binding media and pigments of painting and archaeological artifacts.

  4. Technical and technological investigation of cultural heritage: experience in applications of spectroscopic methods

    Directory of Open Access Journals (Sweden)

    Grigorieva I.A.

    2017-01-01

    Full Text Available Physical and chemical methods of analysis are indispensable for restoration, study of painting techniques, examination and attribution of works of art. Development of new directions of investigations as well as improvements in sample preparation allow applying non-destructive analysis methods, minimizing amount of matter used to obtain informative spectra, preventing alteration and destruction of samples in the course of investigation. This paper observes the examples of applying optical and spectral methods, including molecular spectral analysis and electron microscopy, for study of binding media and pigments of painting and archaeological artifacts.

  5. Synthesis, crystal structure investigation, spectroscopic characterizations and DFT computations on a novel 1-(2-chloro-4-phenylquinolin-3-yl)ethanone

    Science.gov (United States)

    Murugavel, S.; Stephen, C. S. Jacob Prasanna; Subashini, R.; Reddy, H. Raveendranatha; AnanthaKrishnan, Dhanabalan

    2016-10-01

    The title compound 1-(2-chloro-4-phenylquinolin-3-yl)ethanone (CPQE) was synthesised effectively by chlorination of 3-acetyl-4-phenylquinolin-2(1H)-one (APQ) using POCl3 reagent. Structural and vibrational spectroscopic studies were performed by utilizing single crystal X-ray diffraction, FTIR and NMR spectral analysis along with DFT method utilizing GAUSSIAN‧ 03 software. Veda program has been employed to perform a detailed interpretation of vibrational spectra. Mulliken population analyses on atomic charges, MEP, HOMO-LUMO, NBO, Global chemical reactivity descriptors and thermodynamic properties have been examined by (DFT/B3LYP) method with the 6-311G(d,p) basis set level.

  6. Matrix Infrared Spectroscopic and Computational Investigations of Novel Small Uranium Containing Molecules - Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Lester

    2014-10-17

    Direct reactions of f-element uranium, thorium and lanthanide metal atoms were investigated with small molecules. These metal atoms were generated by laser ablation and mixed with the reagent molecules then condensed with noble gases at 4K. The products were analyzed by absorption of infrared light to measure vibrational frequencies which were confirmed by quantum chemical calculations. We have learned more about the reactivity of uranium atoms with common molecules, which will aid in the develolpment of further applications of uranium.

  7. Spectroscopic Investigation of Indium Halides as Substitutes of Mercury in Low Pressure Discharges for Lighting Applications

    OpenAIRE

    Briefi, Stefan

    2012-01-01

    Low pressure discharges with indium halides as radiator are discussed as substitutes for hazardous mercury in conventional fluorescent lamps. In this work, the applicability of InBr and InCl in a low pressure discharge light source is investigated. The aim is to identify and understand the physical processes which determine the discharge characteristics and the efficiency of the generated near-UV emission of the indium halide molecule and of the indium atom which is created due to dissociatio...

  8. Applications of high resolution NMR to geochemistry: crystalline, glass, and molten silicates

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, E.

    1985-11-01

    The nuclear spin interactions and the associated quantum mechanical dynamics which are present in solid state NMR are introduced. A brief overview of aluminosilicate structure is presented and crystalline structure is then reviewed, with emphasis on the contributions made by /sup 29/Si NMR spectroscopy. The local structure of glass aluminosilicates as observed by NMR, is presented with analysis of the information content of /sup 29/Si spectra. A high-temperature (to 1300/sup 0/C) NMR spectroscopic investigation of the local environment and dynamics of molecular motion in molten aluminosilicates is described. A comparison is made of silicate liquid, glass, and crystalline local structure. The atomic and molecular motions present in a melt are investigated through relaxation time (T/sub 1/ and T/sub 2/) measurements as a function of composition and temperature for /sup 23/Na and /sup 29/Si.

  9. In situ vibrational spectroscopic investigation of C4 hydrocarbon selective oxidation over vanadium-phosphorus-oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhi -Yang [Iowa State Univ., Ames, IA (United States)

    1999-05-10

    n-Butane selective oxidation over the VPO catalyst to maleic anhydride is the first and only commercialized process of light alkane selective oxidation. The mechanism of this reaction is still not well known despite over twenty years of extensive studies, which can partially be attributed to the extreme difficulties to characterize catalytic reactions real-time under typical reaction conditions. In situ spectroscopic characterization techniques such as Infrared spectroscopy and laser Raman spectroscopy were used in the current mechanistic investigations of n-butane oxidation over VPO catalysts. To identify the reaction intermediates, oxidation of n-butane, 1,3-butadiene and related oxygenates on the VPO catalyst were monitored using FTIR spectroscopy under transient conditions. n-Butane was found to adsorb on the VPO catalyst to form olefinic species, which were further oxidized to unsaturated, noncyclic carbonyl species. The open chain dicarbonyl species then experienced cycloaddition to form maleic anhydride. VPO catalyst phase transformations were investigated using in situ laser Raman spectroscopy. This report contains Chapter 1: General introduction; Chapter 2: Literature review; and Chapter 5: Conclusion and recommendations.

  10. Investigation on the interaction between isorhamnetin and bovine liver catalase by spectroscopic techniques under different pH conditions.

    Science.gov (United States)

    Yang, Yumin; Li, Daojin

    2016-08-01

    The binding of isorhamnetin to bovine liver catalase (BLC) was first investigated at 302, 310 and 318 K at pH 7.4 using spectroscopic methods including fluorescence spectra, circular dichroism (CD) and UV-vis absorption. Spectrophotometric observations are rationalized mainly in terms of a static quenching process. The binding constants and binding sites were evaluated by fluorescence quenching methods. Enzymatic activity of BLC in the absence and presence of isorhamnetin was measured using a UV/vis spectrophotometer. The result revealed that the binding of isorhamnetin to BLC led to a reduction in the activity of BLC. The positive entropy change and enthalpy change indicated that the interaction of isorhamnetin with BLC was mainly driven by hydrophobic forces. The distance r between the donor (BLC) and acceptor (isorhamnetin) was estimated to be 2.99 nm according to fluorescence resonance energy transfer. Fluorescence, synchronous fluorescence, and CD spectra showed no obvious change in the conformation of BLC upon the binding of isorhamnetin. In addition, the influence of pH on the binding of isorhamnetin to BLC was investigated and the binding ability of the drug to BLC deceased under other pH conditions (pH 9.0, 6.5, 5.0, 3.5, or 2.0) as compared with that at pH 7.4. Copyright © 2016 John Wiley & Sons, Ltd.

  11. In situ vibrational spectroscopic investigation of C{sub 4} hydrocarbon selective oxidation over vanadium-phosphorus-oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Z.Y.

    1999-05-10

    n-Butane selective oxidation over the VPO catalyst to maleic anhydride is the first and only commercialized process of light alkane selective oxidation. The mechanism of this reaction is still not well known despite over twenty years of extensive studies, which can partially be attributed to the extreme difficulties to characterize catalytic reactions real-time under typical reaction conditions. In situ spectroscopic characterization techniques such as Infrared spectroscopy and laser Raman spectroscopy were used in the current mechanistic investigations of n-butane oxidation over VPO catalysts. To identify the reaction intermediates, oxidation of n-butane, 1,3-butadiene and related oxygenates on the VPO catalyst were monitored using FTIR spectroscopy under transient conditions. n-Butane was found to adsorb on the VPO catalyst to form olefinic species, which were further oxidized to unsaturated, noncyclic carbonyl species. The open chain dicarbonyl species then experienced cycloaddition to form maleic anhydride. VPO catalyst phase transformations were investigated using in situ laser Raman spectroscopy. This report contains Chapter 1: General introduction; Chapter 2: Literature review; and Chapter 5: Conclusion and recommendations.

  12. Spectroscopic, DFT and Z-scan supported investigation of dicyanoisophorone based push-pull NLOphoric styryl dyes

    Science.gov (United States)

    Erande, Yogesh; Sreenath, Mavila C.; Chitrambalam, Subramaniyan; Joe, Isaac H.; Sekar, Nagaiyan

    2017-04-01

    The dicyanoisophorone acceptor based NLOphores with Intramolecular Charge Transfer (ICT) character are newly synthesised, characterised and explored for linear and non linear optical (NLO) property investigation. Strong ICT character of these D-π-A styryl NLOphores is established with support of emission solvatochromism, polarity functions and Generalised Mulliken Hush (GMH) analysis. First, second and third order polarizability of these NLOphores is investigated by spectroscopic and TDDFT computational approach using CAM/B3LYP-6-311 + g (d, p) method. BLA and BOA values of these chromophores are evaluated from ground and excited state optimized geometries and found that the respective structures are approaching towards cyanine limit. Third order nonlinear susceptibility (X(3)/SUP>) along with nonlinear absorption coefficient (β) and nonlinear refraction (n2) are evaluated for these NLOphores using Z-scan experiment. All four chromophores exhibit large polarization anisotropy (Δα), first order hyperpolarizability (β0), second order hyperpolarizability (γ) and third order nonlinear susceptibility (X(3)/SUP>). TGA analysis proved these NLOphores are stable up to 320 °C and hence can be used in device fabrication.

  13. Resonance Enhanced Multi-Photon Ionization (rempi) and Double Resonance Uv-Uv and Ir-Uv Spectroscopic Investigation Isocytosine

    Science.gov (United States)

    Lee, Seung Jun; Min, Ahreum; Ahn, Ahreum; Moon, Cheol Joo; Choi, Myong Yong; Ishiuchi, Shun-Ichi; Miyazaki, Mitsuhiko; Fujii, Masaaki

    2013-06-01

    Isocytosine(iC), 2-aminouracil, is a non-natural nucleobase and its functional group's positions resemble those of guanine; therefore, its spectroscopic investigation is worthy of attention especially for the natural/unnatural base pairs with guanine and isoguanine. In this study, resonance enhanced multi-photon ionization (REMPI) and UV/IR-UV double resonance spectra of iC in the gas phase are presented. The collaboration work between Tokyo Institute of Technology, Japan and Gyeongsang National University, Korea using laser ablation and thermal evaporation, respectively, for producing jet-cooled iC is presented and discussed. The REMPI spectrum of iC monomers is recorded in the spectral range of 35000 to 36400cm-1, showing very congested π-π* vibronic bands. UV-UV hole burning spectroscopy is further conducted to investigate the conformational landscapes of iC monomers. Moreover, the presence of free OH band from IR-UV double resonance spectroscopy in combination with quantum chemical calculations convinces that the iC monomer in free-jet expansion experiment is an enol tautomer. However, a possible presence of a keto tautomer of iC may be provided by employing a pico-second experiment on iC.

  14. Spectroscopic investigations on Pr³+ and Nd³+ doped strontium-lithium-bismuth borate glasses.

    Science.gov (United States)

    Rajesh, D; Balakrishna, A; Seshadri, M; Ratnakaram, Y C

    2012-11-01

    Spectroscopic investigations on different concentrations (0.1, 0.5, 1.0, 1.5 and 2.0mol%) of Pr(3+) and Nd(3+) doped strontium lithium bismuth borate glasses have been done. X-ray diffraction, SEM with EDS, absorption and luminescence spectra were recorded for all the glass matrices and analyzed. X-ray diffraction profiles and SEM images conformed amorphous nature of investigated glass samples. EDS spectra of host glass and Pr(3+)doped glass matrices gave information about the chemical composition of glass samples. From the absorption spectra of Pr(3+) and Nd(3+) ions, Judd-Ofelt (J-O) intensity parameters (Ω(λ),λ=2, 4 and 6) have been calculated and compared with other glass matrices. The emission characteristics such as radiative lifetimes (τ(R)), measured and calculated branching ratios (β) and stimulated emission cross-sections (σ(P)) have been obtained for the observed emission transitions of Pr(3+) and Nd(3+) ions in the above glass matrix for all the concentrations. From the emission spectra of Pr(3+) and Nd(3+) doped glass matrices, the effect of concentration on the quenching of intensity of (1)D(2)→(3)H(4) transition of Pr(3+) ion and (4)F(3/2)→(4)I(9/2), (4)I(11/2) and (4)I(13/2) transitions of Nd(3+) have been studied and discussed.

  15. Nano sized Powder of Jackfruit Seed: Spectroscopic and Anti-microbial Investigative Approach

    CERN Document Server

    Theivasanthi, T; Palanivelu, M; Alagar, M

    2011-01-01

    This work reports aspect related to nano-sized particles of jackfruit seed. FTIR spectrum was recorded for functional groups analysis and EDAX analysis was done to identify the various elements of the sample. Both FTIR and EDAX analysis results indicated the presence of Starch. FTIR analysis confirmed the availability of anti-microbial Sulphur derivatives compounds. Microbiology assay found that jackfruit seed nanoparticles were effective against Escherichia coli and Bacillus megaterium bacteria. This work also investigated about the dual-function of the sample i.e. food ingredients possessing antimicrobial activities. Specific surface area of bacteria analysis revealed that it played a major role while on reactions with jackfruit seed nanoparticles.

  16. Co speciation in hardened cement paste: a macro- and micro-spectroscopic investigation.

    Science.gov (United States)

    Vespa, M; Dähn, R; Grolimund, D; Wieland, E; Scheidegger, A M

    2007-03-15

    Cement-based materials play an important role in multi-barrier concepts developed worldwide for the safe disposal of hazardous and radioactive wastes. Cement is used to condition and stabilize the waste materials and to construct the engineered barrier systems (container, backfill and liner materials) of repositories for radioactive waste. In this study, Co uptake by hardened cement paste (HCP) has been investigated with the aim of improving our understanding of the immobilization process of heavy metals in cement on the molecular level. X-ray-absorption spectroscopy (XAS) on powder material (bulk-XAS) was used to determine the local environment of Co in cement systems. Bulk-XAS investigations were complemented with micro-beam investigations to probe the inherent microscale heterogeneity of cement by using micro-X-ray-fluorescence (micro-XRF) and micro-XAS. Micro-XRF was used to gain information on the spatial heterogeneity of the Co distribution, whereas micro-XAS was employed to determine the speciation of Co on the microscale. The Co-doped HCP samples hydrated for time-scales from 1 hour up to 1 year were prepared under normal atmosphere, to simulate similar conditions as for waste packages. To investigate the role of oxygen, further samples were prepared in the absence of oxygen. The study showed that, for the samples prepared in air, Co(II) is oxidized to Co(III) after 1 hour of hydration time. Moreover, the relative amount of Co(III) increases with increasing hydration time. The study further revealed that Co(II) is predominately present as a Co-hydroxide-like phase and/or Co-phyllosilicates, whereas Co(III) tends to be incorporated into a CoOOH-like phase and/or Co-phyllomanganates. In contrast to samples prepared in air, XAS experiments with samples prepared in the absence of oxygen revealed solely the presence of Co(II). This finding indicates that oxygen plays an important role for Co oxidation in cement. Furthermore, the study suggests that Co

  17. IR spectroscopic investigation of the structure of water-fuel microemulsion for diesel engines

    Science.gov (United States)

    Vettegren', V. I.; Mamalimov, R. I.; Lozhkin, V. N.; Morozov, V. A.; Lozhkina, O. V.; Pimenov, Yu. A.

    2016-09-01

    The structures of a microemulsion formed by a surfactant (ammonium oleate), water drops of a linear size of 1-3 µm, and a diesel fuel has been investigated using IR spectroscopy. It has been found that ammonium oleate molecules in the microemulsion are dissociated on the positive NH4 + ion and the negative ion of the remaining part of the molecule, which forms the hydrogen bond with water molecules. This increases the rate of water, evaporation and leads to the more complete combustion of the diesel fuel. As a result, the concentration of harmful nitrogen oxides and soot particles in the exhaust gas of the diesel engine decreases.

  18. The analytical investigations of ancient pottery from Kaveripakkam, Vellore dist, Tamilnadu by spectroscopic techniques

    Science.gov (United States)

    Ravisankar, R.; Naseerutheen, A.; Raja Annamalai, G.; Chandrasekaran, A.; Rajalakshmi, A.; Kanagasabapathy, K. V.; Prasad, M. V. R.; Satpathy, K. K.

    2014-03-01

    Analytical investigations using Fourier Transform infrared spectroscopy (FT-IR), Powder X-ray Diffraction (PXRD), Thermal Analysis (TG-DTA), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) were carried out on ancient pottery fragments from Kaveripakkam, in order to outline manufacturing skills, technology information, firing condition and temperature of potteries. The whole set of data showed the firing temperature in the range of 800-900 °C. The analytical characterization of the potsherds, by different complimentary techniques has allowed to identifying the raw materials and technology applied by the ancient artisans.

  19. Biological applications and spectroscopic investigations of 4-nitrophenol-urea dimer: A DFT approach

    Science.gov (United States)

    Beaula, T. Joselin; Muthuraja, P.; Dhandapani, M.; Joe, I. Hubert; Rastogi, V. K.; Jothy, V. Bena

    2016-02-01

    Molecular geometry of grown crystal 4-nitrophenol-urea has been evaluated and compared with XRD data while the crystalline nature of the compound has been confirmed by PXRD study. Vibrational analysis has been performed using NCA and dielectric studies have been carried out at room temperature. NBO analysis has been applied in comparative study of charge delocalization. Molecular orbital contributions have been investigated by TDOS and αβDOS. Enhancement of microbial treatments against bacteria and fungi has been assessed and a remarkable efficiency has been recorded.

  20. Impedance Spectroscopic Investigation of the Degraded Dye-Sensitized Solar Cell due to Ageing

    Directory of Open Access Journals (Sweden)

    Parth Bhatt

    2016-01-01

    Full Text Available This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DSCs. The electrical characterization of fresh and degraded DSCs is done under AM1.5G spectrum and the current density-voltage (J-V characteristics are analyzed. Short circuit current density (JSC decreases significantly whereas a noticeable increase in open circuit voltage is observed. These results have been further investigated electroanalytically using electrochemical impedance spectroscopy (EIS. An increase in net resistance results in a lower JSC for the degraded DSC. This decrease in current is mainly due to degradation of TiO2-dye interface, which is observed from light and dark J-V characteristics and is further confirmed by EIS measurements. A reduction in the chemical capacitance of the degraded DSC is observed, which is responsible for the shifting of Fermi level with respect to conduction band edge that further results in an increase of open circuit voltage for the degraded DSC. It is also confirmed from EIS that the degradation leads to a better contact formation between the electrolyte and Pt electrode, which improves the fill factor of the DSC. But the recombination throughout the DSC is found to increase along with degradation. This study suggests that the DSC should be used under low illumination conditions and around room temperature for a longer life.

  1. Spectroscopic Investigations and DFT Calculations on 3-(Diacetylamino-2-ethyl-3H-quinazolin-4-one

    Directory of Open Access Journals (Sweden)

    Yusuf Sert

    2016-01-01

    Full Text Available The theoretical and experimental vibrational frequencies of 3-(diacetylamino-2-ethyl-3H-quinazolin-4-one (2 were investigated. The experimental Laser-Raman spectrum (4000–100 cm−1 and FT-IR spectrum (4000–400 cm−1 of the newly synthesized compound were recorded in the solid phase. Both the theoretical vibrational frequencies and the optimized geometric parameters such as bond lengths and bond angles have for the first time been calculated using density functional theory (DFT/B3LYP and DFT/M06-2X quantum chemical methods with the 6-311++G(d,p basis set using Gaussian 03 software. The vibrational frequencies were assigned with the help of potential energy distribution (PED analysis using VEDA 4 software. The calculated vibrational frequencies and the optimized geometric parameters were found to be in good agreement with the corresponding reported experimental data. Also, the energies of the lowest unoccupied molecular orbital (LUMO, highest occupied molecular orbital (HOMO, and other related molecular energies for 3-(diacetylamino-2-ethyl-3H-quinazolin-4-one (2 have been investigated using the same computational methods.

  2. Contribution of proton NMR relaxation to the investigation of molecular dynamics in columnar mesophases of discotic and polycatenar molecules

    Indian Academy of Sciences (India)

    A C Ribeiro; P J Sebastiao; C Cruz

    2003-08-01

    We present in this work a review concerning wide frequency range 1 proton NMR relaxation studies performed in compounds exhibiting columnar mesophases, namely the Colho mesophase in the case of a liquid crystal of discotic molecules and the h mesophase in the case of a liquid crystal of biforked molecules. These NMR relaxation studies were performed combining conventional and fast field cycling NMR techniques in a frequency range between 100 Hz and 300 MHz. The possibility of probing such a large frequency range has provided a way to effectively distinguish the influence, on the 1 relaxation profiles, of the different molecular movements observed in this type of mesophases. In addition, we present a comparison between the molecular dynamics in columnar (h) and lamellar (SmC) mesophases exhibited by the same biforked compound.

  3. Spectroscopic investigation of an intrinsic room temperature ferromagnetism in Co doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    N, Srinatha [Department of Physics, JB Campus, Bangalore University, Bangalore 560056 (India); Angadi, Basavaraj, E-mail: brangadi@gmail.com [Department of Physics, JB Campus, Bangalore University, Bangalore 560056 (India); Nair, K.G.M. [UGC-DAE-CSR, Kalpakkam Node, Kalpakkam, Kokilamedu 603 102 (India); Deshpande, Nishad G.; Shao, Y.C.; Pong, Way-Faung [Department of Physics, Tamkang University, Tamsui, Taipei 251, Taiwan (China)

    2014-08-15

    Highlights: • For the first time L-Valine was used as a fuel to synthesize Co:ZnO nanoparticles by solution combustion method. • Single phase and ferromagnetic nature were confirmed through XRD, SQUID, NEXAFS and XMCD. • Through NEXAFS and XMCD, the effect of ‘Co’ substitution at O K-edge, Co L{sub 3,2} edge, Zn L{sub 3,2} edge have been investigated. • Spectral features of NEXAFS and XMCD confirms an intrinsic RTFM by substitution of ‘Co{sup 2+}’ at ‘Zn{sup 2+}’ site and rules out the presence of secondary phases. - Abstract: Pure and Co substituted ZnO nano crystalline particles were prepared by solution combustion technique using L-Valine as a fuel. As synthesized powder samples were characterized by X-ray diffractometer and SQUID magnetometer to confirm the formation of single phase wurtzite structure and to study the bulk magnetic response of the sample, respectively. Magnetic studies show that Co doped ZnO nanoparticles exhibit ferromagnetism (FM) at room temperature (RT). Furthermore, the electronic structure and element specific magnetic properties were investigated by near-edge X-ray absorption fine structure (NEXAFS) and X-ray magnetic circular dichroism (XMCD) measurements, respectively. The effect of Co substitution on the spectral features of Co–ZnO at O K-edge, Co L{sub 3,2} edge, Zn L{sub 3,2} edge have been investigated. The spectral features of NEXAFS at Co L{sub 3,2} edge is entirely different from the spectral features of metallic clusters and other impurity phases, which rules out the presence of impurity phases. The valence state of ‘Co’ ion is found to be in +2 state. The FM nature of the sample was confirmed through XMCD spectra, which is due to the incorporation of divalent ‘Co’ ions. Hence the presented results confirm the substitution of ‘Co’ ions at ‘Zn’ site in the host lattice, which is responsible for the RTFM.

  4. Direct Speciation of Phosphorus in Alum-Amended Poultry Litter: Solid-State 31P NMR Investigation

    Energy Technology Data Exchange (ETDEWEB)

    Hunger, Stefan; Cho, Herman M.; Sims, James T.; Sparks, Donald L.

    2004-02-01

    Amending poultry litter (PL) with aluminum sulfate (alum) has proven to be effective in reducing water-soluble phosphorus (P) in the litter and in runoff from fields that have received PL applications; it has therefore been suggested as a best management practice. Although its effectiveness has been demonstrated on a macroscopic scale in the field, little is known about P speciation in either alumamended or unamended litter. This knowledge is important for the evaluation of the long-term stability and bioavailability of P, which is a necessary prerequisite for the assessment of the sustainability of intensive poultry operations. Both solid state MAS and CP-MAS {sup 31}P NMR as well as {sup 31}P({sup 27}Al) TRAPDOR were used to investigate P speciation in alumamended and unamended PL. The results indicate the presence of a complex mixture of organic and inorganic orthophosphate phases. A calcium phosphate phase, probably a surface precipitate on calcium carbonate, could be identified in both unamended and alum-amended PL, as well as physically bound HPO{sub 4}{sup 2-}. Phosphate associated with Al was found in the alum-amended PL, most probably a mixture of a poorly ordered wavellite and phosphate surface complexes on aluminum hydroxide that had been formed by the hydrolysis of alum. However, a complex mixture of organic and inorganic phosphate species could not be resolved. Phosphate associated with Al comprised on average 40{+-}14% of the total P in alum-amended PL, whereas calcium phosphate phases comprised on average 7{+-}4% in the alum-amended PL and 14{+-}5% in the unamended PL.

  5. 1H NMR-based metabolomics investigation of copper-laden rat: a model of Wilson's disease.

    Directory of Open Access Journals (Sweden)

    Jingjing Xu

    Full Text Available Wilson's disease (WD, also known as hepatoleticular degeneration (HLD, is a rare autosomal recessive genetic disorder of copper metabolism, which causes copper to accumulate in body tissues. In this study, rats fed with copper-laden diet are used to render the clinical manifestations of WD, and their copper toxicity-induced organ lesions are studied. To investigate metabolic behaviors of 'decoppering' process, penicillamine (PA was used for treating copper-laden rats as this chelating agent could eliminate excess copper through the urine. To date, there has been limited metabolomics study on WD, while metabolic impacts of copper accumulation and PA administration have yet to be established.A combination of 1HNMR spectroscopy and multivariate statistical analysis was applied to examine the metabolic profiles of the urine and blood serum samples collected from the copper-laden rat model of WD with PA treatment.Copper accumulation in the copper-laden rats is associated with increased lactate, creatinine, valine and leucine, as well as decreased levels of glucose and taurine in the blood serum. There were also significant changes in p-hydroxyphenylacetate (p-HPA, creatinine, alpha-ketoglutarate (α-KG, dimethylamine, N-acetylglutamate (NAG, N-acetylglycoprotein (NAC in the urine of these rats. Notably, the changes in p-HPA, glucose, lactate, taurine, valine, leucine, and NAG were found reversed following PA treatment. Nevertheless, there were no changes for dimethylamine, α-KG, and NAC as a result of the treatment. Compared with the controls, the concentrations of hippurate, formate, alanine, and lactate were changed when PA was applied and this is probably due to its side effect. A tool named SMPDB (Small Molecule Pathway Database is introduced to identify the metabolic pathway influenced by the copper-laden diet.The study has shown the potential application of NMR-based metabolomic analysis in providing further insights into the molecular

  6. An NMR-based metabolomic approach to investigate the effects of supplementation with glutamic acid in piglets challenged with deoxynivalenol.

    Science.gov (United States)

    Wu, Miaomiao; Xiao, Hao; Ren, Wenkai; Yin, Jie; Hu, Jiayu; Duan, Jielin; Liu, Gang; Tan, Bie; Xiong, Xia; Oso, Abimbola Oladele; Adeola, Olayiwola; Yao, Kang; Yin, Yulong; Li, Tiejun

    2014-01-01

    Deoxynivalenol (DON) has various toxicological effects in humans and pigs that result from the ingestion of contaminated cereal products. This study was conducted to investigate the protective effects of dietary supplementation with glutamic acid on piglets challenged with DON. A total of 20 piglets weaned at 28 d of age were randomly assigned to receive 1 of 4 treatments (5 piglets/treatment): 1) basal diet, negative control (NC); 2) basal diet +4 mg/kg DON (DON); 3) basal diet +2% (g/g) glutamic acid (GLU); 4) basal diet +4 mg/kg DON +2% glutamic acid (DG). A 7-d adaptation period was followed by 30 days of treatment. A metabolite analysis using nuclear magnetic resonance spectroscopy (1H-NMR)-based metabolomic technology and the determination of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities for plasma, as well as the activity of Caspase-3 and the proliferation of epithelial cells were conducted. The results showed that contents of low-density lipoprotein, alanine, arginine, acetate, glycoprotein, trimethylamine-N-oxide (TMAO), glycine, lactate, and urea, as well as the glutamate/creatinine ratio were higher but high-density lipoprotein, proline, citrate, choline, unsaturated lipids and fumarate were lower in piglets of DON treatment than that of NC treatment (Pglutamic acid increased the plasma concentrations of proline, citrate, creatinine, unsaturated lipids, and fumarate, and decreased the concentrations of alanine, glycoprotein, TMAO, glycine, and lactate, as well as the glutamate/creatinine ratio (Pglutamic acid to DON treatment increased the plasma activities of SOD and GSH-Px and the proliferating cell nuclear antigen (PCNA) labeling indexes for the jejunum and ileum (Pglutamic acid has the potential to repair the injuries associated with oxidative stress as well as the disturbances of energy and amino acid metabolism induced by DON.

  7. Spectroscopic (FT-IR, (1)H, (13)C NMR, UV), DOS and orbital overlap population analysis of copper complex of (E)-4-(2-(4-nitrophenyl) diazenyl)-N, N bis ((pyridin-2-yl) methyl) benzamine by density functional theory.

    Science.gov (United States)

    Diwaker

    2015-02-05

    The geometric parameters, chemical shifts, FTIR, NMR and orbital overlap population along with DOS (density of states) to know different kinds of interactions for binding of copper atom with (E)-4-(2-(4-nitrophenyl) diazenyl)-N, N bis ((pyridin-2-yl) methyl) benzamine to form its copper complex has been reported by DFT methods. The theoretically predicted values for structural parameters are in agreement with the experimentally reported values. NMR chemical shifts calculated using B3LYP/DFT/GIAO level of theory gives information about binding of copper atom with three nitrogen atoms namely N (3, 8 and 11). Orbital overlap population analysis using DFT/B3LYP/SDD level of theory is used to study the kind of interactions involved in binding of copper with the three nitrogen atoms. DOS studies are done to know about the contribution of alpha, beta electrons to the valence and conduction band. IR spectroscopy investigations gave the absorption bands for the formation of title compound. Electronic spectrum along with HOMO-LUMO energies of the title compound has been investigated using Time-dependent (TD-DFT) approach.

  8. Multi-spectroscopic methods investigation on the interaction of tenoxicam with DNA.

    Science.gov (United States)

    Liu, Bing-Mi; Zhang, Jun; Liu, Yang; Zhang, Li-Ping; Ma, Ping; Wang, Xin; Liu, Bin

    2015-12-01

    Non-steroidal anti-inflammatory drugs (NSAIDs) show chemopreventive and chemosuppressive effects on various cancer cell lines. They exert anticancer activities by inhibiting both at the protein level and/or at the transcription level. Thus, in this paper, the interaction between tenoxicam (TXM) and calf thymus DNA (ct-DNA) was investigated by UV-visible light, fluorescence, viscosity experiments and DNA melting studies. The results showed that TXM could bind to ct-DNA in the groove binding mode. The binding constants were 7.67 × 10(3) and 5.48 × 10(3) M(-1) at 293 and 300 K, respectively. Furthermore, the calculated thermodynamic parameters suggested that hydrogen bonds or van der Waals force might play an important role in the binding of TXM to ct-DNA. The obtained results should give new insight into the pharmacological activity of TXM.

  9. Spectroscopic investigations on the interactions between isopropanol and trypsin at molecular level.

    Science.gov (United States)

    Hu, Xinxin; Yu, Zehua; Liu, Rutao

    2013-05-01

    The toxicity of hydroxyl group of isopropanol to trypsin in aqueous solution was investigated by techniques including UV-visible absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, enzyme activity assay and molecular docking technology. The results of UV-visible absorption spectroscopy and CD spectra indicate that isopropanol could change the secondary structure of trypsin by increasing the content of α-helix and decreasing the content of β-sheet. The tertiary structure of trypsin was also changed owing to the loss of environmental asymmetry of amino acid residues. Isopropanol bound into a hydrophobic cavity on the surface of trypsin by a hydrogen bond located between the hydrogen atom on the hydroxyl of isopropanol and the oxygen atoms on SER 214 and hydrophobic interaction, as the molecular docking results showed. In addition, isopropanol could affect the function of trypsin by increasing its catalytic activity.

  10. Femtosecond laser irradiation of indium phosphide in air: Raman spectroscopic and atomic force microscopic investigations

    Energy Technology Data Exchange (ETDEWEB)

    Bonse, J.; Wrobel, J.M.; Brzezinka, K.-W.; Esser, N.; Kautek, W

    2002-12-30

    Surface modification and ablation of crystalline indium phosphide was performed with single and double 130 fs pulses from a Ti:sapphire laser. The morphological features resulting from laser processing, have been investigated by means of micro Raman spectroscopy as well as by optical, atomic force and scanning electron microscopy. The studies indicate amorphous, ablated and recrystallized zones on the processed surface. In the single-pulse irradiation experimentsveral different threshold fluences could be assigned to the processes of melting, ablation and polycrystalline resolidification. Residual stress has been detected within the irradiated areas. Double-pulse exposure experiments have been analyzed in order to clarify the effect of cumulative damage in the ablation process of indium phosphide.

  11. Spectroscopic Investigation on the Interaction of a Cyanine Dye with Serum Albumins

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ya-Zhou; YANG Qian-Fan; DU Hong-Yan; TANG Ya-Lin; XU Guang-Zhi; YAN Wen-Peng

    2008-01-01

    The interactions of a cyanine dye with human serum albumin (HSA) and bovine serum albumin (BSA) have been investigated by using absorption and fluorescence spectra.Absorption spectral studies show that binding to the serum albumins leads to a bathochromic shift of the monomer band together with a notable intensity change.Furthermore, the number of binding sites (n) was identified by the absorption spectra.There is a constant enhancement of fluorescence quantum yield when the cyanine dye complexes with HSA or BSA.The apparent binding constant (Ka) and the free energy changes (△G) were obtained by analysis of fluorescence data of the cyanine dye in the absence and presence of HSA and BSA.Compared to BSA, HSA associates with the dye in a stronger way.

  12. Interaction of sulfanilamide and sulfamethoxazole with bovine serum albumin and adenine: spectroscopic and molecular docking investigations.

    Science.gov (United States)

    Rajendiran, N; Thulasidhasan, J

    2015-06-05

    Interaction between sulfanilamide (SAM) and sulfamethoxazole (SMO) with BSA and DNA base (adenine) was investigated by UV-visible, fluorescence, cyclic voltammetry and molecular docking studies. Stern-Volmer fluorescence quenching constant (Ka) suggests SMO is more quenched with BSA/adenine than that of SAM. The distance r between donor (BSA/adenine) and acceptor (SAM and SMO) was obtained according to fluorescence resonance energy transfer (FRET). The results showed that hydrophobic forces, electrostatic interactions, and hydrogen bonds played vital roles in the SAM and SMO with BSA/adenine binding interaction. During the interaction, sulfa drugs could insert into the hydrophobic pocket, where the non-radioactive energy transfer from BSA/adenine to sulfa drugs occurred with high possibility. Cyclic voltammetry results suggested that when the drug concentration is increased, the anodic electrode potential deceased. The docking method indicates aniline group is interacted with the BSA molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. A spectroscopic and theoretical investigation of the proton-transfer laser. [Fisetin and 3-hydroxyflavone

    Energy Technology Data Exchange (ETDEWEB)

    Parthenopoulos, D.A.

    1988-01-01

    The lasing characteristics and the spectroscopy of intramolecular proton-transfer molecules were investigated in nonpolar and polar solvents. In addition, molecular orbital calculations on intramolecular proton-transfer molecules were performed. The efficient generation of coherent stimulated emission from 3-hydroxyflavone (3-HF) and fisetin, two molecules that exhibit intramolecular proton transfer was shown. Amplified spontaneous emission from 3-HF is achieved in polar aprotic and moderately protic solvents. The observed shifts of the tautomer fluorescence are attributed to hydrogen bonding interactions with the solvent. In contrast, 3-hydroxychromone does not exhibit amplified spontaneous emission in various solvents and concentrations. Picosecond transient absorption experiments reveal the existence of absorption bands overlapping the emission, which leads to high-loss terms in the gain equation.

  14. Spectroscopic investigation of the interaction of p-benzoquinone with casein in the solid state.

    Science.gov (United States)

    Vieira, Isadora S; Zaia, Dimas A M; Balena, Solange P; Mangrich, Antonio S; de Santana, Henrique

    2010-02-01

    The reaction between p-benzoquinone (PBQ) and casein (protein) in the solid state was studied. After reaction with protein, the FT-IR spectra showed a new band at 1215 cm(-1), with an intense sign attributed for casein/PBQ product. An optimum amount of PBQ for determination of the product when mixed with casein was 100mg and a reaction time of 30 min. The product was stable for a period of 24h after the reacting by heating. The interaction of PBQ with casein was investigated by FT-IR, reflectance, Raman and EPR spectroscopies. The reaction between PBQ and casein in the solid state yields a radical species (p-benzosemiquinone) that it is stabilized by the presence of p-biphenolate and p-benzoquinone species in the solid state. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  15. Glass transition of polystyrene (PS) studied by Raman spectroscopic investigation of its phenyl functional groups

    Science.gov (United States)

    Bertoldo Menezes, D.; Reyer, A.; Marletta, A.; Musso, M.

    2017-01-01

    In polymeric materials the glass transition (GT) is a well-known and very important relaxation process related to movements of functional groups in the polymeric chain. In this work, we show the potential of Raman spectroscopy for exploring the GT process in the polymer polystyrene. We collected Raman spectra during a step-by-step heating process of the sample, which allowed us to collect signatures of the GT process from peak parameters of specific vibrational modes, and to verify the GT temperature. Results of the latter were in accordance with published values obtained via other methods. We identified the aromatic ring vibrational modes of the phenyl functional groups to be those which, due to steric hindrance, suffer the largest influence during the GT process. This confirms that Raman spectroscopy can be used as a complementary technique to perform GT investigations in polymeric materials due to its sensitivity to small intermolecular changes affecting vibrational properties of relevant functional side groups.

  16. Interaction of cyclodextrins with human and bovine serum albumins: A combined spectroscopic and computational investigation

    Indian Academy of Sciences (India)

    Saptarshi Ghosh; Bijan Kumar Paul; Nitin Chattopadhyay

    2014-07-01

    Interaction of cyclodextrins (CDs) with the two most abundant proteins, namely human serum albumin (HSA) and bovine serum albumin (BSA), has been investigated using steady-state and time-resolved fluorometric techniques, circular dichroism measurements and molecular docking simulation. The study reveals that the three CDs interact differently on the fluorescence and fluorescence lifetimes of the serum albumins. However, fluorescence anisotropy and circular dichroism are not affected. Depending on their size, different CDs bind to the serum albumins in different positions, resulting in changes in the spectral behaviour of the proteins. Docking study suggests the probable binding sites of the three CDs with the proteins. Combined experimental and computational studies imply that sufficiently high concentration of CDs causes loosening of the rigid structures of these transport proteins, although their secondary structures remain intact. Thus, CDs are found to be safe for the serum proteins from the structural point of view.

  17. Spectroscopic and molecular modeling investigation on the binding of a synthesized steroidal amide to protein

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hua-xin, E-mail: h.x.zhang@yeah.net; Liu, E.

    2014-09-15

    Owing to the various valuable biological activities, steroidal amides have become a hot topic in steroidal pharmaceutical chemistry. In this paper, an anti-tumor steroid derivate (DAAO) was synthesized and identified. The interaction between DAAO and human serum albumin (HSA) was studied by fluorescence spectra, circular dichroism (CD) spectra, molecular modeling and molecular probe techniques. The results suggested that DAAO had reacted with HSA through hydrogen bonds and van der Waals power. The formation of DAAO–HSA complex at ground state led to static quenching of HSA's fluorescence. The number of binding sites, binding constants, enthalpy change (ΔH{sup θ}), Gibbs free energy change (ΔG{sup θ}) and entropy change (ΔS{sup θ}) were calculated at different temperatures based on fluorescence quenching theory and classic equation. Molecular modeling investigation indicated that DAAO was more inclined to absorb on Sudlow's site I in subdomain IIA of HSA molecule on grounds of the lowest energy principle and steric hindrance effect. The binding location was further confirmed by fluorescence probe experiment using warfarin (site I probe) for displacement. Furthermore, the conformational changes of HSA in presence of DAAO were investigated by CD spectra. The results could provide new evidence explaining the relationship between the chemical structure and biological activity and may be useful for understanding the anti-cancer mechanism of steroidal drug. - Highlights: • A designed steroidal amide compound (DAAO) was synthesized by introducing amido bonds into a steroid nucleus. • DAAO binds to Sudlow's site I in HSA through hydrogen bonds and van der Waals power. • The interaction was a spontaneous and exothermic process with modest degree of reversibility. • The secondary structure of HSA and the microenvironment of TRP214 altered. • Amido bond in steroid nucleus (–NH–CO–) plays important role in stabling the structure of

  18. Mode of bindings of zinc oxide nanoparticles to myoglobin and horseradish peroxidase: A spectroscopic investigations

    Science.gov (United States)

    Mandal, Gopa; Bhattacharya, Sudeshna; Ganguly, Tapan

    2011-07-01

    The interactions between two heme proteins myoglobin (HMb) and horseradish peroxidase (HRP) with zinc oxide (ZnO) nanoparticles are investigated by using UV-vis absorption, steady state fluorescence, synchronous fluorescence, time-resolved fluorescence, FT-IR, atomic force microscopy (AFM) and circular dichroism (CD) techniques under physiological condition of pH˜7.4. The presence of mainly static mode in fluorescence quenching mechanism of HMb and HRP by ZnO nanoparticle indicates the possibility of formation of ground state complex. The processes of bindings of ZnO nanoparticles with the two proteins are spontaneous molecular interaction procedures. In both cases hydrogen bonding plays a major role. The circular dichroism (CD) spectra reveal that a helicity of the proteins is reduced by increasing ZnO nanoparticle concentration although the α-helical structures of HMb and HRP retain their identity. On binding to the ZnO nanoparticles the secondary structure of HRP molecules (or HMb molecules) remains unchanged while there is a substantial change in the environment of the tyrosin active site in case of HRP molecules and tryptophan active site in case of HMb molecules. Tapping mode atomic force microscopy (AFM) was applied for the investigation the structure of HRP adsorbed in the environment of nanoparticles on the silicon and on the bare silicon. HRP molecules adsorb and aggregate on the mica with ZnO nanoparticle. The aggregation indicates an attractive interaction among the adsorbed molecules. The molecules are randomly distributed on the bare silicon wafer. The adsorption of HRP in the environment of ZnO nanoparticle changes drastically the domains due to a strong interaction between HRP and ZnO nanoparticles. Similar situation is observed in case of HMb molecules. These findings demonstrate the efficacy of biomedical applications of ZnO nanoparticles as well as in elucidating their mechanisms of action as drugs in both human and plant systems.

  19. IR spectroscopic investigation of charge transfer at interfaces of organic semiconductors (Conference Presentation)

    Science.gov (United States)

    Beck, Sebastian; Hillebrandt, Sabina; Pucci, Annemarie

    2016-09-01

    In organic electronics, the interactions at interfaces between different organic and inorganic layers play a decisive role for device functionality and performance. Therefore, more detailed, quantitative studies of charge transfer (CT) at such interfaces are needed to improve the understanding of the underlying mechanisms. In this study we show that in-situ infrared spectroscopy can be used to investigate CT effects at organic/organic as well as inorganic/organic interfaces quantitatively. For different combinations of commonly used organic semiconductors such as 4,4´-bis(N-carbazolyl)-1,1´-biphenyl (CBP) or fluorinated zinc phthalocyanine (F4ZnPc) and inorganic contact materials such as molybdenum oxide (MoO3) or indium tin oxide (ITO) the CT at the interface was investigated using in-situ IR spectroscopy. The measurements were carried out under UHV conditions during film growth what enables a careful study of the influence of different parameters such as substrate temperature and layer thickness in a controlled way even on a nanometer scale. When the organic molecules are deposited onto the underlying layer charged and non-charged species form which can be identified and quantitatively analyzed in the IR spectra. It was also found that the deposition sequence can strongly influence the interface properties what might have strong implications on the layer stack design. For example, when MoO3 is deposited onto CBP, the CBP layer is strongly doped, due to diffusion of the deposited transition metal oxide clusters into the organic layer. Financial support by BMBF (project INTERPHASE) is gratefully acknowledged.

  20. Acoustic and NMR investigations of melting and crystallization of indium-gallium alloys in pores of synthetic opal matrices

    Science.gov (United States)

    Pirozerskii, A. L.; Charnaya, E. V.; Lee, M. K.; Chang, L. J.; Nedbai, A. I.; Kumzerov, Yu. A.; Fokin, A. V.; Samoilovich, M. I.; Lebedeva, E. L.; Bugaev, A. S.

    2016-05-01

    The paper presents the results of studying the crystallization and melting processes of Ga-In eutectic alloys, which are embedded in opal matrices, using acoustic and NMR methods. The indium concentrations in the alloys were 4, 6, 9, and 15 at %. Measurements were performed upon cooling from room temperature to complete crystallization of the alloys and subsequent heating. It is revealed how the size effects and alloy composition influence the formation of phases with α- and β-Ga structures and on changes in the melting-temperature ranges. A difference was observed between the results obtained using acoustic and NMR methods, which was attributed to different temperature measurement conditions.

  1. Relation Between Acid and Catalytic Properties of Chlorinated Gamma-Alumina. a 31p Mas Nmr and Ftir Investigation

    Directory of Open Access Journals (Sweden)

    Guillaume D.

    1999-07-01

    Full Text Available In this paper, we have studied the effect of chlorine on the surface properties of gamma-alumina, especially on their acid properties. The use of FTIR spectroscopy and 31P MAS NMR of adsorbed trimethylphosphine allows to propose a chlorination mechanism. To correlate the surface properties of these chlorinated gamma-alumina with their catalytic properties, we have used a model reaction, the cracking of n-heptane under reforming conditions. The analysis of the correlation between acid properties determined by 31P MAS NMR and the catalytic results (in terms of activities and selectivities allows to identify which sites are involved in the cracking reaction.

  2. Infrared spectroscopic investigations of environmental deNOx and hydrotreating catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Topsoee, Nan-Yu

    1998-02-01

    The present work describes the application of infrared spectroscopy to the investigation of two very important of environmental catalyst systems, i.e. vanadia/titania catalysts for the selective catalytic reduction (SCR) of NOx by ammonia and molybdena/alumina catalyst systems for sulfur removal and other hydrotreating reactions. It is seen that the infrared studies have provided new insight into the surface structures present in the catalyst systems. Furthermore, and more importantly the results have made it possible to establish direct relationships between the fundamental molecular properties and the industrial performance. For these studies the application of a variety of different steady-state and transient FTIR techniques/approaches is shown to be very important. Infrared spectroscopy is one of the few techniques which can provide in situ surface information about real catalysts. Vanadia/titania deNOx catalysts are discussed. The reactivity of various surface species is discussed further based on transient temperature programmed surface reaction (TPSR) studies employing a combined in situ FTIR on-line mass spectrometric approach. The studies are performed by exposing different catalysts with chemisorbed NH{sub 3} to various reaction gases. Part II deals with the studies of hydrotreating catalysts. The catalysts (typically Co-Mo/Al{sub 2}O{sub 3} and Ni-Mo/Al{sub 2}O{sub 3}) are normally prepared in the oxidic (calcined) state but requires sulfiding in order to become activated. The infrared investigation of calcined alumina supported catalysts is discussed. The alumina support has a number of very specific hydroxyl groups. Mo is seen to interact with these groups resulting in the formation of monolayer-type structures bonded to the support via Mo-O-Al bridges. The monolayer structures are seen to be restricted to the original hydroxyl part of the alumina surface. It is seen that there is a preference for Mo to interact with the most basic Al-OH groups and

  3. Effect of chitosan/riboflavin modification on resin/dentin interface: spectroscopic and microscopic investigations.

    Science.gov (United States)

    Daood, Umer; Iqbal, Kulsum; Nitisusanta, Lorraine I; Fawzy, Amr S

    2013-07-01

    The aim of this study is to investigate the morphological and chemical changes of demineralized dentin collagen-matrix and resin/dentin interface associated with chitosan/riboflavin modification. Dentin disc specimens were prepared from sound molars, acid-etched with 35% phosphoric acid and modified with either 0.1% riboflavin or chitosan/riboflavin (Ch/RF ratios 1:4 or 1:1) and photo-activated by UVA. Morphological and chemical changes associated with surface modification were characterized by SEM and micro-Raman spectroscopy. Dentin surfaces of sound molars were exposed, acid-etched, and modified as described before. Etch-and-rinse dentin adhesive was applied, light-cured, and layered with resin-restorative composite. The resin infiltration and resin/dentin interface were characterized by micro-Raman spectroscopy and SEM. An open-intact collagen network-structure, formation of uniform hybrid-layer and higher resin infiltration were found with 0.1%RF and Ch/RF 1:4 modifications. Raman analysis revealed chemical changes and shifts in Amide bands with the modification of dentin collagen-matrix. The use of riboflavin and chitosan/riboflavin formulations to modify dentin-collagen matrix, with the defined ratios, stabilizes the collagen fibrillar network and enhances resin infiltration and hybrid layer formation. These preliminary results are encouraging for subsequent consideration of chitosan/riboflavin modification in adhesive dentistry.

  4. Investigation on the inclusion and toxicity of acriflavine with cyclodextrins: A spectroscopic approach

    Science.gov (United States)

    Manivannan, C.; Meenakshi Sundaram, K.; Sundararaman, M.; Renganathan, R.

    2014-03-01

    Acriflavine hydrochloride (AFN) is a prospective drug worn in the eradication of HIV1 infection. The toxicity and adverse side effects renders the potent drug to limits its usage. However, to overcome the dilemma we have aimed to select carriers with great complexation efficiencies in different cyclodextrins (CDs) of varying cavity size. The interaction of AFN with α, β and γ-CDs were investigated using absorption and steady state as well as lifetime measurements. From the obtained data it was found that AFN fits in the cavity of α and β-CDs but unable to form inclusion complex with γ-CD. The effect of quencher molecules during the inclusion phenomena of AFN with CDs was explored via steady state measurements. The nature of binding forces responsible for the inclusion of AFN with CDs was discussed by using thermodynamic parameters. Using Benesi-Hildebrand equation the stoichiometry of AFN with CDs was predominantly found to be 1:1. To get deeper in situ, the in vitro toxicity of AFN and its complexation product were probed by Artemia salina sp. The toxicity of AFN was reduced when complexed with α and β-CDs.

  5. Micro-spectroscopic investigation of selenium-bearing minerals from the Western US Phosphate Resource Area

    Directory of Open Access Journals (Sweden)

    Gunter Mickey E

    2005-01-01

    Full Text Available Mining activities in the US Western Phosphate Resource Area (WPRA have released Se into the environment. Selenium has several different oxidation states and species, each having varying degrees of solubility, reactivity, and bioavailability. In this study we are investigating the speciation of Se in mine-waste rocks. Selenium speciation was determined using bulk and micro-x-ray absorption spectroscopy (XAS, as well as micro-x-ray fluorescence mapping. Rocks used for bulk-XAS were ground into fine powders. Shale used for micro-XAS was broken along depositional planes to expose unweathered surfaces. The near edge region of the XAS spectra (XANES for the bulk rock samples revealed multiple oxidation states, with peaks indicative of Se(-II, Se(IV, and Se(+VI species. Micro-XANES analysis of the shale indicated that three unique Se-bearing species were present. Using the XANES data together with ab initio fitting of the extended x-ray absorption fine structure region of the micro-XAS data (micro-EXAFS the three Se-bearing species were identified as dzharkenite, a di-selenide carbon compound, and Se-substituted pyrite. Results from this research will allow for a better understanding of the biogeochemical cycling of Se in the WPRA.

  6. Mid-infrared spectroscopic investigation of the perfect vitrification of poly(ethylene glycol) aqueous solutions.

    Science.gov (United States)

    Gemmei-Ide, Makoto; Miyashita, Takashi; Kagaya, Shigehiro; Kitano, Hiromi

    2015-10-01

    Crystallization/recrystallization behaviors of poly(ethylene glycol) (PEG) aqueous solutions with water contents (WC's) of ∼36-51 wt % were investigated by temperature-variable mid-infrared spectroscopy. At a WC of 43.2 wt %, crystallization and recrystallization of water and PEG were not observed. At this specific WC value (WCPV), perfect vitrification occurred. Below and above the WCPV value, crystallization/recrystallization behaviors changed drastically. The crystallization temperature below WCPV (237 K) was ∼10 K greater than that above WCPV (226 K). Recrystallization above and below WCPV occurred in one (213 K) and two (198 and 210 K) steps, respectively. These findings resulted from the difference in the (re)crystallization behaviors of water molecules associated with PEG chains with helical and random-coil conformations. These two types of water molecules might have limiting concentrations for their (re)crystallization, indicating that perfect vitrification might have occurred when the concentrations of the two types of water molecules were less than the limiting concentrations of their (re)crystallization.

  7. Spectroscopic investigation of plasma electrolytic borocarburizing on q235 low-carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Run [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Zhenjiang Watercraft College, Zhenjiang 212000, Jiangsu (China); Wang, Bin; Wu, Jie [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Jin, Xiaoyue; Du, Jiancheng; Hua, Ming [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2014-12-01

    Highlights: • The plasma discharge behaviors for PEB/C on steels were evaluated by OES. • Electron temperature, concentration, atomic ionization degree were calculated. • The decomposition mechanism of electrolyte and was analyzed. - Abstract: A plasma electrolytic borocarburizing process (PEB/C) in borax electrolyte with glycerin additive was employed to fabricate a hardening layer on Q235 low-carbon steel. Optical emission spectroscopy (OES) was utilized to investigate the spectroscopy characteristics of plasma discharge around the steel during PEB/C process. Some plasma parameters were calculated in terms of OES. The electron temperature and electron concentration in plasma discharge zone is about 3000–12,000 K and 2 × 10{sup 22} m{sup −3}–1.4 × 10{sup 23} m{sup −3}. The atomic ionization degrees of iron, carbon and boron are 10{sup −16}–10{sup −3}, and 10{sup −23}–10{sup −6}, 10{sup −19}–10{sup −4}, respectively, which depend on discharge time. The surface morphology and cross-sectional microstructure of PEB/C hardening layer were observed, and the electrolyte decomposition and plasma discharge behaviors were discussed.

  8. Vibrational spectroscopic and structural investigations of 2-amino-6-methoxy-3-nitropyridine: a DFT approach

    Energy Technology Data Exchange (ETDEWEB)

    Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin [Department of Physics, Nadar Mahajana Sangam S.Vellaichamy Nadar College, Tamil Nadu (India); Rekha, T.N.; Rajkumar, Beulah J.M.; Jawahar, A., E-mail: miltonfranklin@yahoo.com [Department of Physics, Lady Doak College, Tamilnadu (India)

    2015-12-15

    The conformational analysis of 2-amino-6-methoxy-3-nitropyridine molecule (AMNP) has been carried out using density functional theory calculations. The vibrational spectra of the molecule is simulated theoretically and compared experimentally, and the vibrational frequencies are assigned on the basis of potential energy distribution calculations. Electronic properties of the molecule derived from the theoretical ultraviolet–visible spectrum are validated experimentally. The higher non-linear optical activity of the molecule is indicated in the first-order hyperpolarizability calculations. The natural bond orbital and Mulliken atomic charge distribution analysis confirm intramolecular charge transfers and intramolecular interactions. The Frontier molecular orbitals are plotted, and the related molecular properties are calculated and discussed. The molecular electrostatic potential contour map is simulated. As the presence of intramolecular interactions and the associated charge transfers between the pyridine ring of AMNP molecule and the lone pair of oxygen is a common molecular feature of a pharmaceutical compound, this investigation paves the way for its possible biomedical applications. Further, the considerably higher non-linear optical (NLO) activity of the molecule identified suggests its potential applications in the design of new optical materials. (author)

  9. Investigation of Interaction Between Ozagrel and Human Serum Albumin by Spectroscopic and Electrochemical Methods

    Science.gov (United States)

    Li, S.; Wang, Li; Hao, J.; Wang, L.; Tong, Y.-J.; Fu, Z.-Q.; Zhang, A.-P.

    2017-01-01

    The interaction between ozagrel and human serum albumin (HSA) was investigated by fl uorescence spectroscopy, UV-Vis absorption spectroscopy, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and Fourier transform infrared spectroscopy (FTIR) under simulative physiological conditions. The results of CV, DPV and fl uorescence titration revealed that ozagrel bound to HSA. The enthalpy change (ΔH) and the entropy change (ΔS) were derived to be positive values, indicating that the hydrophobic force played the main role in the binding of ozagrel with HSA. The binding distance between ozagrel and HSA was 1.75 nm. Upon binding with ozagrel, the conformation and the secondary structure of HSA molecules were changed. The percentage of α-helix and β-sheet structures decreased by 7.25% and 4.58%, respectively, while the percentage of a β-turn structure increased by 2.67%. The effect of common ions on the binding of ozagrel with HSA was also examined. This study will give an insight into the evaluation of the drug's stabi-lity during transport and its releasing effi ciency at the target site under simulative physiological conditions.

  10. Spectroscopic investigations on SrAl{sub 2}O{sub 4} polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Boutinaud, P., E-mail: philippe.boutinaud@ensccf.fr [Clermont Université, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Boyer, D. [Clermont Université, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Perthue, A. [Clermont Université, UBP, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Mahiou, R. [CNRS, UMR 6296, ICCF, F-63177 Aubière (France); Cavalli, E. [Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Università di Parma, Parma (Italy); Brik, M.G. [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia)

    2015-03-15

    Nominally undoped and Eu{sup 3+} or Eu{sup 3+}–Dy{sup 3+} doped SrAl{sub 2}O{sub 4} powders are prepared using source chemicals of standard grade (99–99.99%) by solid state and sol–gel procedures, in order to vary the proportions of monoclinic (P2{sub 1}) and hexagonal (P6{sub 3} and P6{sub 3}22) polymorphs in the compounds. Electron spin resonance reveals systematic contamination of the compounds by transition metal ions. The emission properties of the materials are investigated at 77 K upon UV and blue excitations. The optical features are ascribed, for the essential, to Mn{sup 4+} ions. The spectroscopy of this ion in conjunction with X-ray diffraction data and theoretical considerations is used to individuate P6{sub 3}22, P6{sub 3} and P2{sub 1} phases in the doped and undoped SrAl{sub 2}O{sub 4} powders. - Highlights: • Different polymorphs of SrAl{sub 2}O{sub 4}, undoped or doped with Eu{sup 3+}, were synthesized. • Contamination by transition metals is proved by ESR and photoluminescence. • The Mn{sup 4+} spectroscopy allows the identification of the SrAl{sub 2}O{sub 4} polymorph.

  11. Internal structure changes in bleached black human hair resulting from chemical treatments: A Raman spectroscopic investigation

    Science.gov (United States)

    Kuzuhara, Akio

    2014-11-01

    In order to investigate in detail the influence of chemical treatments (reduction, hydrolyzed eggwhite protein (HEWP) treatment, and oxidation) on damaged hair keratin fibers, the structure of cross-sections at various depths of excessively bleached (damaged) black human hair resulting from a permanent waving process was directly analyzed using Raman spectroscopy. It was found that L-cysteine (CYS) largely reacted with the gauche-gauche-gauche (GGG) conformation of disulfide (-SS-) groups (while CYS did not react with the trans-gauche-trans (TGT) conformation). In particular, not only the GGG content, but also the cysteic acid content existing throughout the cortex region of the excessively bleached human hair remarkably decreased by performing the oxidation process after reduction. On the other hand, the GGG content of the excessively bleached black human hair increased, while the TGT content decreased by performing the oxidation process after reduction and then HEWP treatment processes. From these experiments, the authors concluded that some of the keratin associated protein (KAP), which has a rich -SS- content and cysteic acid content was eluted from the cortex region along with the disconnection of -SS- groups, thereby leading to the remarkable reduction in the reconnection of -SS- groups of the excessively bleached black human hair after the permanent waving process (the reduction and oxidation processes). Also, the authors concluded that the HEWP treatment process in the permanent waving process caused the reconstruction of the KAP, thereby contributing to the acceleration of the reconnection of -SS- groups during the oxidation process.

  12. Spectroscopic investigations of arrays containing vertically and horizontally aligned silicon nanowires

    Science.gov (United States)

    Volpati, Diogo; Mårtensson, Niklas; Anttu, Nicklas; Viklund, Per; Sundvall, Christian; Åberg, Ingvar; Bäckström, Joakim; Olin, Håkan; Björk, Mikael T.; Castillo-Leon, Jaime

    2016-12-01

    The properties of nanowire arrays have been investigated mainly in comparison with isolated nanowires or thin films, owing to the difficulty in controlling the nanowire alignment. In this study, we report on arrays containing vertically or horizontally aligned silicon nanowires, whose alignment and structure were determined using x-ray diffraction and scanning electron microscopy. The Raman spectra of the nanowire arrays differ from those of isolated nanowires because of distinct heat dissipation rates of the absorbed energy from the laser, in agreement with recent theoretical calculations. The tailored alignment of the nanowires on solid substrates up to 1 inch of diameter also enabled the observation of resonance modes associated with light trapped into the nanowires. This was proven by comparing the light absorbed and scattered by the arrays, and may be exploited to enhance light harvesting in tandem solar cells. Significantly, the control of the assembly of nanowire arrays may have a direct impact on bottom-up technologies of high anisotropy nanomaterials.

  13. The Human Telomere Sequence, (TTAGGG4, in the Absence and Presence of Cosolutes: A Spectroscopic Investigation

    Directory of Open Access Journals (Sweden)

    Vishal R. Sharma

    2014-01-01

    Full Text Available Historically, biophysical studies of nucleic acids have been carried out under near ideal conditions, i.e., low buffer concentration (e.g., 10 mM phosphate, pH 7, low ionic strength (e.g., 100 mM and, for optical studies, low concentrations of DNA (e.g., 1 × 10−6 M. Although valuable structural and thermodynamic data have come out of these studies, the conditions, for the most, part, are inadequate to simulate realistic cellular conditions. The increasing interest in studying biomolecules under more cellular-like conditions prompted us to investigate the effect of osmotic stress on the structural and thermodynamic properties of DNA oligomers containing the human telomere sequence (TTAGGG. Here, we report the characterization of (TTAGGG4 in potassium phosphate buffer with increasing percent PEG (polyethylene glycol or acetonitrile. In general, the presence of these cosolutes induces a conformational change from a unimolecular hybrid structure to a multimolecular parallel stranded structure. Hence, the structural change is accompanied with a change in the molecularity of quadruplex formation.

  14. Nuclear structure investigations of 84Sr and 86Sr using γ-ray spectroscopic methods

    Science.gov (United States)

    Duckwitz, H.; Petkov, P.; Thomas, T.; Ahn, T.; Blazhev, A.; Cooper, N.; Fransen, C.; Hinton, M.; Ilie, G.; Jolie, J.; Werner, V.

    2017-09-01

    To investigate the low-spin structure of 84Sr and 86Sr, two fusion-evaporation experiments using the (p,2n) reaction have been performed. The data have been evaluated in terms of γ-ray spectroscopy, i.e. the level scheme was built up, branching intensities were determined, nuclear state spin and parity assignments were made after γγ angular correlation analyses. The previously known level scheme information was extended. In addition, lifetimes were determined by means of the Doppler Shift Attenuation Method (DSAM). In 86Sr, a new method for lifetime determinations, the Spectral Difference Method (SDM), was applied for the first time. In cases where all necessary input variables were known, reduced transition strengths were calculated with Monte Carlo simulated probability density functions. It is stressed that linear error propagation for the calculated errors of reduced transition strengths is not universally applicable. As both nuclei lie in the vicinity of the N=50 neutron shell closure and on a possible proton subshell closure of the 2p3/2 orbital at Z=38, Nuclear Shell Model calculations for 84Sr, 86Sr, and 88Sr have been performed in the truncated (2p3/2, 1f5/2, 2p1/2, 1g9/2) model space for protons and neutrons with the empirical JUN45 residual interaction. The comparison between experimental results and theoretical predictions show a large degree of consistency.

  15. Spectroscopic investigation of the electronic structure of the chlorine molecule in the VUV

    Science.gov (United States)

    Moeller, Thomas; Jordan, Bernhard; Gürtler, Peter; Zimmerer, Georg; Haaks, Dieter; Le Calve, Jacques; Castex, Marie-Claude

    1983-04-01

    Vacuum ultraviolet absorption spectroscopy and fluorescence analysis under selective optical excitation have been combined to deduce the electronic structure of Cl 2. Between 73000 and 81000 cm -1 five bound electronic states could be analysed. Some of them are affected by pronounced Rydberg—valence mixing. Especially the 1 1∑ u+ state clearly yields a double-well structure which results from an avoided crossing between an ionic valence and a Rydberg state. The double-well structure is responsible for an irregular vibrational sequence between 73000 and 74500 cm -1 which either prevented an analysis in earlier investigations or lead to wrong assignments. The FC factors of the 1 1∑ u+ fluorescence with its bound—bound and bound—free contributions between ≈ 73000 and 50000 cm -1 are also severely affected by the double-well structure. The results are compared with the first ab initio calculations of the electronic structure of Cl 2. In general, excellent agreement is found.

  16. Investigation of the interaction of deltamethrin (DM) with human serum albumin by multi-spectroscopic method

    Science.gov (United States)

    Wang, Jiaman; Ma, Liang; Zhang, Yuhao; Jiang, Tao

    2017-02-01

    The interaction of Deltamethrin (DM) with human serum albumin (HSA) under the condition of simulating human blood pH environment (pH = 7.4) was investigated by fluorescence, UV-Vis absorbance and circular dichroism (CD) spectroscopy. It was shown that DM was a static quencher of HSA. The binding constants (Ka) are 3.598 × 104 L mol-1 (25 °C); the thermodynamic parameters (ΔH = -3.269 × 104 kJ mol-1, ΔS = -22.81 kJ mol-1 k-1, ΔG = -25889.8 kJ mol-1) obtained with the thermodynamic equation. The hydrogen bond and Vander Waals were the main driving force. The effect of DM on the conformation of HSA was observed by three-dimensional (3D) fluorescence and circular dichroism spectra, indicating that the interaction between DM and HSA was achieved through the binding of DM with the tryptophan and tyrosine residues of HSA. The study on the interaction of DM and Bovine Serum Albumin (BSA) was researched and compared. Difference exists in the interactions of with each of the serum albumins. We will verify and supplement that DM residue in animals and human metabolism, toxicology and other mechanisms are different.

  17. Non intrusive spectroscopic investigations of soot and unburnt hydrocarbons in combustion gases

    Science.gov (United States)

    Hilton, Moira; Arrigone, Giovanni M.; Miller, Michael N.

    1999-09-01

    Fourier Transform Infrared (FTIR) spectroscopy was used to investigate the IR spectral absorption of soot particles from a Palas smoke generator. A TSI Condensation Particle Counter was used to quantify the number of soot particles produced and this was related to the intensity of the IR absorption. The broad band IR absorption increases with soot particle count but quantitative measurements of total soot mass were not obtained because accurate size distributions of the particles were not available. A sample of gas turbine engine exhaust gas was analyzed by Gas Chromatography-Mass Spectroscopy to determine the primary constituent unburnt hydrocarbon (UHC) species. Their relative proportions were measured with a Flame Ionization Detector (FID). These species are predominantly unsaturated C2 to C6 hydrocarbons. The infrared absorption spectrum of the exhaust gas sample was compared with that of combustion products from a laboratory kerosene burner using a multipass White cell. These were also compared with reference spectra and IR spectra of UHCs obtained non-intrusively from gas turbine engine tests. There are IR spectral band shape differences indicating that the relative proportions of the constituent UHCs in gas turbine exhaust are different from those in a kerosene burner plume.

  18. Raman spectroscopic investigation of spinal cord injury in a rat model

    Science.gov (United States)

    Saxena, Tarun; Deng, Bin; Stelzner, Dennis; Hasenwinkel, Julie; Chaiken, Joseph

    2011-02-01

    Raman spectroscopy was used to study temporal molecular changes associated with spinal cord injury (SCI) in a rat model. Raman spectra of saline-perfused, injured, and healthy rat spinal cords were obtained and compared. Two injury models, a lateral hemisection and a moderate contusion were investigated. The net fluorescence and the Raman spectra showed clear differences between the injured and healthy spinal cords. Based on extensive histological and biochemical characterization of SCI available in the literature, these differences were hypothesized to be due to cell death, demyelination, and changes in the extracellular matrix composition, such as increased expression of proteoglycans and hyaluronic acid, at the site of injury where the glial scar forms. Further, analysis of difference spectra indicated the presence of carbonyl containing compounds, hypothesized to be products of lipid peroxidation and acid catalyzed hydrolysis of glycosaminoglycan moieties. These results compared well with in vitro experiments conducted on chondroitin sulfate sugars. Since the glial scar is thought to be a potent biochemical barrier to nerve regeneration, this observation suggests the possibility of using near infrared Raman spectroscopy to study injury progression and explore potential treatments ex vivo, and ultimately monitor potential remedial treatments within the spinal cord in vivo.

  19. Electrical characterization, phase transition and vibrational spectroscopic investigations of a new organic-inorganic material (C7H10NO)SnCl3

    Science.gov (United States)

    Karoui, Sahel; Chouaib, Hassen; Kamoun, Slaheddine

    2017-10-01

    The X-ray powder analysis, thermogravimetric analysis, differential scanning calorimetry analysis, solid CP-MAS 13C NMR characterization, vibrational spectroscopy and complex impedance spectroscopic data have been carried out on (C7H10NO)SnCl3 compound. The results show that this compound exhibits a phase transition at 314 K which was characterized by 1H NMR between 298 and 336 K, differential scanning calorimetry (DSC), X-rays powder diffraction, Raman spectroscopy and dielectric measurements. The temperature dependence of the 1H NMR spectrum for (C7H10NO)SnCl3 could be explained by invoking reorientation of ammonium group of the 2-methoxyanilinium cation. The most important changes are observed for two lines at 3087 cm-1 and 3175 cm-1 (at room temperature) issued from asymmetric and symmetric stretching vibrations of νs(NH3) and νas(NH3) band, respectively. AC and DC conductivities, complex dielectric permittivity ε*(ω) and complex electrical modulus M*(ω) were respectively studied as temperature and frequency functions. Moreover, the temperature dependence of the DC conductivity and relaxation frequency followed the Arrhenius relation. The frequency dependence of the real part of the AC conductivity in both phases follows the Jonscher's universal dynamic law: σTot.(ω,T) = σDC(T) + B(T) ωS(T). The close values of activation energies, obtained from the thermal behavior of the conductivity and the relaxation time confirm that the transport is through ion-hopping mechanism.

  20. Raman spectroscopic and mass spectrometric investigations of the hydrogen isotopes and isotopically labelled methane

    Energy Technology Data Exchange (ETDEWEB)

    Jewett, J.R., Fluor Daniel Hanford

    1997-02-24

    Suitable analytical methods must be tested and developed for monitoring the individual process steps within the fuel cycle of a fusion reactor and for tritium accountability. The utility of laser-Raman spectroscopy accompanied by mass spectrometry with an Omegatron was investigated using the analysis of all hydrogen isotopes and isotopically labeled methanes as an example. The Omegatron is useful for analyzing all hydrogen isotopes mixed with the stable helium isotopes. The application of this mass spectrometer were demonstrated by analyzing mixtures of deuterated methanes. In addition, it was employed to study the radiochemical Witzbach exchange reaction between tritium and methanes. A laser-Raman spectrometer was designed for analysis of tritium-containing gases and was built from individual components. A tritium-compatible, metal-sealed Raman cuvette having windows with good optical properties and additional means for measuring the stray light was first used successfully in this work. The Raman spectra of the hydrogen isotopes were acquired in the pure rotation mode and in the rotation-vibration mode and were used for on. The deuterated methanes were measured by Raman spectroscopy, the wavenumbers determined were assigned to the corresponding vibrations, and the wavenumbers for the rotational fine-structure were summarized in tables. The fundamental Vibrations of the deuterated methanes produced Witzbach reactions were detected and assigned. The fundamental vibrations of the molecules were obtained with Raman spectroscopy for the first time in this work. The @-Raman spectrometer assembled is well suited for the analysis of tritium- containing gases and is practical in combination with mass spectrometry using an Omegatron, for studying gases used in fusion.

  1. Spectroscopic investigation on the interaction of some surfactant-cobalt(III) complexes with serum albumins

    Energy Technology Data Exchange (ETDEWEB)

    Vignesh, Gopalaswamy; Nehru, Selvan; Manojkumar, Yesaiyan; Arunachalam, Sankaralingam, E-mail: arunasurf@yahoo.com

    2014-01-15

    The interaction of HSA/BSA with single and double chain surfactant-cobalt(III) complexes, cis-[Co(phen){sub 2}(UA)Cl](ClO{sub 4}){sub 2}·2H{sub 2}O (1), cis-[Co(phen){sub 2}(UA){sub 2}](ClO{sub 4}){sub 3}·2H{sub 2}O (2), cis-[Co(en){sub 2}(UA)Cl](ClO{sub 4}){sub 2}·2H{sub 2}O (3), cis-[Co(en){sub 2}(UA){sub 2}](ClO{sub 4}){sub 3}·2H{sub 2}O (4), were investigated by steady state fluorescence, UV–vis absorption, synchronous, three dimensional fluorescence and circular dichroism spectroscopy. The results reveal that the quenching of HSA/BSA by all the four complexes takes place through static mechanism. The binding constant, binding sites and thermodymamic parameter were calculated. The results illustrate that the double chain surfactant-cobalt(III) complexes bind more strongly than the corresponding single chain complexes. The distance between donor (HSA/BSA) and acceptor (surfactant-cobalt(III) complexes) was obtained according to FRET. The results of synchronous, three dimensional and circular dichroism spectroscopy studies show that all the complexes caused considerable amount of conformational and some amount of environment changes in HSA/BSA. -- Highlights: • Binding of single and double chain surfactant-cobalt(III) complexes with serum albumins. • Hydrophobic attraction plays a major role in the binding process. • Binding induces considerable amount of conformational changes in the protein.

  2. Spectroscopic investigation of the charge dynamics of heavy ions penetrating solid and gaseous targets

    Energy Technology Data Exchange (ETDEWEB)

    Korostiy, S.

    2007-01-15

    This thesis presents the study of the slowing down process of fast heavy ions inside matter. In the framework of this research, the influence of the target density on the stopping process is investigated. Experiments on the interaction of {sup 48}Ca{sup 6+}-{sup 48}Ca{sup 10+} and {sup 26}Mg{sup 5+} ion beams with initial energies of 11.4 MeV/u and 5.9 MeV/u with solid and gaseous targets have been carried out. A novel diagnostic method, X-ray spectroscopy of K-shell projectile radiation, is used to determine the ion charge state in relation to its velocity during the penetration of fast heavy ions inside the stopping material. A spatially resolved analysis of the projectile and target radiation in solids is achieved for the first time. The application of low-density silica aerogels as stopping media provided a stretching of the ion stopping length by 20 - 100 times in comparison with solid quartz. The Doppler Effect observed on the projectile K-shell spectra is used to calculate the ion velocity in dependence on the ion penetration depth in the target material. A comparative analysis of K{sub {alpha}} spectra of fast heavy ions is performed in solid (silica aerogels) and gaseous targets (Ar and Ne gases) at the same ion energy. It is shown that the dominant role of collisions in dense matter leads to an increase of the effective ionization cross section at high ion velocity and suppression of the electron capture to the projectile ion excited states at low ion velocity. As a result, an increase of the ion charge state in dense matter is observed. The experimentally detected effects are interpreted with numerical calculations of the projectile population kinetics, which are in good agreement with measurements. (orig.)

  3. A spectroscopic investigation of the interaction between c-MYC DNA and tetrapyridinoporphyrazinatozinc(II).

    Science.gov (United States)

    Hassani, Leila; Fazeli, Zahra; Safaei, Elham; Rastegar, Hossein; Akbari, Minoo

    2014-06-01

    The c-MYC gene plays an important role in the regulation of cell proliferation and growth and it is overexpressed in a wide variety of human cancers. Around 90% of c-MYC transcription is controlled by the nuclease-hypersensitive element III1 (NHE III1), whose 27-nt purine-rich strand has the ability to form a G-quadruplex structure under physiological conditions. Therefore, c-MYC DNA is an attractive target for drug design, especially for cancer chemotherapy. Here, the interaction of water-soluble tetrapyridinoporphyrazinatozinc(II) with 27-nt G-rich strand (G/c-MYC), its equimolar mixture with the complementary sequence (GC/c-MYC) and related C-rich oligonucleotide (C/c-MYC) is investigated. Circular dichroism (CD) measurements of the G-rich 27-mer oligonucleotide in 150 mM KCl, pH 7 demonstrate a spectral signature consistent with parallel G-quadruplex DNA. Furthermore, the CD spectrum of the GC rich oligonucleotide shows characteristics of both duplex and quadruplex structures. Absorption spectroscopy implies that the complex binding of G/c-MYC and GC/c-MYC is a two-step process; in the first step, a very small red shift and hypochromicity and in the second step, a large red shift and hyperchromicity are observed in the Q band. Emission spectra of zinc porphyrazine are quenched upon addition of three types of DNA. According to the results of spectroscopy, it can be concluded the dominant binding mode is probably, outside binding and end stacking.

  4. Spectroscopic and bond-topological investigation of interstitial volatiles in beryl from Slovakia

    Science.gov (United States)

    Fridrichová, Jana; Bačík, Peter; Bizovská, Valéria; Libowitzky, Eugen; Škoda, Radek; Uher, Pavel; Ozdín, Daniel; Števko, Martin

    2016-06-01

    Nine beryl samples from Western Carpathians, Slovakia, were investigated by infrared and Raman spectroscopy and differential thermal analysis. Two types of water H2O I and H2O II were detected. Infrared spectroscopy proved the presence of water type I and II in the presence of alkali cations with several bands: (1) symmetric stretching vibration—ν1; (2) antisymmetric stretching mode—ν3; (3) bending vibration—ν2. The presence of singly and doubly coordinated type II water (IIs and IId) was confirmed by single-crystal IR spectroscopy. From Raman spectra a band at 3606 cm-1 was assigned to ν1 of water type I and the range of 3597-3600 cm-1 to water type II. The presence of doubly coordinating water indicates a relatively highly hydrated environment with the presence of alkali ions including Na as the dominant cation coordinated by H2O II. CO2 bands were detected only by single-crystal IR spectroscopy. Thermal analysis proved total water loss in the range of 1.4-2.0 wt% and three main dehydration events. Based on the study of bond-topological arrangements two molecules of H2O IId are each bound with two H···O1 bonds and one Na-OW bond with an angular distortion, and by releasing one H2O molecule more stable H2O IIs is produced. The H2O I molecule is bound only by two equivalent hydrogen bonds. The H2O IIs molecule with a Na-OW bond strength of 0.28 vu and two H···O1 bonds of 0.14 vu without any forced angular distortion is the most stable of all.

  5. Effect of hybrid oxidation on the titanium oxide layer's properties investigated by spectroscopic methods

    Science.gov (United States)

    Jasinski, J. J.; Kurpaska, L.; Lubas, M.; Lesniak, M.; Jasinski, J.; Sitarz, M.

    2016-12-01

    In this work the study of hybrid Ti Grade 2 during oxidation using FADT - fluidized bed atmospheric diffusive treatment and PVD - magnetron sputtering have been investigated. Additionally, the influence of the oxidation method on the change in the mechanism of oxygen transport to the substrate have been discussed (phenomenon responsible for the improvement of bioactivity). Presented method consists in forming the titanium surface layer saturated with oxygen due to the diffusion and deposition of a thin homogeneous oxide coating on the Ti surface. Discussed processes diminish the surface roughness and increase bio-compatibility of the surface, which results in easier hydroxyapatite cluster deposition. The diffusion process was conducted on Al2O3 fluidized bed, with air as the fluidizing factor at 913 K for 8 h. The deposition of the oxide coatings were carried out with magnetron sputtering, with the use of a TiO2 target at a pressure of 3 × 10-2 mbars and power of 350 W. To evaluate the effects of hybrid oxidation and to determine the mechanism of oxygen transport, the following research methods have been applied: spectroscopy (GDOS, SIMS, RS), microscopic methods (SEM-EDS, SEM-EBSD, TEM-EFTEM), X-ray tests (μ-XRD, GID). Obtained test results were used to identify the type of oxide coatings, to assess the thickness of the layers and to study the influence of crystallographic orientation on oxygen transport and concentration in the surface layer and in the oxide coating. It has been found that the formation of oxide coatings created by using the hybrid method (FADT + PVD leads to a change in oxygen concentration in the substrate due to introduced defects. This phenomenon is in opposition to the conventional methods such as: electrochemical or laser oxidation. In contrast, forming a tight homogeneous oxide coating on Ti surface improves the biocompatibility, which is particularly important in the context of biomedical applications.

  6. Effect of an allophanic soil on humification reactions between catechol and glycine: Spectroscopic investigations of reaction products

    Science.gov (United States)

    Fukushima, Masami; Miura, Akitaka; Sasaki, Masahide; Izumo, Kenji

    2009-01-01

    Adduction of amino acids to phenols is a possible humification reaction pathway [F.J. Stevenson, Humus Chemistry: Genesis, Composition, Reaction, second ed., Wiley, New York, 1994, pp. 188-211; M.C. Wang, P.M. Huang, Sci. Total Environ. 62 (1987) 435; M.C. Wang, P.M. Huang, Soil Sci. Soc. Am. J. 55 (1991) 1156; M.C. Wang, P.M. Huang, Geoderma 112 (2003) 31; M.C. Wang, P.M. Huang, Geoderma 124 (2005) 415]. To elucidate the reaction kinetics and products of abiotic humification, the effects of an allophanic soil on the adduction of amino acids to phenols were investigated using catechol (CT) and glycine (Gly) as a model phenol and amino acid, respectively. An aqueous solution containing CT and Gly (pH 7.0) in the presence of allophanic soil was incubated for 2 weeks, and the kinetics of the humification reactions were monitored by analysis of absorptivity at 600 nm ( E600). A mixture of CT and Gly in the absence of allophanic soil was used as a control. The E600 value increased markedly in the presence of allophanic soil. In addition, unreacted CT was detected in the control reaction mixture, but not in the allophane-containing reaction mixture. Under the sterilized conditions, absorbance at 600 nm for the control reaction mixture was significantly smaller than that for the allophanic soil-containing reaction mixture, which indicates there was no microbial participation during incubation. These results indicate that the allophanic soil effectively facilitated humification reactions between CT and Gly. The reaction mixtures were acidified and humic-like acid (HLA) was isolated as a precipitate. The elemental composition, acidic functional group contents, molecular weight, FT-IR, solid-state CP-MAS 13C NMR, and 1H NMR spectra of the purified HLAs were analyzed. The results of these analyses indicate that the nitrogen atom of Gly binds to the aromatic carbon of CT in the HLA products.

  7. Spectroscopic Investigation of the Canopy Configurations in Nanoparticle Organic Hybrid Materials of Various Grafting Densities during CO 2 Capture

    KAUST Repository

    Petit, Camille

    2012-01-12

    Novel liquid-like nanoparticle organic hybrid materials (NOHMs) made of polyetheramine chains tethered onto functionalized silica nanoparticles were synthesized and characterized before and after exposure to CO 2 using NMR, Raman, and ATR FT-IR spectroscopies in order to investigate the effect of the grafting densities on the NOHM canopy structure. Considering the promising tunable properties for CO 2 capture of NOHMs, this study was conducted to provide important structural information to better design NOHMs for CO 2 capture. In order to minimize the CO 2 absorption via enthalpic effect and provide a more accurate assessment of the structural effects, the NOHMs were synthesized without task-specific groups. A greater chain ordering and decreased intermolecular interactions were observed in NOHMs compared to the unbound polymer. This was attributed to the specific structural arrangement of the frustrated canopy. The distinct configuration of grafted polymer chains caused different CO 2 packing and CO 2-induced swelling behaviors between the NOHMs and the unbound polymer. The grafting density influenced the ordering and coupling of the polymer chains and CO 2-induced swelling. Its effect on the CO 2 packing behavior was less pronounced. © 2011 American Chemical Society.

  8. Spectroscopic investigation, HOMO-LUMO and NLO studies on L-histidinium maleate based on DFT approach

    Science.gov (United States)

    Dhanavel, S.; Stephen, A.; Asirvatham, P. Samuel

    2017-05-01

    The molecular structure of the title compound L-Histidinium Maleate (LHM) was constructed and optimized based on Density Functional Theory method (DFT-B3LYP) with the 6-31G (d,p) basis set. The fundamental vibrational spectral assignment was analyzed with the aid of optimized structure of LHM. The study on electronic properties such as, HOMO-LUMO energies and absorption wavelength were performed using Time dependent DFT (TD-DFT) approach which reveals that energy transfer occur within the molecule. 13C NMR chemical shift values were measured using Gauge independent atomic orbital method (GIAO) and the obtained values are in good agreement with the reported experimental values. Hardness, ionization potential and electrophilicity index also calculated. The electric dipole moment (μtot) and hyperpolarizability (βtot) values of the investigated molecules were computed. The calculated value (β) was 3.7 times higher than that of urea, which confirms the LHM molecule is a potential candidate for NLO applications.

  9. Structure and function of proteins investigated by crystallographic and spectroscopic time-resolved methods

    Science.gov (United States)

    Purwar, Namrta

    crystal. Time-resolved X-ray data collected at pH's of 4, 7 and 9 demonstrate that pH alters the kinetics of the PYP photocycle dramatically. At pH 4 the photocycle lasts almost one order of magnitude longer in time compared to pH 7. The final intermediate that accumulates at both pH 7 and pH 4 is absent at pH 9. Results from the dose- and the pH-dependent time-resolved crystallographic experiments show that it is imperative to carefully control the conditions under which time-resolved data are collected. With these considerations we collected a comprehensive time-series from nanoseconds to seconds at 14 different temperature settings from -40 °C to 70 °C. Results from time-resolved crystallography are corroborated by employing time-resolved absorption spectroscopy. For this, absorption spectra on crystals and solution are collected by a fast micro-spectrophotometer custom-designed in our lab. We identify kinetic phases of the PYP photocycle at all 14 temperature settings. Relaxation times associated with these phases are temperature-dependent and can be fit by the Van't Hoff-Arrhenius equation. Kinetic modeling yields entropy and enthalpy values at the barriers of the activation solely from the time-resolved crystallographic data. With this, we advance crystallography to a new frontier: the determination of free energy surfaces. Investigating enzymatic reactions can be challenging, because they are non-cyclic. After one turnover product must be washed away and substrate must be reloaded. A promising approach for routine application can be envisioned at the new 4th generation X-ray sources, such as X-ray free electron lasers (XFELs). With our results we set the scene to comprehensively investigate all kinds of enzymatic reactions with these instruments.

  10. Spectroscopic investigation of Dy3+:Lu2Si2O7 single crystal: A potential 589 nm laser medium

    Science.gov (United States)

    Huang, Jianhui; Chen, Yujin; Huang, Jianhua; Gong, Xinghong; Lin, Yanfu; Luo, Zundu; Huang, Yidong

    2017-10-01

    A trivalent dysprosium-doped Lu2Si2O7 single crystal was grown by the Czochralski method. Segregation coefficient of Dy3+ ion in the crystal is about 0.56. Spectroscopic properties of the crystal were investigated at room temperature. In particular, the polarized absorption spectra were analyzed using the Judd-Ofelt theory and the intensity parameters were determined. Then the spontaneous transition probabilities, branching ratios, and radiative lifetime related to the 4F9/2 multiplet were calculated. Emission cross-section for the 4F9/2 → 6H13/2 transition at 589 nm is up to 1.27 × 10-21 cm2 for E//Y polarization. Thermal conductivity of the crystal was measured to be 9.46 Wm-1K-1 at room temperature. The experimental results show that the Dy3+:Lu2Si2O7 crystal is a promising gain medium for solid state 589 nm laser.

  11. Investigation of role of silver nanoparticles on spectroscopic properties of biologically active coumarin dyes 4PTMBC and 1IPMBC.

    Science.gov (United States)

    Raghavendra, U P; Basanagouda, Mahantesha; Thipperudrappa, J

    2015-01-01

    The role of silver nanoparticles on spectroscopic properties of biologically active coumarin dyes 4-p-tolyloxymethyl-benzo[h]coumarin (4PTMBC) and 1-(4-iodophenoxymethyl)-benzo[f]coumarin (1IPMBC) has been investigated using absorption and fluorescence spectroscopy. Silver nanoparticles are synthesized by chemical reduction method and the estimated size by Mie theory is 12 nm. The absorption spectral changes of dyes in the presence of silver nanoparticles suggest their possible interaction with silver nanoparticles. The apparent association constants of the interaction are estimated using Benesi-Hildebrand model. Fluorescence quenching has been observed in both the dyes with the addition of silver nanoparticles. The Stern-Volmer plots of fluorescence quenching are found to be nonlinear showing positive deviation. The magnitudes of quenching rate parameter and fluorescence lifetime measurements indicate the presence of both collisional and static quenching mechanisms. The binding constants and the number of binding sites for the static type of quenching have been estimated from the fluorescence data. The role of diffusion, energy transfer and electron transfer processes in fluorescence quenching mechanism has been discussed.

  12. Investigation of a transiting planet candidate in Trumpler 37: an astrophysical false positive eclipsing spectroscopic binary star

    CERN Document Server

    Errmann, R; Schmidt, T O B; Seeliger, M; Howard, A W; Maciejewski, G; Neuhäuser, R; Meibom, S; Kellerer, A; Dimitrov, D P; Dincel, B; Marka, C; Mugrauer, M; Ginski, Ch; Adam, Ch; Raetz, St; Schmidt, J G; Hohle, M M; Berndt, A; Kitze, M; Trepl, L; Moualla, M; Eisenbeiß, T; Fiedler, S; Dathe, A; Graefe, Ch; Pawellek, N; Schreyer, K; Kjurkchieva, D P; Radeva, V S; Yotov, V; Chen, W P; Hu, S C -L; Wu, Z -Y; Zhou, X; Pribulla, T; Budaj, J; Vaňko, M; Kundra, E; Hambálek, Ľ; Krushevska, V; Bukowiecki, Ł; Nowak, G; Marschall, L; Terada, H; Tomono, D; Fernandez, M; Sota, A; Takahashi, H; Oasa, Y; Briceño, C; Chini, R; Broeg, C H

    2014-01-01

    We report our investigation of the first transiting planet candidate from the YETI project in the young (~4 Myr old) open cluster Trumpler 37. The transit-like signal detected in the lightcurve of the F8V star 2M21385603+5711345 repeats every 1.364894+/-0.000015 days, and has a depth of 54.5+/-0.8 mmag in R. Membership to the cluster is supported by its mean radial velocity and location in the color-magnitude diagram, while the Li diagnostic and proper motion are inconclusive in this regard. Follow-up photometric monitoring and adaptive optics imaging allow us to rule out many possible blend scenarios, but our radial-velocity measurements show it to be an eclipsing single-lined spectroscopic binary with a late-type (mid-M) stellar companion, rather than one of planetary nature. The estimated mass of the companion is 0.15-0.44 solar masses. The search for planets around very young stars such as those targeted by the YETI survey remains of critical importance to understand the early stages of planet formation a...

  13. Investigation of the mouse cerebellum using STIM and {mu}-PIXE spectrometric and FTIR spectroscopic mapping and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hackett, M.J. [School of Chemistry, University of Sydney, NSW 2006 (Australia); Siegele, R., E-mail: rns@ansto.gov.au [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights NSW 2234 (Australia); El-Assaad, F. [Vascular Immunology Unit, Bosch Institute and School of Medical Sciences, University of Sydney, NSW 2006 (Australia); McQuillan, J.A. [Molecular Immunopathology Unit, Bosch Institute and School of Medical Sciences, University of Sydney, NSW 2006 (Australia); Aitken, J.B.; Carter, E.A. [School of Chemistry, University of Sydney, NSW 2006 (Australia); Grau, G.E. [Vascular Immunology Unit, Bosch Institute and School of Medical Sciences, The University of Sydney, NSW 2006 (Australia); Hunt, N.H. [Molecular Immunopathology Unit, Bosch Institute and School of Medical Sciences, The University of Sydney, NSW 2006 (Australia); Cohen, D. [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights NSW 2234 (Australia); Lay, P.A. [School of Chemistry, The University of Sydney, NSW 2006 (Australia)

    2011-10-15

    The cerebral biochemistry associated with the development of many neurological diseases remains poorly understood. In particular, incomplete understanding of the mechanisms through which vascular inflammation manifests in tissue damage and altered brain function is a significant hindrance to the development of improved patient therapies. To this extent, a combination of spectrometric/spectroscopic mapping/imaging methods with an inherent ability to provide a wealth of biochemical and physical information have been investigated to understand further the pathogenesis of brain disease. In this study, proton-induced X-ray emission (PIXE) mapping was combined with scanning transmission ion microscopy (STIM) mapping and Fourier-transform infrared (FTIR) imaging of the same tissue sample to study directly the composition of the murine (mouse) cerebellum. The combination of the elemental, density and molecular information provided by these techniques enabled differentiation between four specific tissue types within the murine cerebellum (grey matter, white matter, molecular layer and micro blood vessels). The results presented are complementary, multi-technique measurements of the same tissue sample. They show elemental, density and molecular differences among the different tissue types.

  14. An investigation of the photophysical properties of minor groove bound and intercalated DAPI through quantum-mechanical and spectroscopic tools.

    Science.gov (United States)

    Biancardi, Alessandro; Biver, Tarita; Secco, Fernando; Mennucci, Benedetta

    2013-04-07

    The fluorescent probe 4',6-diamidino-2-phenylindole (DAPI) is a dye known to interact with polynucleotides in a non-univocal manner, both intercalation and minor groove binding modes being possible, and to specifically change its photophysical properties according to the different environments. To investigate this behavior, quantum-mechanical calculations using time-dependent density functional theory (TDDFT), coupled with polarizable continuum and/or atomistic models, were performed in combination with spectroscopic measurements of the probe in the different environments, ranging from a homogeneous solution to the minor groove or intercalation pockets of double stranded nucleic acids. According to our simulation, the electronic transition involves a displacement of the electron charge towards the external amidine groups and this feature makes the absorption energies very environment-sensitive while a much smaller sensitivity is seen in the fluorescence energies. Moreover, the calculations show that the DAPI molecule, when minor groove bound to the nucleic acid, presents both a reduced geometrical flexibility because of the rigid DNA pocket and a reduced polarization due to the very "apolar" microenvironment. All these effects can be used to better understand the observed enhancement of the fluorescence, which makes it an excellent marker for DNA.

  15. Microwave spectroscopic and theoretical investigations of the strongly hydrogen bonded hexafluoroisopropanol···water complex.

    Science.gov (United States)

    Shahi, A; Arunan, E

    2015-10-14

    This paper reports microwave spectroscopic and theoretical investigations on the interaction of water with hexafluoroisopropanol (HFIP). The HFIP monomer can exist in two conformations, antiperiplanar (AP) and synclinical (SC). The former is about 5 kJ mol(-1) more stable than the latter. Theoretical calculations predicted three potential minima for the complex, two having AP and one having SC conformations. Though, the binding energy for the HFIP(SC)···H2O turned out to be larger than that for the other two conformers having HFIP in the AP form, the global minimum for the complex in the potential energy hypersurface had HFIP in the AP form. Experimental rotational constants for four isotopologues measured using a pulsed nozzle Fourier transform microwave spectrometer, correspond to the global minimum in the potential energy hypersurface. The structural parameters and the internal dynamics of the complex could be determined from the rotational spectra of the four isotopologues. The global minimum has the HFIP(AP) as a hydrogen bond donor forming a strong hydrogen bond with H2O. To characterize the strength of the bonding and to probe the other interactions within the complex, atoms in molecules, non-covalent interaction index and natural bond orbital theoretical analyses have been performed.

  16. Investigation of the behavior of HSA upon binding to amlodipine and propranolol: Spectroscopic and molecular modeling approaches

    Science.gov (United States)

    Housaindokht, Mohammad Reza; Rouhbakhsh Zaeri, Zeinab; Bahrololoom, Mahmood; Chamani, Jamshid; Bozorgmehr, Mohammad Reza

    2012-01-01

    The interaction between human serum albumin (HSA) and two drugs - amlodipine and propranolol - was investigated using fluorescence, UV absorption and circular dichroism (CD) spectroscopy. In addition, the binding site was established by applying molecular modeling technique. Fluorescence data suggest that amlodipine will quench the intrinsic fluorescence of HSA; whereas propranolol enhances the fluorescence of HSA. The binding constants for the interaction of amlodipine and propranolol with HSA were found to be 3.63 × 10 5 M -1 and 2.29 × 10 4 M -1, respectively. The percentage of secondary structure feature of each one of the HSA-bound drugs, i.e. the α-helix content, was estimated empirically by circular dichroism. The results indicated that amlodipine causes an increase, and that propranolol leads to a decrease in α-helix content of HSA. The spectroscopic analysis indicates that the binding mechanisms of the two drugs are different from each other. The data obtained by the molecular modeling study indicated that these drugs bind, with different affinity, to different sites located in subdomain IIA and IIIA.

  17. Raman spectroscopic investigation of the chemopreventive response of naringenin and its nanoparticles in DMBA-induced oral carcinogenesis

    Science.gov (United States)

    Krishnakumar, N.; Sulfikkarali, N. K.; Manoharan, S.; Venkatachalam, P.

    2013-11-01

    Raman spectroscopy is a vibrational spectroscopic technique that can be used to optically probe the biomolecular changes associated with tumor progression. The aim of the present study is to investigate the biomolecular changes in chemopreventive response of prepared naringenin-loaded nanoparticles (NARNPs) relative to efficacy of free naringenin (NAR) during 7,12-dimethyl benz(a)anthracene (DMBA)-induced oral carcinogenesis by Fourier Transform Raman (FT-Raman) spectroscopy. Oral squamous cell carcinoma (OSCC) was developed in the buccal pouch of golden Syrian hamsters by painting with 0.5% DMBA in liquid paraffin three times a week for 14 weeks. Raman spectra differed significantly between the control and tumor tissues, with tumors showing higher percentage signals for nucleic acids, phenylalanine and tryptophan and a lower in the percentage of phospholipids. Moreover, oral administration of free NAR and NARNPs significantly increased phospholipids and decreased the levels of tryptophan, phenylalanine and nucleic acid contents. On a comparative basis, NARNPs was found to have a more potent antitumor effect than free NAR in completely preventing the formation of squamous cell carcinoma and in improving the biochemical status to a normal range in DMBA-induced oral carcinogenesis. The present study further suggest that Raman spectroscopy could be a valuable tool for rapid and sensitive detection of specific biomolecular changes in response to chemopreventive agents.

  18. Hydration behaviour of POPC/C(12)-Bet mixtures investigated by sorption gravimetry, (31)P NMR spectroscopy and X-ray diffraction.

    Science.gov (United States)

    Pfeiffer, H; Weichert, H; Klose, G; Heremans, K

    2012-02-01

    The hydration behaviour of mixtures of the zwitterionic phospholipid 1-palmitoyl-2-oleolyl-sn-glycero-3-phosphocholine (POPC) and the zwitterionic surfactant N,N-dimethyl-N-dodecyl-betain (C(12)-Bet) was investigated by sorption gravimetry, solid-state (31)P NMR-spectroscopy and small angle X-ray diffraction (SAXD). Negative excess hydration (dehydration) was found for almost all hydration degrees investigated. This behaviour is explained by the formation of an inner salt between the dipoles of phospholipid and surfactant headgroups that show a reverse sequence of partial charges with respect to the hydrocarbon backbone. The formation of an inner-salt most probably reduces potential water binding sites. Moreover, NMR data suggest that the incorporation of the zwitterionic surfactant into the phospholipid membrane is correlated with reorientation of the phosphate axis towards the membrane director as well as with reduced lateral and wobbling diffusion.

  19. Spectroscopic investigations of Np(V/VI) redox speciation in hyperalkaline TMA-(OH, Cl) solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gaona, X.; Dardenne, K.; Liu, X.; Rothe, J.; Denecke, M.A.; Altmaier, M. [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. fuer Nukleare Entsorgung; Tits, J.; Wieland, E. [Paul Scherrer Institut (PSI), Villigen (Switzerland). Lab. for Waste Management

    2012-07-01

    The redox chemistry of Np(V/VI) was investigated in {proportional_to} 0.6 M tetramethylammonium hydroxide/chloride (TMA-(OH, Cl)) solutions with 9 {<=} -log [H{sup +}] {<=} 13.5. Redox conditions were defined by the absence or presence of ClO{sup -} as oxidizing agent (Na-salt, 5 x 10{sup -3} M and 5 x 10{sup -2} M). The high total Np concentration ([Np]{sub tot} {proportional_to} 2 x 10{sup -3} M) led to the precipitation of solid phases in some of the samples. The carbonate concentration (as impurity of TMA-OH) was 2-3 x 10{sup -3} M. UV-vis/NIR spectra obtained from the supernatant in TMA-(OH, Cl) solutions and absence of ClO{sup -} showed clear Np(V) features, identified as NpO{sub 2}{sup +}, NpO{sub 2}CO{sub 3}{sup -} and (NpO{sub 2}){sub x}(CO{sub 3}){sub y}(OH){sub z}{sup x-2y-z}. No NIR features were observed within 800 nm {<=} {lambda} {<=} 1300 nm for samples with ClO{sup -}. XANES edge energies and features of these samples confirmed the predominance of Np(V) in the absence of ClO{sup -} and Np(VI) in the presence of ClO{sup -}, by comparison to XANES reference spectra of Np(III/IV/V/VI) prepared within the present work by in-situ electrolysis. A similar Np redox distribution was observed for the solid phases based on XANES and EXAFS measurements. EXAFS spectra indicative of Np{sup V}O{sub 2}OH(s) and Np{sup VI}O{sub 3} . xH{sub 2}O(s) were obtained for samples in absence and presence of ClO{sup -}, respectively. The formation of a Na-Np(VI) phase in 5 x 10{sup -2} M ClO{sup -} and -log [H{sup +}] {proportional_to} 12 was also indicated from the EXAFS, chemical analysis and SEM-EDS. These results indicate that Np(VI) aqueous species and solid compounds prevail far below the oxidation border of water in alkaline solutions and also far below the E{sub H} border calculated with the current NEA data selection [1]. These observations are further supported by correlations of literature thermodynamic data for actinides (U, Np, Pu and Am), which predict the

  20. Solid-state {sup 27}Al and {sup 29}Si NMR investigations on Si-substituted hydrogarnets

    Energy Technology Data Exchange (ETDEWEB)

    Rivas Mercury, J.M. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Pena, P. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain)]. E-mail: ppena@icv.csic.es; Aza, A.H. de [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Turrillas, X. [Instituto de Ciencias de la Construccion Eduardo Torroja, CSIC, Serrano Galvache, 4, 28033 Madrid (Spain); Sobrados, I. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain); Sanz, J. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain)

    2007-02-15

    Partially deuterated Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} hydrates prepared by a reaction in the presence of D{sub 2}O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by {sup 29}Si and {sup 27}Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The {sup 29}Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} was followed by {sup 27}Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH){sub 6} and Al(OSi)(OH){sub 5} environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data.

  1. Investigating the reactivity of pMDI with wood cell walls using high-resolution solution-state NMR spectroscopy

    Science.gov (United States)

    Daniel J. Yelle; John Ralph; Charles R. Frihart

    2009-01-01

    The objectives of this study are the following: (1) Use solution-state NMR to assign contours in HSQC spectra of the reaction products between pMDI model compounds and: (a) lignin model compounds, (b) milled-wood lignin, (c) ball-milled wood, (d) microtomed loblolly pine; (2) Determine where and to what degree urethane formation occurs with loblolly pine cell wall...

  2. DNTF的核磁表征及理论研究%NMR Characterization and Theoretical Investigation of DNTF

    Institute of Scientific and Technical Information of China (English)

    王民昌; 毕福强; 张皋; 栾洁玉; 徐敏; 宁艳利; 樊学忠

    2013-01-01

    为了完善3,4-双(4′-硝基呋咱-3′-基)氧化呋咱(DNTF)的核磁表征,采用 NMR 实验与 GIAO-NMR 理论计算相结合的方法区分并归属13 C 和15 N 的化学位移。采用二甲基亚砜( DMSO-d6)、丙酮( Acetone-d6)和氯仿( CDCl3)为溶剂,进行了 DNTF 的一维13 C NMR和15 N NMR实验,并在 DMSO-d6中获得 DNTF的所有核磁信号。采用二维 INADEQUATE实验完成了13 C NMR 的归属。采用高斯09程序,在 DFT-B3LYP/6-311+G(2d,p)水平上优化了 DNTF 结构,用 GIAO 方法在不同基组上计算了13C NMR和15N NMR的化学位移,计算结果与实验值一致性较好。结果表明,受氧化呋咱环上氧原子 O(22)吸电子作用的影响, C(9)与 C(13)的化学位移出现较大的差别,与 C(13)相比,C(9)出现在高场。%In order to optimize the NMR assignment of 3,4-dinitrofurazanfuroxan(DNTF),a combination of experimental NMR and computational GIAO-NMR techniques was utilized to distinguish the chemical shifts of 13C and 15N. One dimensional(1D) 13 C and 15 N NMR analyses were performed using DMSO-d6 ,acetone-d6 and CDCl3 as solvent. All signals of DNTF were found in DMSO-d6 . In the 13 C NMR,the chemical shifts were assigned by 2D INADEQUATE NMR experiment. Based on the geometry of DNTF optimized at the DFT-B3LYP/6-311 +G(2d,p)level by using Guassian 09 program,the 13C and 15N NMR chemical shifts were calculated by GIAO method at different level,which agree with experimental data. Results show that the electro-withdrawing effect of the O(22)in furoxan cycle leads to large 13C chemical shift changes of C(9)and C(13),and makes C(9)appear in higher field than C(13).

  3. Radiation induced crosslinking in a silica-filled silicone elastomer as investigated by multiple quantum H NMR

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R S; Chinn, S C; Solyom, D; Cohenour, R

    2005-05-24

    DC745 is a commercially available silicone elastomer consisting of dimethyl, methylphenyl, and vinyl-methyl siloxane monomers crosslinked with a peroxide vinyl specific curing agent. It is generally considered to age gracefully and to be resistant to chemical and thermally harsh environments. However, little data exists on the radiation resistance of this commonly used silicone elastomer. We report static {sup 1}H NMR studies of residual dipolar couplings in DC745 solid elastomers subject to exposure to ionizing gamma radiation. {sup 1}H spin-echo NMR data shows that with increasing dose, the segmental dynamics decrease is consistent with radiatively induced crosslinking. {sup 1}H multiple quantum NMR was used to assess changes in the network structure and observed the presence of a bimodal distribution of residual dipolar couplings, <{Omega}{sub d}>, that were dose dependent. The domain with the lower <{Omega}{sub d}> has been assigned to the polymer network while the domain with the higher <{Omega}{sub d}> has been assigned to polymer chains interacting with the inorganic filler surfaces. In samples exposed to radiation, the residual dipolar couplings in both reservoirs were observed to increase and the populations were observed to be dose dependent. The NMR results are compared to Differential Scanning Calorimetry (DSC) and a two-step solvent swelling technique. The solvent swelling data lend support to the interpretation of the NMR results and the DSC data show both a decrease in the melt temperature and the heat of fusion with cumulative dose, consistent with radiative crosslinking. In addition, DSC thermograms obtained following a 3 hr isothermal soak at -40 C showed the presence of a second melt feature at T{sub m} {approx} -70 C consistent with a network domain with significantly reduced segmental motion.

  4. Evaluation of chemopreventive response of two cycloxygenase-2 inhibitors, etoricoxib and diclofenac in rat colon cancer using FTIR and NMR spectroscopic techniques Evaluación de la respuesta quimiopreventiva de dos inhibidores de la ciclooxigenasa 2, etoricoxib y diclofenaco en el cáncer de colon murino empleando las técnicas espectroscópicas FTIR Y NMR

    Directory of Open Access Journals (Sweden)

    M. Kaur Saini

    2010-08-01

    Full Text Available Non steroidal anti inflammatory drugs (NSAIDs are efficacious in chemoprevention of colorectal cancer. Therefore, the potential ability of Etoricoxib, a selective cycloxygenase-2(COX-2 inhibitor and Diclofenac, a preferential COX-2 inhibitor are considered in the chemoprevention of 1, 2-dimethylhydrazine (DMH induced colon carcinogenesis in rat model. DMH was injected s.c. for six weeks while Etoricoxib and Diclofenac were fed daily orally alone and also in combination with an weekly subcutaneous injection of 1,2-dimethylhydrazine dihydrochloride (DMH to the rats. After the treatment period of 6 weeks the animals were sacrificed by an overdose of ether anesthesia and the colonic tissues were removed and studied by the FTIR and NMR Spectroscopic techniques to evaluate the changes occurring in the lipid bilayer of colonic membrane lipids. The alterations in wave number of FTIR spectra as well as the chemical shifts of NMR spectra were recorded which signify the modulation of membrane lipids during colon carcinogenesis and possible cancer prevention by the oral administration of NSAIDs in an experimental model of chemical induced colon carcinogenesis.Los fármacos antiinflamatorios no esteroideos (AINE son eficaces en la prevención del cáncer colorrectal. Por lo tanto, la capacidad potencial de Etoricoxib, un inhibidor selectivo de la ciclooxigenasa-2(COX-2, y de Diclofenaco, un inhibidor preferencial de la COX-2, se considera en la quimioprevención de la carcinogénesis de colon inducida por 1, 2-dimetilhidracina (DMH en el modelo murino. Se inyectó s.c. DMH durante 6 semanas a la vez que se administraban diariamente por vía oral Etoricoxib y Diclofenaco solos y en combinación con una inyección s.c. semanal de dihidrocloruro de 1,2-dimetilhidracina (DMH a las ratas. Después del período de tratamiento de 6 semanas, se sacrificó a los animales mediante una sobredosis de anestesia con éter y se extirpó el tejido colónico para estudio con

  5. Transport properties investigation of aqueous protic ionic liquid solutions through conductivity, viscosity, and NMR self-diffusion measurements.

    Science.gov (United States)

    Anouti, Mérièm; Jacquemin, Johan; Porion, Patrice

    2012-04-12

    We present a study on the transport properties through conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of two pure protic ionic liquids--pyrrolidinium hydrogen sulfate, [Pyrr][HSO(4)], and pyrrolidinium trifluoroacetate, [Pyrr][CF(3)COO]--and their mixtures with water over the whole composition range at 298.15 K and atmospheric pressure. Based on these experimental results, transport mobilities of ions have been then investigated in each case through the Stokes-Einstein equation. From this, the proton conduction in these PILs follows a combination of Grotthuss and vehicle-type mechanisms, which depends also on the water composition in solution. In each case, the displacement of the NMR peak attributed to the labile proton on the pyrrolidinium cation with the PILs concentration in aqueous solution indicates that this proton is located between the cation and the anion for a water weight fraction lower than 8%. In other words, for such compositions, it appears that this labile proton is not solvated by water molecules. However, for higher water content, the labile protons are in solution as H(3)O(+). This water weight fraction appears to be the solvation limit of the H(+) ions by water molecules in these two PILs solutions. However, [Pyrr][HSO(4)] and [Pyrr][CF(3)COO] PILs present opposed comportment in aqueous solution. In the case of [Pyrr][CF(3)COO], η, σ, D, and the attractive potential, E(pot), between ions indicate clearly that the diffusion of each ion is similar. In other words, these ions are tightly bound together as ion pairs, reflecting in fact the importance of the hydrophobicity of the trifluoroacetate anion, whereas, in the case of the [Pyrr][HSO(4)], the strong H-bond between the HSO(4)(-) anion and water promotes a drastic change in the viscosity of the aqueous solution, as well as on the conductivity which is up to 187 mS·cm(-1) for water weight fraction close to 60% at 298 K.

  6. NMR spectroscopy using liquid crystal solvents

    CERN Document Server

    Emsley, JW

    2013-01-01

    NMR Spectroscopy using Liquid Crystal Solvents covers the importance of using a liquid crystal solvent in NMR to derive nuclear dipolar spin-spin coupling constants. This book is composed of ten chapters, and begins with a brief description of the features and benefits of liquid crystal in NMR spectroscopic analysis. The succeeding chapters deal with the mode of operation of nuclear spin Hamiltonian for partially oriented molecules and the analysis of NMR spectra of partially oriented molecules, as well as the determination of rigid molecule structure. These topics are followed by discussions

  7. Structural determination of Zn and Cd-DTPA complexes: MS, infrared, (13)C NMR and theoretical investigation.

    Science.gov (United States)

    Silva, Vanézia L; Carvalho, Ruy; Freitas, Matheus P; Tormena, Cláudio F; Melo, Walclée C

    2007-12-31

    The joint application of MS, infrared and (13)C NMR techniques for the determination of metal-DTPA structures (metal=Zn and Cd; DTPA=diethylenetriaminepentacetic acid) is reported. Mass spectrometry allowed determining the 1:1 stoichiometry of the complexes, while infrared analysis suggested that both nitrogen and carboxyl groups are sites for complexation. The (13)C NMR spectrum for the cadmium-containing complex evidenced the existence of free and complexed carboxyl groups, due to a straight singlet at 179.0 ppm (free carboxylic (13)C) and to two broad singlets or a broad doublet at 178.3 ppm (complexed carboxylic (13)C, (2)J(Cd-C(=O))=45.2 Hz). A similar interpretation might be given for the zinc derivative and, with the aid of DFT calculations, structures for both complexes were then proposed.

  8. Synthesis of LaF{sub 3} nanosheets with high fluorine mobility investigated by NMR relaxometry and diffusometry

    Energy Technology Data Exchange (ETDEWEB)

    Gulina, L. B.; Tolstoy, V. P.; Murin, I. V. [Institute of Chemistry of St. Petersburg State University 198504, Universitetsky pr., 26 Peterhof, St. Petersburg (Russian Federation); Schäfer, M.; Privalov, A. F. [Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstr. 6, 64289 Darmstadt (Germany)

    2015-12-21

    Ionically conducting lanthanum fluoride (LaF{sub 3}), displaying a nanoscopic lamellar structure, has been synthesized at the surface of an aqueous solution of LaCl{sub 3} and HF. The structure and the chemical composition of the conductor have been analyzed by SEM, electron probe microanalysis, X-ray powder diffraction, FTIR, and {sup 19}F magic angle spinning nuclear magnetic resonance (NMR) spectroscopy. The fluorine dynamics have been studied by NMR diffusometry and relaxometry in a temperature range from room temperature up to 875 K. The fluorine self-diffusion coefficient of the nanostructured LaF{sub 3} is about two orders of magnitude larger than that of bulk LaF{sub 3}. This novel material is highly promising for many typical applications of fluorine ionic systems.

  9. Investigating fatty acids inserted into magnetically aligned phospholipid bilayers using EPR and solid-state NMR spectroscopy

    Science.gov (United States)

    Nusair, Nisreen A.; Tiburu, Elvis K.; Dave, Paresh C.; Lorigan, Gary A.

    2004-06-01

    This is the first time 2H solid-state NMR spectroscopy and spin-labeled EPR spectroscopy have been utilized to probe the structural orientation and dynamics of a stearic acid incorporated into magnetically aligned phospholipid bilayers or bicelles. The data gleaned from the two different techniques provide a more complete description of the bilayer membrane system. Both methods provided similar qualitative information on the phospholipid bilayer, high order, and low motion for the hydrocarbon segment close to the carboxyl groups of the stearic acid and less order and more rapid motion at the end towards the terminal methyl groups. However, the segmental order parameters differed markedly due to the different orientations that the nitroxide and C-D bond axes transform with the various stearic acid acyl chain conformations, and because of the difference in dynamic sensitivity between NMR and EPR over the timescales examined. 5-, 7-, 12-, and 16-doxylstearic acids spin-labels were used in the EPR experiments and stearic acid-d 35 was used in the solid-state NMR experiments. The influence of the addition of cholesterol and the variation of temperature on the fatty acid hydrocarbon chain ordering in the DMPC/DHPC phospholipid bilayers was also studied. Cholesterol increased the degree of ordering of the hydrocarbon chains. Conversely, as the temperature of the magnetically aligned phospholipid bilayers increased, the order parameters decreased due to the higher random motion of the acyl chain of the stearic acid. The results indicate that magnetically aligned phospholipid bilayers are an excellent model membrane system and can be used for both NMR and EPR studies.

  10. Characterisation of agricultural waste-derived biochars and their sorption potential for sulfamethoxazole in pasture soil: A spectroscopic investigation

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, Prakash; Sarmah, Ajit K., E-mail: a.sarmah@auckland.ac.nz

    2015-01-01

    We investigated the effects of feedstock type and pyrolysis temperatures on the sorptive potential of a model pastoral soil amended with biochars for sulfamethoxazole (SMO), using laboratory batch sorption studies. The results indicated that high temperature chars exhibited enhanced adsorptive potential, compared to low temperature chars. Pine sawdust (PSD) biochar produced at 700 °C using the steam gasification process exhibited the highest sorptive capacity (2-fold greater than the control treatment) for SMO among the three biochars used. Soils amended with green waste (GW) biochars produced at three different pyrolysis temperatures showed a small increase in SMO sorption with the increases in temperature. The NMR spectra, the elemental molar ratios (H/C, O/C) and polarity index (O + N)/C of the biochars revealed that PSD biochar possessed the highest degree of aromatic condensation compared to CC and GW chars. These results correlated well with the sorption affinity of each biochar, with effective distribution coefficient (K{sub d}{sup eff}) being highest for PSD and lowest for GW biochars. X-ray photoelectron spectroscopy results for the biochars showed a relatively large difference in oxygen containing surface functional groups amongst the GW biochars. However, they exhibited nearly identical sorption affinity to SMO, indicating negligible role of oxygen containing surface functional groups on SMO sorption. These observations provide important information on the use of biochars as engineered sorbents for environmental applications, such as reducing the bioavailability of antibiotics and/or predicting the fate of sulfonamides in biochar-amended soils. - Highlights: • High temperature chars showed enhanced adsorptive potential, compared to low temperature chars. • Oxygen containing acidic functional groups of biochar play negligible role in sorption. • Biochar properties like specific surface area and aromaticity enhanced its sorption capacity.

  11. Investigating miscibility and molecular mobility of nifedipine-PVP amorphous solid dispersions using solid-state NMR spectroscopy.

    Science.gov (United States)

    Yuan, Xiaoda; Sperger, Diana; Munson, Eric J

    2014-01-06

    Solid-state NMR (SSNMR) (1)H T1 and T1ρ relaxation times were used to evaluate the miscibility of amorphous solid dispersions of nifedipine (NIF) and polyvinylpyrrolidone (PVP) prepared by three different methods: melt quenching in the typical lab setting, spray drying and melt quenching in the NMR rotor while spinning. Of the five compositions prepared by melt quenching in the lab setting, the 95:5 and 90:10 NIF:PVP (w:w) amorphous solid dispersions were not miscible while 75:25, 60:40, and 50:50 NIF:PVP dispersions were miscible by the (1)H T1ρ measurements. The domain size of the miscible systems was estimated to be less than 4.5 nm. Amorphous solid dispersions with composition of 90:10 NIF:PVP prepared by spray drying and melt quenching in the NMR rotor showed miscibility by (1)H T1ρ values. Variable-temperature SSNMR (1)H T1ρ relaxation measurements revealed a change in relaxation time at approximately 20 °C below Tg, suggesting increased molecular mobility above that temperature.

  12. Protein secondary structure of Green Lynx spider dragline silk investigated by solid-state NMR and X-ray diffraction.

    Science.gov (United States)

    Xu, Dian; Shi, Xiangyan; Thompson, Forrest; Weber, Warner S; Mou, Qiushi; Yarger, Jeffery L

    2015-11-01

    In this study, the secondary structure of the major ampullate silk from Peucetia viridans (Green Lynx) spiders is characterized by X-ray diffraction and solid-state NMR spectroscopy. From X-ray diffraction measurement, β-sheet nanocrystallites were observed and found to be highly oriented along the fiber axis, with an orientational order, fc≈0.98. The size of the nanocrystallites was determined to be on average 2.5nm×3.3nm×3.8nm. Besides a prominent nanocrystalline region, a partially oriented amorphous region was also observed with an fa≈0.89. Two-dimensional (13)C-(13)C through-space and through-bond solid-state NMR experiments were employed to elucidate structure details of P. viridans silk proteins. It reveals that β-sheet nanocrystallites constitutes 40.0±1.2% of the protein and are dominated by alanine-rich repetitive motifs. Furthermore, based upon the NMR data, 18±1% of alanine, 60±2% glycine and 54±2% serine are incorporated into helical conformations. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. a Combined Gigahertz and Terahertz Synchrotron-Based Fourier Transform Infrared Spectroscopic Investigation of Ortho-D

    Science.gov (United States)

    Albert, Sieghard; Chen, Ziqiu; Fábri, Csaba; Prentner, Robert; Quack, Martin; Zindel, Daniel

    2017-06-01

    Tunneling switching is a fundamental phenomenon of interest in molecular quantum dynamics including also chiral molecules and parity violation. Deuterated phenols have been identified as prototypical achrial candidates. We report the high resolution spectroscopic investigation of the ortho-D-phenol in the GHz and THz ranges following our recent discovery of tunneling switching in its isotopomer meta-D-phenol. Here we report new results on ortho-D-phenol.The pure rotational spectra were recorded in the range of 72-117 GHz and assigned to the syn- and anti- structures in the ground and the first excited torsional states. Specific torsional states were assigned based on a comparison of experimental rotational constants with the quasiadiabatic channel reaction path Hamiltonian (RPH) calculations. The torsional fundamental at 308 cm^{-1} and the first hot band at 275 cm^{-1} were subsequently assigned. The analyses of pure rotational and rovibrational spectra shall be discussed in detail in relation to possible tunneling switching. M. Quack , Fundamental Symmetries and Symmetry Violations from High-resolution Spectroscopy, Handbook of High Resolution Spectroscopy, M. Quack and F. Merkt eds.,John Wiley & Sons Ltd, Chichester, New York, 2001, vol. 1, ch. 18, pp. 659-722. R. Prentner, M. Quack, J. Stohner and M. Willeke, J. Phys. Chem. A 119, 12805-12822 (2015). S. Albert, Z. Chen, C. Fábri, R. Prentner M. Quack and D. Zindel, paper at this meeting. S. Albert, Ph. Lerch, R. Prentner and M. Quack, Angew. Chem. Int. Ed. 52, 346-349 (2013). S. Albert, Z. Chen, C. Fábri,P. Lerch, R. Prentner and M. Quack, Mol.Phys. 114, 2751-2768 (2016) and 71st International Symposium on Molecular Spectroscopy, Urbana-Champaign, USA, June 20-24, Talk FE04 (2016).

  14. Linear and nonlinear optical investigations of nano-scale Si-doped ZnO thin films: spectroscopic approach

    Science.gov (United States)

    Jilani, Asim; Abdel-wahab, M. Sh.; Zahran, H. Y.; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-09-01

    Pure and Si-doped ZnO (SZO) thin films at different concentration of Si (1.9 and 2.4 wt%) were deposited on highly cleaned glass substrate by radio frequency (DC/RF) magnetron sputtering. The morphological and structural investigations have been performed by atomic force electron microscope (AFM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy was employed to study the composition and the change in the chemical state of Si-doped ZnO thin films. The optical observations like transmittance, energy band gap, extinction coefficient, refractive index, dielectric loss of pure and Si-doped ZnO thin films have been calculated. The linear optical susceptibility, nonlinear refractive index, and nonlinear optical susceptibility were also studied by the spectroscopic approach rather than conventional Z-scan method. The energy gap of Si-doped ZnO thin films was found to increase as compared to pure ZnO thin films. The crystallinity of the ZnO thin films was effected by the Si doping. The O1s spectra in pure and Si-doped ZnO revealed the bound between O-2 and Zn+2 ions and reduction in the surface oxygen with the Si doping. The chemical state analysis of Si 2p showed the conversation of Si to SiOx and SiO2. The increase in the first-order linear optical susceptibility χ (1) and third-order nonlinear optical susceptibility χ (3) was observed with the Si doping. The nonlinear studies gave some details about the applications of metal oxides in nonlinear optical devices. In short, this study showed that Si doping through sputtering has effected on the structural, surface and optical properties of ZnO thin films which could be quite useful for advanced applications such as metal-oxide-based optical devices.

  15. Spectroscopic investigation of the interaction between G-quadruplex of KRAS promoter sequence and three isoquinoline alkaloids

    Science.gov (United States)

    Wen, Li-Na; Xie, Meng-Xia

    2017-01-01

    KRAS promoter can form G-quadruplex structure and regulate gene transcription. The drugs which can bind with G-quadruplex of KRAS promoter may be potential remedy for treatment of cancers associated with KRAS mutation. The interaction mechanism between the G-quadruplex of KRAS promoter and three isoquinoline alkaloids (jatrorrhizine, berberine and sanguinarine) has been investigated by UV-visible, fluorescence and circular dichroism spectroscopic methods. The results showed that the three alkaloids can form complexes with G-quadruplex KRAS promoter with the molecular ratio of 1:1, and the binding constants were (0.90 ± 0.16) × 106 L mol- 1, (0.93 ± 0.21) × 106 L mol- 1 and (1.16 ± 0.45) × 106 L mol- 1 for jatrorrhizine, berberine and sanguinarine. The absorption spectra, KI quenching and fluorescence anisotropy and polarization studies suggested jatrorrhizine and berberine interacted with G-quadruplex by not only end-stacking binding mode but also grooves or loops binding mode, while sanguinarine by end-stacking binding mode. Sanguinarine was more beneficial to maintain the stability and parallel conformation of KRAS promoter G-quadruplex. MTT assay was performed to evaluate antiproliferation effects of the three isoquinoline alkaloids on SW620 cells, and the antiproliferation effects of the three alkaloids were sanguinarine > berberine > jatrorrhizine. All the three alkaloids can bind with KRAS promoter G-quadruplex, and sanguinarine had the better binding property and antiproliferation effects on SW620 cells. The results obtained are meaningful to explore potential reagents targeting the parallel G-quadruplex structure of KRAS promoter for gene theraphy of colorectal carcinomas.

  16. Molecular interaction of 2,4-diacetylphloroglucinol (DAPG) with human serum albumin (HSA): The spectroscopic, calorimetric and computational investigation

    Science.gov (United States)

    Pragna Lakshmi, T.; Mondal, Moumita; Ramadas, Krishna; Natarajan, Sakthivel

    2017-08-01

    Drug molecule interaction with human serum albumin (HSA) affects the distribution and elimination of the drug. The compound, 2,4-diacetylphloroglucinol (DAPG) has been known for its antimicrobial, antiviral, antihelminthic and anticancer properties. However, its interaction with HSA is not yet reported. In this study, the interaction between HSA and DAPG was investigated through steady-state fluorescence, time-resolved fluorescence (TRF), circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopy, isothermal titration calorimetry (ITC), molecular docking and molecular dynamics simulation (MDS). Fluorescence spectroscopy results showed the strong quenching of intrinsic fluorescence of HSA due to interaction with DAPG, through dynamic quenching mechanism. The compound bound to HSA with reversible and moderate affinity which explained its easy diffusion from circulatory system to target tissue. The thermodynamic parameters from fluorescence spectroscopic data clearly revealed the contribution of hydrophobic forces but, the role of hydrogen bonds was not negligible according to the ITC studies. The interaction was exothermic and spontaneous in nature. Binding with DAPG reduced the helical content of protein suggesting the unfolding of HSA. Site marker fluorescence experiments revealed the change in binding constant of DAPG in the presence of site I (warfarin) but not site II marker (ibuprofen) which confirmed that the DAPG bound to site I. ITC experiments also supported this as site I marker could not bind to HSA-DAPG complex while site II marker was accommodated in the complex. In silico studies further showed the lowest binding affinity and more stability of DAPG in site I than in site II. Thus the data presented in this study confirms the binding of DAPG to the site I of HSA which may help in further understanding of pharmacokinetic properties of DAPG.

  17. Vibrational spectroscopic studies, NMR, HOMO-LUMO, NLO and NBO analysis of 1-(2-nitrobenzoyl)-3,5-diphenyl-4,5-dihydro-1H-pyrazole with use X-ray diffractions and DFT calculations

    Science.gov (United States)

    Demir, Sibel; Tinmaz, Feyza; Dege, Necmi; Ilhan, Ilhan Ozer

    2016-03-01

    The crystal and molecular structure of the title compound, 1-(2-nitrobenzoyl)-3,5-diphenyl-4,5-dihydro-1H-pyrazole, was reported and confirmed by single crystal X-ray diffraction and spectroscopic data. The structure, geometry optimization, vibrational frequencies and nuclear magnetic resonance were also investigated. Stability of the molecule arising from hyperconjugative interactions and charge delocalisation was analysed using natural bond orbital analysis. The results show that charge in electron density (ED) in the σ∗ and π∗ antibonding orbitals and second-order delocalisation energies E(2) confirms the occurrence of intramolecular charge transfer within the molecule. Satisfactory theoretical aspects were made for the stable conformer of the molecule using density functional theory DFT-B3LYP methods with the 6-311G++(d,p) basis set.

  18. Quantum mechanical and spectroscopic (FT-IR, FT-Raman,1H,13C NMR, UV-Vis) studies, NBO, NLO, HOMO, LUMO and Fukui function analysis of 5-Methoxy-1H-benzo[d]imidazole-2(3H)-thione by DFT studies

    Science.gov (United States)

    Pandey, Manju; Muthu, S.; Nanje Gowda, N. M.

    2017-02-01

    Theoretical analysis of the molecular structure, spectroscopic (FT-IR, FT-Raman, 1H, 13C NMR, UV-Vis) studies, and thermodynamic characteristics of 5-Methoxy-1H-benzo[d]imidazole-2(3H)-thione (5MBIT) molecule were done by DFT/B3LYP using 6-311++G(d, p) basis set. Theoretical parameters were compared with experimental data. The dipole moment (μ), polarizability (Δα) and first order hyperpolarizability (β) of the molecule were calculated. Thermodynamic properties, HOMO and LUMO energies were determined. Global reactivity parameters and Fukui function of the 5MBIT molecule were predicted.

  19. 99Tc NMR as a promising technique for structural investigation of biomolecules: theoretical studies on the solvent and thermal effects of phenylbenzothiazole complex.

    Science.gov (United States)

    Mancini, Daiana T; Souza, Eugenio F; Caetano, Melissa S; Ramalho, Teodorico C

    2014-04-01

    The phenylbenzothiazole compounds show antitumor properties and are highly selective. In this paper, the (99)Tc chemical shifts based on the ((99m)Tc)(CO)3 (NNO) complex conjugated to the antitumor agent 2-(4'-aminophenyl)benzothiazole are reported. Thermal and solvent effects were studied computationally by quantum-chemical methods, using the density functional theory (DFT) (DFT level BPW91/aug-cc-pVTZ for the Tc and BPW91/IGLO-II for the other atoms) to compute the NMR parameters for the complex. We have calculated the (99)Tc NMR chemical shifts of the complex in gas phase and solution using different solvation models (polarizable continuum model and explicit solvation). To evaluate the thermal effect, molecular dynamics simulations were carried, using the atom-centered density matrix propagation method at the DFT level (BP86/LanL2dz). The results highlight that the (99)Tc NMR spectroscopy can be a promising technique for structural investigation of biomolecules, at the molecular level, in different environments.

  20. 1H NMR and FT-IR dataset based structural investigation of poly(amic acid)s and polyimides from 4,4′-diaminostilbene

    Science.gov (United States)

    Kumar, Amit; Tateyama, Seiji; Yasaki, Katsuaki; Ali, Mohammad Asif; Takaya, Naoki; Singh, Rajeev; Kaneko, Tatsuo

    2016-01-01

    Structural investigation of polymers by various available analytical methods is important in order to correlate the structure with polymer properties for which understanding of polymer structure is very important factor. The data presented here in this article shows the 1H NMR spectra used for the characterization of prepared poly(amic acid)s (PAAs). It is often difficult to assigns the peak in NMR of polymers due to its complexity. Data presented here helps in assigning the proton peak in complex NMR of PAAs prepared from aromatic diamines. Further functionality in polymer chains can be confirmed by FT-IR spectra. Change in functionality during some reaction or process can be monitored by disappearance or appearance of peaks in FT-IR. The complete imidization of PAAs to Polyimides (PIs) is difficult to analyze because of the chemical stability i.e. insolubility of PIs in most of the solvent therefore the completion of imidization process was confirmed using FTIR. PMID:26933669

  1. Experimental (XRD, IR and NMR) and theoretical investigations on 1-(2-nitrobenzoyl)3,5-bis(4-methoxyphenyl)-4,5-dihydro-1H-pyrazole

    Science.gov (United States)

    Evecen, Meryem; Tanak, Hasan; Tinmaz, Feyza; Dege, Necmi; Özer İlhan, İlhan

    2016-12-01

    The pyrazole compound 1-(2-nitrobenzoyl)3,5-bis(4-methoxyphenyl)-4,5-dihydro-1H-pyrazole (I) has been synthesized and characterized by IR, NMR and X-ray diffraction methods. The compound crystallizes in the monoclinic space group C2/c with a = 36.126(5) Ǻ, b = 8.1963(7) Ǻ, c = 14.3983(18) Ǻ, β = 100.825(10)° and Z = 8. The molecular geometry, vibrational frequencies and Gauge-Independent Atomic Orbital (GIAO) 1H and 13C NMR chemical shift values of 1-(2-nitrobenzoyl)3,5-bis(4-methoxyphenyl)-4,5-dihydro-1H-pyrazole in the ground state have been calculated using the density functional method (B3LYP) with the 6-311++G(d,p) basis set. The optimized parameters are in agreement with X-ray data. The calculated vibrational frequencies and chemical shift values were compared with experimental IR and NMR values. In addition, frontier molecular orbitals, molecular electrostatic potential and NBO analysis of (I) were investigated by DFT calculations.

  2. Comparison of diffusivity data derived from electrochemical and NMR investigations of the SeCN¯/(SeCN)2/(SeCN)3¯ system in ionic liquids.

    Science.gov (United States)

    Solangi, Amber; Bond, Alan M; Burgar, Iko; Hollenkamp, Anthony F; Horne, Michael D; Rüther, Thomas; Zhao, Chuan

    2011-06-02

    Electrochemical studies in room temperature ionic liquids are often hampered by their relatively high viscosity. However, in some circumstances, fast exchange between participating electroactive species has provided beneficial enhancement of charge transport. The iodide (I¯)/iodine (I(2))/triiodide (I(3)¯) redox system that introduces exchange via the I¯ + I(2) ⇌ I(3)¯ process is a well documented example because it is used as a redox mediator in dye-sensitized solar cells. To provide enhanced understanding of ion movement in RTIL media, a combined electrochemical and NMR study of diffusion in the {SeCN¯-(SeCN)(2)-(SeCN)(3)¯} system has been undertaken in a selection of commonly used RTILs. In this system, each of the Se, C and N nuclei is NMR active. The electrochemical behavior of the pure ionic liquid, [C(4)mim][SeCN], which is synthesized and characterized here for the first time, also has been investigated. Voltammetric studies, which yield readily interpreted diffusion-limited responses under steady-state conditions by means of a Random Assembly of Microdisks (RAM) microelectrode array, have been used to measure electrochemically based diffusion coefficients, while self-diffusion coefficients were measured by pulsed field gradient NMR methods. The diffusivity data, derived from concentration and field gradients respectively, are in good agreement. The NMR data reveal that exchange processes occur between selenocyanate species, but the voltammetric data show the rates of exchange are too slow to enhance charge transfer. Thus, a comparison of the iodide and selenocyanate systems is somewhat paradoxical in that while the latter give RTILs of low viscosity, sluggish exchange kinetics prevent any significant enhancement of charge transfer through direct electron exchange. In contrast, faster exchange between iodide and its oxidation products leads to substantial electron exchange but this effect does not compensate sufficiently for mass transport

  3. Micro-spectroscopic investigation of valence change processes in resistive switching SrTiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Koehl, Annemarie

    2014-05-15

    Due to physical limitations of the currently used flash memory in terms of writing speed and scalability, new concepts for data storage attract great interest. A possible alternative with promising characteristics are so-called ''Resistive Random Access Memories'' (ReRAM). These memory devices are based on the resistive switching effect where the electrical resistance of a metal-insulator-metal (MIM) structure can be switched reversibly by a current or voltage pulse. Although this effect attracted wide scientific as well as commercial interest, up to now the it is not fully understood on a microscopic scale. Consequently, in this work the chemical and physical modifications caused by the resistive switching process are studied by spectroscopic techniques. As most switching models predict a strongly localized rather than a homogeneous effect, advanced micro-spectroscopy techniques are employed where additionally the lateral structure of the sample is imaged. In this work Fe-doped SrTiO{sub 3} films are used as model material due to the thorough understanding of their defect chemistry. The epitaxial thin films are prepared by pulsed laser deposition. In a first approach, transmission X-ray microscopy is employed to study the bulk properties of ReRAM devices. At first, a new procedure for sample preparation based on a selective etching process is developed in order to realize photon-transparent samples. Investigations of switched devices reveal a significant contribution of Ti{sup 3+} states within growth defects. In contrast to the indirect evidence in previous studies, this observation directly confirms that the resistance change is based on a local redox-process. The localization of the switching process within the growth defects is explained by a self-accelerating process due to Joule heating within the pre-reduced defects. In a second approach, after removal of the top electrode the chemical and electronic structure of the former interface

  4. The study of polymers in geometrically confined states by the thermal analysis, the spectroscopic study, and the morphological investigation

    Science.gov (United States)

    Lu, Xiaolin

    2005-07-01

    This thesis focuses on the study of the different geometrically confined states of polyacrylamide (PAL) in bulk film, single chain globules, and thin films. The thermal analysis, the spectroscopic study, and the morphological investigation were carried out. The main contribution of this thesis is that we have acquired a better understanding about the glass transition (T g) behavior of polymers. Although the glass transition is a well known phenomenon for liquids with strong covalently bonded structures, and is especially noteworthy for amorphous polymers, understanding the glass transition still remains one of the most intriguing puzzles in condensed matter physics at present. The solution of the glass transition puzzle will ultimately influence different fields in polymer science, particularly biophysics and biochemistry. Our approach to this complicated assignment, the glass transition phenomenon, is to examine the glass transition behavior of polymer chains in 3 dimensional confinement for single molecular single chain globules, 1 dimensional confinement for polymer thin films, and 0 dimensional confinement for bulk state polymer. We found that the glass transition temperature of a polymer depends on several factors, such as the inter-chain interlock entanglement, the inter-chain molecular interactions, the intra-chain cohesional entanglement, and the local chain orientation and conformational entropy. These factors have been systematically investigated by carefully preparing the polymer samples in different confined states. The main conclusion is that, although the glass transition is a non-equilibrium dynamic property, the true glass transition can be reached when polymer chains are free of the inter-chain entanglement. A better example is illustrated, in this thesis, of the glass transition behavior for the well-annealed single chain globules. PAL single chain globules are prepared by spray drying from the dilute solution. The size and morphology of the

  5. Using 31P-NMR to investigate dynamics of soil phosphorus compounds in the Rothamsted Long Term Experiments

    Science.gov (United States)

    Blackwell, Martin; Turner, Ben; Granger, Steve; Hooper, Tony; Darch, Tegan; Hawkins, Jane; Yuan, Huimin; McGrath, Steve

    2015-04-01

    The technique of 31P-NMR spectroscopy has done more to advance the knowledge of phosphorus forms (especially organic phosphorus) in environmental samples than any other method. The technique has advanced such that specific compounds can be identified where previously only broad categories such as orthophosphate monoesters and diesters were distinguishable. The Soil Archive and Long Term Experiments at Rothamsted Research, UK, potentially provides an unequalled opportunity to use this technique to observe changes in soil phosphorus compounds with time and under different treatments, thereby enhancing our understanding of phosphorus cycling and use by plants. Some of the earliest work using this technique on soils was carried out by Hawkes et al. in 1984 and this used soils from two of the oldest Rothamsted Long Term Experiments, namely Highfield and Park Grass. Here we revisit the samples studied in this early work and reanalyse them using current methodology to demonstrate how the 31P-NMR technique has advanced. We also present results from a study on the phosphorus chemistry in soils along the Hoosfield acid strip (Rothamsted, UK), where a pH gradient from 3.7 to 7.8 occurs in a single soil with little variation in total phosphorus (mean ± standard deviation 399 ± 27 mg P kg-1). Soil pH was found to be an important factor in determining the proportion of phosphomonoesters and phosphodiesters in the soil organic phosphorus, although total organic phosphorus concentrations were a relatively consistent proportion of the total soil phosphorus (36 ± 2%) irrespective of soil pH. Key words. 31P-NMR, soil organic phosphorus, long term experiments, Hoosfield acid strip

  6. A 125Te and 23Na NMR investigation of the structure and crystallisation of sodium tellurite glasses.

    Science.gov (United States)

    Holland, D; Bailey, J; Ward, G; Turner, B; Tierney, P; Dupree, R

    2005-01-01

    125Te static nuclear magnetic resonance (NMR) and 23Na and 125Te magic angle spinning (MAS) NMR have been used, in conjunction with X-ray diffraction, to examine the structure and crystallisation behaviour of glasses of composition xNa2O.(1-x)TeO2 (0.075 x 0.4). The MAS NMR 23Na spectra from the glasses are broad and featureless but shift by approximately +5 ppm with increased x, i.e. as the system becomes more ionic. The static 125Te NMR spectra show an increase in axial symmetry with increasing x, indicating a shift from predominantly [TeO4] to [TeO3] structural units. The 23Na and 125Te spectra from the crystallised samples have been fitted to obtain information on the sites in the metastable crystal phases, which are the first to form on heating and which are therefore more closely related to the glass structure than thermodynamically stable crystal phases. New sodium tellurite phases are reported, including a sodium stabilised, face centred cubic phase related to delta-TeO2; a metastable form of Na2Te4O9 containing 3 sodium and 4 tellurium sites; and a metastable form of Na2Te2O5 containing 2 sodium sites. There is evidence of oxidation of TeIV to TeVI occurring in glasses with high values of x and, at x=0.40 and 0.50 (outside the glass forming range), some sodium metatellurate (Na2TeO4) is formed at the same time as sodium metatellurite (Na2TeO3). The 125Te shift is very sensitive to environment within the sodium tellurite system, covering more than 320 ppm, with anisotropies varying from 640 to 1540 ppm. The lack of features in the 125Te spectra of the glass phases, combined with the large shift range and high but variable anisotropy, means than it is not possible to obtain a unique fit to any presumed species present. Furthermore, the chemical shift anisotropy parameters for three of the four Te sites in the Na2Te4O9 phase are found to lie outside the range used for previous simulations of glass spectra.

  7. Lipid–protein interactions in DHPC micelles containing the integral membrane protein OmpX investigated by NMR spectroscopy

    OpenAIRE

    Fernández, César; Hilty, Christian; Wider, Gerhard; Wüthrich, Kurt

    2002-01-01

    Intermolecular nuclear Overhauser effects (NOEs) between the integral outer membrane protein OmpX from Escherichia coli and dihexanoylphosphatidylcholine (DHPC) provided a detailed description of protein–detergent interactions. The NOEs were measured in 3D 15N- and 13C-resolved [1H,1H]-NOESY spectra recorded with selectively methyl-protonated and otherwise uniformly 2H,13C,15N-labeled OmpX in micelles of DHPC at natural isotope abundance. In these mixed micelles the NMR structure of OmpX cons...

  8. Lipid–protein interactions in DHPC micelles containing the integral membrane protein OmpX investigated by NMR spectroscopy

    OpenAIRE

    Fernández, César; Hilty, Christian; Wider, Gerhard; Wüthrich, Kurt

    2002-01-01

    Intermolecular nuclear Overhauser effects (NOEs) between the integral outer membrane protein OmpX from Escherichia coli and dihexanoylphosphatidylcholine (DHPC) provided a detailed description of protein–detergent interactions. The NOEs were measured in 3D 15N- and 13C-resolved [1H,1H]-NOESY spectra recorded with selectively methyl-protonated and otherwise uniformly 2H,13C,15N-labeled OmpX in micelles of DHPC at natural isotope abundance. In these mixed micelles the NMR structure of OmpX cons...

  9. Preparation of Uniformly 13C,15N-Labeled Recombinant Human Amylin for Solid-State NMR Investigation

    DEFF Research Database (Denmark)

    Kosicka, Iga; Kristensen, Torsten; Bjerring, Morten

    2014-01-01

    of amyloidogenic proteins in large amounts remains challenging due to their aggregation potential, toxicity for cells and difficult purification. In this work, we report a method for the production of large amounts of uniformly labeled 13C,15N-human amylin, being one of the most amyloidogenic peptides known...... crystal ordering, solid-state NMR forms the most suited method to determine the structures of the fibrils with atomic resolution. To exploit this potential, large amounts of isotopic-labeled protein need to be obtained through recombinant protein expression. However, expression and purification...

  10. Interference of spin-, charge- and orbital degrees of freedom in low-carrier rare earth compounds, investigated by NMR

    Science.gov (United States)

    Wada, S.

    2006-05-01

    In rare earth compounds, the concentration of charge carriers is known to strongly influence the nature, and the charge carriers caused by valence fluctuations result in a complete suppression of the magnetic state, as typically observed for YbInCu4. The notable exception has been reported for the cubic (NaCl structure) TmX and YbX families with low carrier, that exhibits antiferro-magnetic (AFM) order at low temperatures. Among these families, TmTe and YbSb with degenerate low-lying multiplets have an additional transition of antiferro-quadrupolar (AFQ) orderings. To elucidate the interplay between the electronic transport and magnetic and/or orbital phenomena close to a semiconductor-to-metal transition, we have carried NMR measurements of 63Cu in YbInCu4, 125Te in TmTe, and 121Sb in YbSb down to 1.2 K and the implication of NMR findings is discussed in terms of the CEF splitting.

  11. Proton NMR investigation of heme and surrounding proton in low-spin cyanide-ligated bacterial hemoglobin from Vitreoscilla

    Institute of Scientific and Technical Information of China (English)

    夏佑林; 吴季辉; 光寿红; 张海阳; 梁山; 施蕴渝

    2000-01-01

    1H NMR spectra of low-spin cyanide-ligated bacterial hemoglobin from Vitreoscilla (VtHb-CN) are reported. The assignments of the 1H NMR spectra of VtHb-CN have been made through MCOSY, NOESY, 1D TOE and SUPERWEFT experiments. Almost all resonance peaks of heme and ligated His85 are identified. The spin-lattice relaxation time T1’s and the variation relationships of chemical shifts of these peaks with temperature have been acquired, from which the distances between the measured protons and Fe3+, and the diamagnetic chemical shifts have been acquired, respectively. The ionization constants of pKa’s of ligated His85 are determined through pH titration of chemical shift, which is 4.95 for ligated His85 C2H proton. The lower pKa is attributed to the influence of the Fe3+ of carrying positive charge and the coordination of His85 and Fe3+ of heme.

  12. 15N NMR investigation of the covalent binding of reduced TNT amines to soil humic acid, model compounds, and lignocellulose.

    Science.gov (United States)

    Thorn, K A; Kennedy, K R

    2002-09-01

    The five major reductive degradation products of TNT-4ADNT (4-amino-2,6-dinitrotoluene), 2ADNT (2-amino-4,6-dinitrotoluene), 2,4DANT (2,4-diamino-6-nitrotoluene), 2,6DANT (2,6-diamino-4-nitrotoluene), and TAT (2,4,6-triaminotoluene)-labeled with 15N in the amine positions, were reacted with the IHSS soil humic acid and analyzed by 15N NMR spectrometry. In the absence of catalysts, all five amines underwent nucleophilic addition reactions with quinone and other carbonyl groups in the soil humic acid to form both heterocyclic and nonheterocyclic condensation products. Imine formation via 1,2-addition of the amines to quinone groups in the soil humic acid was significant with the diamines and TAT but not the monoamines. Horseradish peroxidase (HRP) catalyzed an increase in the incorporation of all five amines into the humic acid. In the case of the diamines and TAT, HRP also shifted the binding away from heterocyclic condensation product toward imine formation. A comparison of quantitative liquid phase with solid-state CP/MAS 15N NMR indicated that the CP experiment underestimated imine and heterocyclic nitrogens in humic acid, even with contact times optimal for observation of these nitrogens. Covalent binding of the mono- and diamines to 4-methylcatechol, the HRP catalyzed condensation of 4ADNT and 2,4DANT to coniferyl alcohol, and the binding of 2,4DANT to lignocellulose with and without birnessite were also examined.

  13. Hydrogen-bond and solvent dynamics in transition metal complexes: a combined simulation and NMR-investigation.

    Science.gov (United States)

    Huang, Jing; Häussinger, Daniel; Gellrich, Urs; Seiche, Wolfgang; Breit, Bernhard; Meuwly, Markus

    2012-12-13

    Self-assembling ligands through complementary hydrogen-bonding in the coordination sphere of a transition metal provides catalysts with unique properties for carbon-carbon and carbon-heteroatom formation. Their most distinguishing chemical bonding pattern is a double-hydrogen-bonded motif, which determines much of the chemical functionality. Here, we discuss the possibility of double proton transfer (DPT) along this motif using computational and experimental methods. The infrared and NMR spectral signatures for the double-hydrogen-bonded motif are analyzed. Atomistic simulations and experiments suggest that the dynamics of the catalyst is surprisingly complex and displays at least three different dynamical regimes which can be distinguished with NMR spectroscopy and analyzed from computation. The two hydrogen bonds are kept intact and in rapid tautomeric exchange down to 125 K, which provides an estimate of 5 kcal/mol for the barrier for DPT. This is confirmed by the simulations which predict 5.8 kcal/mol for double proton transfer. A mechanistic interpretation is provided and the distribution of the solvent shell surrounding the catalyst is characterized from extensive simulations.

  14. Comparative Investigation of the Ionicity of Aprotic and Protic Ionic Liquids in Molecular Solvents by using Conductometry and NMR Spectroscopy.

    Science.gov (United States)

    Thawarkar, Sachin; Khupse, Nageshwar D; Kumar, Anil

    2016-04-01

    Electrical conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium-based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15 K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, [bmIm][BF4 ], displays 100 % ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the (1) H NMR chemical shifts of the ionic liquids. The self-diffusion coefficients D of the cation and anion of [HmIm][CH3 COO] in D2 O and in [D6 ]DMSO are determined by using (1) H nuclei with pulsed field gradient spin-echo NMR spectroscopy.

  15. Spectroscopic investigations on sorption of uranium onto suspended bentonite. Effects of pH, ionic strength and complexing anions

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Parveen Kumar; Pathak, Priyanath; Mohapatra, Manoj; Mohapatra, Prasanta Kumar [Bhabha Atomic Research Centre, Mumbai (India). Radiochemistry Div.; Yadav, Ashok Kumar; Jha, Sambhunath; Bhattacharyya, Dibyendu [Bhabha Atomic Research Centre, Mumbai (India). Atomic and Molecular Physics Div.

    2015-06-01

    Batch sorption experiments were carried out under aerobic conditions to understand the sorption behavior of U(VI) onto bentonite clay under varying pH (2-8) and ionic strength (I = 0.01 - 1 M (NaClO{sub 4})) conditions. The influences of different complexing anions (1 x 10{sup -4} M) such as oxalic acid (ox), carbonate (CO{sub 3}{sup 2-}), citric acid (cit), and humic acid (HA, 10 mg/L) on the sorption behavior were also investigated. The sorption of U(VI) increased with increasing pH up to pH 6 beyond which a decrease was attributed to the formation of anionic carbonate species. Marginal influence of the change in the ionic strength of the medium on the sorption profile of uranium suggested inner-sphere complexation onto the bentonite surface. The presence of humic acid showed interesting sorption profile with varying pH. Initially, there was an enhancement in the sorption with increased pH followed by a plateau and finally a decrease thereafter due to the formation of aqueous U(VI)-humate complexes. Spectroscopic studies such as UV spectrophotometry, luminescence and extended X-ray absorption fine structure (EXAFS) measurements were also performed to understand the changes in aqueous speciation of U(VI) ion. The luminescence yields of different aqueous U(VI) species followed the order: U(VI){sub Hydroxy} > U(VI){sub HumicAcid} > U(VI){sub carbonate} > U(VI){sub citrate}. The lower luminescence yield of U(VI)carbonate complex can be attributed to the strong dynamic quenching by carbonate at room temperature. The U(VI) samples shows two distinct life-time suggesting the presence of the different luminescent U(VI) species. Similar trend was observed for U(VI)-bentonite suspension in presence/absence of the complexing ligands. There was luminescence quenching for the sorbed U(VI) due to surface complexation. These observations were further supported by spectrophotometric measurements. EXAFS spectra of U(VI) samples were recorded in luminescence mode at the U L{sub 3

  16. Interaction of an aluminum atom with an alkaline earth atom: Spectroscopic and ab initio investigations of AlCa

    Science.gov (United States)

    Behm, Jane M.; Morse, Michael D.; Boldyrev, Alexander I.; Simons, Jack

    1994-10-01

    A spectroscopic analysis of diatomic AlCa generated by laser vaporization of a 2:1 Al:Ca metal alloy followed by supersonic expansion has been completed using resonant two-photon ionization spectroscopy. Four excited electronic states have been identified and investigated in the energy region from 13 500 to 17 900 cm-1. These are the [13.5] 2Πr, the [15.8] 2Σ, the [17.0] 2Δ3/2(?), and the [17.6] 2Δ3/2 states. From rotational analysis excited state bond lengths have been measured for three of the four excited states, and the ground state has been unambiguously determined as a 2Πr state with a weighted least squares value of the ground state bond length of r0` = 3.1479± 0.0010 Å. The ionization energy of the molecule has also been directly determined as 5.072±0.028 eV. Ab initio calculations for the potential energy curves of seven low-lying states of AlCa [X 2Πr, 2Σ+, 4Σ-, 4Πr, 2Πr(2), 2Δ, and 2Σ-] and for the X 1Σ+ ground electronic state of AlCa+ have been carried out. In agreement with experiment, 2Πr is calculated to be the ground electronic state of the neutral molecule. The dissociation energies of AlCa (X 2Πr) into Al(3s23p1,2P0)+Ca(4s2,1S) and for AlCa+ (X 1Σ+) into Al+(3s2,1S)+Ca(4s2,1S) are calculated to be 0.47 and 1.50 eV, respectively. The excited 2Σ+, 4Σ-, 4Πr, 2Πr(2), 2Δ, and 2Σ- states are calculated to lie 0.2, 0.7, 0.7, 1.1, 1.1, and 1.1 eV above X 2Πr, respectively, and the vertical and adiabatic ionization energies of AlCa have been calculated to be 5.03 and 4.97 eV, respectively.

  17. Thermodynamic and Spectroscopic Investigation of Interactions between Reactive Red 223 and Reactive Orange 122 Anionic Dyes and Cetyltrimethyl Ammonium Bromide (CTAB Cationic Surfactant in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Muhammad Irfan

    2014-01-01

    Full Text Available The present study describes the conductometric and spectroscopic study of the interaction of reactive anionic dyes, namely, reactive red 223 and reactive orange 122 with the cationic surfactant cetyltrimethyl ammonium bromide (CTAB. In a systematic investigation, the electrical conductivity data was used to calculate various thermodynamic parameters such as free energy (ΔG, enthalpy (ΔH, and the entropy (ΔS of solubilization. The trend of change in these thermodynamic quantities indicates toward the entropy driven solubilization process. Moreover, the results from spectroscopic data reveal high degree of solubilization, with strong interactions observed in the cases of both dyes and the CTAB. The spontaneous nature of solubilization and binding was evident from the observed negative values of free energies (ΔGp and ΔGb.

  18. Thermodynamic and spectroscopic investigation of interactions between reactive red 223 and reactive orange 122 anionic dyes and cetyltrimethyl ammonium bromide (CTAB) cationic surfactant in aqueous solution.

    Science.gov (United States)

    Irfan, Muhammad; Usman, Muhammad; Mansha, Asim; Rasool, Nasir; Ibrahim, Muhammad; Rana, Usman Ali; Siddiq, Mohammad; Zia-Ul-Haq, Muhammad; Jaafar, Hawa Z E; Khan, Salah Ud-Din

    2014-01-01

    The present study describes the conductometric and spectroscopic study of the interaction of reactive anionic dyes, namely, reactive red 223 and reactive orange 122 with the cationic surfactant cetyltrimethyl ammonium bromide (CTAB). In a systematic investigation, the electrical conductivity data was used to calculate various thermodynamic parameters such as free energy (ΔG), enthalpy (ΔH), and the entropy (ΔS) of solubilization. The trend of change in these thermodynamic quantities indicates toward the entropy driven solubilization process. Moreover, the results from spectroscopic data reveal high degree of solubilization, with strong interactions observed in the cases of both dyes and the CTAB. The spontaneous nature of solubilization and binding was evident from the observed negative values of free energies (ΔG p and ΔG b).

  19. Structural features of a bituminous coal and their changes during low-temperature oxidation and loss of volatiles investigated by advanced solid-state NMR spectroscopy

    Science.gov (United States)

    Mao, J.-D.; Schimmelmann, A.; Mastalerz, Maria; Hatcher, P.G.; Li, Y.

    2010-01-01

    Quantitative and advanced 13C solid-state NMR techniques were employed to investigate (i) the chemical structure of a high volatile bituminous coal, as well as (ii) chemical structural changes of this coal after evacuation of adsorbed gases, (iii) during oxidative air exposure at room temperature, and (iv) after oxidative heating in air at 75 ??C. The solid-state NMR techniques employed in this study included quantitative direct polarization/magic angle spinning (DP/MAS) at a high spinning speed of 14 kHz, cross polarization/total sideband suppression (CP/TOSS), dipolar dephasing, CH, CH2, and CHn selection, 13C chemical shift anisotropy (CSA) filtering, two-dimensional (2D) 1H-13C heteronuclear correlation NMR (HETCOR), and 2D HETCOR with 1H spin diffusion. With spectral editing techniques, we identified methyl CCH 3, rigid and mobile methylene CCH2C, methine CCH, quaternary Cq, aromatic CH, aromatic carbons bonded to alkyls, small-sized condensed aromatic moieties, and aromatic C-O groups. With direct polarization combined with spectral-editing techniques, we quantified 11 different types of functional groups. 1H-13C 2D HETCOR NMR experiments indicated spatial proximity of aromatic and alkyl moieties in cross-linked structures. The proton spin diffusion experiments indicated that the magnetization was not equilibrated at a 1H spin diffusion time of 5 ms. Therefore, the heterogeneity in spatial distribution of different functional groups should be above 2 nm. Recoupled C-H long-range dipolar dephasing showed that the fraction of large charcoal-like clusters of polycondensed aromatic rings was relatively small. The exposure of this coal to atmospheric oxygen at room temperature for 6 months did not result in obvious chemical structural changes of the coal, whereas heating at 75 ??C in air for 10 days led to oxidation of coal and generated some COO groups. Evacuation removed most volatiles and caused a significant reduction in aliphatic signals in its DP

  20. Using solid 13C NMR coupled with solution 31P NMR spectroscopy to investigate molecular species and lability of organic carbon and phosphorus from aquatic plants in Tai Lake, China

    Science.gov (United States)

    Aquatic plants are involved in the storage and release capacity for organic matter and nutrients. In this study, solid 13C and solution 31P nuclear magnetic resonance (NMR) spectroscopy were used to characterize the biomass samples of six aquatic plants. Solid 13C NMR spectroscopy revealed the domin...

  1. Investigation of a shock wave in an arcjet He plasma by using an electric probe and emission spectroscope

    Energy Technology Data Exchange (ETDEWEB)

    Kumagawa, G.; Kozue, K.; Fujino, S.; Matsuoka, L.; Endo, T.; Namba, S. [Hiroshima University, Higashi-Hiroshima (Japan); Tamura, N. [National Institute for Fusion Science, Gifu (Japan); Ezumi, N. [Nagano National College of Technology, Nagano (Japan)

    2014-10-15

    We developed an arcjet plasma device having a converging and diverging supersonic conical nozzle. Bright and dark emission structures were formed, depending on the gas pressure in the expansion section. In order to understand the mechanism for the formation of the structures, we evaluated the plasma parameters (electron density and temperature) by using a single probe and a visible emission spectroscope. The analysis of the probe measurements showed no temperature variation around the bright emission region. The plasma density increased significantly by a factor of two. Similar trends were also observed in the spectroscopic measurements. Moreover, the cell width (wavelength) of the shock wave calculated from the compressible fluid dynamics was in good agreement with the experimental value, indicating that this emission structure was caused by a shock cell that could be described by using compressible flow dynamics.

  2. Spectroscopic (FT-IR, FT-Raman, UV, 1H and 13C NMR) profiling and theoretical calculations of (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]hydrazinecarboxamide: An anticonvulsant agent

    Science.gov (United States)

    Haress, Nadia G.; Govindarajan, Munusamy; AL-Wabli, Reem I.; Almutairi, Maha S.; Al-Alshaikh, Monirah A.; Al-Saadi, Abdulaziz A.; Attia, Mohamed I.

    2016-08-01

    Vibrational characteristics of the anticonvulsant agent, (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]hydrazinecarboxamide ((2E)-IPHC) have been investigated. The computational data are obtained by adopting ab initio Hartree-Fock (HF) and DFT/B3LYP/6-31 + G(d,p) methods. The most stable conformer is identified by a potential energy scan. The optimized geometrical parameters indicated that the overall symmetry of the most stable conformer is CS. Atoms in molecules (AIM) analysis is contained out and the chemical bondings between the atoms are as characterized. Mulliken atomic charges and simulated thermo-molecular (heat capacity and enthalpy) characteristics of the (2E)-IPHC molecule also have been analyzed. The magnitude of the molecular electrostatic potential (MEP) of oxygen, hydrogen, and nitrogen atoms as well as phenyl and imidazole rings in the title molecule were investigated along with their contribution to the biological activity. The energy gap between HOMO and LUMO orbitals has been found to be 5.1334 eV in the gaseous phase. Excitation energies, oscillator strength and wavelengths were computed by the time-dependent density function theory (TD-DFT) approach. Predicted wavenumbers have been assigned and they are consistent with the experimental values. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the (2E)-IPHC molecule were computed by the gauge independent atomic orbital (GIAO) method and were compared with the experimental results.

  3. Spectroscopic investigations of newly formed betulin-cyclodextrin guest-host type complexes as potential anti skin cancer candidates

    Science.gov (United States)

    Falamaş, A.; Pînzaru, S. Cînta; Chiş, V.; Dehelean, C.

    2011-05-01

    Betulin and the related compounds found in the outer bark of the birch tree have attached an increasing interest in the pharmaceutical formulation, due to their anti-cancer activity. Betulin exhibits a very poor solubility; therefore new approaches are required, such as the preparation of the guest-host type complexes using cyclodextrins. The new prepared betulin - hydroxy-propyl-gamma-cyclodextrin (HPGCD) complexes have been obtained and characterized using vibrational spectroscopic techniques in conjunction with quantum chemical calculation.

  4. αB-Crystallin. A Hybrid Solid-State/Solution-State NMR Investigation Reveals Structural Aspects of the Heterogeneous Oligomer

    Energy Technology Data Exchange (ETDEWEB)

    Jehle, Stefan [Freie Univ., Berlin (Germany); Leibniz Inst. for Molecular Pharmacology, Berlin (Germany); van Rossum, Barth [Leibniz Inst. for Molecular Pharmacology, Berlin (Germany); Stout, Joseph R. [Univ. of Washington, Seattle, WA (United States); Noguchi, Satoshi M. [Univ. of Washington, Seattle, WA (United States); Falber, Katja [Leibniz Inst. for Molecular Pharmacology, Berlin (Germany); Rehbein, Kristina [Leibniz Inst. for Molecular Pharmacology, Berlin (Germany); Oschkinat, Hartmut [Freie Univ., Berlin (Germany); Leibniz Inst. for Molecular Pharmacology, Berlin (Germany); Klevit, Rachel E. [Univ. of Washington, Seattle, WA (United States); Rajagopal, Ponni [Univ. of Washington, Seattle, WA (United States)

    2008-11-14

    Atomic-level structural information on αB-Crystallin (αB), a prominent member of the small heat-shock protein family, has been a challenge to obtain due its polydisperse oligomeric nature. We show that magic-angle spinning solid-state NMR can be used to obtain high-resolution information on an ~580-kDa human αB assembled from 175-residue 20-kDa subunits. An ~100-residue α-crystallin domain is common to all small heat-shock proteins, and solution-state NMR was performed on two different α- crystallin domain constructs isolated from αB. In vitro, the chaperone-like activities of full-length αB and the isolated α-crystallin domain are identical. Chemical shifts of the backbone and Cβ resonances have been obtained for residues 64–162 (α-crystallin domain plus part of the C-terminus) in αB and the isolated α-crystallin domain by solid-state and solution-state NMR, respectively. Both sets of data strongly predict six β-strands in the α-crystallin domain. A majority of residues in the α-crystallin domain have similar chemical shifts in both solid-state and solution-state, indicating similar structures for the domain in its isolated and oligomeric forms. Sites of intersubunit interaction are identified from chemical shift differences that cluster to specific regions of the α-crystallin domain. Multiple signals are observed for the resonances of M68 in the oligomer, identifying the region containing this residue as existing in heterogeneous environments within αB. Evidence for a novel dimerization motif in the human α-crystallin domain is obtained by a comparison of (i) solid-state and solution-state chemical shift data and (ii) 1H–15N heteronuclear single quantum coherence spectra as a function of pH. The isolated α-crystallin domain undergoes a dimer–monomer transition over the pH range 7.5–6.8. This steep pHdependent switch may be important for αB to function optimally (e.g., to preserve the filament integrity

  5. Recent Advances in Solution NMR: Fast Methods and Heteronuclear Direct Detection

    Energy Technology Data Exchange (ETDEWEB)

    Felli, I.C. [CERM and Depatment of Chemistry, University of Florence, 50019 (Italy); Brutscher, B. [DSV-IBS, 38027 Grenoble (France)

    2009-07-01

    Today, NMR spectroscopy is the technique of choice to investigate molecular structure, dynamics, and interactions in solution at atomic resolution. A major limitation of NMR spectroscopy for the study of biological macromolecules such as proteins, nucleic acids, and their complexes, has always been its low sensitivity, a consequence of the weak magnetic spin interactions. Therefore many efforts have been invested in the last decade to improve NMR instrumentation in terms of experimental sensitivity. As a result of these efforts, the availability of high-field magnets, cryogenically cooled probes, and probably in the near future hyper-polarization techniques, the intrinsic NMR sensitivity has increased by at least one order of magnitude. Stimulated by new challenges in the life sciences, these technical improvements have triggered the development of new NMR methods for the study of molecular systems of increasing size and complexity. Herein, we focus on two examples of recently developed NMR methodologies. First, advanced multidimensional data acquisition schemes provide a speed increase of several orders of magnitude. Second, NMR methods based on the direct detection of low-gamma nuclei present a new spectroscopic tool, highly complementary to conventional NMR techniques. These new methods provide powerful new NMR tools for the study of short-lived molecules, large and intrinsically unstructured proteins, paramagnetic systems, as well as for the characterization of molecular kinetic processes at atomic resolution. These examples illustrate how NMR is continuously adapting to the new challenges in the life sciences, with the focus shifting from the characterization of single biomolecules to an integrated view of interacting molecular networks observed at varying levels of biological organization. (authors)

  6. Supramolecular self-assembly of a new multi-conformational Schiff base through hydrogen bonds: Crystal structure, spectroscopic and theoretical investigation

    Science.gov (United States)

    Rocha, Mariana; Di Santo, A.; Echeverría, G. A.; Piro, O. E.; Cukiernik, F. D.; Ulic, S. E.; Gil, Diego M.

    2017-04-01

    The compound 4-(4-dimethylaminobenzylidene)aminoacetophenone was synthesized by condensation of 4-aminoacetophenone and 4-(dimethylamino) benzaldehyde in ethanol. This compound was characterized by CG-MS, infrared, Raman, UV-Vis, 1H and 13C NMR spectroscopy. The crystal structure was solved by single-crystal X-ray diffraction methods. The crystallographic data reveals that there are four independent molecules per asymmetric unit, that mainly differ from one another in rotations around the σ-bond of the azomethine N-atom with the phenyl ring. A detailed analysis of the intermolecular interactions in the four conformers of the compound has been performed using Hirshfeld surfaces and their associated two-dimensional fingerprint plots. The optimized geometrical parameters and calculated spectroscopic features obtained by quantum chemical calculations at B3LYP method show a very good agreement with the experimental data. Moreover, Natural Bond Orbital (NBO) analysis confirms the strong hyper-conjugative LP N(n1)→ σ* C(n9)sbnd H interaction between the lone pair located in the N-atom of the azomethine group and the Csbnd H bond. Liquid crystalline properties of the Schiff base were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and Powder X-ray diffraction techniques. Mesomorphic behaviour was observed in this unsymmetrical azomethine. Based on POM and DSC measurements, the hexatic Smetic B phase was detected.

  7. Synthesis, spectroscopic characterization and structural investigations of a new charge transfer complex of 2,6-diaminopyridine with 3,5-dinitrobenzoic acid: DNA binding and antimicrobial studies

    Science.gov (United States)

    Khan, Ishaat M.; Ahmad, Afaq; Kumar, Sarvendra

    2013-03-01

    A new charge transfer (CT) complex [(DAPH)+(DNB)-] consisting of 2,6-diaminopyridine (DAP) as donor and 3,5-dinitrobenzoic acid (DNB-H) as acceptor, was synthesized and characterized by FTIR, 1H and 13C NMR, ESI mass spectroscopic and X-ray crystallographic techniques. The hydrogen bonding (N+-H⋯O-) plays an important role to consolidate the cation and anion together. CT complex shows a considerable interaction with Calf thymus DNA. The CT complex was also tested for its antibacterial activity against two Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis and two Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa strains by using Tetracycline as standard, and antifungal property against Aspergillus niger, Candida albicans, and Penicillium sp. by using Nystatin as standard. The results were compared with standard drugs and significant conclusions were obtained. A polymeric net work through H-bonding interactions between neighboring moieties was observed. This has been attributed to the formation of 1:1 type CT complex.

  8. Magnetic properties of MnF3 investigated by 55Mn NMR and M(H) measurement

    Science.gov (United States)

    Choi, Baeksoon; Kang, Byeongki; Kim, Changsoo; Park, Sejun; Lee, Soonchil

    2017-01-01

    The M(T) and M(H) curves were measured to study the spin-ordered state in MnF3 at low temperatures. In order to obtain the temperature dependence of magnetization, Mn3+ NMR resonance frequency was measured as a function of temperature. The resulting curve fits well to the initial temperature dependence of the magnetization expected for antiferromagnets with magnetic anisotropy, T 3 / 2 exp(-EG /kB T) , with an energy gap EG of about 30 K. From the comparison of the M(H) curve and classical theory, the relation between the anisotropy energy, Ka, and the exchange coupling constant between the nearest neighbors, J1, was found to be Ka ∼ - 1.8J1 + 9.8 in the absolute temperature unit.

  9. NMR-Based Metabonomic Investigation of Heat Stress in Myotubes Reveals a Time-Dependent Change in the Metabolites

    DEFF Research Database (Denmark)

    Straadt, Ida K; Young, Jette F; Bross, Peter;

    2010-01-01

    NMR-based metabonomics was applied to elucidate the time-dependent stress responses in mouse myotubes after heat exposure of either 42 or 45 degrees C for 1 h. Principal component analysis (PCA) revealed that the gradual time-dependent changes in metabolites contributing to the clustering...... and separation of the control samples from the different time points after heat stress primarily are in the metabolites glucose, leucine, lysine, phenylalanine, creatine, glutamine, and acetate. In addition, PC scores revealed a maximum change in metabolite composition 4 h after the stress exposure; thereafter......, samples returned toward control samples, however, without reaching the control samples even 10 h after stress. The results also indicate that the myotubes efficiently regulate the pH level by release of lactate to the culture medium at a heat stress level of 42 degrees C, which is a temperature level...

  10. NMR-based metabolomic investigation of bioactivity of chemical constituents in black raspberry (Rubus occidentalis L.) fruit extracts.

    Science.gov (United States)

    Paudel, Liladhar; Wyzgoski, Faith J; Giusti, M Monica; Johnson, Jodee L; Rinaldi, Peter L; Scheerens, Joseph C; Chanon, Ann M; Bomser, Joshua A; Miller, A Raymond; Hardy, James K; Reese, R Neil

    2014-02-26

    Black raspberry (Rubus occidentalis L.) (BR) fruit extracts with differing compound profiles have shown variable antiproliferative activities against HT-29 colon cancer cell lines. This study used partial least-squares (PLS) regression analysis to develop a high-resolution (1)H NMR-based multivariate statistical model for discerning the biological activity of BR constituents. This model identified specific bioactive compounds and ascertained their relative contribution against cancer cell proliferation. Cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside were the predominant contributors to the extract bioactivity, but salicylic acid derivatives (e.g., salicylic acid glucosyl ester), quercetin 3-glucoside, quercetin 3-rutinoside, p-coumaric acid, epicatechin, methyl ellagic acid derivatives (e.g., methyl ellagic acetyl pentose), and citric acid derivatives also contributed significantly to the antiproliferative activity of the berry extracts. This approach enabled the identification of new bioactive components in BR fruits and demonstrates the utility of the method for assessing chemopreventive compounds in foods and food products.

  11. NMR-based metabolite profiling of human milk: A pilot study of methods for investigating compositional changes during lactation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Junfang [Department of Chemistry, Umeå University (Sweden); Domellöf, Magnus [Department of Clinical Sciences, Pediatrics, Umeå University (Sweden); Zivkovic, Angela M. [Foods for Health Institute, University of California, Davis, CA (United States); Department of Nutrition, University of California, Davis, CA (United States); Larsson, Göran [Department of Medical Biochemistry and Biophysics, Unit of Research, Education and Development-Östersund, Umeå University (Sweden); Öhman, Anders, E-mail: anders.ohman01@umu.se [Department of Pharmacology and Clinical Neuroscience, Umeå University (Sweden); Nording, Malin L., E-mail: malin.nording@umu.se [Department of Chemistry, Umeå University (Sweden)

    2016-01-15

    Low-molecular-weight metabolites in human milk are gaining increasing interest in studies of infant nutrition. In the present study, the milk metabolome from a single mother was explored at different stages of lactation. Metabolites were extracted from sample aliquots using either methanol/water (MeOH/H{sub 2}O) extraction or ultrafiltration. Nuclear magnetic resonance (NMR) spectroscopy was used for metabolite identification and quantification, and multi- and univariate statistical data analyses were used to detect changes over time of lactation. Compared to MeOH/H{sub 2}O extraction, ultrafiltration more efficiently reduced the interference from lipid and protein resonances, thereby enabling the identification and quantification of 36 metabolites. The human milk metabolomes at the early (9–24 days after delivery) and late (31–87 days after delivery) stages of lactation were distinctly different according to multi- and univariate statistics. The late lactation stage was characterized by significantly elevated concentrations of lactose, choline, alanine, glutamate, and glutamine, as well as by reduced levels of citrate, phosphocholine, glycerophosphocholine, and N-acetylglucosamine. Our results indicate that there are significant compositional changes of the human milk metabolome also in different phases of the matured lactation stage. These findings complement temporal studies on the colostrum and transitional metabolome in providing a better understanding of the nutritional variations received by an infant. - Highlights: • 36 metabolites were simultaneously quantified in human milk by NMR. • Ultrafiltration more efficiently reduces interferences than MeOH/H{sub 2}O extraction. • Compositional changes of the human milk exist during the matured lactation stage.

  12. Structural properties of carbon nanotubes derived from 13C NMR

    KAUST Repository

    Abou-Hamad, E.

    2011-10-10

    We present a detailed experimental and theoretical study on how structural properties of carbon nanotubes can be derived from 13C NMR investigations. Magic angle spinning solid state NMR experiments have been performed on single- and multiwalled carbon nanotubes with diameters in the range from 0.7 to 100 nm and with number of walls from 1 to 90. We provide models on how diameter and the number of nanotube walls influence NMR linewidth and line position. Both models are supported by theoretical calculations. Increasing the diameter D, from the smallest investigated nanotube, which in our study corresponds to the inner nanotube of a double-walled tube to the largest studied diameter, corresponding to large multiwalled nanotubes, leads to a 23.5 ppm diamagnetic shift of the isotropic NMR line position δ. We show that the isotropic line follows the relation δ = 18.3/D + 102.5 ppm, where D is the diameter of the tube and NMR line position δ is relative to tetramethylsilane. The relation asymptotically tends to approach the line position expected in graphene. A characteristic broadening of the line shape is observed with the increasing number of walls. This feature can be rationalized by an isotropic shift distribution originating from different diamagnetic shielding of the encapsulated nanotubes together with a heterogeneity of the samples. Based on our results, NMR is shown to be a nondestructive spectroscopic method that can be used as a complementary method to, for example, transmission electron microscopy to obtain structural information for carbon nanotubes, especially bulk samples.

  13. (F(8)TPP)Fe(II)/O(2) reactivity studies [F(8)TPP = tetrakis(2,6-difluorophenyl)porphyrinate(2-)]: spectroscopic (UV-Visible and NMR) and kinetic study of solvent-dependent (Fe/O(2) = 1:1 or 2:1) reversible O(2)-reduction and ferryl formation.

    Science.gov (United States)

    Ghiladi, R A; Kretzer, R M; Guzei, I; Rheingold, A L; Neuhold, Y M; Hatwell, K R; Zuberbühler, A D; Karlin, K D

    2001-11-05

    )Fe(II) (1)/O(2) reaction was also examined at reduced temperatures in noncoordinating solvents (toluene, CH(2)Cl(2)), where UV-visible and (2)H and (19)F NMR spectroscopies also revealed the presence of a reversibly formed adduct, formulated as the peroxo-bridged dinuclear complex [(F(8)TPP)Fe(III)](2)-(O(2)(2)(-)) (3) [CH(2)Cl(2): UV-visible, 414 (Soret), 535 nm; (2)H NMR, delta(pyrrole) 17.5 ppm]. Dioxygen-uptake spectrophotometric titrations revealed a stoichiometry of 2 (F(8)TPP)Fe(II) (1) per O(2) upon full formation of 3. Addition of a nitrogenous base, 4-(dimethylamino)pyridine, to a cold solution of 3 in dichloromethane gave rapid formation of the iron(IV)-oxo ferryl species (DMAP)(F(8)TPP)Fe(IV)==O (4), based upon UV-visible [417 (Soret), 541 nm] and (2)H NMR (delta(pyrrole) = 3.5 ppm) spectroscopic characterization. These detailed investigations into the O(2)-adducts and "ferryl" species formed from (F(8)TPP)Fe(II) (1) may be potentially important for a full understanding of our ongoing heme-copper oxidase model studies, which employ 1 or similar "tethered" (i.e., covalently attached Cu-chelate) porphyrin analogues in heme/Cu heterobinuclear systems.

  14. Formation and decomposition of N,N,N-trimethylanilinium cations on zeolite H-Y investigated by in situ stopped-flow MAS NMR spectroscopy.

    Science.gov (United States)

    Wang, Wei; Seiler, Michael; Ivanova, Irina I; Sternberg, Ulrich; Weitkamp, Jens; Hunger, Michael

    2002-06-26

    Methylation of aniline by methanol on zeolite H-Y has been investigated by in situ (13)C MAS NMR spectroscopy under flow conditions. The in situ (13)C continuous-flow (CF) MAS NMR experiments were performed at reaction temperatures between 473 and 523 K, molar methanol-to-aniline ratios of 1:1 to 4:1, and modified residence times of (13)CH(3)OH between 20 and 100 (g x h)/mol. The methylation reaction was shown to start at 473 K. N,N,N-Trimethylanilinium cations causing a (13)C NMR signal at 58 ppm constitute the major product on the catalyst surface. Small amounts of protonated N-methylaniline ([PhNH(2)CH(3)](+)) and N,N-dimethylaniline ([PhNH(CH(3))(2)](+)) were also observed at ca. 39 and 48 ppm, respectively. After increase of the temperature to 523 K, the contents of N,N-dimethylanilinium cations and ring-alkylated reaction products strongly increased, accompanied by a decrease of the amount of N,N,N-trimethylanilinium cations. With application of the in situ stopped-flow (SF) MAS NMR technique, the decomposition of N,N,N-trimethylanilinium cations on zeolite H-Y to N,N-dimethylanilinium and N-methylanilinium cations was investigated to gain a deeper insight into the reaction mechanism. The results obtained allow the proposal of a mechanism consisting of three steps: (i) the conversion of methanol to surface methoxy groups and dimethyl ether (DME); (ii) the alkylation of aniline with methanol, methoxy groups, or DME leading to an equilibrium mixture of N,N,N-trimethylanilinium, N,N-dimethylanilinium, and N-methylanilinium cations attached to the zeolite surface; (iii) the deprotonation of N,N-dimethylanilinium and N-methylanilinium cations causing the formation of N,N-dimethylaniline (NNDMA) and N-methylaniline (NMA) in the gas phase, respectively. The chemical equilibrium between the anilinium cations carrying different numbers of methyl groups is suggested to play a key role for the products distribution in the gas phase.

  15. NMR and Electrochemical Investigation of the Transport Properties of Methanol and Water in Nafion and Clay-Nanocomposites Membranes for DMFCs

    Directory of Open Access Journals (Sweden)

    Vincenzo Baglio

    2012-06-01

    Full Text Available Water and methanol transport behavior, solvents adsorption and electrochemical properties of filler-free Nafion and nanocomposites based on two smectite clays, were investigated using impedance spectroscopy, DMFC tests and NMR methods, including spin-lattice relaxation and pulsed-gradient spin-echo (PGSE diffusion under variable temperature conditions. Synthetic (Laponite and natural (Swy-2 smectite clays, with different structural and physical parameters, were incorporated into the Nafion for the creation of exfoliated nanocomposites. Transport mechanism of water and methanol appears to be influenced from the dimensions of the dispersed platelike silicate layers as well as from their cation exchange capacity (CEC. The details of the NMR results and the effect of the methanol solution concentration are discussed. Clays particles, and in particular Swy-2, demonstrate to be a potential physical barrier for methanol cross-over, reducing the