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Sample records for terbium iii carboxylates

  1. Arginine-responsive terbium luminescent hybrid sensors triggered by two crown ether carboxylic acids

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    Jiang, Lasheng [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Tang, Ke; Ding, Xiaoping [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Wang, Qianming, E-mail: qmwang@scnu.edu.cn [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Zhou, Zhan; Xiao, Rui [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China)

    2013-12-01

    Crown ether carboxylic acids constitute main building blocks for the synthesis of terbium containing covalent cross-linked luminescent materials. Both the complexes and the hybrid nanomaterials could exhibit remarkable green emissions in pure water. More importantly, they were found to have a profound effect on the luminescence responses to arginine compared with glutamic acid, histidine, tryptophan, threonine, tyrosine and phenylalanine in aqueous environment. The present study provided the possibility of using a host–guest mechanism as a way of signal transduction based on lanthanide supramolecular hybrid materials. - Highlights: • Crown ether carboxylic acids were found to sensitize terbium ions among a group of ethers. • The complexes and silica hybrid materials were both prepared and characterized. • They could exhibit remarkable green emissions in pure water.

  2. Structural investigation and photoluminescent properties of gadolinium(III), europium(III) and terbium(III) 3-mercaptopropionate complexes.

    Science.gov (United States)

    Souza, E R; Mazali, I O; Sigoli, F A

    2014-01-01

    This work reports on the synthesis, crystallographic determination and spectroscopic characterization of gadolinium(III), terbium(III) and europium(III) 3-mercaptopropionate complexes, aqua-tris(3-mercaptopropionate)lanthanide(III)--[Ln(mpa)3(H2O)]. The Judd-Ofelt intensity parameters were experimentally determined from emission spectrum of the [Eu(mpa)3(H2O)]complex and they were also calculated from crystallographic data. The complexes are coordination polymers, where the units of each complex are linked together by carboxylate groups leading to an unidimensional and parallel chains that by chemical interactions form a tridimensional framework. The emission spectrum profile of the [Eu(mpa)3(H2O)] complex is discussed based on point symmetry of the europium(III) ion, that explains the bands splitting observed in its emission spectrum. Photoluminescent analysis of the [Gd(mpa)3(H2O)] complex show no efficient ligand excitation but an intense charge transfer band. The excitation spectra of the [Eu(mpa)3(H2O)] and [Tb(mpa)3(H2O)] complexes do not show evidence of energy transfer from the ligand to the excited levels of these trivalent ions. Therefore the emission bands are originated only by direct f-f intraconfigurational excitation of the lantanide(III) ions.

  3. Highly luminescent charge-neutral europium(iii) and terbium(iii) complexes with tridentate nitrogen ligands.

    Science.gov (United States)

    Senthil Kumar, Kuppusamy; Schäfer, Bernhard; Lebedkin, Sergei; Karmazin, Lydia; Kappes, Manfred M; Ruben, Mario

    2015-09-21

    We report on the synthesis of tridentate-nitrogen pyrazole-pyridine-tetrazole (L(1)H) and pyrazole-pyridine-triazole (L(2)H) ligands and their complexation with lanthanides (Ln = Gd(iii), Eu(iii) and Tb(iii)) resulting in stable, charge-neutral complexes Ln(L(1))3 and Ln(L(2))3, respectively. X-ray crystallographic analysis of the complexes with L(1) ligands revealed tricapped trigonal coordination geometry around the lanthanide ions. All complexes show bright photoluminescence (PL) in the solid state, indicating efficient sensitization of the lanthanide emission via the triplet states of the ligands. In particular, the terbium complexes show high PL quantum yields of 65 and 59% for L(1) and L(2), respectively. Lower PL efficiencies of the europium complexes (7.5 and 9%, respectively) are attributed to large energy gaps between the triplet states of the ligands and accepting levels of Eu(iii). The triplet state energy can be reduced by introducing an electron withdrawing (EW) group at the 4 position of the pyridine ring. Such substitution of L(1)H with a carboxylic ester (COOMe) EW group leads to a europium complex with increased PL quantum yield of 31%. A comparatively efficient PL of the complexes dissolved in ethanol indicates that the lanthanide ions are shielded against nonradiative deactivation via solvent molecules.

  4. Structural variations in terbium(III) complexes with 1,3-adamantanedicarboxylate and diverse co-ligands

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    Thuéry, Pierre, E-mail: pierre.thuery@cea.fr

    2015-07-15

    Terbium nitrate was reacted with 1,3-adamantanedicarboxylic acid (LH{sub 2}) under solvo-hydrothermal conditions with either N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) as organic solvents. Hydrolysation of the latter co-solvents resulted in the formation of formate or acetate ions, which are present as co-ligands in the 1D coordination polymer [Tb(L)(HCOO)(H{sub 2}O){sub 2}] (1) and the 2D assembly [Tb(L)(CH{sub 3}COO)(H{sub 2}O)] (2). The increase in dimensionality in the latter arises from the higher connectivity provided by acetate versus formate, the L{sup 2−} ligand being bis-chelating in both cases. The complex [Tb{sub 2}(L){sub 3}(H{sub 2}O){sub 5}][Tb{sub 2}(L){sub 3}(H{sub 2}O){sub 4}]·3H{sub 2}O (3), another 1D species, crystallizes alongside crystals of 2. Further addition of cucurbit[6]uril (CB6), with DMF as co-solvent, gave the two complexes [Tb{sub 2}(L){sub 2}(CB6)(H{sub 2}O){sub 6}](NO{sub 3}){sub 2}·6H{sub 2}O (4) and [H{sub 2}NMe{sub 2}]{sub 2}[Tb(L)(HCOO){sub 2}]{sub 2}·CB6·3H{sub 2}O (5). Complex 4 crystallizes as a 3D framework in which Tb(L){sup +} chains are connected by tetradentate CB6 molecules, while 5 unites a carboxylate-bridged anionic 2D planar assembly and layers of CB6 molecules with counter-cations held at both portals. - Graphical abstract: One- to three-dimensional assemblies are formed in terbium(III) complexes with 1,3-adamantanedicarboxylate obtained under solvo-hydrothermal conditions, these species including formate or acetate co-ligands formed in situ, or additional cucurbit[6]uril molecules. - Highlights: • We report structures of terbium(III) complexes with 1,3-adamantanedicarboxylate. • Solvents able to generate co-ligands or counter-ions in situ have been used. • A 3D species including additional cucurbituril molecules is decribed. • One species displays an alternation of metal–organic and organic sheets.

  5. Synthesis, crystal structure and photophysical properties of europium(III) and terbium(III) complexes with pyridine-2,6-dicarboxamide

    NARCIS (Netherlands)

    Tanase, S.; Gallego, P.M.; Gelder, R. de; Fu, W.T.

    2007-01-01

    The reactions of pyridine-2,6-dicarboxamide with europium(III) and terbium(III) triflates led to the formation of mononuclear complexes of formula [Ln(pcam)(3)](CF3SO3)(3) (Ln = Eu 1, Tb 2; pcam stands for pyridine-2,6-dicarboxamide). From single-crystal X-ray diffraction analysis, the complexes

  6. Laser control and temperature switching of luminescence intensity in photostable transparent film based on terbium(III) β-diketonate complex

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    Lapaev, Dmitry V.; Nikiforov, Victor G.; Safiullin, Georgy M.; Lobkov, Vladimir S.; Salikhov, Kev M.; Knyazev, Andrey A.; Galyametdinov, Yury G.

    2014-11-01

    The study of the terbium(III) and gadolinium(III) β-diketonate complexes by photoluminescence spectroscopy reveals considerable changes of the photophysical properties of the complexes under the UV laser irradiation. The measurements show the enhancement of the luminescence intensities in the vitrified transparent film of the terbium(III) complex as well as the gadolinium(III) complex under the 337 nm laser irradiation at room temperature. The irradiated film of the terbium(III) complex restores the initial photophysical properties after heating close to the melting temperature (∼353 K) and cooling. We observe no change of the luminescent properties of the irradiated film for months. These features can be used for the design of new lanthanide-based photostable systems with laser control of the luminescence intensity.

  7. Study of Silver Nanoparticles Sensitized Fluorescence and Second-Order Scattering of Terbium(III-Pefloxacin Mesylate Complex and Determination of Pefloxacin Mesylate

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    Aiyun Li

    2014-01-01

    Full Text Available α-Keto acid of pefloxacin mesylate (PFLX can form the complex with Terbium(III. The intramolecular energy from PFLX to Terbium(III ion takes place when excited, and thus Terbium(III excited state is formed and then emits the characteristic fluorescence of Terbium(III, locating at 490, 545, 580, and 620 nm. The second-order scattering (SOS peak at 545 nm also appears for the complex with the exciting wavelength of 273 nm. When the silver nanoparticles are added to the system, the luminescence intensity at 545 nm greatly increased. So, with the adding of nanoparticles to the Terbium(III-PFLX complex, not only is the intramolecular energy promoted but also the SOS intensity is enhanced. The experimental results show that it is the silver nanoparticles with certain size and certain concentration which can greatly enhance the fluorescence-SOS intensity, and the relative intensity at 545 nm is proportional to the amount of PFLX. Based on this phenomenon, a novel method for the determination of PFLX has been developed and applied to the determination of PFLX in capsule and serum samples.

  8. Preparation and photoluminescence enhancement in terbium(III ternary complexes with β-diketone and monodentate auxiliary ligands

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    Devender Singh

    2016-12-01

    Full Text Available A series of new solid ternary complexes of terbium(III ion based on β-diketone ligand acetylacetone (acac and monodentate auxiliary ligands (aqua/urea/triphenylphosphineoxide/pyridine-N-oxide had been prepared. The structural characterizations of synthesized ternary compounds were studied by means of elemental analysis, infrared (IR, and proton nuclear magnetic resonance (NMR spectral techniques. The optical characteristics were investigated with absorption as well as photoluminescence spectroscopy. Thermal behavior of compounds was examined by TGA/DTA analysis and all metal complexes were found to have good thermal stability. The luminescence decay time of complexes were also calculated by monitoring at emission wavelength corresponding to 5D4 → 7F5 transition. A comparative inspection of the luminescent behavior of prepared ternary compounds was performed in order to determine the function of auxiliary ligands in the enhancement of luminescence intensity produced by central terbium(III ion. The color coordinates values suggested that compounds showed bright green emission in visible region in electromagnetic spectrum. Complexes producing green light could play a significant role in the fabrication of efficient light conversion molecular devices for display purposes and lightning systems.

  9. A Nanoscale Multiresponsive Luminescent Sensor Based on a Terbium(III) Metal-Organic Framework.

    Science.gov (United States)

    Dang, Song; Wang, Ting; Yi, Feiyan; Liu, Qinghui; Yang, Weiting; Sun, Zhong-Ming

    2015-08-01

    A nanoscale terbium-containing metal-organic framework (nTbL), with a layer-like structure and [H2 NMe2 ](+) cations located in the framework channels, was synthesized under hydrothermal conditions. The structure of the as-prepared sample was systematically confirmed by powder XRD and elemental analysis; the morphology was characterized by field-emission SEM and TEM. The photoluminescence studies revealed that rod-like nTbL exhibited bright-green emission, corresponding to (5)D4 →(7)FJ (J=6-3) transitions of the Tb(3+) ion under excitation. Further sensing measurements revealed that as-prepared nTbL could be utilized as a multiresponsive luminescent sensor, which showed significant and exclusive detection ability for Fe(3+) ions and phenylmethanol. These results highlight the practical applications of lanthanide-containing metal-organic frameworks as fluorescent probes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Luminescent investigations of terbium(III) biosorption as a surrogate for heavy metals and radionuclides.

    Science.gov (United States)

    Achyuthan, Komandoor E; Arango, Dulce C; Carles, Elizabeth L; Cutler, Christopher E; Meyer, Lauren A; Brozik, Susan M

    2009-07-01

    We describe a metal transport system for investigating the interfacial interactions between the anionic surface charge of a gram-negative bacterium (Escherichia coli) and a trivalent cationic metal, Tb3+. We believe this is the first description of the uptake kinetics, sub- and intracellular distribution, and temporal fate of Tb3+ ion in E. coli. We used the luminescence of the terbium-dipicolinic acid chelate to study metal ion transport. The bacteria had a high tolerance for the metal (IC(50) = 4 mM Tb3+). Metal ion transport was passive and metabolism independent. The uptake kinetics rapidly reached a maximum within 15 min, followed by a stasis for 60 min, and declining thereafter between 120 and 240 min, resulting in a biphasic curve. During this period, greater than one-third of the metal ion was sequestered within the cell. Our choice of a safe Biosafety Level I E. coli bacteria and the relatively non-toxic Tb3+ metal represents a model system for luminescent investigations of biosorption, for studying bacterial-water interfacial chemistry and for the bioremediation of heavy metals and radionuclides.

  11. Fluorometric determination of proteins using the terbium (III)-2-thenoyltrifluoroacetone-sodium dodecyl benzene sulfonate-protein system

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    Jia Zhen [Key Laboratory of Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Department of Chemistry, Dezhou University, Dezhou 253023 (China); Yang Jinghe [Key Laboratory of Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)]. E-mail: yjh@sdu.edu.cn; Wu Xia [Key Laboratory of Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Wang Fei [Key Laboratory of Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Guo Changying [Key Laboratory of Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Liu Shufang [Key Laboratory of Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2006-12-15

    It is found that in hexamethylene tetramine (HMTA)-HCl buffer of pH=8.00, proteins can enhance the fluorescence of terbium (III) (Tb{sup 3+})-2-thenoyltrifluoroacetone (TTA)-sodium dodecyl benzene sulfonate (SDBS) system. Based on this, a sensitive method for the determination of proteins is proposed. The experiments indicate that under the optimum conditions, the enhanced fluorescence intensity is in proportion to the concentration of proteins in the range of 4.0x10{sup -9}-7.5x10{sup -6}g/mL for bovine serum albumin (BSA), 5.0x10{sup -9}-1.5x10{sup -5}g/mL for human serum albumin (HSA), 1.0x10{sup -8}-7.5x10{sup -6}g/mL for egg albumin (EA). Their detection limits (S/N=3) are 0.5, 0.8 and 2.0ng/mL, respectively. The interaction mechanism is also studied.

  12. Optical properties and electrical transport of thin films of terbium(III bis(phthalocyanine on cobalt

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    Peter Robaschik

    2014-11-01

    Full Text Available The optical and electrical properties of terbium(III bis(phthalocyanine (TbPc2 films on cobalt substrates were studied using variable angle spectroscopic ellipsometry (VASE and current sensing atomic force microscopy (cs-AFM. Thin films of TbPc2 with a thickness between 18 nm and 87 nm were prepared by organic molecular beam deposition onto a cobalt layer grown by electron beam evaporation. The molecular orientation of the molecules on the metallic film was estimated from the analysis of the spectroscopic ellipsometry data. A detailed analysis of the AFM topography shows that the TbPc2 films consist of islands which increase in size with the thickness of the organic film. Furthermore, the cs-AFM technique allows local variations of the organic film topography to be correlated with electrical transport properties. Local current mapping as well as local I–V spectroscopy shows that despite the granular structure of the films, the electrical transport is uniform through the organic films on the microscale. The AFM-based electrical measurements allow the local charge carrier mobility of the TbPc2 thin films to be quantified with nanoscale resolution.

  13. Photoluminescence studies of a Terbium(III) complex as a fluorescent probe for DNA detection

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    Khorasani-Motlagh, Mozhgan, E-mail: mkhorasani@chem.usb.ac.ir; Noroozifar, Meissam; Niroomand, Sona; Moodi, Asieh

    2013-11-15

    The photoluminescence properties of a Tb(III) complex of the form [Tb(phen){sub 2}Cl{sub 3}·OH{sub 2}] (phen=1,10-phenanthroline) in different solvents are presented. It shows the characteristic luminescence of the corresponding Ln{sup 3+} ion in the visible region. The emission intensity of this complex in coordinating solvent is higher than non-coordinating one. The suggested mechanism for the energy transfer between the ligand and Tb{sup 3+} ion is the intramolecular energy transfer mechanism. The interactions of the Tb(III) complex with fish salmon DNA are studied by fluorescence spectroscopy, circular dichroism study and viscosity measurements. The results of fluorescence titration reveal that DNA strongly quenches the intrinsic fluorescence of the complex through a static quenching procedure. The binding constant (K{sub b}) of the above metal complex at 25 °C is determined by the fluorescence titration method and it is found to be (8.06±0.01)×10{sup 3} M{sup −1}. The thermodynamic parameters (ΔH{sup 0}>0, ΔS{sup 0}>0 and ΔG{sup 0}<0) indicate that the hydrophobic interactions play a major role in DNA–Tb complex association. The results support the claim that the title complex bonds to FS-DNA by a groove mode. -- Highlights: • Photoluminescence of [Tb(phen){sub 2}Cl{sub 3}·OH{sub 2}] in different solvents are studied. • Tb(III) complex shows good binding affinity to FS DNA with K{sub b}=(8.06±0.01)×10{sup 3} M{sup −1}. • Viscosity of DNA almost unchanged by increasing amount of Tb complex. • CD spectrum of DNA has a little change with increasing amount of Tb complex. • Thermodynamic parameters indicate that the binding reaction is entropically driven.

  14. Crystal structures of two mononuclear complexes of terbium(III) nitrate with the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane.

    Science.gov (United States)

    Gregório, Thaiane; Giese, Siddhartha O K; Nunes, Giovana G; Soares, Jaísa F; Hughes, David L

    2017-02-01

    Two new mononuclear cationic complexes in which the TbIII ion is bis-chelated by the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane (H3LEt, C6H14O3) were prepared from Tb(NO3)3·5H2O and had their crystal and mol-ecular structures solved by single-crystal X-ray diffraction analysis after data collection at 100 K. Both products were isolated in reasonable yields from the same reaction mixture by using different crystallization conditions. The higher-symmetry complex dinitratobis[1,1,1-tris-(hy-droxy-meth-yl)propane]-terbium(III) nitrate di-meth-oxy-ethane hemisolvate, [Tb(NO3)2(H3LEt)2]NO3·0.5C4H10O2, 1, in which the lanthanide ion is 10-coordinate and adopts an s-bicapped square-anti-prismatic coordination geometry, contains two bidentate nitrate ions bound to the metal atom; another nitrate ion functions as a counter-ion and a half-mol-ecule of di-meth-oxy-ethane (completed by a crystallographic twofold rotation axis) is also present. In product aqua-nitratobis[1,1,1-tris-(hy-droxy-meth-yl)propane]-terbium(III) dinitrate, [Tb(NO3)(H3LEt)2(H2O)](NO3)2, 2, one bidentate nitrate ion and one water mol-ecule are bound to the nine-coordinate terbium(III) centre, while two free nitrate ions contribute to charge balance outside the tricapped trigonal-prismatic coordination polyhedron. No free water mol-ecule was found in either of the crystal structures and, only in the case of 1, di-meth-oxy-ethane acts as a crystallizing solvent. In both mol-ecular structures, the two tripodal ligands are bent to one side of the coordination sphere, leaving room for the anionic and water ligands. In complex 2, the methyl group of one of the H3LEt ligands is disordered over two alternative orientations. Strong hydrogen bonds, both intra- and inter-molecular, are found in the crystal structures due to the number of different donor and acceptor groups present.

  15. Trinuclear rhenium(III) halide clusters with carboxylate ligands

    Science.gov (United States)

    Dougan, Jeffrey Steven

    Four mono(carboxylato)trirhenium complexes and three bis(carboxylato)trirhenium complexes have been synthesized and characterized, principally by mass spectrometry, with supporting evidence from X-ray diffraction. These compounds represent the first trinuclear rhenium carboxylate complexes. The reactions generally proceed readily under comparatively mild conditions. Mass spectrometry has again proved its usefulness as a technique in the field of metal cluster chemistry, having provided the initial identification of the products of the reactions studied. These compounds provide a further base to which future mass spectra of metal cluster compounds can be compared. Re-examination of a reaction reported by Taha and Wilkinson has also cast considerable doubt onto the validity of a conversion widely reported in the literature that transforms (Re3Cl9) x into [Re2(O2CCH3)4Cl 2]. We believe that the literature result is a consequence of the purity of the metal precursor, and suggest that the starting material in the earlier work may have contained ReCl4 or ReCl5. The importance of mass spectrometry in the characterization of the new compounds synthesized in this project has led to a thorough study of calculated isotopic distributions. The information gathered suggests that for isotopically simple molecules, the choice of algorithm for computing an isotopic distribution is unimportant. However, it is important to compute the mass spectrum of an isotopically complex molecule using an algorithm that can, if desired, show the underlying isotopic fine structure of a peak of interest. In the last chapter of this thesis, the results of a project in chemistry education research are presented. Predicting the success of students in general chemistry has long been of interest to the chemistry education community, and several factors have been identified as contributing factors. An off-hand comment by a student inspired an examination of whether continuity with the same instructor for

  16. The response behavior of PPy-DB18C6 electrode to terbium(III in acetonitrile and its thermodynamic application

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    Mohammad Hossein Arbab Zavar

    2016-11-01

    Full Text Available Polypyrrole modified electrode prepared by electropolymerization of pyrrole in the presence of a complexing ligand, dibenzo-18-crown-6(DB18C6, was prepared and investigated as a Tb3+-selective electrode in acetonitrile. The potentiometric response of the electrode was linear within the Tb3+ concentration range 1 × 10−5–1 × 10−2 M with a Nernstian slope of 20.9 mVdecade−1 in AN. The electrode was applied to study the complexation of the terbium(III ion in acetonitrile with such other basic aprotic solvent molecules (D as dimethyl sulfoxide, N,N-dimethyl formamide, propylene carbonate and pyridine. The successive complex formation constant (βi and Gibbs energies of transfer (ΔGtr of Tb3+ in AN in relation to such D were obtained.

  17. Crystal structure of a mixed-ligand terbium(III coordination polymer containing oxalate and formate ligands, having a three-dimensional fcu topology

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    Chainok Kittipong

    2016-01-01

    Full Text Available The title compound, poly[(μ3-formato(μ4-oxalatoterbium(III], [Tb(CHO2(C2O4]n, is a three-dimensional coordination polymer, and is isotypic with the LaIII, CeIII and SmIII analogues. The asymmetric unit contains one TbIII ion, one formate anion (CHO2− and half of an oxalate anion (C2O42−, the latter being completed by application of inversion symmetry. The TbIII ion is nine-coordinated in a distorted tricapped trigonal–prismatic manner by two chelating carboxylate groups from two C2O42− ligands, two carboxylate oxygen atoms from another two C2O42− ligands and three oxygen atoms from three CHO2− ligands, with the Tb—O bond lengths and the O—Tb—O bond angles ranging from 2.4165 (19 to 2.478 (3 Å and 64.53 (6 to 144.49 (4°, respectively. The CHO2− and C2O42− anions adopt μ3-bridging and μ4-chelating-bridging coordination modes, respectively, linking adjacent TbIII ions into a three-dimensional 12-connected fcu topology with point symbol (324.436.56. The title compound exhibits thermal stability up to 623 K, and also displays strong green photoluminescence in the solid state at room temperature.

  18. Electrochemiluminescence Study of Europium (III Complex with Coumarin3-Carboxylic Acid

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    Stefan Lis

    2008-01-01

    Full Text Available The europium (III complex of coumarin-3-carboxylic acid (C3CA has been prepared and characterized on the basis of elemental analysis, IR, and emission (photoluminescence and electrochemiluminescence spectroscopy. The synthesised complex having a formula Eu(C3CA2(NO3(H2O2 was photophysically characterized in solution and in the solid state. Electrochemiluminescence, ECL, of the system containing the Eu(III/C3CA complex was studied using an oxide-covered aluminium electrode. The goal of these studies was to show the possibility of the use of electrochemical excitation of the Eu(III ion in aqueous solution for emission generation. The generated ECL emission was very weak, and therefore its measurements and spectral analysis were carried out with the use of cut-off filters method. The studies proved a predominate role of the ligand-to-metal energy transfer (LMET in the generated ECL.

  19. Picomolar Traces of Americium(III) Introduce Drastic Changes in the Structural Chemistry of Terbium(III): A Break in the "Gadolinium Break".

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    Welch, Jan M; Müller, Danny; Knoll, Christian; Wilkovitsch, Martin; Giester, Gerald; Ofner, Johannes; Lendl, Bernhard; Weinberger, Peter; Steinhauser, Georg

    2017-10-16

    The crystallization of terbium 5,5'-azobis[1H-tetrazol-1-ide] (ZT) in the presence of trace amounts (ca. 50 Bq, ca. 1.6 pmol) of americium results in 1) the accumulation of the americium tracer in the crystalline solid and 2) a material that adopts a different crystal structure to that formed in the absence of americium. Americium-doped [Tb(Am)(H 2 O) 7 ZT] 2 ZT⋅10 H 2 O is isostructural to light lanthanide (Ce-Gd) 5,5'-azobis[1H-tetrazol-1-ide] compounds, rather than to the heavy lanthanide (Tb-Lu) 5,5'-azobis[1H-tetrazol-1-ide] (e.g., [Tb(H 2 O) 8 ] 2 ZT 3 ⋅6 H 2 O) derivatives. Traces of Am seem to force the Tb compound into a structure normally preferred by the lighter lanthanides, despite a 10 8 -fold Tb excess. The americium-doped material was studied by single-crystal X-ray diffraction, vibrational spectroscopy, radiochemical neutron activation analysis, and scanning electron microcopy. In addition, the inclusion properties of terbium 5,5'-azobis[1H-tetrazol-1-ide] towards americium were quantified, and a model for the crystallization process is proposed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. An integrated logic system for time-resolved fluorescent "turn-on" detection of cysteine and histidine base on terbium (III) coordination polymer-copper (II) ensemble.

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    Xue, Shi-Fan; Lu, Ling-Fei; Wang, Qi-Xian; Zhang, Shengqiang; Zhang, Min; Shi, Guoyue

    2016-09-01

    Cysteine (Cys) and histidine (His) both play indispensable roles in many important biological activities. An enhanced Cys level can result in Alzheimer's and cardiovascular diseases. Likewise, His plays a significant role in the growth and repair of tissues as well as in controlling the transmission of metal elements in biological bases. Therefore, it is meaningful to detect Cys and His simultaneously. In this work, a novel terbium (III) coordination polymer-Cu (II) ensemble (Tb(3+)/GMP-Cu(2+)) was proposed. Guanosine monophosphate (GMP) can self-assemble with Tb(3+) to form a supramolecular Tb(3+) coordination polymer (Tb(3+)/GMP), which can be suited as a time-resolved probe. The fluorescence of Tb(3+)/GMP would be quenched upon the addition of Cu(2+), and then the fluorescence of the as-prepared Tb(3+)/GMP-Cu(2+) ensemble would be restored again in the presence of Cys or His. By incorporating N-Ethylmaleimide and Ni(2+) as masking agents, Tb(3+)/GMP-Cu(2+) was further exploited as an integrated logic system and a specific time-resolved fluorescent "turn-on" assay for simultaneously sensing His and Cys was designed. Meanwhile it can also be used in plasma samples, showing great potential to meet the need of practical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Thermodynamic parameters of complexation of lanthanoids(III) by [alpha]-substituted carboxylate anions

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    Hasegawa, Yuko (Department of Chemistry, Science Univ. of Tokyo (Japan)); Yamazaki, Nobuhiko (Department of Chemistry, Science Univ. of Tokyo (Japan)); Tanaka, Miho (Department of Chemistry, Science Univ. of Tokyo (Japan)); Rizkalla, E.N. (Faculty of Science, Ain Shams Univ., Cairo (Egypt))

    1993-01-01

    The protonation enthalpy of [alpha]-hydroxyphenylacetate, [alpha]-phenyllactate, and [alpha]-methoxyphenylacetate anions and the complexation enthalpy of lanthanoid(III) with these carboxylate ions have been measured by calorimetric technique in 0.1 mol/dm[sup 3] (NaClO[sub 4]) at 25 C. The results are compared to those of the phenylacetate complexation. The low protonation enthalpy of [alpha]-hydroxycarboxylate relative to other monocarboxylates is attributed to intra hydrogen-bond formation. The difference between [Delta]H[sub 101] of [alpha]-hydroxycarboxylates of light lanthanoid(III) and those of the heavy ions is smaller than the corresponding difference for complexation by phenylacetate. By contrast, the difference in [Delta]S[sub 101] for complexation of light and heavy ions by the two ligands is similar. Complexation by [alpha]-methoxyphenylacetate, however did not follow either pattern. (orig.)

  2. Graphene quantum dots-terbium ions as novel sensitive and selective time-resolved luminescent probes.

    Science.gov (United States)

    Llorent-Martínez, Eulogio J; Durán, Gema M; Ríos, Ángel; Ruiz-Medina, Antonio

    2018-01-01

    We propose an alternative approach for the development of analytical methods based on terbium-sensitized luminescence (TSL). TSL is based on the complexation between Tb(III) ions and fluorescent organic compounds that have appropriate functional groups to complex with Tb(III). We report the use of graphene quantum dot (GQDs) nanoparticles to improve the sensitivity and selectivity of TSL detection. GQDs can react with terbium ions through the carboxylic groups present in their structure. These Tb(III)-GQD complexes, formed in situ in aqueous solution, can be used as time-resolved luminescent probes. Ascorbic acid was selected as a target analyte to demonstrate the suitability of the proposed method. The selectivity of the TSL method was highly improved for most of the interferences tested. Under the optimum conditions [Tb(III) concentration 5 × 10-4 mol L-1, GQD concentration 4 mg L-1], a minimum 100% increase in selectivity was observed for several vitamins and common cations that may be present in the samples to be analyzed. In addition, the analytical signal showed a 30% enhancement with the use of GQDs compared with the use of merely Tb(III) ions, with a detection limit of 0.12 μg mL-1. The repeatability and intermediate precision were lower than 3% and 5%, respectively. From the results obtained, the implementation of GQDs in TSL can lead to the development of novel time-resolved luminescent probes with high analytical potential. Graphical abstract Quenching of Tb(III)-graphene quantum dot (GQD) luminescence by ascorbic acid (AA). TBL terbium-sensitized luminescence.

  3. Crystal structure of an eight-coordinate terbium(III ion chelated by N,N′-bis(2-hydroxybenzyl-N,N′-bis(pyridin-2-ylmethylethylenediamine (bbpen2− and nitrate

    Directory of Open Access Journals (Sweden)

    Thaiane Gregório

    2015-01-01

    Full Text Available The reaction of terbium(III nitrate pentahydrate in acetonitrile with N,N′-bis(2-hydroxybenzyl-N,N′-bis(pyridin-2-ylmethylethylenediamine (H2bbpen, previously deprotonated with triethylamine, produced the mononuclear compound [N,N′-bis(2-oxidobenzyl-κO-N,N′-bis(pyridin-2-ylmethyl-κNethylenediamine-κ2N,N′](nitrato-κ2O,O′terbium(III, [Tb(C28H28N4O2(NO3]. The molecule lies on a twofold rotation axis and the TbIII ion is eight-coordinate with a slightly distorted dodecahedral coordination geometry. In the symmetry-unique part of the molecule, the pyridine and benzene rings are both essentially planar and form a dihedral angle of 61.42 (7°. In the molecular structure, the N4O4 coordination environment is defined by the hexadentate bbpen ligand and the bidentate nitrate anion. In the crystal, a weak C—H...O hydrogen bond links molecules into a two-dimensional network parallel to (001.

  4. Synthesis, crystal structures, and luminescent properties of two series' of new lanthanide (III) amino-carboxylate-phosphonates.

    Science.gov (United States)

    Zhou, Tian-Hua; Yi, Fei-Yan; Li, Pei-Xin; Mao, Jiang-Gao

    2010-02-01

    Hydrothermal reactions of lanthanide(III) chlorides with 4-HOOC-C(6)H(4)-CH(2)NHCH(2)PO(3)H(2) (H(3)L) at different ligand-to-metal (L/M) ratios afforded nine new lanthanide(III) carboxylate-phosphonates with two types of 3D network structures, namely, LnCl(HL)(H(2)O)(2) (Ln = Sm, 1; Eu, 2; Gd, 3; Tb, 4; Dy, 5; Er, 6) and [Ln(2)(HL)(H(2)L)(L)(H(2)O)(2)].4H(2)O (Ln = Nd, 7; Sm, 8; Eu, 9). Compounds 1-6 are isostructural and feature a 3D network in which the LnO(7)Cl polyhedra are interconnected by bridging CPO(3) tetrahedra into 2D inorganic layers parallel to the bc plane. These layers are further cross-linked by organic groups of the carboxylate-phosphonate ligands via the coordination of the carboxylate groups into a pillared-layered architecture. Compounds 7-9 are also isostructural and feature a 3D open-framework composed of 1D lanthanide(III) phosphonate inorganic slabs which are further bridged by organic groups of the carboxylate-phosphonate liagnds via the coordination of the carboxylate groups, forming large 1D tunnels along the b-axis which are filled by lattice water molecules. Luminescent measurements indicate that compounds 2, 4, and 5 show strong emission bands in red, green, and yellow light region, respectively. Magnetic properties of 2, 3, 5, and 7 have also been studied.

  5. Role of Fe(III)-carboxylates in AMZ photodegradation: A response surface study based on a Doehlert experimental design.

    Science.gov (United States)

    Graça, Cátia A L; Correia de Velosa, Adriana; Teixeira, Antonio Carlos S C

    2017-10-01

    Photochemical redox reactions of Fe(III) complexes in surface waters are important sources of radical species, therefore contributing to the sunlight-driven elimination of waterborne recalcitrant contaminants. In this study, the effects of three Fe(III)-carboxylates (i.e., oxalate, citrate, and tartrate) on the UVA photoinduced oxidation of the herbicide amicarbazone (AMZ) were investigated. A Doehlert experimental design was applied to find the Fe(III):ligand ratios and pH that achieved the fastest AMZ degradation rate. The results indicated optimal ratios of 1:10 (Fe(III):oxalate), 1:4 (Fe(III):citrate), and 1:1 (Fe(III):tartrate), with the [Fe(III)]0 set at 0.1 mmol L-1 and the best pH found to be 3.5 for all the complexes. In addition, a statistical model that predicts the observed degradation rate constant (kobs) as a function of pH and Fe(III):carboxylate ratio was obtained for each complex, enabling AMZ-photodegradation predictions based on these two variables. To the best of our knowledge, this is the first time that such models are proposed. Not only the pH-dependent speciation of Fe(III) in solution but also the time profiles of photogenerated OH, Fe(II), and H2O2 gave appropriate support to the experimental results. Additional experiments using a sampled sewage treatment plant effluent suggest that the addition of aqua and/or Fe(III)-oxalate complexes to the matrix may also be effective for AMZ removal from natural waters in case their natural occurrence is not high enough to promote pollutant degradation. Therefore, the inclusion of Fe(III)-complexes in investigations dealing with the environmental fate of emerging pollutants in natural waterbodies is strongly recommended. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Europium(III) complexes of polyfunctional carboxylic acids: Luminescence probes of possible binding sites in fulvic acid

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.H.; Chung, K.H.; Shin, H.S.; Moon, H. [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Chemistry; Park, Y.J. [Korea Atomic Energy Research Inst., Taejon (Korea, Republic of)

    1997-04-15

    The {sup 7}F{sub 0} {r_arrow} {sup 5}D{sub 0} excitation spectra of Eu(III) complexed with polyfunctional dicarboxylic acid containing neutral O, N, and S donors were investigated using Eu(III) luminescence spectroscopy. Three distinct peaks are seen in the excitation spectra in the Eu(III)-diglycolic acid (ODA) and Eu(III)-iminodiacetic acid (IMDA) systems showing the formation of three species, where each tridentate ODA {sup 2{minus}} and IMDA{sup 2{minus}} displace approximately three coordinated water molecules; however, the central S donor of Eu(III)-thiodiglycolate and 2,5-thiophenedicarboxylate are shown to be poor chelators for free Eu{sup 3+} ions. The neutral O and N donors in combination with neighboring carboxylates may form strong metal chelation sites on fulvic acid.

  7. Concomitant carboxylate and oxalate formation from the activation of CO{sub 2} by a thorium(III) complex

    Energy Technology Data Exchange (ETDEWEB)

    Formanuik, Alasdair; Ortu, Fabrizio; Mills, David P. [School of Chemistry, The University of Manchester (United Kingdom); Inman, Christopher J. [Department of Chemistry and Biochemistry, School of Life Sciences, University of Sussex, Brighton (United Kingdom); Kerridge, Andrew [Department of Chemistry, Lancaster University (United Kingdom); Castro, Ludovic; Maron, Laurent [LPCNO, CNRA et INSA, Universite Paul Sabatier, Toulouse (France)

    2016-12-12

    Improving our comprehension of diverse CO{sub 2} activation pathways is of vital importance for the widespread future utilization of this abundant greenhouse gas. CO{sub 2} activation by uranium(III) complexes is now relatively well understood, with oxo/carbonate formation predominating as CO{sub 2} is readily reduced to CO, but isolated thorium(III) CO{sub 2} activation is unprecedented. We show that the thorium(III) complex, [Th(Cp''){sub 3}] (1, Cp''={C_5H_3(SiMe_3)_2-1,3}), reacts with CO{sub 2} to give the mixed oxalate-carboxylate thorium(IV) complex [{Th(Cp'')_2[κ"2-O_2C{C_5H_3-3,3'-(SiMe_3)_2}]}{sub 2}(μ-κ{sup 2}:κ{sup 2}-C{sub 2}O{sub 4})] (3). The concomitant formation of oxalate and carboxylate is unique for CO{sub 2} activation, as in previous examples either reduction or insertion is favored to yield a single product. Therefore, thorium(III) CO{sub 2} activation can differ from better understood uranium(III) chemistry. (copyright 2016 The Authors. Published by Wiley-VCH Verlag GmbH and Co. KGaA.)

  8. Sodium terbium(III polyphosphate

    Directory of Open Access Journals (Sweden)

    Abdelghani Oudahmane

    2010-04-01

    Full Text Available Single crystals of the title compound, NaTb(PO34, were obtained by solid-state reaction. This compound belongs to type II of long-chain polyphosphates with the general formula AIBIII(PO34. It is isotypic with the NaNd(PO34 and NaEr(PO34 homologues. The crystal structure is built up of infinite crenelated chains of corner-sharing PO4 tetrahedra with a repeating unit of four tetrahedra. These chains, extending parallel to [100], are linked by isolated TbO8 square antiprisms, forming a three-dimensional framework. The Na+ ions are located in channels running along [010] and are surrounded by six oxygen atoms in a distorted octahedral environment within a cut-off distance <2.9 Å.

  9. Phthalimides: Supramolecular Interactions in Crystals, Hypersensitive Solution 1H-NMR Dynamics and Energy Transfer to Europium(III and Terbium(III States

    Directory of Open Access Journals (Sweden)

    David J. Williams

    2003-07-01

    Full Text Available Detailed crystal structures and 1H-NMR characteristics of some alkylaminephthalimides, including dendritic polyphthalimides, are reported. These investigations were undertaken in order to obtain a better understanding of the relationship between solid-state supramolecular interactions, their persistence in solution and associated dynamics of magnetically hypersensitive phthalimide aromatic AA'BB'-AA'XX' proton NMR resonances. Some alkylamine phthalimides feature folded molecular geometries, which we attribute to n-π interactions among proximal amine-phthalimide sites; those alkylamine-phthalimides that have no possibility for such interactions feature fully extended phthalimide functionalities. Accordingly, alkylamine phthalimide compounds with folded solid-state geometries feature solvent and temperature dependent hypersensitive AA'BB'-AA'XX' 1H-NMR line profiles, which we attribute to the n-π interactions. Luminescence of Eu3+(5D0 and Tb3+(5D4 states show well defined metal ion environments in their complexes with dendritic phthalimides, as well as relatively weak phthalimide-lanthanide(III interactions.

  10. Elastic properties of terbium

    DEFF Research Database (Denmark)

    Spichkin, Y.I.; Bohr, Jakob; Tishin, A.M.

    1996-01-01

    The temperature dependence of the Young modulus along the crystallographic axes b and c (E(b) and E(c)), and the internal friction of a terbium single crystal have been measured. At 4.2 K, E(b) and E(c) are equal to 38 and 84.5 GPa, respectively. The lattice part of the Young modulus and the Debye...... temperature has been calculated. The origin of the Young modulus anomalies arising at the transition to the magnetically ordered state is discussed....

  11. Porous, rigid metal(III)-carboxylate metal-organic frameworks for the delivery of nitric oxide

    Science.gov (United States)

    Eubank, Jarrod F.; Wheatley, Paul S.; Lebars, Gaëlle; McKinlay, Alistair C.; Leclerc, Hervé; Horcajada, Patricia; Daturi, Marco; Vimont, Alexandre; Morris, Russell E.; Serre, Christian

    2014-12-01

    The room temperature sorption properties of the biological gas nitric oxide (NO) have been investigated on the highly porous and rigid iron or chromium carboxylate based metal-organic frameworks Material Institut Lavoisier (MIL)-100(Fe or Cr) and MIL-127(Fe). In all cases, a significant amount of NO is chemisorbed at 298 K with a loading capacity that depends both on the nature of the metal cation, the structure and the presence of additional iron(II) Lewis acid sites. In a second step, the release of NO triggered by wet nitrogen gas has been studied by chemiluminescence and indicates that only a partial release of NO occurs as well as a prolonged delivery at the biological level. Finally, an in situ infrared spectroscopy study confirms not only the coordination of NO over the Lewis acid sites and the stronger binding of NO on the additional iron(II) sites, providing further insights over the partial release of NO only in the presence of water at room temperature.

  12. Porous, rigid metal(III-carboxylate metal-organic frameworks for the delivery of nitric oxide

    Directory of Open Access Journals (Sweden)

    Jarrod F. Eubank

    2014-12-01

    Full Text Available The room temperature sorption properties of the biological gas nitric oxide (NO have been investigated on the highly porous and rigid iron or chromium carboxylate based metal-organic frameworks Material Institut Lavoisier (MIL-100(Fe or Cr and MIL-127(Fe. In all cases, a significant amount of NO is chemisorbed at 298 K with a loading capacity that depends both on the nature of the metal cation, the structure and the presence of additional iron(II Lewis acid sites. In a second step, the release of NO triggered by wet nitrogen gas has been studied by chemiluminescence and indicates that only a partial release of NO occurs as well as a prolonged delivery at the biological level. Finally, an in situ infrared spectroscopy study confirms not only the coordination of NO over the Lewis acid sites and the stronger binding of NO on the additional iron(II sites, providing further insights over the partial release of NO only in the presence of water at room temperature.

  13. Waterborne carboxyl-terminated hyperbranched oligomer polyester ligand: Synthesis, characterization and chelation with chromium(III)

    Science.gov (United States)

    Yao, Qi; Li, Chenying; Huang, Henghui; Chen, Hualin; Liu, Bailing

    2017-09-01

    A series of carboxyl-terminated hyperbranched oligomer polyester (HBP) with different degree of branching (DB) and number average molar mass (Mbarn) have been prepared. The molecular structure, degree of branching, molecular mass and its distribution of HBP were investigated by FTIR, 1H NMR, and GPC, respectively. And the coordination number, stability constant and degree of dissociation (α) between HBP and chromium(Ⅲ) were measured via continuous variation method (Job's plot). Experimental results show that the coordination capability between HBP and chromium(Ⅲ) affected by both DB and molecular mass, and the latter plays a decisive role. Moreover HBP outperforms low molecular weight of organic acids (citric acid, acetic acid) and linear polyacrylic acid with similar molecular mass. The coordination number and stability constants of HBP-3 (Mbarn = 1713 Da, Mbarw /Mbarn (PDI) = 1.11 and DB = 0.72) can reach 4 and 6.55e+008, which demonstrated it can be selected as a good ligand to coordination with chromium(Ⅲ). Therefore HBP can be used as chrome auxiliary in chrome tanning to improve the absorption of chromium.

  14. Phosphorescent biscyclometallated iridium(III) ethylenediamine complexes functionalised with polar ester or carboxylate groups as bioimaging and visualisation reagents.

    Science.gov (United States)

    Tang, Tommy Siu-Ming; Leung, Kam-Keung; Louie, Man-Wai; Liu, Hua-Wei; Cheng, Shuk Han; Lo, Kenneth Kam-Wing

    2015-03-21

    We report the synthesis, characterisation and photophysical properties of new phosphorescent biscyclometallated iridium(III) ethylenediamine (en) complexes functionalised with polar ester or carboxylate groups [Ir(N^C)2(en)](n)(X) (n = +1, X = Cl(-), HN^C = methyl 4-(2-pyridyl)benzoate Hppy-COOMe (1a), methyl 2-phenyl-4-quinolinecarboxylate Hpq-COOMe (2a); n = -1, X = Li(+), HN^C = 4-(2-pyridyl)benzoate Hppy-COO(-) (1b), 2-phenyl-4-quinolinecarboxylate Hpq-COO(-) (2b)). In aqueous solutions, the carboxylate complexes 1b and 2b displayed emission quenching (ca. 7 and 74 fold, respectively) and lifetime shortening upon protonation, and their pKa values were determined to be 5.13 and 3.46, respectively. The pq complexes 2a and 2b exhibited hypsochromic shifts in their emission maxima and a significant increase in emission intensity (ca. 84 and 15 fold, respectively) upon nonspecific binding to the protein bovine serum albumin (BSA). Inductively coupled plasma-mass spectroscopy (ICP-MS) and laser-scanning confocal microscopy (LSCM) results revealed that the ester complexes 1a and 2a were efficiently internalised by the human cervix epithelioid carcinoma (HeLa) cells through energy-requiring pathways and subsequently localised in endosomes and mitochondria, respectively. They showed good biocompatibility in the dark, but became significantly cytotoxic upon photoirradiation due to the generation of singlet oxygen. In contrast, in aqueous solutions of physiological pH, the carboxylate complexes 1b and 2b existed as the anionic form and hardly entered cells due to limited membrane permeability, as evidenced by the intense emission surrounding the plasma membrane of the cells. They showed negligible cytotoxicity and the cell viability remained over 95% for an incubation period of 24 hours. In view of the low cytotoxicity and strongly emissive nature of the hydrophilic ppy-COO(-) complex 1b in an aqueous medium, the potential application of the complex as a visualisation

  15. Chloridobis(dimethylglyoximato-κ2N,N′(ethyl pyridine-3-carboxylate-κNcobalt(III

    Directory of Open Access Journals (Sweden)

    Ning Wang

    2012-01-01

    Full Text Available In the title compound, [Co(C4H7N2O22Cl(C8H9NO2], which was prepared as a model complex of vitamin B12, the CoIII atom, which is linked to four N atoms of the pseudo-macrocyclic (dmgH2 ligand (dmgH is dimethylglyoximate in the equatorial plane and one Cl− anion and one N atom of ethyl nicotinate in apical positions, displays an approximately octahedral coordination. The Co atom is 0.0187 (8 Å out of the mean plane of the four equatorial N atoms. The structure has an O...H...O bridge, which is very common in cobaloxime derivatives, with O...H distances of 1.24 (2 and 1.25 (2 Å.

  16. Synthesis and crystal structure of terbium(III) meta-oxoborate Tb(BO{sub 2}){sub 3} ({identical_to} TbB{sub 3}O{sub 6}); Synthese und Kristallstruktur von Terbium(III)-meta-Oxoborat Tb(BO{sub 2}){sub 3} ({identical_to} TbB{sub 3}O{sub 6})

    Energy Technology Data Exchange (ETDEWEB)

    Nikelski, Tanja; Schleid, Thomas [Institut fuer Anorganische Chemie der Universitaet Stuttgart (Germany)

    2003-06-01

    The terbium meta-oxoborate Tb(BO{sub 2}){sub 3} ({identical_to} TbB{sub 3}O{sub 6}) is obtained as single crystals by the reaction of terbium, Tb{sub 4}O{sub 7} and TbCl{sub 3} with an excess of B{sub 2}O{sub 3} in gastight sealed platinum ampoules at 950 C after three weeks. The compound appears to be air- and water-resistant and crystallizes as long, thin, colourless needles which tend to growth-twinning due to their marked fibrous habit. The crystal structure of Tb(BO{sub 2}){sub 3} (orthorhombic, Pnma; a = 1598.97(9), b = 741.39(4), c = 1229.58(7) pm; Z = 16) contains strongly corrugated oxoborate layers {sub {infinity}}{sup 2}{l_brace}(BO{sub 2}){sup -}{r_brace} built of vertex-linked [BO{sub 4}]{sup 5-} tetrahedra (d(B-O) = 143 - 154 pm, and angsph;(O-B-O) = 102-115 ) which spread out parallel (100). The four crystallographically different Tb{sup 3+} cations all exhibit coordination numbers of eight towards the oxygen atoms (d(Tb-O) = 228-287 pm). The corresponding metal cation polyhedra [TbO{sub 8}]{sup 13+} too convene to layers (composition: {sub {infinity}}{sup 2}{l_brace}(Tb{sub 2}O{sub 11}){sup 16-}{r_brace}) which are likewise oriented parallel to the (100) plane. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Das Terbium-meta-Oxoborat Tb(BO{sub 2}){sub 3} ({identical_to} TbB{sub 3}O{sub 6}) entsteht einkristallin bei der Reaktion von Terbium, Tb{sub 4}O{sub 7} und TbCl{sub 3} mit einem Ueberschuss von B{sub 2}O{sub 3} in gasdicht verschlossenen Platinampullen nach drei Wochen bei 950 C. Die Verbindung ist luft- und wasserstabil und faellt in langen, duennen, farblosen Nadeln an, die aufgrund ihres ausgepraegt faserigen Habitus zur Wachstumsverzwillingung neigen. Die Kristallstruktur von Tb(BO{sub 2}){sub 3} (orthorhombisch, Pnma; a = 1598, 97(9), b = 741, 39(4), c = 1229, 58(7) pm; Z = 16) enthaelt parallel (100) verlaufende, stark gewellte Oxoborat-Schichten {sub {infinity}}{sup 2}{l_brace}(BO{sub 2}){sup -}{r_brace} aus

  17. Bismuth(III) α-hydroxy carboxylates: highly selective toxicity of glycolates towards Leishmania major.

    Science.gov (United States)

    Loh, Allan; Ong, Yih Ching; Blair, Victoria L; Kedzierski, Lukasz; Andrews, Philip C

    2015-10-01

    Eight bismuth(III) complexes derived from the simple α-hydroxycarboxylic acids; gluconic (H₆-glu), tartaric (H₄-tar), mandelic (H₂-man), malic (H₃-mal) and glycolic (H₂-gly) have been synthesised and characterised. The complexes are formed through direct treatment of the organic acids with Bi(NO₃)3·5H₂O ([Bi(H₂-tar)(H₃- tar)] 2, [Bi(mal)(NO₃)(H₂O)₂] 6, [Bi(gly)(NO₃)(H₂O)] 8) or Bi(OtBu)₃ ([Bi(H-tar)(H₂O)₂] 1, [Bi(man)(H-man) (H₂O)] 4, [Bi2(H-mal)₃] 5, [Bi(gly)(H-gly)] 7), or through metathesis of the sodium salts with Bi(NO₃)3·5H₂O ([Bi(H3-glu)]₃). Reactions with both glucuronic and mucic acid proved to be unsuccessful. Small crystals of [Bi(gly)4(NO₃)4(H₂O)₄]·5H₂O 8 were obtained from aqueous solution and analysed by synchrotron X-ray diffraction. The data were relatively poor but composition and connectivity were established, confirming and supporting other analyses. Those complexes which displayed sufficient solubility; 2, 4, 7 and 8, were tested for their anti-Leishmanial activity against parasite promastigotes and amastigotes, and for toxicity against human fibroblast cells. All four complexes and their parent acids showed no toxicity towards either the promastigotes or fibroblast cells. However, the two glycolate complexes showed selective toxicity towards amastigotes with complex 8 providing for a low % viability of 1.8 ± 0.9 at 50.0 μM. Graphical Abstract Novel bismuth(III) complexes derived from α-hydroxycarboxylic acids have been synthesised, characterised and assessed for their anti-leishmanial activity. The glycolate complexes are selectively toxic against parasite amastigotes, with all complexes being nontoxic towards promastigotes and human fibroblast cells.

  18. Picomolar traces of americium(III) introduce drastic changes in the structural chemistry of terbium(III). A break in the ''gadolinium break''

    Energy Technology Data Exchange (ETDEWEB)

    Welch, Jan M. [TU Wien, Atominstitut, Vienna (Austria); Mueller, Danny; Knoll, Christian; Wilkovitsch, Martin; Weinberger, Peter [TU Wien, Institute of Applied Synthetic Chemistry, Vienna (Austria); Giester, Gerald [University of Vienna, Institute of Mineralogy and Crystallography, Vienna (Austria); Ofner, Johannes; Lendl, Bernhard [TU Wien, Institute of Chemical Technologies and Analytics, Vienna (Austria); Steinhauser, Georg [Leibniz Universitaet Hannover, Institute of Radioecology and Radiation Protection (Germany)

    2017-10-16

    The crystallization of terbium 5,5{sup '}-azobis[1H-tetrazol-1-ide] (ZT) in the presence of trace amounts (ca. 50 Bq, ca. 1.6 pmol) of americium results in 1) the accumulation of the americium tracer in the crystalline solid and 2) a material that adopts a different crystal structure to that formed in the absence of americium. Americium-doped [Tb(Am)(H{sub 2}O){sub 7}ZT]{sub 2} ZT.10 H{sub 2}O is isostructural to light lanthanide (Ce-Gd) 5,5{sup '}-azobis[1H-tetrazol-1-ide] compounds, rather than to the heavy lanthanide (Tb-Lu) 5,5{sup '}-azobis[1H-tetrazol-1-ide] (e.g., [Tb(H{sub 2}O){sub 8}]{sub 2}ZT{sub 3}.6 H{sub 2}O) derivatives. Traces of Am seem to force the Tb compound into a structure normally preferred by the lighter lanthanides, despite a 10{sup 8}-fold Tb excess. The americium-doped material was studied by single-crystal X-ray diffraction, vibrational spectroscopy, radiochemical neutron activation analysis, and scanning electron microscopy. In addition, the inclusion properties of terbium 5,5{sup '}-azobis[1H-tetrazol-1-ide] towards americium were quantified, and a model for the crystallization process is proposed. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. [?-N,N?-Bis(3-meth?oxy-2-oxidobenzyl?idene)propane-1,3-diamine]trinitratocopper(II)terbium(III) acetone solvate

    OpenAIRE

    Zhang Fang; Liu Fei

    2008-01-01

    In the title complex, [CuTb(C19H20N2O4)(NO3)3]·CH3COCH3, the CuII atom is four-coordinated by two O atoms and two N atoms from the deprotonated Schiff base in a square-planar geometry, while the TbIII atom is ten-coordinated by four O atoms from the deprotonated Schiff base and six O atoms from three bidentate nitrate anions. The compound is isostructural with the previously reported GdIII analogue [Elmali & Elerman (2004). Z. Naturforsch. Teil B, 59, 535–540], which was described ...

  20. Tetrakis(μ-2-phenoxypropionato-κ3O,O′:O′;κ3O:O,O′,κ4O:O′-bis[(1,10-phenanthroline-κ2N,N′(2-phenoxypropionato-κ2O,O′praseodymium(III

    Directory of Open Access Journals (Sweden)

    Jin-Bei Shen

    2011-09-01

    Full Text Available In the centrosymmetric binuclear title complex, [Pr2(C9H9O36(C12H8N22], the two PrIII ions are linked by four 2-phenoxypropionate (L groups through their bi- and tridentate bridging modes. Each PrIII ion is nine-coordinated by one 1,10-phenanthroline molecule, one bidentate carboxylate group and four bridging carboxylate groups in a distorted PrN2O7 monocapped square-antiprismatic geometry. The title compound is isotypic with its terbium- and dysprosium-containing analogues.

  1. Bis(acridine-9-carboxylate)-nitro-europium(III) dihydrate complex a new apoptotic agent through Flk-1 down regulation, caspase-3 activation and oligonucleosomes DNA fragmentation.

    Science.gov (United States)

    Azab, Hassan A; Hussein, Belal H M; El-Azab, Mona F; Gomaa, Mohamed; El-Falouji, Abdullah I

    2013-01-01

    New bis(acridine-9-carboxylate)-nitro-europium(III) dihydrate complex was synthesized and characterized. In vivo anti-angiogenic activities of bis(acridine-9-carboxylate)-nitro-europium(III) dihydrate complex against Ehrlich ascites carcinoma (EAC) cells are described. The newly synthesized complex resulted in inhibition of proliferation of EAC cells and ascites formation. The anti-tumor effect was found to be through anti-angiogenic activity as evident by the reduction of microvessel density in EAC solid tumors. The anti-angiogenic effect is mediated through down-regulation of VEGF receptor type-2 (Flk-1). The complex was also found to significantly increase the level of caspase-3 in laboratory animals compared to the acridine ligand and to the control group. This was also consistent with the DNA fragmentation detected by capillary electrophoresis that proved the apoptotic effect of the new complex. Our complex exhibited anti-angiogenic and apoptotic activity in vivo, a thing that makes it a potential effective chemotherapeutic agent. The interaction of calf thymus DNA (ct-DNA) with bis(acridine-9-carboxylate)-nitro-europium(III) dihydrate complex has been investigated using fluorescence technique. A competitive experiment of the europium(III)-acridine complex with ethidium bromide (EB) to bind DNA revealed that interaction between the europium(III)-acridine and DNA was via intercalation. The interaction of the synthesized complex with tyrosine kinases was also studied using molecular docking simulation to further substantiate its mode of action. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. A Water-Stable Dual-Channel Luminescence Sensor for UO22+Ions Based on an Anionic Terbium(III) Metal-Organic Framework.

    Science.gov (United States)

    Ye, Junwei; Bogale, Raji F; Shi, Yangwei; Chen, Yanzhen; Liu, Xigang; Zhang, Siqi; Yang, Yaoyao; Zhao, Jianzhang; Ning, Guiling

    2017-06-07

    A stable 3D Tb III -based metal-organic framework [Tb(BPDC) 2 ]⋅(CH 3 ) 2 NH 2 (DUT-101) was synthesized, and it is the first efficient dual-channel luminescence sensor for aqueous UO 2 2+ ions. DUT-101 contains an anionic three-dimensional framework and protonated dimethylamine molecules embedded within the channels. The intense green emission of DUT-101 could be highly selectively and sensitively quenched by UO 2 2+ ions even in the presence of other competing metal ions. A possible sensing mechanism was proposed based on both suppression of luminescence resonance energy transfer and enhancement of intermolecular electron transfer. Furthermore, visual green fluorescent test papers based on DUT-101 were fabricated and could be used to discriminate UO 2 2+ ions among various metal ions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Comparative analysis of conjugated alkynyl chromophore-triazacyclononane ligands for sensitized emission of europium and terbium.

    Science.gov (United States)

    Soulié, Marine; Latzko, Frédéric; Bourrier, Emmanuel; Placide, Virginie; Butler, Stephen J; Pal, Robert; Walton, James W; Baldeck, Patrice L; Le Guennic, Boris; Andraud, Chantal; Zwier, Jurriaan M; Lamarque, Laurent; Parker, David; Maury, Olivier

    2014-07-07

    A series of europium and terbium complexes based on a functionalized triazacyclononane carboxylate or phosphinate macrocyclic ligand is described. The influence of the anionic group, that is, carboxylate, methylphosphinate, or phenylphosphinate, on the photophysical properties was studied and rationalized on the basis of DFT calculated structures. The nature, number, and position of electron-donating or electron-withdrawing aryl substituents were varied systematically within the same phenylethynyl scaffold in order to optimize the brightness of the corresponding europium complexes and investigate their two-photon absorption properties. Finally, the europium complexes were examined in cell-imaging applications, and selected terbium complexes were studied as potential oxygen sensors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Luminescent pillared Ln{sup III}–Zn{sup II} heterometallic coordination frameworks with two kinds of N-heterocyclic carboxylate ligands

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Sui-Jun; Jia, Ji-Min; Cui, Yu; Han, Song-De; Chang, Ze, E-mail: changze@nankai.edu.cn

    2014-04-01

    In our efforts toward rational design and systematic synthesis of ‘pillar-layer’ structure coordination frameworks, four new Ln{sup III}–Zn{sup II} heterometallic coordination polymers (CPs) based on two kinds of N-heterocyclic carboxylic ligands with formula ([LnZn(L1){sub 2}(L2)(H{sub 2}O){sub m}]·nH{sub 2}O){sub ∞} (Ln=La (1), Eu (2), Gd (3) and Dy (4), m=3 (for 1) and 2 (for 2–4), n=8 (for 1) and 7 (for 2–4), H{sub 2}L1=pyridine-2,3-dicarboxylate acid, HL2=isonicotinic acid), have been synthesized under hydrothermal reaction of Ln{sub 2}O{sub 3}, ZnO, H{sub 2}L1 and HL2. CP 1 has a three-dimensional (3D) structure with a (3,6)-connected sit topology network, while CPs 2–4 are isostructural with 3D single-node pcu alpha-Po topology network. Also, luminescent properties of these CPs have also been investigated. The emission of 1 and 3 should be attributed to the coordination-perturbed ligand-centered luminescence and the emission spectra of 2 and 4 show the characteristic bands of the corresponding Ln{sup III} ions. - Graphical abstract: Four new 3D Ln{sup III}–Zn{sup II} coordination frameworks with “pillar-layer” sit or pcu alpha-Po topology have been successfully obtained. Moreover, the photoluminescent properties of compounds 1–4 have also been investigated. - Highlights: • Four new Ln{sup III}–Zn{sup II} heterometallic coordination frameworks with two types of topologies have been synthesized. • Metal oxides and two kinds of N-heterocyclic carboxylate ligands were used for the construction of targeted coordination polymers. • The luminescent properties of the coordination polymers are investigated.

  5. Iron(III)- and copper(II) complexes of an asymmetric, pentadentate salen-like ligand bearing a pendant carboxylate group.

    Science.gov (United States)

    Jancsó, Attila; Paksi, Zoltán; Mikkola, Satu; Rockenbauer, Antal; Gajda, Tamás

    2005-07-01

    The equilibrium and solution structural properties of the iron(III) and copper(II) complexes of an asymmetric salen-like ligand (N,N'-bis(2-hydroxybenzyl)-2,3-diamino-propionic acid, H(3)bhbdpa) bearing a pendant carboxylate group were characterized in aqueous solution by potentiometric, pH-dependent electron paramagnetic resonance (EPR) and UV-Vis (UV-Visible) measurements. In the equimolar systems the pentadentate ligand forms very stable, differently protonated mononuclear complexes with both metal ions. In the presence of iron(III) {NH, PhO(-), COO(-)}, {2NH, 2PhO(-), COO(-)} and {2NH, 2PhO(-), COO(-), OH(-)} coordinated complexes are dominant. The EPR titrations reflected the presence of microscopic complex formation pathways, leading to the formation of binding isomers in case of Cu(H(2)bhbdpa)(+), Cu(Hbhbdpa) and Cu(bhbdpa)(-). The {2NH, 2PhO(-)+COO(-)/H(2)O} coordinated Cu(bhbdpa) is the only species between pH 6-11. At twofold excess of metal ion dinuclear complexes were detected with both iron(III) and copper(II). In presence of iron(III) a mu-carboxylato-mu-hydroxo-bridged dinuclear complex (Fe(2)(bhbdpa)(OH)(3)) is formed from Fe(H(2)bhbdpa)(2+) through overlapping proton release processes, providing one of the rare examples for the stabilization of an endogenous carboxylate bridged diiron core in aqueous solution. The complex Cu(2)(bhbdpa)(+) detected in the presence of copper(II) is a paramagnetic (S=1) species with relatively weakly coupled metal ions.

  6. Luminescence quenching of Eu(III) carboxylates by Cu(II) in a composite polymer xerogel film.

    Science.gov (United States)

    Barja, Beatriz C; Remorino, Amanda; Aramendía, Pedro F

    2006-01-01

    Three Eu(III) luminescent compounds were separately entrapped in a xerogel porous silica matrix and finely ground particles of it were deposited on a glass support with polyvinylacetate (PVAc) as a binder to build a thin film sensor. These 3 devices were immersed in aqueous solutions of Cu(II) and the content of this metal was evaluated by emission-quenching experiments. The sensor containing the highly luminescent antenna chelate of diethylenetriaminepentaacetic acid (dtpa) sensitized with Coumarin120 rendered the largest Stern-Volmer constant (K(SV) = 1.49 x 10(4) M(-1)), showing no leaching of the Eu(III) complex to the aqueous solution and a reproducible value of the luminescence ratio between water and Cu(II) solution. The in situ sensor we developed can measure the concentration of Cu(II) in aqueous media down to the ppm level by emission-quenching experiments. This methodology permits a simple calibration of the sensor and an easy to use reusable device.

  7. Chloridobis(dimethylglyoximato-κ2N,N′(ethyl pyridine-4-carboxylate-κNcobalt(III chloroform monosolvate

    Directory of Open Access Journals (Sweden)

    Ning Wang

    2012-02-01

    Full Text Available The title compound, [Co(C4H7N2O22Cl(C8H9NO2]·CHCl3, was synthesized as a model complex of vitamin B12. The CoIII cation displays an approximately octahedral coordination environment, being displaced by 0.0240 (15 Å from the mean plane of the four N atoms of the equatorial plane. The O—H distances in the dimethylglyoximate hydroxy groups are 0.89 (6 and 1.14 (6 Å; such long O—H bonds are very common in cobaloxime derivatives. Weak classical O—H...N and non-classical C—H...Cl hydrogen-bonding interactions further consolidate the crystal packing.

  8. Critical scattering of neutrons from terbium

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Dietrich, O.W.; Marshall, W.

    1968-01-01

    The inelasticity of the critical scattering of neutrons in terbium has been measured above the Neél temperature at the (0, 0, 2−Q) satellite position. The results show that dynamic slowing down of the fluctuations does occur in a second‐order phase transition in agreement with the general theory...

  9. Semiconductor composition containing iron, dysprosium, and terbium

    Energy Technology Data Exchange (ETDEWEB)

    Pooser, Raphael C.; Lawrie, Benjamin J.; Baddorf, Arthur P.; Malasi, Abhinav; Taz, Humaira; Farah, Annettee E.; Kalyanaraman, Ramakrishnan; Duscher, Gerd Josef Mansfred; Patel, Maulik K.

    2017-09-26

    An amorphous semiconductor composition includes 1 to 70 atomic percent iron, 15 to 65 atomic percent dysprosium, 15 to 35 atomic percent terbium, balance X, wherein X is at least one of an oxidizing element and a reducing element. The composition has an essentially amorphous microstructure, an optical transmittance of at least 50% in at least the visible spectrum and semiconductor electrical properties.

  10. Circularly Polarized Luminescence in Enantiopure Europium and Terbium Complexes with Modular, All-Oxygen Donor Ligands

    Science.gov (United States)

    Seitz, Michael; Do, King; Ingram, Andrew J.; Moore, Evan G.; Muller, Gilles; Raymond, Kenneth N.

    2009-01-01

    Abstract: Circulaly polarized luminescence from terbium(III) complexed and excited by chiral antenna ligands gives strong emission The modular synthesis of three new octadentate, enantiopure ligands are reported - one with the bidentate chelating unit 2-hydroxyisophthalamide (IAM) and two with 1-hydroxy-2-pyridinone (1,2-HOPO) units. A new design principle is introduced for the chiral, non-racemic hexamines which constitute the central backbones for the presented class of ligands. The terbium(III) complex of the IAM ligand, as well as the europium(III) complexes of the 1,2-HOPO ligands are synthesized and characterized by various techniques (NMR, UV, CD, luminescence spectroscopy). All species exhibit excellent stability and moderate to high luminescence efficiency (quantum yields ΦEu = 0.05–0.08 and ΦTb = 0.30–0.57) in aqueous solution at physiological pH. Special focus is put onto the properties of the complexes in regard to circularly polarized luminescence (CPL). The maximum luminescence dissymmetry factors (glum) in aqueous solution are high with |glum|max = 0.08 – 0.40. Together with the very favorable general properties (good stability, high quantum yields, long lifetimes), the presented lanthanide complexes can be considered as good candidates for analytical probes based on CPL in biologically relevant environments. PMID:19639983

  11. Indium(III)-catalyzed reductive bromination and iodination of carboxylic acids to alkyl bromides and iodides: scope, mechanism, and one-pot transformation to alkyl halides and amine derivatives.

    Science.gov (United States)

    Moriya, Toshimitsu; Yoneda, Shinichiro; Kawana, Keita; Ikeda, Reiko; Konakahara, Takeo; Sakai, Norio

    2013-11-01

    Highly effective indium(III)-catalyzed reductive bromination or iodination of a variety of carboxylic acids with 1,1,3,3-tetramethyldisiloxane (TMDS) and a source of bromine or iodine is described. This functional group interconversion has high tolerance for several functional groups, such as halogens, a hydroxy group, a nitro group, an olefin part, and a sulfide moiety. This indium catalytic system is also applicable to the reductive iodination of aldehyded, acyl chlorides, and esters. Furthermore, this reducing system can be applied to the one-pot synthesis of alkyl halides and amine derivatives via the addition of nucleophiles. Insight into the reaction mechanism was gained via the time course of (1)H and (13)C NMR monitoring experiments and the corresponding stepwise reactions.

  12. The 33 carboxyl-terminal residues of Spa40 orchestrate the multi-step assembly process of the type III secretion needle complex in Shigella flexneri

    NARCIS (Netherlands)

    Botteaux, Anne; Kayath, Christian A.; Page, Anne-Laure; Jouihri, Nouredine; Sani, Musa; Boekema, Egbert; Biskri, Latefa; Parsot, Claude; Allaoui, Abdelmounaaim

    The type III secretion apparatus (T3SA) is a central virulence factor of many Gram-negative bacteria. Its overall morphology consists of a cytoplasmic region, inner- and outer-membrane sections and an extracellular needle. In Shigella, the length of the needle is regulated by Spa32. To understand

  13. Raman spectroscopy study of the doping effect of the encapsulated terbium halogenides on single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kharlamova, M.V.; Kramberger, C.; Mittelberger, A. [University of Vienna, Faculty of Physics, Vienna (Austria)

    2017-04-15

    In the present work, the doping effect of terbium chloride, terbium bromide, and terbium iodide on single-walled carbon nanotubes (SWCNTs) was compared by Raman spectroscopy. A precise investigation of the doping-induced alterations of the Raman modes of the filled SWCNTs was conducted. The shifts of the components of the Raman modes and modification of their profiles allowed concluding that the inserted terbium halogenides have acceptor doping effect on the SWCNTs, and the doping efficiency increases in the line with terbium iodide, terbium bromide, and terbium chloride. (orig.)

  14. Structural and thermodynamic study of rare earth(III) complexation by poly-hydroxylated carboxylic acids: synthesis of new extractants and outlook for the extraction of these cations; Etude structurale et thermodynamique de la complexation de lanthanides (III) par des acides carboxyliques polyhydroxyles: synthese de nouveaux extractants et perspectives pour l'extraction de ces cations

    Energy Technology Data Exchange (ETDEWEB)

    Aury, S

    2002-12-15

    The aim of this work is: to improve the knowledge on the binding sites of the poly-hydroxylated carboxylic acids with the trivalent lanthanide(III) ions by comparing them to gluconic acid (previously studied) and to molecules with different configuration and with a variable number of OH functions (threonic acid, glyceric acid, 2-hydroxy-butanoic acid, 3-hydroxy-butanoic acid). To find the best complexing agent among different acids (aldonic acids, aldaric acids, di-hydroxybenzoic acids) (determination of the set of complexes and their stability constants by potentiometry, NMR and UV-Visible spectroscopy). To synthesize hydrophobic monoamides from one lactone form of saccharic acid, to study their complexing power and their capacity to extract the trivalent lanthanide(III) ions. (author)

  15. The 33 carboxyl-terminal residues of Spa40 orchestrate the multi-step assembly process of the type III secretion needle complex in Shigella flexneri.

    Science.gov (United States)

    Botteaux, Anne; Kayath, Christian A; Page, Anne-Laure; Jouihri, Nouredine; Sani, Musa; Boekema, Egbert; Biskri, Latéfa; Parsot, Claude; Allaoui, Abdelmounaaïm

    2010-09-01

    The type III secretion apparatus (T3SA) is a central virulence factor of many Gram-negative bacteria. Its overall morphology consists of a cytoplasmic region, inner- and outer-membrane sections and an extracellular needle. In Shigella, the length of the needle is regulated by Spa32. To understand better the role of Spa32 we searched for its interacting partners using a two-hybrid screen in yeast. We found that Spa32 interacts with the 33 C-terminal residues (CC*) of Spa40, a member of the conserved FlhB/YscU family. Using a GST pull-down assay we confirmed this interaction and identified additional interactions between Spa40 and the type III secretion components Spa33, Spa47, MxiK, MxiN and MxiA. Inactivation of spa40 abolished protein secretion and led to needleless structures. Genetic and functional analyses were used to investigate the roles of residues L310 and V320, located within the CC* domain of Spa40, in the assembly of the T3SA. Spa40 cleavage, at the conserved NPTH motif, is required for assembly of the T3SA and for its interaction with Spa32, Spa33 and Spa47. In contrast, unprocessed forms of Spa40 interacted only with MxiA, MxiK and MxiN. Our data suggest that the conformation of the cytoplasmic domain of Spa40 defines the multi-step assembly process of the T3SA.

  16. Micelle-enhanced and terbium-sensitized spectrofluorimetric determination of gatifloxacin and its interaction mechanism

    Science.gov (United States)

    Guo, Changchuan; Wang, Lei; Hou, Zhun; Jiang, Wei; Sang, Lihong

    2009-05-01

    A terbium-sensitized spectrofluorimetric method using an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS), was developed for the determination of gatifloxacin (GFLX). A coordination complex system of GFLX-Tb 3+-SDBS was studied. It was found that SDBS significantly enhanced the fluorescence intensity of the complex (about 11-fold). Optimal experimental conditions were determined as follows: excitation and emission wavelengths of 331 and 547 nm, pH 7.0, 2.0 × 10 -4 mol l -1 terbium (III), and 2.0 × 10 -4 mol l -1 SDBS. The enhanced fluorescence intensity of the system (Δ If) showed a good linear relationship with the concentration of GFLX over the range of 5.0 × 10 -10 to 5.0 × 10 -8 mol l -1 with a correlation coefficient of 0.9996. The detection limit (3 σ) was determined as 6.0 × 10 -11 mol l -1. This method has been successfully applied to the determination of GFLX in pharmaceuticals and human urine/serum samples. Compared with most of other methods reported, the rapid and simple procedure proposed in the text offers higher sensitivity, wider linear range, and better stability. The interaction mechanism of the system is also studied by the research of ultraviolet absorption spectra, surface tension, solution polarity and fluorescence polarization.

  17. Investigation of the luminescent properties of terbium-anthranilate complexes and application to the determination of anthranilic acid derivatives in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Arnaud, N.; Georges, J

    2003-01-10

    The luminescent properties of terbium complexes with furosemide (FR), flufenamic (FF) acid, tolfenamic (TF) acid and mefenamic (MF) acid have been investigated in aqueous solutions. For all four compounds, complexation occurs when the carboxylic acid of the aminobenzoic group is dissociated and is greatly favoured in the presence of trioctylphosphine oxide as co-ligand and Triton X-100 as surfactant. Under optimum conditions, luminescence of the lanthanide ion is efficiently sensitised and the lifetime of the {sup 5}D{sub 4} resonance level of terbium in the complex is ranging between 1 and 1.9 ms, against 0.4 ms for the aqua ion. The sensitivity of the method for the determination of anthranilic acid derivatives is improved by one to two orders of magnitude with respect to that achieved using native fluorescence or terbium-sensitised luminescence in methanol. The limits of detection are 2x10{sup -10}, 5x10{sup -10} and 2x10{sup -9} mol l{sup -1} for flufenamic acid, furosemide and tolfenamic acid, and mefenamic acid, respectively, with within-run RSD values of less than 1%. The method has been applied to the determination of flufenamic acid in spiked calf sera with and without sample pretreatment. Depending on the method and the analyte concentration, the recovery was ranging between 83 and 113% and the lowest concentration attainable in serum samples was close to 1x10{sup -7} mol l{sup -1}.

  18. Magnetocaloric effect of thin Terbium films

    Science.gov (United States)

    Mello, V. D.; Anselmo, D. H. A. L.; Vasconcelos, M. S.; Almeida, N. S.

    2017-12-01

    We report a theoretical study of the magnetocaloric effect of Terbium (Tb) thin films due to finite size and surface effects in the helimagnetic phase, corresponding to a temperature range from TC=219 K to TN=231 K, for external fields of the order of kOe. For a Tb thin film of 6 monolayers submitted to an applied field (ΔH =30 kOe, ΔH =50 kOe and ΔH = 70 kOe) we report a significative change in adiabatic temperature, ΔT / ΔH , near the Néel temperature, of the order ten times higher than that observed for Tb bulk. On the other hand, for small values of the magnetic field, large thickness effects are found. For external field strength around few kOe, we have found that the thermal caloric efficiency increases remarkably for ultrathin films. For an ultrathin film with 6 monolayers, we have found ΔT / ΔH = 43 K/T while for thicker films, with 20 monolayers, ΔT / ΔH = 22 K/T. Our results suggest that thin films of Tb are a promising material for magnetocaloric effect devices for applications at intermediate temperatures.

  19. Femtosecond XUV spectroscopy of gadolinium and terbium

    Energy Technology Data Exchange (ETDEWEB)

    Carley, Robert; Frietsch, Bjoern; Doebrich, Kristian; Teichmann, Martin; Gahl, Cornelius; Noack, Frank [Max-Born-Institute, Berlin (Germany); Schwarzkopf, Olaf; Wernet, Philippe [Helmholtz-Zentrum fuer Materialien und Energie (BESSY II), Berlin (Germany); Weinelt, Martin [Max-Born-Institute, Berlin (Germany); Fachbereich Physik, Freie Universitaet, Berlin (Germany)

    2011-07-01

    We present recent results of time-resolved IR-pump-XUV-probe experiments on the ultrafast demagnetization of thin films of Gadolinium(0001) and Terbium(0001) on Tungsten(110). The experiments are the first to be done using a newly developed high-order harmonics (HHG) XUV beamline at the MBI. The beamline delivers monochromated XUV pulses of approximately 150 fs duration with a photon energy resolution of up to 150 meV. Following excitation by intense femtosecond infrared (IR) pulses, photoemission with 35 eV photons allows us to directly probe the 4f electrons and their interaction with the valence band, both in the bulk and at the surface, to follow the ultrafast magnetization dynamics in the Lanthanide metals. As signatures of ultrafast demagnetization of the metal by the IR pulse, we see for the first time, rapid strong reduction of the exchange splitting in the valence band. This is followed by a slower demagnetization due to the spin-lattice interaction.

  20. Sensitization effects of supramolecular assemblies on the luminescence of terbium-ion prulifloxacin complexes

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hong; Yi Chongyue; Li Xue; Fang Fang [School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Yang Yajiang, E-mail: yjyang@mail.hust.edu.c [School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-04-15

    Luminescence enhancement of terbium-ion prulifloxacin complexes (Tb(III)-PUFX) in supramolecular hydrogels formed by assembly of 1,3:2,4-di-O-benzylidene-D-sorbitol (DBS) was investigated by steady-state fluorescence, varying temperature fluorescence and time-resolved fluorescence. The luminescence images show that Tb(III)-PUFX were dispersed in the DBS gels. The luminescence intensity of Tb(III)-PUFX in the DBS gels was significantly increased in comparison with that in corresponding aqueous solutions. The varying temperature fluorescent spectra show that the luminescence intensity of Tb(III)-PUFX decreased with an increase in the temperature. This implies that the luminescence enhancement of Tb(III)-PUFX is related to the dissociation and the formation of the DBS assemblies. Time-resolved fluorescence measurements show slower rotational motion in DBS gels in comparison with that in the corresponding aqueous solutions. This may be ascribed to a unique microstructure of three-dimensional network formed by DBC aggregates, resulting in deactivation of the nonradiative relaxation. The images of field emission scanning electron microscopy and polarized optical microscopy indicate that the morphology of the DBS assemblies was not influenced upon addition of Tb(III)-PUFX to the DBS gels.

  1. Green fluorescence of terbium ions in lithium fluoroborate glasses ...

    Indian Academy of Sciences (India)

    Glasses; terbium ion; oscillator strengths; fluorescence; lifetimes; fibre lasers. 1. Introduction. Today glasses are most favourable engineering materials for abundant applications due to the wide ability of property altering by compositional modifications. The considerable examination of glass science to achieve required ...

  2. Green fluorescence of terbium ions in lithium fluoroborate glasses ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 3. Green fluorescence of terbium ions in lithium fluoroborate glasses for fibre lasers and display devices. G R DILLIP C MADHUKAR REDDY M RAJESH SHIVANAND CHAURASIA B DEVA PRASAD RAJU S W JOO. Volume 39 Issue 3 June 2016 pp 711-717 ...

  3. Terbium fluorescence as a sensitive, inexpensive probe for UV-induced damage in nucleic acids

    Energy Technology Data Exchange (ETDEWEB)

    El-Yazbi, Amira F.; Loppnow, Glen R., E-mail: glen.loppnow@ualberta.ca

    2013-07-05

    Graphical abstract: -- Highlights: •Simple, inexpensive, mix-and-read assay for positive detection of DNA damage. •Recognition of undamaged DNA via hybridization to a hairpin probe. •Terbium(III) fluorescence reports the amount of damage by binding to ssDNA. •Tb/hairpin is a highly selective and sensitive fluorescent probe for DNA damage. -- Abstract: Much effort has been focused on developing methods for detecting damaged nucleic acids. However, almost all of the proposed methods consist of multi-step procedures, are limited, require expensive instruments, or suffer from a high level of interferences. In this paper, we present a novel simple, inexpensive, mix-and-read assay that is generally applicable to nucleic acid damage and uses the enhanced luminescence due to energy transfer from nucleic acids to terbium(III) (Tb{sup 3+}). Single-stranded oligonucleotides greatly enhance the Tb{sup 3+} emission, but duplex DNA does not. With the use of a DNA hairpin probe complementary to the oligonucleotide of interest, the Tb{sup 3+}/hairpin probe is applied to detect ultraviolet (UV)-induced DNA damage. The hairpin probe hybridizes only with the undamaged DNA. However, the damaged DNA remains single-stranded and enhances the intrinsic fluorescence of Tb{sup 3+}, producing a detectable signal directly proportional to the amount of DNA damage. This allows the Tb{sup 3+}/hairpin probe to be used for sensitive quantification of UV-induced DNA damage. The Tb{sup 3+}/hairpin probe showed superior selectivity to DNA damage compared to conventional molecular beacons probes (MBs) and its sensitivity is more than 2.5 times higher than MBs with a limit of detection of 4.36 ± 1.2 nM. In addition, this probe is easier to synthesize and more than eight times cheaper than MBs, which makes its use recommended for high-throughput, quantitative analysis of DNA damage.

  4. Terahertz Cherenkov radiation from ultrafast magnetization in terbium gallium garnet

    Science.gov (United States)

    Gorelov, S. D.; Mashkovich, E. A.; Tsarev, M. V.; Bakunov, M. I.

    2013-12-01

    We report an experimental observation of terahertz Cherenkov radiation from a moving magnetic moment produced in terbium gallium garnet by a circularly polarized femtosecond laser pulse via the inverse Faraday effect. Contrary to some existing theoretical predictions, the polarity of the observed radiation unambiguously demonstrates the paramagnetic, rather than diamagnetic, nature of the ultrafast inverse Faraday effect. From measurements of the radiation field, the Verdet constant in the subpicosecond regime is ˜3-10 times smaller than its table quasistatic value.

  5. Interaction of 3-Hydroxypicolinamide with Tb III and its Sensitizing ...

    African Journals Online (AJOL)

    Interaction of 3-Hydroxypicolinamide with Tb III and its Sensitizing Effect on Terbium Luminescence as a Function of pH and Medium. ... The complex formed exists asML2 species in which HPA behaves as anO,O,N,N-chelating ligand. The solid complex is isolated from aqueous medium and characterized employing ...

  6. New broad-spectrum cephalosporins with anti-pseudomonal activity. III. Synthesis and antibacterial activity of 7 beta-[D-2-(4-hydroxy-6-methylpyridine-3-carbonylamino)-2-(4-hydroxyphenyl) acetamido]-3-(methyl or substituted methyl)-ceph-3-em-4-carboxylic acids.

    Science.gov (United States)

    Yamada, H; Tobiki, H; Jimpo, K; Komatsu, T; Okuda, T; Noguchi, H; Nakagome, T

    1983-05-01

    The influence of various 3-substituents on the antibacterial activity of 7 beta-[D-2-(4-hydroxy-6-methylpyridine-3-carbonylamino)-2-(4-hydroxyphenyl) acetamido]ceph-3-em-4-carboxylic acids (III) was investigated. Introduction of an acidic substituent, such as a sulfo or a carboxyl group, to a 3-(1-methyl-1H-tetrazolyl)thiomethyl substituent (IIIf--i) resulted in a marked loss of activity against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, Escherichia coli, Klebsiella pneumoniae, and Enterobacter aerogenes, in contrast to an in crease of activity against Proteus mirabilis. Displacement of the acetoxy group of IIIb with pyridines (IIIm--p) enhanced the activity against P. aeruginosa and E. aerogenes: their activity against those strains were superior to that of the cephalosporin IIId having a 3-(1-methyl-1H-tetrazolyl)thiomethyl substituent. As a result of extensive studies in addition to the study of in vitro activity in this series, 7 beta-[D-2-(4-hydroxy-6-methylpyridine-3-carbonylamino)-2-(4-hydroxyphenyl) acetamido]-3-[(1-methyl-1H-tetrazol-5-yl)thiomethyl]ceph-3-em-4-carboxylic acid, code No. SM-1652, cefpiramide (generic name), was selected as a candidate for further biological and clinical investigations.

  7. Complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III)

    OpenAIRE

    Ferenc, W.; Bernat, M.; Sarzyński, J.; Głuchowska, H.

    2010-01-01

    The complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) have been synthesized as polycrystalline hydrated solids, and characterized by elemental analysis, spectroscopy, magnetic studies and also by X-ray diffraction and thermogravimetric measurements. The analysed complexes have the following colours: violet for Nd(III), white for Gd(III) and cream for Ho(III) compounds. The carboxylate groups bind as bidentate chelating (Ho) or bridging ligands (Nd, Gd). On heating to 1173K ...

  8. Terbium luminescence in alumina xerogel fabricated in porous anodic alumina matrix under various excitation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gaponenko, N. V., E-mail: nik@nano.bsuir.edu.by [Belarusian State University of Informatics and Radioelectronics (Belarus); Kortov, V. S. [Yeltsin Ural Federal University (Russian Federation); Orekhovskaya, T. I.; Nikolaenko, I. A. [Belarusian State University of Informatics and Radioelectronics (Belarus); Pustovarov, V. A.; Zvonarev, S. V.; Slesarev, A. I. [Yeltsin Ural Federal University (Russian Federation); Prislopski, S. Ya. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus)

    2011-07-15

    Terbium-doped alumina xerogel layers are synthesized by the sol-gel method in pores of a porous anodic alumina film 1 {mu}m thick with a pore diameter of 150-180 nm; the film is grown on a silicon substrate. The fabricated structures exhibit terbium photoluminescence with bands typical of trivalent terbium terms. Terbium X-ray luminescence with the most intense band at 542 nm is observed for the first time for such a structure. Morphological analysis of the structure by scanning electron microscopy shows the presence of xerogel clusters in pore channels, while the main pore volume remains unfilled and pore mouths remain open. The data obtained confirm the promising applications of fabricated structures for developing matrix converters of X-rays and other ionizing radiations into visible light. The possibilities of increasing luminescence intensity in the matrix converter are discussed.

  9. Optical Properties of Lithium Terbium Fluoride and Implications for Performance in High Power Lasers (Postprint)

    Science.gov (United States)

    2016-02-01

    AFRL-RX-WP-JA-2016-0323 OPTICAL PROPERTIES OF LITHIUM TERBIUM FLUORIDE AND IMPLICATIONS FOR PERFORMANCE IN HIGH POWER LASERS... AMERICA (STINFO COPY) AIR FORCE RESEARCH LABORATORY MATERIALS AND MANUFACTURING DIRECTORATE WRIGHT-PATTERSON AIR FORCE BASE, OH 45433-7750 AIR...OPTICAL PROPERTIES OF LITHIUM TERBIUM FLUORIDE AND IMPLICATIONS FOR PERFORMANCE IN HIGH POWER LASERS (POSTPRINT) 5a. CONTRACT NUMBER IN-HOUSE 5b

  10. Detection of biothiols in cells by a terbium chelate-Hg (II) system

    Science.gov (United States)

    Tan, Hongliang; Chen, Yang

    2012-01-01

    Great efforts have been devoted to the development of sensitive and specific analysis methods for biothiols because of their important roles in biological systems. We present a new detection system for biothiols that is based on the reversible quenching and restoration of fluorescence of terbium chelate caused by Hg2+ and thiol species. In the presence of biothiols, a restoration of fluorescence of terbium chelate after quenching by Hg2+ was observed due to the interaction of Hg2+ with thiol groups, and the restored fluorescence increased with the concentration of biothiols. This method was sensitive and selective for biothiols. The detection limit was 80 nM for glutathione, 100 nM for Hcy, and 400 nM for Cysteine, respectively. The terbium chelate-Hg (II) system was successfully applied to determine the levels of biothiols in cancer cells and urine samples. Further, it was also shown to be comparable to Ellman's assay. Compared to other fluorescence methods, the terbium chelate probe is advantageous because interference from short-lived nonspecific fluorescence can be efficiently eliminated due to the long fluorescence lifetime of terbium chelate, which allows for detection by time-resolved fluorescence. The terbium chelate probe can serve as a diagnostic tool for the detection of abnormal levels of biothiols in disease.

  11. Cryogenic temperature characteristics of Verdet constant of terbium sesquioxide ceramics

    Science.gov (United States)

    Snetkov, I. L.; Palashov, O. V.

    2016-12-01

    The dependence of the Verdet constant on temperature in the (80-300 K) range for a promising magneto-active material terbium sesquioxide Tb2O3 at the wavelengths of 405-1064 nm is considered. For each of the studied wavelengths, the Verdet constant of the material cooled down to the liquid nitrogen temperature increased by more than a factor of 3.2 as compared to the room temperature value. Similarly to the other paramagnetics, the increase follows the law ∼1/T. Approximations for the temperature dependence of the Verdet constant have been obtained and the value of 1/V·(dV/dT) has been estimated. This information is needed to determine the angle of rotation as well as the variation of the extinction ratio of a Faraday isolator with temperature and extremely important at creation a cryogenic Faraday devices.

  12. Synthesis, structure, and magnetic properties of a new family of tetra-nuclear {Mn2(III)Ln2}(Ln = Dy, Gd, Tb, Ho) clusters with an arch-type topology: single-molecule magnetism behavior in the dysprosium and terbium analogues.

    Science.gov (United States)

    Chandrasekhar, Vadapalli; Bag, Prasenjit; Speldrich, Manfred; van Leusen, Jan; Kögerler, Paul

    2013-05-06

    Sequential reaction of Mn(II) and lanthanide(III) salts with a new multidentate ligand, 2,2'-(2-hydroxy-3-methoxy-5-methylbenzylazanediyl)diethanol (LH3), containing two flexible ethanolic arms, one phenolic oxygen, and a methoxy group afforded heterometallic tetranuclear complexes [Mn2Dy2(LH)4(μ-OAc)2](NO3)2·2CH3OH·3H2O (1), [Mn2Gd2(LH)4(μ-OAc)2](NO3)2·2CH3OH·3H2O (2), [Mn2Tb2(LH)4(μ-OAc)2](NO3)2·2H2O·2CH3OH·Et2O (3), and [Mn2Ho2(LH)4(μ-OAc)2]Cl2·5CH3OH (4). All of these dicationic complexes possess an arch-like structural topology containing a central Mn(III)-Ln-Ln-Mn(III) core. The two central lanthanide ions are connected via two phenolate oxygen atoms. The remaining ligand manifold assists in linking the central lanthanide ions with the peripheral Mn(III) ions. Four doubly deprotonated LH(2-) chelating ligands are involved in stabilizing the tetranuclear assembly. A magnetochemical analysis reveals that single-ion effects dominate the observed susceptibility data for all compounds, with comparably weak Ln···Ln and very weak Ln···Mn(III) couplings. The axial, approximately square-antiprismatic coordination environment of the Ln(3+) ions in 1-4 causes pronounced zero-field splitting for Tb(3+), Dy(3+), and Ho(3+). For 1 and 3, the onset of a slowing down of the magnetic relaxation was observed at temperatures below approximately 5 K (1) and 13 K (3) in frequency-dependent alternating current (AC) susceptibility measurements, yielding effective relaxation energy barriers of ΔE = 16.8 cm(-1) (1) and 33.8 cm(-1) (3).

  13. Biogenic terbium oxide nanoparticles as the vanguard against osteosarcoma

    Science.gov (United States)

    Iram, Sana; Khan, Salman; Ansary, Abu Ayoobul; Arshad, Mohd; Siddiqui, Sahabjada; Ahmad, Ejaz; Khan, Rizwan H.; Khan, Mohd Sajid

    2016-11-01

    The synthesis of inner transition metal nanoparticles via an ecofriendly route is quite difficult. This study, for the first time, reports synthesis of terbium oxide nanoparticles using fungus, Fusarium oxysporum. The biocompatible terbium oxide nanoparticles (Tb2O3 NPs) were synthesized by incubating Tb4O7 with the biomass of fungus F. oxysporum. Multiple physical characterization techniques, such as UV-visible and photoluminescence spectroscopy, TEM, SAED, and zeta-potential were used to confirm the synthesis, purity, optical and surface characteristics, crystallinity, size, shape, distribution, and stability of the nanoemulsion of Tb2O3 NPs. The Tb2O3 NPs were found to inhibit the propagation of MG-63 and Saos-2 cell-lines (IC50 value of 0.102 μg/mL) and remained non-toxic up to a concentration of 0.373 μg/mL toward primary osteoblasts. Cell viability decreased in a concentration-dependent manner upon exposure to 10 nm Tb2O3 NPs in the concentration range 0.023-0.373 μg/mL. Cell toxicity was evaluated by observing changes in cell morphology, cell viability, oxidative stress parameters, and FACS analysis. Morphological examinations of cells revealed cell shrinkage, nuclear condensation, and formation of apoptotic bodies. The level of ROS within the cells-an indicator of oxidative stress was significantly increased. The induction of apoptosis at concentrations ≤ IC50 was corroborated by 4‧,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining (DNA damage and nuclear fragmentation). Flow-cytometric studies indicated that the response was dose dependent with a threshold effect.

  14. Column solid phase extraction and flame atomic absorption spectrometric determination of manganese(II) and iron(III) ions in water, food and biological samples using 3-(1-methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid on synthesized graphene oxide.

    Science.gov (United States)

    Pourjavid, Mohammad Reza; Sehat, Ali Akbari; Arabieh, Masoud; Yousefi, Seyed Reza; Hosseini, Majid Haji; Rezaee, Mohammad

    2014-02-01

    A modified, selective, highly sensitive and accurate procedure for the determination of trace amounts of manganese and iron ions is established in the presented work. 3-(1-Methyl-1H-pyrrol-2-yl)-1H-pyrazole-5-carboxylic acid (MPPC) and graphene oxide (GO) were used in a glass column as chelating reagent and as adsorbent respectively prior to their determination by flame atomic absorption spectrometry. The adsorption mechanism of titled metals complexes on GO was investigated by using computational chemistry approach based on PM6 semi-empirical potential energy surface (PES). The effect of some parameters including pH, flow rate and volume of sample and type, volume and concentration of eluent, as well as the adsorption capacity of matrix ions on the recovery of Mn(II) and Fe(III) was investigated. The limit of detection was 145 and 162 ng L(-1) for Mn(II) and Fe(III), respectively. Calibration was linear over the range of 0.31-355 μg L(-1) for Mn(II) and 0.34-380 μg L(-1) for Fe(III) ions. The method was successfully applied for the determination of understudied ions in water, food and biological samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Family of carboxylate- and nitrate-diphenoxo triply bridged dinuclear Ni(II)Ln(III) complexes (Ln = Eu, Gd, Tb, Ho, Er, Y): synthesis, experimental and theoretical magneto-structural studies, and single-molecule magnet behavior.

    Science.gov (United States)

    Colacio, Enrique; Ruiz, José; Mota, Antonio J; Palacios, María A; Cremades, Eduard; Ruiz, Eliseo; White, Fraser J; Brechin, Euan K

    2012-05-21

    Seven acetate-diphenoxo triply bridged M(II)-Ln(III) complexes (M(II) = Ni(II) and Ln(III) = Gd, Tb, Ho, Er, and Y; M(II) = Zn(II) and Ln(III) = Ho(III) and Er(III)) of formula [M(μ-L)(μ-OAc)Ln(NO(3))(2)], one nitrate-diphenoxo triply bridged Ni(II)-Tb(III) complex, [Ni(μ-L)(μ-NO(3))Tb(NO(3))(2)]·2CH(3)OH, and two diphenoxo doubly bridged Ni(II)-Ln(III) complexes (Ln(III) = Eu, Gd) of formula [Ni(H(2)O)(μ-L)Ln(NO(3))(3)]·2CH(3)OH have been prepared in one pot reaction from the compartmental ligand N,N',N"-trimethyl-N,N"-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H(2)L). Moreover, Ni(II)-Ln(III) complexes bearing benzoate or 9-anthracenecarboxylate bridging groups of formula [Ni(μ-L)(μ-BzO)Dy(NO(3))(2)] and [Ni(μ-L)(μ-9-An)Dy(9-An)(NO(3))(2)]·3CH(3)CN have also been successfully synthesized. In acetate-diphenoxo triply bridged complexes, the acetate bridging group forces the structure to be folded with an average hinge angle in the M(μ-O(2))Ln bridging fragment of ~22°, whereas nitrate-diphenoxo doubly bridged complexes and diphenoxo-doubly bridged complexes exhibit more planar structures with hinge angles of ~13° and ~2°, respectively. All Ni(II)-Ln(III) complexes exhibit ferromagnetic interactions between Ni(II) and Ln(III) ions and, in the case of the Gd(III) complexes, the J(NiGd) coupling increases weakly but significantly with the planarity of the M-(O)(2)-Gd bridging fragment and with the increase of the Ni-O-Gd angle. Density functional theory (DFT) theoretical calculations on the Ni(II)Gd(III) complexes and model compounds support these magneto-structural correlations as well as the experimental J(NiGd) values, which were found to be ~1.38 and ~2.1 cm(-1) for the folded [Ni(μ-L)(μ-OAc)Gd(NO(3))(2)] and planar [Ni(H(2)O)(μ-L)Gd(NO(3))(3)]·2CH(3)OH complexes, respectively. The Ni(II)Dy(III) complexes exhibit slow relaxation of the magnetization with Δ/k(B) energy barriers under 1000 Oe applied magnetic fields of 9.2 and 10

  16. Phenyl acridine-9-carboxylate

    Directory of Open Access Journals (Sweden)

    Michał Wera

    2013-02-01

    Full Text Available The acridine ring system and the benzene ring in the title compound, C20H13NO2, are oriented at a dihedral angle of 6.4 (2°. The carboxyl group is twisted at an angle of 83.6 (2° relative to the acridine skeleton. The molecules in the crystal are arranged in stacks along the b axis, with two of the acridine rings involved in multiple π–π interactions [centroid–centroid distances in the range 3.536 (2–3.894 (2 Å]. Stacks arranged parallel are linked via C—H...π interactions, forming layers in the ac plane that are in contact with adjacent, inversely oriented layers via other C—H...π interactions, giving rise to double layers. The inversely oriented double layers interact dispersively. The acridine units are parallel within the parallel-oriented stacks, but inclined at an angle of 79.6 (2° in the inversely oriented stacks.

  17. 1-Azaniumylcyclobutane-1-carboxylate monohydrate

    Directory of Open Access Journals (Sweden)

    Ray J. Butcher

    2014-02-01

    Full Text Available In the title compound, C5H9NO2·H2O, the amino acid is in the usual zwitterionic form involving the α-carboxylate group. The cyclobutane backbone of the amino acid is disordered over two conformations, with occupancies of 0.882 (7 and 0.118 (7. In the crystal, N—H...O and O—H...O hydrogen bonds link the zwitterions [with the water molecule involved as both acceptor (with the NH3+ and donor (through a single carboxylate O from two different aminocyclobutane carboxylate moities], resulting in a two-dimensional layered structure lying parallel to (100.

  18. Autofluorescence-free Live-cell Imaging Using Terbium Nanoparticles.

    Science.gov (United States)

    Cardoso Dos Santos, Marcelina; Goetz, Joan; Bartenlian, Hortense; Wong, Ka-Leung; Charbonniere, Loïc Joanny; Hildebrandt, Niko

    2018-02-20

    Fluorescent nanoparticles (NPs) have become irreplaceable tools for advanced cellular and sub-cellular imaging. While very bright NPs require excitation with UV or visible light, which can create strong autofluorescence of biological components, NIR-excitable NPs without autofluorescence issues exhibit much lower brightness. Here, we show the application of a new type of surface-photosensitized terbium NPs (Tb-NPs) for autofluorescence-free intracellular imaging in live HeLa cells. Combination of exceptionally high brightness, high photostability, and long photoluminecence (PL) lifetimes for highly efficient suppression of the short-lived autofluorescence, allowed for time-gated PL imaging of intracellular vesicles over 72 h without toxicity and at extremely low Tb-NP concentrations down to 12 pM. Detection of highly resolved long-lifetime (ms) PL decay curves from small (~10 µm2) areas within single cells within a few seconds emphasized the unprecedented photophysical properties of Tb-NPs for live-cell imaging that extend well beyond currently available nanometric imaging agents.

  19. Solar Thermochemical Hydrogen Production via Terbium Oxide Based Redox Reactions

    Directory of Open Access Journals (Sweden)

    Rahul Bhosale

    2016-01-01

    Full Text Available The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2 into Tb and O2, whereas the 2nd step corresponds to the production of H2 through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2 and effect of water splitting temperature (TL on Gibbs free energy related to the H2 production step were examined in detail. The cycle (ηcycle and solar-to-fuel energy conversion (ηsolar-to-fuel efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate that ηcycle and ηsolar-to-fuel increase with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (TH. It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. At TH=2280 K, by applying 60% heat recuperation, maximum ηcycle of 39.0% and ηsolar-to-fuel of 47.1% for the Tb-WS cycle can be attained.

  20. Folate Receptor Targeted Alpha-Therapy Using Terbium-149

    CERN Document Server

    Müller, Cristina; Haller, Stephanie; Dorrer, Holger; Köster, Ulli; Johnston, Karl; Zhernosekov, Konstantin; Türler, Andreas; Schibli, Roger

    2014-01-01

    Terbium-149 is among the most interesting therapeutic nuclides for medical applications. It decays by emission of short-range α-particles (Eα = 3.967 MeV) with a half-life of 4.12 h. The goal of this study was to investigate the anticancer efficacy of a 149Tb-labeled DOTA-folate conjugate (cm09) using folate receptor (FR)-positive cancer cells in vitro and in tumor-bearing mice. 149Tb was produced at the ISOLDE facility at CERN. Radiolabeling of cm09 with purified 149Tb resulted in a specific activity of ~1.2 MBq/nmol. In vitro assays performed with 149Tb-cm09 revealed a reduced KB cell viability in a FR-specific and activity concentration-dependent manner. Tumor-bearing mice were injected with saline only (group A) or with 149Tb-cm09 (group B: 2.2 MBq; group C: 3.0 MBq). A significant tumor growth delay was found in treated animals resulting in an increased average survival time of mice which received 149Tb-cm09 (B: 30.5 d; C: 43 d) compared to untreated controls (A: 21 d). Analysis of blood parameters rev...

  1. Hardness and dielectric characteristics of flux grown terbium aluminate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, K.K.; Kotru, P.N. [Jammu Univ. (India). Dept. of Physics; Tandon, R.P. [National Physical Laboratory, New Delhi (India); Wanklyn, B.M. [Clarendon Laboratory, University of Oxford, Oxford (United Kingdom)

    1999-01-29

    Results of indentation induced Vickers hardness testing and dielectric studies conducted on flux-grown terbium aluminate crystals are presented. It is shown that the Vickers hardness value (H{sub v}) is independent of indentation time, but depends on the applied load. Applying the concept of Hays and Kendall, the load independent values are estimated for (110) and (001) planes. Differential behaviour in the crack formation of two different planes (110) and (001) is observed, while (001) plane develops Palmqvist cracks in the whole load range of 10-100 g, (110) plane shows a transition from Palmqvist to median cracks at 70 g. The fracture toughness, brittleness index and yield strength are determined for both the planes. The hardness anisotropy is reported. The dielectric constant, dielectric loss and conductivity are shown to be dependent on temperature and frequency of the applied a.c. field. The dielectric constant versus temperature shows a transition peak at 230 C, which remains independent of the frequency of the applied a.c. field in the range 1 kHz-13 MHz. (orig.) 36 refs.

  2. Thermoluminescence of cerium and terbium -doped calcium pyrophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Roman L, J.; Cruz Z, E. [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Lozano R, I. B.; Diaz G, J. A. I., E-mail: jesus.roman@nucleares.unam.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria No. 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    The aim of this work is to report the thermoluminescence (Tl) response of Calcium Pyrophosphate phosphor doped with Cerium and Terbium impurities (Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+}). The phosphors were synthesized using the co-precipitation method and annealed at 900 degrees C by two hours for obtain the β phase. The intentional doping with Ce and Tb ions was 1 at.% and 0.1 at.%, whereas in the EDS results the concentration of impurities was 0.39 at.% and 0.05 at.%, respectively. The superficial morphology of phosphor is mainly composed by thin wafers of different size. All samples were exposed to gamma rays from {sup 60}Co in the Gammacell-200 irradiator. The Tl response of the phosphor was measured from Rt up to 350 degrees C and under nitrogen atmosphere in a Harshaw TLD 3500 reader. The glow curves of the Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} powders showed a broad intense Tl peak centered at 165 degrees C and a shoulder at approximate 260 degrees C was observed. A linear Tl response in the range of absorbed dose of 0.2 to 10 Gy was obtained. Tl glow curves were analyzed using the initial rise (IR)and computerized glow curve deconvolution methods to evaluate the kinetics parameters such as activation energy (E), frequency factor (s) and kinetic order (b). (Author)

  3. Solvent polarity and oxygen sensitivity, rather than viscosity, determine lifetimes of biaryl-sensitised terbium luminescence.

    Science.gov (United States)

    Walter, Edward R H; Williams, J A Gareth; Parker, David

    2017-12-14

    In a macrocyclic terbium complex incorporating a biaryl sensitiser, the observed variation of emission lifetime is shown to be determined by the solubility of oxygen in the solvent system and the relative energy of the chromophore excited state, rather than any dependence on solvent viscosity.

  4. Carboxylic ester hydrolases from hyperthermophiles

    NARCIS (Netherlands)

    Levisson, M.; Oost, van der J.; Kengen, S.W.M.

    2009-01-01

    Carboxylic ester hydrolyzing enzymes constitute a large group of enzymes that are able to catalyze the hydrolysis, synthesis or transesterification of an ester bond. They can be found in all three domains of life, including the group of hyperthermophilic bacteria and archaea. Esterases from the

  5. Poly[[aqua-?3-picolinato-?2-picolinato-dipicolinatopotassium(I)terbium(III)] 2.5-hydrate

    OpenAIRE

    Filipe A. Almeida Paz; João Rocha; Jacek Klinowski; Tito Trindade; Nogueira,Helena I. S.; Soares-Santos, Paula C. R.; Cunha-Silva, Lu?s

    2008-01-01

    In the title compound, [KTb(C6H4NO2)4(H2O)]·2.5H2O, each Tb3+ centre is coordinated by four N and five O atoms from five distinct picolinate ligands in a geometry resembling a highly distorted tricapped trigonal prism. One of the ligands establishes a skew bridge between neighbouring Tb3+ centres, leading to the formation of one-dimensional anionic polymeric chains, {[(C6H4NO2)4Tb]−}n, running along the direction [010]. Each K+ cation is seven-coordinated by six O atoms from one an...

  6. Spin waves in terbium. III. Magnetic anisotropy at zero wave vector

    DEFF Research Database (Denmark)

    Houmann, Jens Christian Gylden; Jensen, J.; Touborg, P.

    1975-01-01

    The energy gap at zero wave vector in the spin-wave dispersion relation of ferromagnetic. Tb has been studied by inelastic neutron scattering. The energy was measured as a function of temperature and applied magnetic field, and the dynamic anisotropy parameters were deduced from the results....... The axial anisotropy is found to depend sensitively on the orientation of the magnetic moments in the basal plane. This behavior is shown to be a convincing indication of considerable two-ion contributions to the magnetic anisotropy at zero wave vector. With the exception of the sixfold basal...... the effects of zero-point deviations from the fully aligned ground state, and we tentatively propose polarization-dependent two-ion couplings as their origin....

  7. Assessment of terbium (III) as a luminescent probe for the detection of tuberculosis biomarkers

    Energy Technology Data Exchange (ETDEWEB)

    Bamogo, W. [CNRS, IRAMIS, UMR 3685 NIMBE/LEDNA, F-91191 Gif-sur-Yvette (France); Mugherli, L. [CEA, IRAMIS, UMR 3685 NIMBE/LEDNA, F-91191 Gif-sur-Yvette (France); Banyasz, A. [CNRS, IRAMIS, LIDyL/Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette (France); Novelli-Rousseau, A.; Mallard, F. [BioMérieux SA, F-38000 Grenoble (France); Tran-Thi, T.-H., E-mail: thu-hoa.tran-thi@cea.fr [CNRS, IRAMIS, UMR 3685 NIMBE/LEDNA, F-91191 Gif-sur-Yvette (France)

    2015-10-08

    A detection method for nicotinic acid, a specific metabolite marker of Mycobacterium tuberculosis present in cultures and patients' breath, is studied in complex solutions containing other metabolites and in biological media such as urine, saliva and breath condensate. The method is based on the analysis of the luminescence increase of Tb{sup 3+} complexes in the presence of nicotinic acid due to the energy transfer from the excited ligand to the lanthanide ion. It is shown that other potential markers found in M. tuberculosis culture supernatant, such as methyl phenylacetate, p-methyl anisate, methyl nicotinate and 2-methoxy biphenyl, can interfere with nicotinic acid via a competitive absorption of the excitation photons. A new strategy to circumvent these interferences is proposed with an upstream trapping of volatile markers preceding the detection of nicotinic acid in the liquid phase via the luminescence of Tb{sup 3+} complexes. The cost of the method is evaluated and compared with the Xpert MTB/RIF test endorsed by the World Health Organization. - Highlights: • Nicotinic acid, a specific marker of M. tuberculosis, can be detected via luminescence. • The detection limit with a commercial phosphorimeter is 0.4 µmol·L{sup -1}. • Other metabolites of M. tuberculosis can interfere via absorbed excitation light. • The interference can be removed via trapping of the most volatile metabolites. • A breath analysis procedure's cost is compared with the Xpert TBM/RIF test.

  8. Efficient and convenient synthesis of symmetrical carboxylic ...

    African Journals Online (AJOL)

    An efficient and convenient procedure for the synthesis of symmetrical carboxylic anhydrides from carboxylic acids with sulfated zirconia by PEG-1000 phase transfer catalysis has been developed. The reactions proceeded under mild and solvent-free conditions to provide the carboxylic anhydrides in good to excellent ...

  9. efficient and convenient synthesis of symmetrical carboxylic

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. An efficient and convenient procedure for the synthesis of symmetrical carboxylic anhydrides from carboxylic acids with sulfated zirconia by PEG-1000 phase transfer catalysis has been developed. The reactions proceeded under mild and solvent-free conditions to provide the carboxylic anhydrides in good to.

  10. Synthesis and Characterization of Europium(III) and Terbium(III) Complexes: An Advanced Undergraduate Inorganic Chemistry Experiment

    Science.gov (United States)

    Swavey, Shawn

    2010-01-01

    Undergraduate laboratories rarely involve lanthanide coordination chemistry. This is unfortunate in light of the ease with which many of these complexes are made and the interesting and instructive photophysical properties they entail. The forbidden nature of the 4f transitions associated with the lanthanides is overcome by incorporation of…

  11. Spectrofluorimetric Determination of Human Serum Albumin Using Terbium-Danofloxacin Probe

    OpenAIRE

    Ramezani, Amir M.; Manzoori, Jamshid L.; Amjadi, Mohammad; Jouyban, Abolghasem

    2012-01-01

    A spectrofluorimetric method is proposed for the determination of human serum albumin (HSA) and bovine serum albumin (BSA) using terbium-danofloxacin (Tb3+-Dano) as a fluorescent probe. These proteins remarkably enhance the fluorescence intensity of the Tb3+-Dano complex at 545 nm, and the enhanced fluorescence intensity of Tb3+-Dano is proportional to the concentration of proteins (HSA and BSA). Optimum conditions for the determination of HSA were investigated and found that the maximum resp...

  12. Genetically Encoded FRET-Sensor Based on Terbium Chelate and Red Fluorescent Protein for Detection of Caspase-3 Activity

    Directory of Open Access Journals (Sweden)

    Alexander S. Goryashchenko

    2015-07-01

    Full Text Available This article describes the genetically encoded caspase-3 FRET-sensor based on the terbium-binding peptide, cleavable linker with caspase-3 recognition site, and red fluorescent protein TagRFP. The engineered construction performs two induction-resonance energy transfer processes: from tryptophan of the terbium-binding peptide to Tb3+ and from sensitized Tb3+ to acceptor—the chromophore of TagRFP. Long-lived terbium-sensitized emission (microseconds, pulse excitation source, and time-resolved detection were utilized to eliminate directly excited TagRFP fluorescence and background cellular autofluorescence, which lasts a fraction of nanosecond, and thus to improve sensitivity of analyses. Furthermore the technique facilitates selective detection of fluorescence, induced by uncleaved acceptor emission. For the first time it was shown that fluorescence resonance energy transfer between sensitized terbium and TagRFP in the engineered construction can be studied via detection of microsecond TagRFP fluorescence intensities. The lifetime and distance distribution between donor and acceptor were calculated using molecular dynamics simulation. Using this data, quantum yield of terbium ions with binding peptide was estimated.

  13. Understanding biocatalyst inhibition by carboxylic acids

    OpenAIRE

    Jarboe, Laura R.; Royce, Liam A.; Liu, Ping

    2013-01-01

    Carboxylic acids are an attractive biorenewable chemical in terms of their flexibility and usage as precursors for a variety of industrial chemicals. It has been demonstrated that such carboxylic acids can be fermentatively produced using engineered microbes, such as Escherichia coli and Saccharomyces cerevisiae. However, like many other attractive biorenewable fuels and chemicals, carboxylic acids become inhibitory to these microbes at concentrations below the desired yield and titer. In fac...

  14. [Studies on luminescence properties of seven ternary complexes of terbium with 1,10-phenanthroline and benzoic acid and its derivatives].

    Science.gov (United States)

    Gao, Zhi-hua; Wang, Shu-ping; Liu, Cui-ge; Ma, Rui-xia; Wang, Rui-fen

    2006-04-01

    Seven ternary complexes of Tb(III) were synthesized with benzoic acid (BA), o-, m-, p-methylbenzoic acid (o-MBA, m-MBA, p-MBA), and o-, m-, p-methoxybenzoic acid (o-MOBA, m-MOBA, p-MOBA) as the first ligand, and 1,10-phenanthroline (phen) as the second ligand. The content of C, H and N were measured by using a Flash-EA model 1112 elemental analyzer. Excitation and luminescence spectra of the title solid complexes were recorded by using a Hitachi F-4500 fluorescence spectrophotometer at room temperature. The effects of different varieties and different positions of replacing benzoic acid as the first ligand on fluorescence properties of the ternary complexes of terbium were discussed. The results indicated that the intensity of 5D4-->7F6 (489 nm) and 5D4-->7F5 (545 nm) of substituting benzoic acid complexes was stronger than benzoic acid. Three ternary complexes of Tb(III) with o-, m-, p-methylbenzoic acid showed emission intensity in the consecution: Tb(o-MBA)3 phenMOBA)3phen x H2O>Tb(m-MOBA)3phen x H2O>Tb(p-MOBA)3 phen.

  15. Cellular uptake and anticancer activity of carboxylated gallium corroles.

    Science.gov (United States)

    Pribisko, Melanie; Palmer, Joshua; Grubbs, Robert H; Gray, Harry B; Termini, John; Lim, Punnajit

    2016-04-19

    We report derivatives of gallium(III) tris(pentafluorophenyl)corrole, 1 [Ga(tpfc)], with either sulfonic (2) or carboxylic acids (3, 4) as macrocyclic ring substituents: the aminocaproate derivative, 3 [Ga(ACtpfc)], demonstrated high cytotoxic activity against all NCI60 cell lines derived from nine tumor types and confirmed very high toxicity against melanoma cells, specifically the LOX IMVI and SK-MEL-28 cell lines. The toxicities of 1, 2, 3, and 4 [Ga(3-ctpfc)] toward prostate (DU-145), melanoma (SK-MEL-28), breast (MDA-MB-231), and ovarian (OVCAR-3) cancer cells revealed a dependence on the ring substituent: IC50values ranged from 4.8 to >200 µM; and they correlated with the rates of uptake, extent of intracellular accumulation, and lipophilicity. Carboxylated corroles 3 and 4, which exhibited about 10-fold lower IC50values (gallium corroles by all human cancer cells that followed the order: 4 > 3 > 2 > 1 (intracellular accumulation of gallium corroles was fastest in melanoma cells). We conclude that carboxylated gallium corroles are promising chemotherapeutics with the advantage that they also can be used for tumor imaging.

  16. Recovery of carboxylic acids produced by fermentation.

    Science.gov (United States)

    López-Garzón, Camilo S; Straathof, Adrie J J

    2014-01-01

    Carboxylic acids such as citric, lactic, succinic and itaconic acids are useful products and are obtained on large scale by fermentation. This review describes the options for recovering these and other fermentative carboxylic acids. After cell removal, often a primary recovery step is performed, using liquid-liquid extraction, adsorption, precipitation or conventional electrodialysis. If the carboxylate is formed rather than the carboxylic acid, the recovery process involves a step for removing the cation of the formed carboxylate. Then, bipolar electrodialysis and thermal methods for salt splitting can prevent that waste inorganic salts are co-produced. Final carboxylic acid purification requires either distillation or crystallization, usually involving evaporation of water. Process steps can often be combined synergistically. In-situ removal of carboxylic acid by extraction during fermentation is the most popular approach. Recovery of the extractant can easily lead to waste inorganic salt formation, which counteracts the advantage of the in-situ removal. For industrial production, various recovery principles and configurations are used, because the fermentation conditions and physical properties of specific carboxylic acids differ. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Green light emission in aluminum oxide powders doped with different terbium concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Mariscal B, L; Falcony, C. [IPN, Centro de Investigacion y de Estudios Avanzados, 07360 Ciudad de Mexico (Mexico); Carmona T, S.; Murrieta, H.; Sanchez A, M. A. [UNAM, Instituto de Fisica, 04510 Ciudad de Mexico (Mexico); Vazquez A, R. [IPN, Escuela Superior de Computo, 07738 Ciudad de Mexico (Mexico); Garcia R, C. M., E-mail: mariscal2005@gmail.com [UNAM, Facultad de Ciencias, 04510 Ciudad de Mexico (Mexico)

    2016-11-01

    Different emission intensities presented in aluminum oxide phosphors corresponding to different concentrations of doping performed with terbium are analyzed. The phosphors were synthesized by the evaporation technique and were characterized by photo and cathodoluminescence, X-ray diffraction and EDS techniques for different incorporation percentages of terbium as dopant; they show characteristic transitions in 494, 543, 587 and 622 nm, corresponding to {sup 5}D{sub 4} → {sup 7}F{sub 6}, {sup 5}D{sub 4} → {sup 7}F{sub 5}, {sup 5}D{sub 4} → {sup 7}F{sub 4} and {sup 5}D{sub 4} → {sup 7}F{sub 3}, respectively when they are excited with λ{sub exc} = 380 nm wavelength at room temperature. The results of X-ray diffraction show the presence of α-Al{sub 2}O{sub 3} phases with peaks located at 2θ = 25.78, 35.34, 37.96, 43.56, 45.8, 52.74, 57.7, 61.5, 66.74, 68.44, 77.12 and 80.94, and the δ-Al{sub 2}O-3 phase 2θ = 32.82, 45.8, 61.36 and 66.74. These compounds were heat treated for two hours at 1100 degrees Celsius. EDS analyzes indicate that these compounds have close to 60% oxygen around of 40% aluminum in the presence of terbium as dopant which indicates a stoichiometry close to the expected one for alumina. (Author)

  18. Novel Polymers with Carboxylic Acid Loading

    DEFF Research Database (Denmark)

    Thomsen, Anders Daugaard; Malmström, Eva; Hvilsted, Søren

    2006-01-01

    Click chemistry has been used to prepare a range of novel polymers with pendant carboxylic acid side groups. Four azido carboxylic acids, either mono- or difunctional and aliphatic or aromatic, have been prepared and thoroughly characterized. Extensive model reactions with 1-ethyl-4-hydroxybenzene...... in the derivatized polymers and the glass-transition temperature has emerged: the aromatic carboxylic acids give high glass-transition temperatures (90–120 °C), and the aliphatic carboxylic acids give lower glass-transition temperatures (50–65 °C). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44......, the simplest model for poly(4-hydroxystyrene), and the four azido carboxylic acids have been conducted to establish the proper reaction conditions and provide an analytical frame for the corresponding polymers. Poly(4-hydroxystyrene) moieties in three different polymers—poly(4-hydroxystyrene), poly(4...

  19. Fluorescence study of some terbium-oligopeptide complexes in methanolic solution.

    Science.gov (United States)

    Rabouan, S; Delage, J; Durand, W; Prognon, P; Barthes, D

    2000-04-03

    This study concerned the use of lanthanide chelates to detect glycyl-leucyl-phenylalanine (GLF) and its homologues. Spectroscopic analysis of peptides without or with terbium complexation revealed the formation of (LF)(3)(Tb)(2), (GF)(3)(Tb)(2), (GLF)(3)(Tb)(2) and (FL)(4)Tb, (FG)(4)Tb complexes with high stability constants in methanolic solutions (pK(d)>13). Lanthanide chelate emission displayed a large Stokes shift (>270 nm), which allowed Tb chelates of GLF and its derivatives to be used for detection purposes. However, this preliminary study indicated some important limitations associated with lanthanide chelation, such as high methanolic content.

  20. Electromagnetic properties of terbium gallium garnet at millikelvin temperatures and low photon energy

    Science.gov (United States)

    Kostylev, Nikita; Goryachev, Maxim; Bushev, Pavel; Tobar, Michael E.

    2017-07-01

    Electromagnetic properties of single crystal terbium gallium garnet are characterised from room down to millikelvin temperatures using the whispering gallery mode method. Microwave spectroscopy is performed at low powers equivalent to a few photons in energy and conducted as functions of the magnetic field and temperature. A phase transition is detected close to the temperature of 3.5 K. This is observed for multiple whispering gallery modes causing an abrupt negative frequency shift and a change in transmission due to extra losses in the new phase caused by a change in complex magnetic susceptibility.

  1. Nuclear excitation functions from 40 to 200 MeV proton irradiation of terbium

    Energy Technology Data Exchange (ETDEWEB)

    Engle, Jonathan W., E-mail: jwengle@lanl.gov; Mashnik, Stepan G.; Parker, Lauren A.; Jackman, Kevin R.; Bitteker, Leo J.; Ullmann, John L.; Gulley, Mark S.; Pillai, Chandra; John, Kevin D.; Birnbaum, Eva R.; Nortier, Francois M.

    2016-01-01

    Nuclear formation cross sections are reported for 26 radionuclides, measured with 40–200 MeV proton irradiations of terbium foils. These data provide the basis for the production of medically relevant radionuclides (e.g., {sup 152}Tb, {sup 155}Tb, {sup 155}Eu, and {sup 156}Eu) and {sup 153}Gd, a potential source used in ongoing efforts to characterize stellar nucleosynthesis routes. Computational predictions from the ALICE2011, CEM03.03, Bertini, and INCL + ABLA codes are compared with newly measured data to contribute to the ongoing process of code development, and yields are calculated for selected radionuclides using measured data.

  2. High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T., E-mail: ktlim@pknu.ac.kr [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-03-30

    Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S’-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.

  3. Understanding biocatalyst inhibition by carboxylic acids

    Directory of Open Access Journals (Sweden)

    Laura R Jarboe

    2013-09-01

    Full Text Available Carboxylic acids are an attractive biorenewable chemical in terms of their flexibility and usage as precursors for a variety of industrial chemicals. It has been demonstrated that such carboxylic acids can be fermentatively produced using engineered microbes, such as Escherichia coli and Saccharomyces cerevisiae. However, like many other attractive biorenewable fuels and chemicals, carboxylic acids become inhibitory to these microbes at concentrations below the desired yield and titer. In fact, their potency as microbial inhibitors is highlighted by the fact that many of these carboxylic acids are routinely used as food preservatives. This review highlights the current knowledge regarding the impact that saturated, straight-chain carboxylic acids, such as hexanoic, octanoic, decanoic and lauric acids can have on E. coli and S. cerevisiae, with the goal of identifying metabolic engineering strategies to increase robustness. Key effects of these carboxylic acids include damage to the cell membrane and a decrease of the microbial internal pH. Certain changes in cell membrane properties, such as composition, fluidity, integrity and hydrophobicity, and intracellular pH are often associated with increased tolerance. The availability of appropriate exporters, such as Pdr12, can also increase tolerance. The effect on metabolic processes, such as maintaining appropriate respiratory function, regulation of Lrp activity and inhibition of production of key metabolites such as methionine, are also considered. Understanding the mechanisms of biocatalyst inhibition by these desirable products can aid in the engineering of robust strains with improved industrial performance.

  4. Luminescent method of determination of composition of europium and terbium complexes in solution by change of intensity ratio of luminescence bands

    Energy Technology Data Exchange (ETDEWEB)

    Bel' tyukova, S.V.; Nazarenko, N.A.; Poluehktov, N.S.

    1982-03-01

    The complexes of europium and terbium with phenanthroline, ethylenediaminetetraacetate, nitrilotriacetate, some acids-phenol derivatives and ..beta..-diketones series have been used as an example to demonstrate that the value of the ratio of intensities on the two bands of europium(terbium) luminescence spectra - the one corresponding to the hypersensitive'' transition and the other, to the magnetic dipole one - can be used for determination of the complexes composition in solutions.

  5. CARBOXYLIC ACIDS ELECTROOXIDATION ON SHUNGITE ELECTRODE

    Directory of Open Access Journals (Sweden)

    Oleksandr Davydenko

    2017-03-01

    Full Text Available Purpose: This article discusses the electrochemical method of directional conversion of carboxylic acids, which are the most aggressive hydrocarbons oxidation products back into the corresponding hydrocarbons. Existing methods for the regeneration of waste petroleum oils have significant drawbacks, which include the formation of new hard-reclaimed waste and loss of a significant part of the oil during regeneration. Methods: Electrooxidation processes of carboxylic acid on various electrode materials: platinum, graphite and shungite anodes were studied. Results: Potentiostatic polarization curves with simultaneous measurement of near-electrode solution pH showed differences in the process on these anode materials: dimer yield for Kolbe is decreased under the transition from platinum to shungite. At potentials higher than 2.0 v, carboxylic acid has a higher adsorbability compared to water. Therefore Faraday’s side-process of water oxidation doesn’t almost occur, which contributes to high yield of expected product according to current. Electrolysis of carboxylic acids solutions under controlled potential (2.0 and 2.4 V and chromatographic analysis of the formed products showed that along with the dimeric structures formation for Kolbe reaction, the occurrence of a hydrocarbons mixture takes place, which may be the result of disproportionation of hydrocarbon radicals (alkane and alkene and hydrocarbons of isomeric structure, by further oxidation of the hydrocarbon radical to carbocation and its subsequent transformation into the corresponding saturated and unsaturated isomers. Such statement is not supported by conception of the process of one- and two-electron carboxylic acid oxidation. Discussion: General carboxylic acid oxidation scheme according to one-electron mechanism (dimerization and disproportionation of the radical and two-electron mechanism (formation and carbocation rearrangement is proposed. The formation of hydrocarbons under

  6. A comprehensive classification and nomenclature of carboxyl-carboxyl(ate) supramolecular motifs and related catemers: implications for biomolecular systems.

    Science.gov (United States)

    D'Ascenzo, Luigi; Auffinger, Pascal

    2015-04-01

    Carboxyl and carboxylate groups form important supramolecular motifs (synthons). Besides carboxyl cyclic dimers, carboxyl and carboxylate groups can associate through a single hydrogen bond. Carboxylic groups can further form polymeric-like catemer chains within crystals. To date, no exhaustive classification of these motifs has been established. In this work, 17 association types were identified (13 carboxyl-carboxyl and 4 carboxyl-carboxylate motifs) by taking into account the syn and anti carboxyl conformers, as well as the syn and anti lone pairs of the O atoms. From these data, a simple rule was derived stating that only eight distinct catemer motifs involving repetitive combinations of syn and anti carboxyl groups can be formed. Examples extracted from the Cambridge Structural Database (CSD) for all identified dimers and catemers are presented, as well as statistical data related to their occurrence and conformational preferences. The inter-carboxyl(ate) and carboxyl(ate)-water hydrogen-bond properties are described, stressing the occurrence of very short (strong) hydrogen bonds. The precise characterization and classification of these supramolecular motifs should be of interest in crystal engineering, pharmaceutical and also biomolecular sciences, where similar motifs occur in the form of pairs of Asp/Glu amino acids or motifs involving ligands bearing carboxyl(ate) groups. Hence, we present data emphasizing how the analysis of hydrogen-containing small molecules of high resolution can help understand structural aspects of larger and more complex biomolecular systems of lower resolution.

  7. Thermo-transferred thermoluminescence (TTTl) in potassium-yttrium double fluoride doped with terbium

    Energy Technology Data Exchange (ETDEWEB)

    Gallegos, A.; Rivera, T.; Diaz G, J. A. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Azorin, J. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Azorin, J. C. [Universidad de Guanajuato, Division de Ciencias e Ingenierias-Campus Leon, Lomas del Bosque No. 103, Col. Lomas del Campestre, 37000 Leon, Guanajuato (Mexico); Licona, R.; Rivas, F.; Hernandez C, G. [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, 14 Sur y San Claudio, Ciudad Universitaria, Puebla de Zaragoza, Puebla (Mexico); Khaidukov, N. [Institute of General and Inorganic Chemistry, Lenin SK 11 Prospect 31, Moscow 117907 (Russian Federation)

    2011-02-15

    This paper presents results of studying the thermo-transferred thermoluminescence (TTTl) phenomenon in potassium-yttrium double fluoride doped with terbium (K{sub 2}YF{sub 5:}Tb) at different impurity concentrations (0.8%, 0.95% and 0.99%). Previously to study the TTTl phenomenon, structural characterization and chemical composition of the materials were determined. The structural studies were conducted using a scanning electron microscope; meanwhile, chemical composition was analyzed using energy dispersive X-ray spectroscopy. Thermoluminescence kinetics was studied irradiating the samples with {sup 137}Cs gamma rays as well as with {sup 90}Sr/{sup 90}Y beta rays, analyzing the glow curves by the deconvolution method for obtaining the kinetic parameters. (Author)

  8. The influence of pressure on the photoluminescence properties of a terbium-adipate framework

    Science.gov (United States)

    Spencer, Elinor C.; Zhao, Jing; Ross, Nancy L.; Andrews, Michael B.; Surbella, Robert G.; Cahill, Christopher L.

    2013-06-01

    The influence of pressure (over the 0-4.7 GPa range) on the photoluminescence emissions and crystal structure of the known 3D terbium-adipate metal-organic framework material Tb-GWMOF6 has been evaluated by high-pressure single-crystal X-ray diffraction and spectroscopic techniques. The results from this study show that this complex lanthanide framework structure undergoes three phase transitions within the 0-4 GPa pressure range that involve alterations in the number of symmetry independent Tb3+ ion sites within the crystal lattice. These pressure induced modifications to the structure of Tb-GWMOF6 lead to pronounced changes in the profiles of the 5D4→7F5 emission spectra of this complex.

  9. Terbium Radionuclides for Theranostics Applications: A Focus On MEDICIS-PROMED

    Science.gov (United States)

    Cavaier, R. Formento; Haddad, F.; Sounalet, T.; Stora, T.; Zahi, I.

    A new facility, named CERN-MEDICIS, is under construction at CERN to produce radionuclides for medical applications. In parallel, the MEDICIS-PROMED, a Marie Sklodowska-Curie innovative training network of the Horizon 2020 European Commission's program, is being coordinated by CERN to train young scientists on the production and use of innovative radionuclides and develop a network of experts within Europe. One program within MEDICIS-PROMED is to determine the feasibility of producing innovative radioisotopes for theranostics using a commercial middle-sized high-current cyclotron and the mass separation technology developed at CERN-MEDICIS. This will allow the production of high specific activity radioisotopes not achievable with the common post-processing by chemical separation. Radioisotopes of scandium, copper, arsenic and terbium have been identified. Preliminary studies of activation yield and irradiation parameters optimization for the production of Tb-149 will be described.

  10. Dielectric and conducting behavior of gadolinium-terbium fumarate heptahydrate crystals

    Science.gov (United States)

    Shah, M. D.; Want, B.

    2015-07-01

    Gadolinium-terbium fumarate heptahydrate crystals were grown in silica gel by using single gel diffusion technique. The crystals were characterized by different physico-chemical techniques of characterization. Powder X-ray diffraction results showed that the grown material is purely crystalline in nature. Elemental analyses suggested the chemical formula of the compound to be Gd Tb (C4H2O4)3ṡ7H2O. Energy dispersive X-ray analysis confirmed the presence of Gd and Tb in the title compound. The dielectric and conductivity studies of the grown compound were carried as function of frequency of applied field and the temperature. The grown material showed a dielectric anomaly which was correlated with its thermal behavior. The ac conductivity of the material showed Jonscher's power law behavior: σ(ω)=σo+Aωs, with a temperature-dependent power exponent s(<1). The conductivity was found to be a function of temperature and frequency.

  11. Highly sensitive detection of dipicolinic acid with a water-dispersible terbium-metal organic framework.

    Science.gov (United States)

    Bhardwaj, Neha; Bhardwaj, Sanjeev; Mehta, Jyotsana; Kim, Ki-Hyun; Deep, Akash

    2016-12-15

    The sensitive detection of dipicolinic acid (DPA) is strongly associated with the sensing of bacterial organisms in food and many types of environmental samples. To date, the demand for a sensitive detection method for bacterial toxicity has increased remarkably. Herein, we investigated the DPA detection potential of a water-dispersible terbium-metal organic framework (Tb-MOF) based on the fluorescence quenching mechanism. The Tb-MOF showed a highly sensitive ability to detect DPA at a limit of detection of 0.04nM (linear range of detection: 1nM to 5µM) and also offered enhanced selectivity from other commonly associated organic molecules. The present study provides a basis for the application of Tb-MOF for direct, convenient, highly sensitive, and specific detection of DPA in the actual samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. A New Bis(phthalocyaninato) Terbium Single-Ion Magnet with an Overall Excellent Magnetic Performance.

    Science.gov (United States)

    Chen, Yuxiang; Ma, Fang; Chen, Xiaoxiang; Dong, Bowei; Wang, Kang; Jiang, Shangda; Wang, Chiming; Chen, Xin; Qi, Dongdong; Sun, Haoling; Wang, Bingwu; Gao, Song; Jiang, Jianzhuang

    2017-11-20

    Bulky and strong electron-donating dibutylamino groups were incorporated onto the peripheral positions of one of the two phthalocyanine ligands in the bis(phthalocyaninato) terbium complex, resulting in the isolation of heteroleptic double-decker (Pc)Tb{Pc[N(C4H9)2]8} {Pc = phthalocyaninate; Pc[N(C4H9)2]8 = 2,3,9,10,16,17,23,24-octakis(dibutylamino)phthalocyaninate} with the nature of an unsymmetrical molecular structure, a square-antiprismatic coordination geometry, an intensified coordination field strength, and the presence of organic radical-f interaction. As a total result of all these factors, this sandwich-type tetrapyrrole lanthanide single-ion magnet (SIM) exhibits an overall enhanced magnetic performance including a high blocking temperature (TB) of 30 K and large effective spin-reversal energy barrier of Ueff = 939 K, rendering it the best sandwich-type tetrapyrrole lanthanide SIM reported thus far.

  13. Ultralarge magneto-optic rotations and rotary dispersion in terbium gallium garnet single crystal.

    Science.gov (United States)

    Shaheen, Amrozia; Majeed, Hassaan; Anwar, Muhammad Sabieh

    2015-06-10

    We report systematically acquired data on the Verdet constant of terbium gallium garnet for wavelengths ranging from visible to near-infrared (405-830 nm) regime. Our experimental method of Stokes polarimetry is based on the Fourier decomposition of the received light intensity and allows unambiguous determination of both the Faraday rotation and the ellipticity of the emergent light. Temperature-dependent investigations in the range of 8-300 K extend earlier reports and verify the Verdet's constant direct dependence on the magnetization, whose first-order approximation is simply a manifestation of the Curie's law. Further, a least-squares fitting of the experimental data correlates well with theoretical predictions. At a wavelength of 405 nm and temperature of 8 K, the rotation is approximately 500°.

  14. Heterometallic trinuclear {CoLn(III)} (Ln = Gd, Tb, Ho and Er) complexes in a bent geometry. Field-induced single-ion magnetic behavior of the Er(III) and Tb(III) analogues.

    Science.gov (United States)

    Goura, Joydeb; Brambleby, Jamie; Topping, Craig V; Goddard, Paul A; Suriya Narayanan, Ramakirushnan; Bar, Arun Kumar; Chandrasekhar, Vadapalli

    2016-05-31

    Through the use of a multi-site compartmental ligand, 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}methyl]phenol (LH3), the family of heterometallic, trinuclear complexes of the formula [CoLn(L)2(μ-O2CCH3)2(H2O)3]·NO3·xMeOH·yH2O has been expanded beyond Ln = Dy(III) to include Gd(III) (), Tb(III) (), Ho(III) () and Er(III) () for , and (x = 1; y = 1) and for (x = 0; y = 2). The metallic core of these complexes consists of a (Co(III)-Ln(III)-Co(III)) motif bridged in a bent geometry resulting in six-coordinated distorted Co(III) octahedra and nine-coordinated Ln(III) monocapped square-antiprisms. The magnetic characterization of these compounds reveals the erbium and terbium analogues to display a field induced single-ion magnetic behavior similar to the dysprosium analogue but at lower temperatures. The energy barrier for the reversal of the magnetization of the CoTb(III) analogue is Ueff ≥ 15.6(4) K, while for the CoEr(III) analogue Ueff ≥ 9.9(8) K. The magnetic properties are discussed in terms of distortions of the 4f electron cloud.

  15. Fine- and hyperfine structure investigations of even configuration system of atomic terbium

    Science.gov (United States)

    Stefanska, D.; Elantkowska, M.; Ruczkowski, J.; Furmann, B.

    2017-03-01

    In this work a parametric study of the fine structure (fs) and the hyperfine structure (hfs) for the even-parity configurations of atomic terbium (Tb I) is presented, based in considerable part on the new experimental results. Measurements on 134 spectral lines were performed by laser induced fluorescence (LIF) in a hollow cathode discharge lamp; on this basis, the hyperfine structure constants A and B were determined for 52 even-parity levels belonging to the configurations 4f85d6s2, 4f85d26s or 4f96s6p; in all the cases those levels were involved in the transitions investigated as the lower levels. For 40 levels the hfs was examined for the first time, and for the remaining 12 levels the new measurements supplement our earlier results. As a by-product, also preliminary values of the hfs constants for 84 odd-parity levels were determined (the investigations of the odd-parity levels system in the terbium atom are still in progress). This huge amount of new experimental data, supplemented by our earlier published results, were considered for the fine and hyperfine structure analysis. A multi-configuration fit of 7 configurations was performed, taking into account second-order of perturbation theory, including the effects of closed shell-open shell excitations. Predicted values of the level energies, as well as of magnetic dipole and electric quadrupole hyperfine structure constants A and B, are quoted in cases when no experimental values are available. By combining our experimental data with our own semi-empirical procedure it was possible to identify correctly the lower and upper level of the line 544.1440 nm measured by Childs with the use of the atomic-beam laser-rf double-resonance technique (Childs, J Opt Soc Am B 9;1992:191-6).

  16. CCDC 954774: Experimental Crystal Structure Determination : Dimethylammonium tri-terbium tris(4'-(tetrazol-2-id-5-yl)biphenyl-4-carboxylate) tetrahydroxide trihydrate unknown solvate

    KAUST Repository

    Xue, Dongxu

    2013-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  17. Structural and optical characterization of terbium doped ZnGa2O4 thin films deposited by RF magnetron sputtering

    Science.gov (United States)

    Somasundaram, K.; Girija, K. G.; Sudarsan, V.; Selvin, P. Christopher; Vatsa, R. K.

    2016-05-01

    Tb3+ doped ZnGa2O4 nanophosphor (21 nm) has been synthesized via low temperature polyol route and subsequently thin films of the same were deposited on glass and ITO substrates by RF magnetron sputtering. The films were characterized by X-ray Diffraction and luminescence measurements. The XRD pattern showed that Tb3+ doped ZnGa2O4 nanophosphor has a cubic spinel phase. Luminescence behavior of the nanophosphor and as deposited sputtered film was investigated. The PL emission spectra of nanophosphor gave a broad ZnGa2O4 host emission band along with a strong terbium emission and the thin films showed only broad host emission band and there was no terbium ion emission.

  18. Hygroscopic Characteristics of Alkylaminium Carboxylate Aerosols.

    Science.gov (United States)

    Gomez-Hernandez, Mario; McKeown, Megan; Secrest, Jeremiah; Marrero-Ortiz, Wilmarie; Lavi, Avi; Rudich, Yinon; Collins, Don R; Zhang, Renyi

    2016-03-01

    The hygroscopic growth factor (HGF) and cloud condensation nuclei (CCN) activity for a series of alkylaminium carboxylate aerosols have been measured using a hygroscopicity tandem differential mobility analyzer coupled to a condensation particle counter and a CCN counter. The particles, consisting of the mixtures of mono- (acetic, propanoic, p-toluic, and cis-pinonic acid) and dicarboxylic (oxalic, succinic, malic, adipic, and azelaic acid) acid with alkylamine (mono-, di-, and trimethylamines), represent those commonly found under diverse environmental conditions. The hygroscopicity parameter (κ) of the alkylaminium carboxylate aerosols was derived from the HGF and CCN results and theoretically calculated. The HGF at 90% RH is in the range of 1.3 to 1.8 for alkylaminium monocarboxylates and 1.1 to 2.2 for alkylaminium dicarboxylates, dependent on the molecular functionality (i.e., the carboxylic or OH functional group in organic acids and methyl substitution in alkylamines). The κ value for all alkylaminium carboxylates is in the range of 0.06-1.37 derived from the HGF measurements at 90% RH, 0.05-0.49 derived from the CCN measurements, and 0.22-0.66 theoretically calculated. The measured hygroscopicity of the alkylaminium carboxylates increases with decreasing acid to base ratio. The deliquescence point is apparent for several of the alkylaminium dicarboxylates but not for the alkylaminium monocarboxylates. Our results reveal that alkylaminium carboxylate aerosols exhibit distinct hygroscopic and deliquescent characteristics that are dependent on their molecular functionality, hence regulating their impacts on human health, air quality, and direct and indirect radiative forcing on climate.

  19. Determination of fluoxetine in pharmaceutical and biological samples based on the silver nanoparticle enhanced fluorescence of fluoxetine-terbium complex.

    Science.gov (United States)

    Lotfi, Ali; Manzoori, Jamshid L

    2016-11-01

    In this study, a simple and sensitive spectrofluorimetric method is presented for the determination of fluoxetine based on the enhancing effect of silver nanoparticles (AgNPs) on the terbium-fluoxetine fluorescence emission. The AgNPs were prepared by a simple reduction method and characterized by UV-Vis spectroscopy and transmission electron microscopy. It was indicated that these AgNPs have a remarkable amplifying effect on the terbium-sensitized fluorescence of fluoxetine. The effects of various parameters such as AgNP and Tb(3+) concentration and the pH of the media were investigated. Under obtained optimal conditions, the fluorescence intensity of the terbium-fluoxetine-AgNP system was enhanced linearly by increasing the concentration of fluoxetine in the range of 0.008 to 19 mg/L. The limit of detection (b + 3s) was 8.3 × 10(-4) mg/L. The interference effects of common species found in real samples were also studied. The method had good linearity, recovery, reproducibility and sensitivity, and was satisfactorily applied for the determination of fluoxetine in tablet formulations, human urine and plasma samples. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Neutron Diffraction and Electrical Transport Studies on Magnetic Transition in Terbium at High Pressures and Low Temperatures

    Science.gov (United States)

    Thomas, Sarah; Montgomery, Jeffrey; Tsoi, Georgiy; Vohra, Yogesh; Weir, Samuel; Tulk, Christopher; Moreira Dos Santos, Antonio

    2013-06-01

    Neutron diffraction and electrical transport measurements have been carried out on the heavy rare earth metal terbium at high pressures and low temperatures in order to elucidate its transition from a helical antiferromagnetic to a ferromagnetic ordered phase as a function of pressure. The electrical resistance measurements using designer diamonds show a change in slope as the temperature is lowered through the ferromagnetic Curie temperature. The temperature of the ferromagnetic transition decreases at a rate of -16.7 K/GPa till 3.6 GPa, where terbium undergoes a structural transition from hexagonal close packed (hcp) to an α-Sm phase. Above this pressure, the electrical resistance measurements no longer exhibit a change in slope. In order to confirm the change in magnetic phase suggested by the electrical resistance measurements, neutron diffraction measurements were conducted at the SNAP beamline at the Oak Ridge National Laboratory. Measurements were made at pressures to 5.3 GPa and temperatures as low as 90 K. An abrupt increase in peak intensity in the neutron diffraction spectra signaled the onset of magnetic order below the Curie temperature. A magnetic phase diagram of rare earth metal terbium will be presented to 5.3 GPa and 90 K based on these studies.

  1. Nitric Acid Dehydration Using Perfluoro Carboxylate and Mixed Sulfonate/Carboxylate Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Ames, Richard L. [Colorado School of Mines, Golden, CO (United States)

    2004-09-01

    Perfluoro ionomer membranes are tetrafluoro ethylene-based materials with microheterogeneous structures consisting of a hydrophobic polymer backbone and a hydrophilic side-chain cluster region. Due to the ionomer cluster morphology, these films exhibit unique transport properties. Recent investigations with perfluoro sulfonate and perfluoro sulfonate/carboxylate composite polymers have demonstrated their value in the dehydration of nitric acid and they show potential as an alternative to conventional, energy intensive unit operations in the concentration of acid feeds. As a result, investigations were conducted to determine the feasibility of using pure perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films for the dehydration of nitric acid because of the speculation of improved water selectivity of the carboxylate pendant chain. During the first phase of these investigations the effort was focused on generating a thin, solution cast perfluoro carboxylate ionomer film, to evaluate the general, chemical and physical characteristics of the polymer, and to assess the material's aqueous transport performance (flux and nitrate separation efficiencies) in pervaporation and high-pressure environments. Results demonstrated that generating robust solution-cast films was difficult yet a number of membranes survived high trans-membrane pressures up to 700 psig. General characterization of the solution cast product showed reduced ion exchange capacities when compared with thicker, ''as received'' perfluoro carboxylate and similar sulfonate films. Small angle x-ray scattering analysis results suggested that the solution cast carboxylate films contained a small fraction of sulfonate terminated side-chains. Aqueous transport experimentation showed that permeate fluxes for both pure water and nitric acid were approximately two orders of magnitude smaller for the carboxylate solution cast membranes when compared to their sulfonate

  2. Luminescent europium and terbium complexes of dipyridoquinoxaline and dipyridophenazine ligands as photosensitizing antennae: structures and biological perspectives.

    Science.gov (United States)

    Dasari, Srikanth; Patra, Ashis K

    2015-12-14

    The europium(III) and terbium(III) complexes, namely [Eu(dpq)(DMF)2(NO3)3] (1), [Eu(dppz)2(NO3)3] (2), [Tb(dpq)(DMF)2Cl3] (3), and [Tb(dppz)(DMF)2Cl3] (4), where dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 1 and 3), dipyrido[3,2-a:2',3'-c]phenazine (dppz in 2 and 4) and N,N'-dimethylformamide (DMF) have been isolated, characterized from their physicochemical data, luminescence studies and their interaction with DNA, serum albumin protein and photo-induced DNA cleavage activity are studied. The X-ray crystal structures of complexes 1-4 show discrete mononuclear Ln(3+)-based structures. The Eu(3+) in [Eu(dpq)(DMF)2(NO3)3] (1) and [Eu(dppz)2(NO3)3] (2) as [Eu(dppz)2(NO3)3]·dppz (2a) adopts a ten-coordinated bicapped dodecahedron structure with a bidentate N,N-donor dpq ligand, two DMF and three NO3(-) anions in 1 and two bidentate N,N-donor dppz ligands and three NO3(-) anions in 2. Complexes 3 and 4 show a seven-coordinated mono-capped octahedron structure where Tb(3+) contains bidentate dpq/dppz ligands, two DMF and three Cl(-) anions. The complexes are highly luminescent in nature indicating efficient photo-excited energy transfer from the dpq/dppz antenna to Ln(3+) to generate long-lived emissive excited states for characteristic f → f transitions. The time-resolved luminescence spectra of complexes 1-4 show typical narrow emission bands attributed to the (5)D0 → (7)F(J) and (5)D4 → (7)F(J) f-f transitions of Eu(3+) and Tb(3+) ions respectively. The number of inner-sphere water molecules (q) was determined from luminescence lifetime measurements in H2O and D2O confirming ligand-exchange reactions with water in solution. The complexes display significant binding propensity to the CT-DNA giving binding constant values in the range of 1.0 × 10(4)-6.1 × 10(4) M(-1) in the order 2, 4 (dppz) > 1, 3 (dpq). DNA binding data suggest DNA groove binding with the partial intercalation nature of the complexes. All the complexes also show binding propensity (K(BSA)

  3. as an inorganic analogue of carboxylate group

    Indian Academy of Sciences (India)

    is a tridentate ONS donor) as an inorganic analogue of carboxylate group: A journey to a new domain of coordination chemistry. SATYABRATA SAMANTAa, SUBODH KANTI DUTTAa,b and. MUKTIMOY CHAUDHURYa,*. aDepartment of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata 700 032.

  4. Crystal structure of 3-amino-pyridinium 1'-carb-oxy-ferrocene-1-carboxyl-ate.

    Science.gov (United States)

    Medved'ko, Aleksei V; Churakov, Andrei V; Yu, Haojie; Li, Wang; Vatsadze, Sergey Z

    2017-06-01

    The structure of the title salt, (C5H7N2)[Fe(C6H4O2)(C6H5O2)], consists of 3-amino-pyridinium cations and 1'-carb-oxy-ferrocene-1-carboxyl-ate monoanions. The ferrocenyl moiety of the anion adopts a typical sandwich structure, with Fe-C distances in the range 2.0270 (15)-2.0568 (17) Å. The anion possesses an eclipsed conformation, with the torsion angle φ (Csubst-Cpcent-Cpcent- Csubst) equal to 66.0°. The conformations of other 1'-carb-oxy-ferrocene-1-carboxyl-ate monoanions are compared and analyzed on the basis of literature data.

  5. Influence of crystalline structure on the luminescence properties of terbium orthotantalates

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira, Kisla P.F. [Departamento de Química, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, ICEB II, Ouro Preto 35400-000, Minas Gerais (Brazil); Carmo, Alexandre P. [Instituto Federal Fluminense, Campus Cabo Frio, RJ 28909-971 (Brazil); Bell, Maria J.V. [Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora 36036-330, MG (Brazil); Dias, Anderson, E-mail: anderson_dias@iceb.ufop.br [Departamento de Química, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, ICEB II, Ouro Preto 35400-000, Minas Gerais (Brazil)

    2013-06-15

    Terbium orthotantalate powders were produced with M-fergusonite type (I2/a) and M′-fergusonite type (P2/a) structures. The samples were studied by X-ray diffraction, Raman scattering, and photoluminescence measurements (emission and decay curves). The results showed that crystalline materials were obtained with all the 18 Raman-active modes predicted by group theory calculations. Also, it was observed through photoluminescence decay curves that the Tb{sup 3+} ions occupies only one-symmetry site in both crystallographic arrangements. Photoluminescence emission curves exhibited some variation in spectral shape, peak position, and relative intensity as a consequence of their different crystalline arrangements. The dominated emission of Tb{sup 3+} ({sup 5}D{sub 4}→{sup 7}F{sub 5}) is centered with a maximum intensity at 549.2 nm (M-type) and 543.0 nm (M′-type). Fluorescence lifetimes for M-TbTaO{sub 4} and M′-TbTaO{sub 4} were determined as 33.4 μs and 1.25 ms, respectively. M′-type materials seems to be the most suitable for luminescent devices and could be a potential green luminescent material due to the strongest emission if compared with the M-fergusonite type. -- Highlights: ► Terbium orthotantalates were prepared in two different crystalline structures: I2/a and P2/a. ► XRD and Raman scattering showed that the different space groups obtained were exhibited all the 18 Raman-active modes. ► PL decay curves that the Tb{sup 3+} ions occupies only one-symmetry site in both crystallographic arrangements. ► Dominated emission of Tb{sup 3+} ({sup 5}D{sub 4}→{sup 7}F{sub 5}) is centered with a maximum intensity at 549 nm (M-type) and 543 nm (M′-type). ► Fluorescence lifetimes for M-TbTaO{sub 4} and M′-TbTaO{sub 4} were determined as 33.4 μs and 1.25 ms, respectively.

  6. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for the...

  7. Pyrolysis Mechanisms of Aromatic Carboxylic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Britt, P.F.; Eskay, T.P.; Buchanan, A.C. III

    1997-12-31

    Although decarboxylation of carboxylic acids is widely used in organic synthesis, there is limited mechanistic information on the uncatalyzed reaction pathways of aromatic carboxylic acids at 300-400 {degrees} C. The pyrolysis mechanisms of 1,2-(3,3-dicarboxyphenyl)ethane, 1,2-(4,4-dicarboxylphenyl)ethane, 1-(3-carboxyphenyl)-2-(4- biphenyl)ethane, and substituted benzoic acids have been investigated at 325-425 {degrees} C neat and diluted in an inert solvent. Decarboxylation is the dominant pyrolysis path. Arrhenius parameters, substituent effects, and deuterium isotope effects are consistent with decarboxylation by an electrophilic aromatic substitution reaction. Pyrolysis of benzoic acid in naphthalene, as a solvent, produces significant amounts of 1- and 2-phenylnaphthalenes. The mechanistic pathways for decarboxylation and arylation with be presented.

  8. Development of functionalized terbium fluorescent nanoparticles for antibody labeling and time-resolved fluoroimmunoassay application.

    Science.gov (United States)

    Ye, Zhiqiang; Tan, Mingqian; Wang, Guilan; Yuan, Jingli

    2005-01-15

    Silica-based functionalized terbium fluorescent nanoparticles were prepared, characterized and developed as a fluorescence probe for antibody labeling and time-resolved fluoroimmunoassay. The nanoparticles were prepared in a water-in-oil (W/O) microemulsion containing a strongly fluorescent Tb(3+) chelate, N,N,N(1),N(1)-[2,6-bis(3'-aminomethyl-1'-pyrazolyl)phenylpyridine] tetrakis(acetate)-Tb(3+) (BPTA-Tb(3+)), Triton X-100, octanol, and cyclohexane by controlling copolymerization of tetraethyl orthosilicate (TEOS) and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (AEPS) with ammonia water. The characterizations by transmission electron microscopy and fluorometric methods show that the nanoparticles are spherical and uniform in size, 45 +/- 3nm in diameter, strongly fluorescent with fluorescence quantum yield of 10% and a long fluorescence lifetime of 2.0ms. The amino groups directly introduced to the nanoparticle's surface by using AEPS in the preparation made the surface modification and bioconjugation of the nanoparticles easier. The nanoparticle-labeled anti-human alpha-fetoprotein antibody was prepared and used for time-resolved fluoroimmunoassay of alpha-fetoprotein (AFP) in human serum samples. The assay response is linear from 0.10ngml(-1) to about 100ngml(-1) with the detection limit of 0.10ngml(-1). The coefficient variations (CVs) of the method are less than 9.0%, and the recoveries are in the range of 84-98% for human serum sample measurements.

  9. Highly efficient precipitation of phosphoproteins using trivalent europium, terbium, and erbium ions

    Energy Technology Data Exchange (ETDEWEB)

    Guezel, Yueksel; Rainer, Matthias; Mirza, Munazza Raza; Bonn, Guenther K. [Leopold-Franzens University, Institute of Analytical Chemistry and Radiochemistry, Innsbruck (Austria)

    2012-05-15

    This study describes a highly efficient method for the selective precipitation of phosphoproteins by trivalent europium, terbium, and erbium metal ions. These metal cations belong to the group of lanthanides and are known to be hard acceptors with an overwhelming preference for oxygen-containing anions such as phosphates to which they form very tight ionic bonds. The method could be successfully applied to specifically precipitate phosphoproteins from complex samples including milk and egg white by forming solid metal-protein complexes. Owing to the low solubility product of the investigated lanthanide salts, the produced metal-protein complexes showed high stability. The protein pellets were extensively washed to remove nonphosphorylated proteins and contaminants. For the analysis of proteins the pellets were first dissolved in 30 % formic acid and subjected to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS. For peptide mass-fingerprint analysis the precipitated phosphoproteins were enzymatically digested using microwave-assisted digestion. The method was found to be highly specific for the isolation and purification of phosphoproteins. Protein quantification was performed by colorimetric detection of total precipitated phosphoproteins and revealed more than 95 % protein recovery for each lanthanide salt. (orig.)

  10. A Terbium Sensitized Luminescence Method for the Assay of Flubiprofen in Pharmaceutical Formulations

    Directory of Open Access Journals (Sweden)

    Salma M.Z. Al-Kindy

    2014-12-01

    Full Text Available A sensitive time-resolved luminescence method for the determination of flubiprofen (FLP in methanol and in aqueous solution is described. The method is based on the luminescence sensitization of terbium (Tb3+ by the formation of a ternary complex with FLP in the presence of 4,7 diphenyl 1,10 phenanthroline (DPP as co-ligand, and Tween-20 as surfactant. The signal for Tb-FLP-DPP was monitored at λex  = 285 nm and λem  = 552 nm. Optimum conditions for the formation of the complex in an aqueous system were TRIS buffer, pH 8.0, DPP (2.5Å~10−7  M, Tween-20 (0.30% and 4Å~10-5  mol L-1  of Tb3+  which allowed the determination of 20–1000 ng mL-1  of FLP with a limit of detection (LOD of 10 ng mL-1 . The relative standard deviations of the method ranged between 0.6 and 1.4% indicating excellent reproducibility of the method. The proposed method was successfully applied for the assays of FLP in pharmaceutical formulations and spiked tap water samples with average recoveries of 87% – 95%.

  11. Terbium-Doped VO2 Thin Films: Reduced Phase Transition Temperature and Largely Enhanced Luminous Transmittance.

    Science.gov (United States)

    Wang, Ning; Duchamp, Martial; Dunin-Borkowski, Rafal E; Liu, Shiyu; Zeng, XianTing; Cao, Xun; Long, Yi

    2016-01-26

    Vanadium dioxide (VO2) is a well-known thermochromic material with large IR modulating ability, promising for energy-saving smart windows. The main drawbacks of VO2 are its high phase transition temperature (τ(c) = 68°C), low luminous transmission (T(lum)), and weak solar modulating ability (ΔT(sol)). In this paper, the terbium cation (Tb(3+)) doping was first reported to reduce τ(c) and increase T(lum) of VO2 thin films. Compared with pristine VO2, 2 at. % doping level gives both enhanced T(lum) and ΔT(sol) from 45.8% to 54.0% and 7.7% to 8.3%, respectively. The T(lum) increases with continuous Tb(3+) doping and reaches 79.4% at 6 at. % doping level, representing ∼73.4% relative increment compared with pure VO2. This has surpassed the best reported doped VO2 thin films. The enhanced thermochromic properties is meaningful for smart window applications of VO2 materials.

  12. Carboxylated Polyurethanes Containing Hyperbranched Polyester Soft Segments

    Directory of Open Access Journals (Sweden)

    Žigon, M.

    2006-09-01

    Full Text Available hyperbranched polyester soft segments (HB PU with functional carboxylic groups in order to enable the preparation of stable HB PU dispersions. Carboxylated hyperbranched polyurethanes were synthesized using a hyperbranched polyester based on 2,2-bis(methylolpropionic acid of the fourth pseudo-generation (Boltorn H40 and hexamethylene (HDI or isophorone diisocyanate (IPDI. The reactivity of hyperbranched polyester with HDI was lower than expected, possibly due to the presence of less reactive hydroxyl groups in the linear repeat units. A gel was formed at mole ratios rNCO/OH = 1:2 or 1:4. The synthesis of HB PU was performed with partly esterified hyperbranched polyester with lowered hydroxyl functionality. The carboxyl groups were incorporated in the HB PU backbone by reaction of residual hydroxyl groups with cis-1,2-cyclohexanedicarboxylic anhydride. HB PU aqueous dispersions were stable at least for two months, although their films were brittle. The tensile strength and Young's modulus of blends of linear and HB PU decreased with increasing content of HB PU whereas elongation at break remained nearly constant, which was explained in terms of looser chain packing due to more open tree-like hyperbranched structures.

  13. Construction of the energy matrix for complex atoms. Part VIII: Hyperfine structure HPC calculations for terbium atom

    Science.gov (United States)

    Elantkowska, Magdalena; Ruczkowski, Jarosław; Sikorski, Andrzej; Dembczyński, Jerzy

    2017-11-01

    A parametric analysis of the hyperfine structure (hfs) for the even parity configurations of atomic terbium (Tb I) is presented in this work. We introduce the complete set of 4fN-core states in our high-performance computing (HPC) calculations. For calculations of the huge hyperfine structure matrix, requiring approximately 5000 hours when run on a single CPU, we propose the methods utilizing a personal computer cluster or, alternatively a cluster of Microsoft Azure virtual machines (VM). These methods give a factor 12 performance boost, enabling the calculations to complete in an acceptable time.

  14. Photocaging of carboxylic acids: a modular approach.

    Science.gov (United States)

    Szymański, Wiktor; Velema, Willem A; Feringa, Ben L

    2014-08-11

    Photocaged compounds are important tools for studying and regulating multiple processes, including biological functions. Reported herein is the use of the Passerini multicomponent reaction for modular preparation of photocaged carboxylic acids. The reaction is compatible with several functionalities and proceeds smoothly both in water and dichloromethane. The choice of aldehyde determines the wavelength used for deprotection and enables formation of orthogonally protected products. The isocyanide component can be used for introduction of reactive tags and photosensitizers, as well as for immobilization on a solid support. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Methyl (Sp-2-(diphenylphosphinoferrocene-1-carboxylate

    Directory of Open Access Journals (Sweden)

    Petr Štěpnička

    2009-10-01

    Full Text Available The title compound, [Fe(C5H5(C19H16O2P], obtained serendipitously during recrystallization of 1-hydroxybenzotriazolyl (Sp-2-(diphenylphosphinoferrocene-1-carboxylate from methanol, crystallizes in the chiral space group P212121. Its crystal structure not only confirms the anticipated absolute configuration but also establishes a rather regular geometry for the ferrocene unit, devoid of any significant deformation due to the attached substituents. In the crystal, symmetry-related molecules are linked via weak C—H...O interactions.

  16. Spectrofluorimetric determination of human serum albumin using terbium-danofloxacin probe.

    Science.gov (United States)

    Ramezani, Amir M; Manzoori, Jamshid L; Amjadi, Mohammad; Jouyban, Abolghasem

    2012-01-01

    A spectrofluorimetric method is proposed for the determination of human serum albumin (HSA) and bovine serum albumin (BSA) using terbium-danofloxacin (Tb(3+)-Dano) as a fluorescent probe. These proteins remarkably enhance the fluorescence intensity of the Tb(3+)-Dano complex at 545 nm, and the enhanced fluorescence intensity of Tb(3+)-Dano is proportional to the concentration of proteins (HSA and BSA). Optimum conditions for the determination of HSA were investigated and found that the maximum response was observed at: pH = 7.8, [Tb(3+)] = 8.5 × 10(-5) mol L(-1), [Dano] = 1.5 × 10(-4) mol L(-1). The calibration graphs for standard solutions of BSA, HSA, and plasma samples of HSA were linear in the range of 0.2 × 10(-6) - 1.3 × 10(-6) mol L(-1), 0.2 × 10(-6) - 1.4 × 10(-6) mol L(-1), and 0.2 × 10(-6) - 1 × 10(-6) mol L(-1), respectively. The detection limits (S/N = 3) for BSA, HSA, and plasma sample of HSA were 8.7 × 10(-8) mol L(-1), 6.2 × 10(-8) mol L(-1), and 8.1 × 10(-8) mol L(-1), respectively. The applicability of the method was checked using a number of real biological plasma samples and was compared with the UV spectrometric reference method. The results was showed that the method could be regarded as a simple, practical, and sensitive alternative method for determination of albumin in biological samples.

  17. Spectrofluorimetric Determination of Human Serum Albumin Using Terbium-Danofloxacin Probe

    Directory of Open Access Journals (Sweden)

    Amir M. Ramezani

    2012-01-01

    Full Text Available A spectrofluorimetric method is proposed for the determination of human serum albumin (HSA and bovine serum albumin (BSA using terbium-danofloxacin (Tb3+-Dano as a fluorescent probe. These proteins remarkably enhance the fluorescence intensity of the Tb3+-Dano complex at 545 nm, and the enhanced fluorescence intensity of Tb3+-Dano is proportional to the concentration of proteins (HSA and BSA. Optimum conditions for the determination of HSA were investigated and found that the maximum response was observed at: pH=7.8, [Tb3+] =8.5×10−5 mol L−1, [Dano] =1.5×10−4 mol L−1. The calibration graphs for standard solutions of BSA, HSA, and plasma samples of HSA were linear in the range of 0.2×10−6−1.3×10−6 mol L−1, 0.2×10−6−1.4×10−6 mol L−1, and 0.2×10−6−1×10−6 mol L−1, respectively. The detection limits (S/N = 3 for BSA, HSA, and plasma sample of HSA were 8.7×10−8 mol L−1, 6.2×10−8 mol L−1, and 8.1×10−8 mol L−1, respectively. The applicability of the method was checked using a number of real biological plasma samples and was compared with the UV spectrometric reference method. The results was showed that the method could be regarded as a simple, practical, and sensitive alternative method for determination of albumin in biological samples.

  18. Determination of flavonoids in pharmaceutical preparations using Terbium sensitized fluorescence method

    Directory of Open Access Journals (Sweden)

    M Shaghaghi

    2009-12-01

    Full Text Available "nBackground and the Purpose of the Study: The aim of this study was development and validation of a simple, rapid and sensitive spectrofluorimetric method for determination of total flavonoids in two topical formulations of Calendula officinalis, Ziziphus Spina-christi and an oral drop of Hypiran perforatum L. The proposed method is based on the formation of terbium (Tb3+ "n-flavonoids (quercetin as a reference standard complex at pH 7.0, which has fluorescence intensely with maximum emission at 545 nm when excited at 310 nm. "nMethod "n: For ointments masses of topical formulations were weighed and added to ethanol-aqueous buffer (pH 10.0 and the resulting mixtures were shaken and then two phases were separated by centrifugation. Aqueous phases were filtered and then diluted with water. For Hypiran drops an appropriate portion was diluted with ethanol and then aliquots of sample or standard solutions were determined according to the experimental procedure. "nResults "n: Under the optimum conditions, total concentrations of flavonoids (as quercetin equivalent in three tested formulations were found to be 0.204 mg/g (for Dermatin cream, 0.476 mg/g (for Calendula ointment and 13.50 μg/ml (for Hypiran drops. Analytical recoveries from samples spiked with different amounts of quercetin were 96.1-104.0 % with RSD % of less than 3.5. Conclusion : The proposed method which requires a simple dissolution step without any matrix interferences provided high sensitivity and selectivity and was easily applied to determine total flavonoids in real samples of three investigated formulations with excellent reproducibility.

  19. TOF SIMS analysis and generation of white photoluminescence from strontium silicate codoped with europium and terbium

    Energy Technology Data Exchange (ETDEWEB)

    Tshabalala, Modiehi A.; Swart, Hendrik C.; Ntwaeaborwa, Odireleng M., E-mail: ntwaeab@ufs.ac.za [Department of Physics, University of the Free State, P.O Box 339, Bloemfontein 9300 South Africa (South Africa)

    2014-03-15

    White light emitting terbium (Tb{sup 3+}) and europium (Eu{sup 3+}) codoped strontium silicate (Sr{sub 2}SiO{sub 4}) phosphors were prepared by a solid state reaction process. The structure, particle morphology, chemical composition, ion distribution, photoluminescence (PL), and decay characteristics of the phosphors were analyzed by x-ray diffraction (XRD), scanning electron microscopy (SEM), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and PL spectroscopy, respectively. The XRD data showed that our Sr{sub 2}SiO{sub 4} composed of two phases, namely, β-Sr{sub 2}SiO{sub 4} and α′-Sr{sub 2}SiO{sub 4}, and the α′-Sr{sub 2}SiO{sub 4} phase was more prominent than the β-Sr{sub 2}SiO{sub 4} phase. The SEM micrographs showed that the particles were agglomerated together and they did not have definite shapes. All ions (i.e., negative and positive) present in our materials were identified by TOF-SIMS. In addition, the chemical imaging performed with the TOF-SIMS demonstrated how the individual ions including the dopants (Eu{sup 3+} and Tb{sup 3+}) were distributed in the host lattice. White photoluminescence was observed when the Sr{sub 2}SiO{sub 4}:Tb{sup 3+}, Eu{sup 3+} phosphor was excited at 239 nm using a monochromatized xenon lamp as the excitation source. The phosphor exhibited fast decay lifetimes implying that it is not a good candidate for long afterglow applications.

  20. Zinc sulfide and terbium-doped zinc sulfide films grown by traveling wave reactor atomic layer epitaxy

    CERN Document Server

    Yun, S J; Nam, K S

    1998-01-01

    Zinc sulfide (ZnS) and terbium-doped ZnS (ZnS:Tb) thin films were grown by traveling wave reactor atomic layer epitaxy (ALE). In the present work, ZnCl sub 2 , H sub 2 S, and tris (2,2,6,6-tetramethyl-3,5-heptandionato) terbium (Tb(tmhd) sub 3) were used as the precursors. The dependence of crystallinity and Cl content of ZnS films was investigated on the growth temperature. ZnS and ZnS:Tb films grown at temperatures ranging from 400 to 500 .deg. C showed a hexagonal-2H crystalline structure. The crystallinity of ZnS film was greatly enhanced as the temperature increased. At growth temperatures higher than 450.deg.C, the films showed preferred orientation with mainly (002) diffraction peak. The Cl content decreased from approximately 9 to 1 at.% with the increase in growth temperature from 400 to 500 .deg. C. The segregation of Cl near the surface region and the incorporation of O from Tb(tmhd) sub 3 during ALE process were also observed using Auger electron spectroscopy. The ALE-grown ZnS and ZnS:Tb films re...

  1. Commercializing potassium terbium fluoride, KTF (KTb3F10) faraday crystals for high laser power optical isolator applications

    Science.gov (United States)

    Schlichting, Wolfgang; Stevens, Kevin; Foundos, Greg; Payne, Alexis

    2017-10-01

    Many scientific lasers and increasingly industrial laser systems operate in power regime, require high-performance optical isolators to prevent disruptive light feedback into the laser cavity. The optically active Faraday material is the key optical element inside the isolator. SYNOPTICS has been supplying the laser market with Terbium Gallium Garnet (TGG - Tb3Ga5O12) for many years. It is the most commonly used material for the 650-1100nm range and the key advantages for TGG include its cubic crystal structure for alignment free processing, little to no intrinsic birefringence, and ease of manufacture. However, for high-power laser applications TGG is limited by its absorption at 1064nm and its thermo-optic coefficient, dn/dT. Specifically, thermal lensing and depolarization effects become a limiting factor at high laser powers. While TGG absorption has improved significantly over the past few years, there is an intrinsic limit. Now, SYNOPTICS is commercializing the enhanced new crystal Potassium Terbium Fluoride KTF (KTb3F10) that exhibits much smaller nonlinear refractive index and thermo-optic coefficients, and still exhibits a Verdet constant near that of TGG. This cubic crystal has relatively low absorption and thermo-optic coefficients. It is now fully characterized and available for select production orders. At OPTIFAB in October 2017 we present recent results comparing the performance of KTF to TGG in optical isolators and show SYNOPTICS advances in large volume crystal growth and the production ramp up.

  2. Short Carboxylic Acid-Carboxylate Hydrogen Bonds Can Have Fully Localized Protons.

    Science.gov (United States)

    Lin, Jiusheng; Pozharski, Edwin; Wilson, Mark A

    2017-01-17

    Short hydrogen bonds (H-bonds) have been proposed to play key functional roles in several proteins. The location of the proton in short H-bonds is of central importance, as proton delocalization is a defining feature of low-barrier hydrogen bonds (LBHBs). Experimentally determining proton location in H-bonds is challenging. Here, bond length analysis of atomic (1.15-0.98 Å) resolution X-ray crystal structures of the human protein DJ-1 and its bacterial homologue, YajL, was used to determine the protonation states of H-bonded carboxylic acids. DJ-1 contains a buried, dimer-spanning 2.49 Å H-bond between Glu15 and Asp24 that satisfies standard donor-acceptor distance criteria for a LBHB. Bond length analysis indicates that the proton is localized on Asp24, excluding a LBHB at this location. However, similar analysis of the Escherichia coli homologue YajL shows both residues may be protonated at the H-bonded oxygen atoms, potentially consistent with a LBHB. A Protein Data Bank-wide screen identifies candidate carboxylic acid H-bonds in approximately 14% of proteins, which are typically short [⟨dO-O⟩ = 2.542(2) Å]. Chemically similar H-bonds between hydroxylated residues (Ser/Thr/Tyr) and carboxylates show a trend of lengthening O-O distance with increasing H-bond donor pKa. This trend suggests that conventional electronic effects provide an adequate explanation for short, charge-assisted carboxylic acid-carboxylate H-bonds in proteins, without the need to invoke LBHBs in general. This study demonstrates that bond length analysis of atomic resolution X-ray crystal structures provides a useful experimental test of certain candidate LBHBs.

  3. Short Carboxylic Acid-Carboxylate Hydrogen Bonds Can Have Fully Localized Protons

    Science.gov (United States)

    Lin, Jiusheng; Pozharski, Edwin; Wilson, Mark A.

    2018-01-01

    Short hydrogen bonds (H-bonds) have been proposed to play key functional roles in several proteins. The location of the proton in short H-bonds is of central importance, as proton delocalization is a defining feature of low barrier hydrogen bonds (LBHBs). Experimentally determining proton location in H-bonds is challenging. Here, bond length analysis of atomic (1.15–0.98 Å) resolution X-ray crystal structures of the human protein DJ-1 and its bacterial homolog YajL was used to determine the protonation states of H-bonded carboxylic acids. DJ-1 contains a buried, dimer-spanning 2.49 Å H-bond between Glu15 and Asp23 that satisfies standard donor-acceptor distance criteria for a LBHB. Bond length analysis indicates that the proton is localized on Asp24, excluding a LBHB at this location. However, similar analysis of the E. coli homolog YajL shows both residues may be protonated at the H-bonded oxygen atoms, potentially consistent with an LBHB. A PDB-wide screen identifies candidate carboxylic acid H-bonds in approximately 14% of proteins, which are typically short (=2.542(2) Å). Chemically similar H-bonds between hydroxylated residues (Ser/Thr/Tyr) and carboxylates show a trend of lengthening O-O distance with increasing H-bond donor pKa. This trend suggests that conventional electronic effects provide an adequate explanation for short, charge-assisted carboxylic acid-carboxylate H-bonds in proteins, without the need to invoke LBHBs in general. This study demonstrates that bond length analysis of atomic resolution X-ray crystal structures provides a useful experimental test of certain candidate LBHBs. PMID:27989121

  4. Short Carboxylic Acid–Carboxylate Hydrogen Bonds Can Have Fully Localized Protons

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jiusheng; Pozharski, Edwin; Wilson, Mark A.

    2017-01-17

    Short hydrogen bonds (H-bonds) have been proposed to play key functional roles in several proteins. The location of the proton in short H-bonds is of central importance, as proton delocalization is a defining feature of low-barrier hydrogen bonds (LBHBs). Experimentally determining proton location in H-bonds is challenging. Here, bond length analysis of atomic (1.15–0.98 Å) resolution X-ray crystal structures of the human protein DJ-1 and its bacterial homologue, YajL, was used to determine the protonation states of H-bonded carboxylic acids. DJ-1 contains a buried, dimer-spanning 2.49 Å H-bond between Glu15 and Asp24 that satisfies standard donor–acceptor distance criteria for a LBHB. Bond length analysis indicates that the proton is localized on Asp24, excluding a LBHB at this location. However, similar analysis of the Escherichia coli homologue YajL shows both residues may be protonated at the H-bonded oxygen atoms, potentially consistent with a LBHB. A Protein Data Bank-wide screen identifies candidate carboxylic acid H-bonds in approximately 14% of proteins, which are typically short [O–O> = 2.542(2) Å]. Chemically similar H-bonds between hydroxylated residues (Ser/Thr/Tyr) and carboxylates show a trend of lengthening O–O distance with increasing H-bond donor pKa. This trend suggests that conventional electronic effects provide an adequate explanation for short, charge-assisted carboxylic acid–carboxylate H-bonds in proteins, without the need to invoke LBHBs in general. This study demonstrates that bond length analysis of atomic resolution X-ray crystal structures provides a useful experimental test of certain candidate LBHBs.

  5. Decarboxylative Fluorination of Aliphatic Carboxylic Acids via Photoredox Catalysis

    Science.gov (United States)

    Ventre, Sandrine; Petronijevic, Filip R.; MacMillan, David W. C.

    2016-01-01

    The direct conversion of aliphatic carboxylic acids to the corresponding alkyl fluorides has been achieved via visible light-promoted photoredox catalysis. This operationally simple, redox-neutral fluorination method is amenable to a wide variety of carboxylic acids. Photon-induced oxidation of carboxylates leads to the formation of carboxyl radicals, which upon rapid CO2-extrusion and F• transfer from a fluorinating reagent yield the desired fluoroalkanes with high efficiency. Experimental evidence indicates that an oxidative quenching pathway is operable in this broadly applicable fluorination protocol. PMID:25881929

  6. 2,6-Dimethylphenyl acridine-9-carboxylate

    Directory of Open Access Journals (Sweden)

    Damian Trzybiński

    2013-02-01

    Full Text Available In the title compound, C22H17NO2, the acridine ring system and the benzene ring are oriented at a dihedral angle of 37.7 (1°. The carboxyl group is twisted at an angle of 67.7 (1° relative to the acridine skeleton. In the crystal, molecules are arranged in stacks along the b axis, with all of the acridine rings involved in multiple π–π interactions [centroid–centroid distances in the range 3.632 (2–4.101 (2 Å]. The acridine moieties are parallel within the stacks, but inclined at an angle of 52.7 (1° in adjacent stacks.

  7. Synthesis and luminescent study of Ce{sup 3+}-doped terbium-yttrium aluminum garnet

    Energy Technology Data Exchange (ETDEWEB)

    Dotsenko, V.P., E-mail: ssclab@ukr.net [A.V. Bogatsky Physico-Chemical Institute, National Academy of Sciences of Ukraine, Lustdorfskaya doroga 86, 65080 Odessa (Ukraine); Berezovskaya, I.V.; Zubar, E.V.; Efryushina, N.P. [A.V. Bogatsky Physico-Chemical Institute, National Academy of Sciences of Ukraine, Lustdorfskaya doroga 86, 65080 Odessa (Ukraine); Poletaev, N.I.; Doroshenko, Yu.A. [Institute of Combustion and Advanced Technologies, Mechnikov Odessa National University, Dvoryanskaya 2, 65082 Odessa (Ukraine); Stryganyuk, G.B. [Ivan Franko National University of Lviv, Kirilo i Mefodii 8, 79005 Lviv (Ukraine); HASYLAB at DESY, Notkestrasse 85, 22607 Hamburg (Germany); Voloshinovskii, A.S. [Ivan Franko National University of Lviv, Kirilo i Mefodii 8, 79005 Lviv (Ukraine)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer Ce{sup 3+}-doped garnets (TYAG) were prepared using nanostructured reagents. Black-Right-Pointing-Pointer The Ce{sup 3+} ions cause a very efficient yellow emission of the samples. Black-Right-Pointing-Pointer The reasons for the long wavelength position of this emission are discussed. Black-Right-Pointing-Pointer Contribution from Al atoms to the conduction band of TYAG is quite essential. - Abstract: Terbium-yttrium aluminum garnets (TYAG) doped with Ce{sup 3+} ions have been prepared by solid state reactions between nanostructured oxides of aluminum and rare earths. The luminescent properties of Ce{sup 3+} ions in (Tb{sub 0.8}Y{sub 0.2}){sub 3(1-x)}Ce{sub 3x}Al{sub 5}O{sub 12} (x = 0.03) have been studied upon excitation in the 2-20 eV region. The substitution of Tb{sup 3+} for Y{sup 3+} in the garnet structure results in broadening the emission band and shifting its maximum towards the longer wavelengths. It was found that in addition to the 4f{sup n} {yields} 4f{sup n-1}5d excitation bands of Ce{sup 3+} and Tb{sup 3+} ions, the excitation spectra for the Ce{sup 3+} emission contain broad bands at 6.73 and {approx}9.5 eV. These bands are attributed to the Ce{sup 3+}-bound exciton formation and O 2p {yields} Al 3s, 3p transitions, respectively. In contrast to the predictions based on the results of electronic structure calculations on Y{sub 3}Al{sub 5}O{sub 12} and Tb{sub 4}Al{sub 2}O{sub 9}, the threshold of interband transitions in TYAG is at high energies ( Greater-Than-Or-Slanted-Equal-To 7.3 eV), and contributions from Al{sub tetr} and Al{sub oct} atoms to the conduction-band density of states are evaluated as quite essential.

  8. Lysine carboxylation: unveiling a spontaneous post-translational modification

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Morales, David; Adamian, Larisa [University of Illinois at Chicago, 851 South Morgan Street, Room 218, Chicago, IL 60607 (United States); Shi, Dashuang [Center for Genetic Medicine Research, 111 Michigan Avenue NW, Washington, DC 20010-2970 (United States); Liang, Jie, E-mail: jliang@uic.edu [University of Illinois at Chicago, 851 South Morgan Street, Room 218, Chicago, IL 60607 (United States)

    2014-01-01

    A computational method for the prediction of lysine carboxylation (KCX) in protein structures is described. The method accurately identifies misreported KCXs and predicts previously unknown KCX sites. The carboxylation of lysine residues is a post-translational modification (PTM) that plays a critical role in the catalytic mechanisms of several important enzymes. It occurs spontaneously under certain physicochemical conditions, but is difficult to detect experimentally. Its full impact is unknown. In this work, the signature microenvironment of lysine-carboxylation sites has been characterized. In addition, a computational method called Predictor of Lysine Carboxylation (PreLysCar) for the detection of lysine carboxylation in proteins with available three-dimensional structures has been developed. The likely prevalence of lysine carboxylation in the proteome was assessed through large-scale computations. The results suggest that about 1.3% of large proteins may contain a carboxylated lysine residue. This unexpected prevalence of lysine carboxylation implies an enrichment of reactions in which it may play functional roles. The results also suggest that by switching enzymes on and off under appropriate physicochemical conditions spontaneous PTMs may serve as an important and widely used efficient biological machinery for regulation.

  9. Carboxylate-bridged Cu (II) coordination polymeric complex ...

    Indian Academy of Sciences (India)

    Carboxylate-bridged Cu(II) coordination polymeric complex: synthesis, crystal structure, magnetic properties, DNA binding and electrochemical studies ... Abstract. A novel water-soluble carboxylate-bridged copper(II) coordination polymer,Cu-BIG was formed by the reaction of Cu(ClO₄)₂ ·6H₂O and tridentate ...

  10. Novel Polymers with a High Carboxylic Acid Loading

    DEFF Research Database (Denmark)

    Thomsen, Anders Daugaard; Malmström, Eva; Hvilsted, Søren

    2006-01-01

    ABSTRACT: Click chemistry has been used to prepare a range of novel polymers with pendant carboxylic acid side groups. Four azido carboxylic acids, either mono- or difunctional and aliphatic or aromatic, have been prepared and thoroughly characterized. Extensive model reactions with 1-ethyl-4...... of the pendant groups in the derivatized polymers and the glass-transition temperature has emerged: the aromatic carboxylic acids give high glass-transition temperatures (90—120 DC), and the aliphatic carboxylic acids give lower glass-transition temperatures (50—65 DC).......-hydroxybenzene, the simplest model for poly(4-hydroxystyrene), and the four azido carboxylic acids have been conucted to establish the proper reaction conditions and provide an analytical frame for the corresponding polymers. Poly(4-hydroxystyrene) moieties in three different polymers—poly (4-hydroxystyrene...

  11. Richard III

    DEFF Research Database (Denmark)

    Lauridsen, Palle Schantz

    2017-01-01

    Kort analyse af Shakespeares Richard III med fokus på, hvordan denne skurk fremstilles, så tilskuere (og læsere) langt henad vejen kan føle sympati med ham. Med paralleller til Netflix-serien "House of Cards"......Kort analyse af Shakespeares Richard III med fokus på, hvordan denne skurk fremstilles, så tilskuere (og læsere) langt henad vejen kan føle sympati med ham. Med paralleller til Netflix-serien "House of Cards"...

  12. Complete Stokes polarimetry of magneto-optical Faraday effect in a terbium gallium garnet crystal at cryogenic temperatures.

    Science.gov (United States)

    Majeed, Hassaan; Shaheen, Amrozia; Anwar, Muhammad Sabieh

    2013-10-21

    We report the complete determination of the polarization changes caused in linearly polarized incident light due to propagation in a magneto-optically active terbium gallium garnet (TGG) single crystal, at temperatures ranging from 6.3 to 300 K. A 28-fold increase in the Verdet constant of the TGG crystal is seen as its temperature decreases to 6.3 K. In contrast with polarimetry of light emerging from a Faraday material at room temperature, polarimetry at cryogenic temperatures cannot be carried out using the conventional fixed polarizer-analyzer technique because the assumption that ellipticity is negligible becomes increasingly invalid as temperature is lowered. It is shown that complete determination of light polarization in such a case requires the determination of its Stokes parameters, otherwise inaccurate measurements will result with negative implications for practical devices.

  13. Development of Optical Isolators for Visible Light Using Terbium Aluminum Garnet (Tb3Al5O12) Single Crystals

    Science.gov (United States)

    Geho, Mikio; Takagi, Takashi; Chiku, Shinichiro; Fujii, Takashi

    2005-07-01

    We have recently reported the successful growth of incongruently melting terbium aluminum garnet (Tb3Al5O12; TAG) single crystals by the hybrid laser FZ (floating zone) method. Optical property evaluations confirmed a high transmittance and a larger Verdet constant than conventional Tb3Ga5O12 (TGG) crystals and/or Faraday glasses. In this study, we attempted to design, fabricate, and evaluate optical isolators in visible light through near-infrared (NIR) regions using TAG crystals. A finite element method (FEM) simulation of possible models led us to the preferable one based on a radially magnetized magnet. To realize this, we employed a pseudo-radially magnetized magnet. The target wavelengths of the prototype device were 408, 808, and 1064 nm. The typical extinction ratio was more than 30 dB and the insertion loss was less than 0.3 dB for AR-coated devices.

  14. Carboxylate ligands drastically enhance the rates of oxo exchange and hydrogen peroxide disproportionation by oxo manganese compounds of potential biological significance.

    Science.gov (United States)

    Dubois, Lionel; Pécaut, Jacques; Charlot, Marie-France; Baffert, Carole; Collomb, Marie-Noëlle; Deronzier, Alain; Latour, Jean-Marc

    2008-01-01

    To mimic the carboxylate-rich active site of the manganese catalases more closely we introduced carboxylate groups into dimanganese complexes in place of nitrogen ligands. The series of dimanganese(III,IV) complexes of tripodal ligands [Mn(2)(L)(2)(O)(2)](3+/+/-/3-) was extended from those of tpa (1) and H(bpg) (2) to those of H(2)(pda) (3) and H(3)(nta) (4) (tpa=tris-picolylamine, H(bpg)=bis-picolylglycylamine, H(2)(pda)=picolyldiglycylamine, H(3)(nta)=nitrilotriacetic acid). While 3 [Mn(2)(pda)(2)(O)(2)][Na(H(2)O)(3)] could be synthesized at -20 degrees C and characterized in the solid state, 4 [Mn(2)(nta)(2)(O)(2)](3-) could be obtained and studied only in solution at -60 degrees C. A new synthetic procedure for the dimanganese(III,III) complexes was devised, using stoichiometric reduction of the dimanganese(III,IV) precursor by the benzil radical with EPR monitoring. This enabled the preparation of the parent dimanganese(III,III) complex 5 [Mn(2)(tpa)(2)(O)(2)](ClO(4))(2), which was structurally characterized. The UV/visible, IR, EPR, magnetic, and electrochemical properties of complexes 1-3 and 5 were analyzed to assess the electronic changes brought about by the carboxylate replacement of pyridine ligands. The kinetics of the oxo ligand exchanges with labeled water was examined in acetonitrile solution. A dramatic effect of the number of carboxylates was evidenced. Interestingly, the influence of the second carboxylate substitution differs from that of the first one probably because this substitution occurs on an out-of-plane coordination while the former occurs in the plane of the [Mn(2)O(2)] core. Indeed, on going from 1 to 3 the exchange rate was increased by a factor of 50. Addition of triethylamine caused a rate increase for 1, but not for 3. The abilities of 1-3 to disproportionate H(2)O(2) were assessed volumetrically. The disproportionation exhibited a sensitivity corresponding to the carboxylate substitution. These observations strongly suggest that

  15. Location of. gamma. -carboxyglutamyl residues in partially carboxylated prothrombin preparations

    Energy Technology Data Exchange (ETDEWEB)

    Liska, D.J.; Suttie, J.W.

    1988-11-15

    Prothrombin contains 10-..gamma..-carboxylglutamyl (Gla) residues in the N-terminal (fragment 1) domain of the protein. Following anticoagulant administration, a spectrum of undercarboxylated, physiologically less active forms of prothrombin is secreted into bovine or human plasma. The sites of undercarboxylation in these prothrombin species have now been investigated. Plasma containing a mixture of partially carboxylated forms of prothombin was obtained from a dicoumarol-treated bovine, and three pools of partially carboxylated (four, six, or eight Gla) species were purified by adsorption onto barium citrate and barium oxalate, ammonium sulfate fractionation, and chromatography. Fragment 1 obtained from these variants was equilibrated with /sup 3/H/sub 2/O and heated in a dry state to decarboxylate Gla and incorporate /sup 3/H into the resulting Glu residues. This peptide was then sequenced by Edman degradation, and the specific radioactivity of PTH-Glu was determined for each potential Gla-containing site. Data obtained from normal prothrombin fragment 1 fit a linear model when the log of specific activity of PTH-Glu was plotted against the cycle number. Analysis of the 80% variant showed a decrease in carboxylation only in the last two Gla residues, while data obtained from the 60% variant indicated a general decrease in carboxylation from the most amino-terminal of the Gla residues. In the 40% Gla variant, all but the most amino-terminal of the Gla residues appeared to be undercarboxylated. These data indicate that the ..gamma..-carboxylation of glutamyl residues in prothrombin does not occur randomly but instead with preferential carboxylation of the most amino-terminal Gla residues. When carboxylation is limited, the impairment of carboxylation is more severe at the more carboxyl-terminal residues.

  16. Applications of Carboxylic Acid Reductases in Oleaginous Microbes

    Energy Technology Data Exchange (ETDEWEB)

    Resch, Michael G.; Linger, Jeffrey; McGeehan, John; Tyo, Keith; Beckham, Gregg

    2016-05-26

    Carboxylic acid reductases (CARs) are recently emerging reductive enzymes for the direct production of aldehydes from biologically-produced carboxylic acids. Recent work has demonstrated that these powerful enzymes are able to reduce a very broad range of volatile- to long-chain fatty acids as well as aromatic acids. Here, we express four CAR enzymes from different fungal origins to test their activity against fatty acids commonly produced in oleaginous microbes. These in vitro results will inform metabolic engineering strategies to conduct mild biological reduction of carboxylic acids in situ, which is conventionally done via hydrotreating catalysis at high temperatures and hydrogen pressures.

  17. A hydrometallurgical process for the recovery of terbium from fluorescent lamps: Experimental design, optimization of acid leaching process and process analysis.

    Science.gov (United States)

    Innocenzi, Valentina; Ippolito, Nicolò Maria; De Michelis, Ida; Medici, Franco; Vegliò, Francesco

    2016-12-15

    Terbium and rare earths recovery from fluorescent powders of exhausted lamps by acid leaching with hydrochloric acid was the objective of this study. In order to investigate the factors affecting leaching a series of experiments was performed in according to a full factorial plan with four variables and two levels (4 2 ). The factors studied were temperature, concentration of acid, pulp density and leaching time. Experimental conditions of terbium dissolution were optimized by statistical analysis. The results showed that temperature and pulp density were significant with a positive and negative effect, respectively. The empirical mathematical model deducted by experimental data demonstrated that terbium content was completely dissolved under the following conditions: 90 °C, 2 M hydrochloric acid and 5% of pulp density; while when the pulp density was 15% an extraction of 83% could be obtained at 90 °C and 5 M hydrochloric acid. Finally a flow sheet for the recovery of rare earth elements was proposed. The process was tested and simulated by commercial software for the chemical processes. The mass balance of the process was calculated: from 1 ton of initial powder it was possible to obtain around 160 kg of a concentrate of rare earths having a purity of 99%. The main rare earths elements in the final product was yttrium oxide (86.43%) following by cerium oxide (4.11%), lanthanum oxide (3.18%), europium oxide (3.08%) and terbium oxide (2.20%). The estimated total recovery of the rare earths elements was around 70% for yttrium and europium and 80% for the other rare earths. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Chemiluminescence characterisation of the reaction system Tb(III)-amino acid-peroxynitrous acid

    Energy Technology Data Exchange (ETDEWEB)

    Kaczmarek, M. [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan (Poland); Lis, S. [Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan (Poland)], E-mail: blis@amu.edu.pl

    2008-02-28

    Chemiluminescence of the reaction system tryptophan-hydrogen peroxide-nitrite-Tb(III)-H{sub 2}SO{sub 4} was used for the determination of tryptophan. The chemiluminescence intensity observed in the system tryptophan-hydrogen peroxide-nitrite-sulfuric acid, in the presence of Tb(III) ions was five times higher than that in a solution without Tb(III) ions. The chemiluminescence spectrum obtained for the system tryptophan-hydrogen peroxide-nitrite-sulfuric acid solution showed one band, with {lambda}{sub max} {approx} 520 nm, whereas in the presence of Tb(III) ions two bands with {lambda}{sub max} {approx} 520 nm and 550 nm were observed. The peak centered at {approx}550 nm, corresponding to the {sup 5}D{sub 4} {yields} {sup 7}F{sub 5} transition, which is typical for the Tb(III) ion. A linear dependence was found for the CL intensity versus the tryptophan concentration, in the range of 1.2 x 10{sup -7} to 1 x 10{sup -4} mol/l. Terbium(III) ions play the role of sensitizer in the reaction mixture tryptophan-hydrogen peroxide-nitrite-sulfuric acid.

  19. Selective carboxyl methylation of structurally altered calmodulins in Xenopus oocytes

    Energy Technology Data Exchange (ETDEWEB)

    Desrosiers, R.R.; Romanik, E.A.; O' Connor, C.M. (Worcester Foundation for Experimental Biology, Shrewsbury, MA (USA))

    1990-12-05

    The eucaryotic protein carboxyl methyltransferase specifically modifies atypical D-aspartyl and L-isoaspartyl residues which are generated spontaneously as proteins age. The selectivity of the enzyme for altered proteins in intact cells was explored by co-injecting Xenopus laevis oocytes with S-adenosyl-L-(methyl-3H)methionine and structurally altered calmodulins generated during a 14-day preincubation in vitro. Control experiments indicated that the oocyte protein carboxyl methyltransferase was not saturated with endogenous substrates, since protein carboxyl methylation rates could be stimulated up to 8-fold by increasing concentrations of injected calmodulin. The oocyte protein carboxyl methyltransferase showed strong selectivities for bovine brain and bacterially synthesized calmodulins which had been preincubated in the presence of 1 mM EDTA relative to calmodulins which had been preincubated with 1 mM CaCl2. Radioactive methyl groups were incorporated into base-stable linkages with recombinant calmodulin as well as into carboxyl methyl esters following its microinjection into oocytes. This base-stable radioactivity most likely represents the trimethylation of lysine 115, a highly conserved post-translational modification which is present in bovine and Xenopus but not in bacterially synthesized calmodulin. Endogenous oocyte calmodulin incorporates radioactivity into both carboxyl methyl esters and into base-stable linkages following microinjection of oocytes with S-adenosyl-(methyl-3H)methionine alone. The rate of oocyte calmodulin carboxyl methylation in injected oocytes is calculated to be similar to that of lysine 115 trimethylation, suggesting that the rate of calmodulin carboxyl methylation is similar to that of calmodulin synthesis. At steady state, oocyte calmodulin contains approximately 0.0002 esters/mol of protein, which turn over rapidly.

  20. Mechanistic Investigation into the Decarboxylation of Aromatic Carboxylic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Britt, P F; Buchanan, III, A C; Eskay, T P; Mungall, W S

    1999-08-22

    It has been proposed that carboxylic acids and carboxylates are major contributors to cross-linking reactions in low-rank coals and inhibit its thermochemical processing. Therefore, the thermolysis of aromatic carboxylic acids was investigated to determine the mechanisms of decarboxylation at temperatures relevant to coal processing, and to determine if decarboxylation leads to cross-linking (i.e., formation of more refractory products). From the thcrmolysis of simple and polymeric coal model compounds containing aromatic carboxylic acids at 250-425 °C, decarboxylation was found to occur primarily by an acid promoted ionic pathway. Carboxylate salts were found to enhance the decarboxylation rate, which is consistent with the proposed cationic mechanism. Thermolysis of the acid in an aromatic solvent, such as naphthalene, produced a small amount of arylated products (~5 mol%)), which constitute a low-temperature cross-link. These arylated products were formed by the rapid decomposition of aromatic anhydrides, which are in equilibrium with the acid. These anhydrides decompose by a free radical induced decomposition pathway to form atyl radicals that can add to aromatic rings to form cross-links or abstract hydrogen. Large amounts of CO were formed in the thennolysis of the anhydrides which is consistent with the induced decomposition pathway. CO was also formed in the thermolysis of the carboxylic acids in aromatic solvents which is consistent with the formation and decomposition of the anhydride. The formation of anhydride linkages and cross-links was found to be very sensitive to the reactions conditions. Hydrogen donor solvents, such as tetralin, and water were found to decrease the formation of arylated products. Silar reaction pathways were also found in the thermolysis of a polymeric model that contained aromatic carboxylic acids. In this case, anhydride formation and decomposition produced an insoluble polymer, while the O-methylated polymer and the non-carboxylated

  1. A novel tridentate bis(phosphinic acid)phosphine oxide based europium(III)-selective Nafion membrane luminescent sensor.

    Science.gov (United States)

    Sainz-Gonzalo, F J; Popovici, C; Casimiro, M; Raya-Barón, A; López-Ortiz, F; Fernández, I; Fernández-Sánchez, J F; Fernández-Gutiérrez, A

    2013-10-21

    A new europium(III) membrane luminescent sensor based on a new tridentate bis(phosphinic acid)phosphine oxide (3) system has been developed. The synthesis of this new ligand is described and its full characterization by NMR, IR and elemental analyses is provided. The luminescent complex formed between europium(III) chloride and ligand 3 was evaluated in solution, observing that its spectroscopic and chemical characteristics are excellent for measuring in polymer inclusion membranes. Included in a Nafion membrane, all the parameters (ligand and ionic additives) that can affect the sensitivity and selectivity of the sensing membrane as well as the instrumental conditions were carefully optimized. The best luminescence signal (λexc = 229.06 nm and λem = 616.02 nm) was exhibited by the sensing film having a Nafion : ligand composition of 262.3 : 0.6 mg mL(-1). The membrane sensor showed a short response time (t95 = 5.0 ± 0.2 min) and an optimum working pH of 5.0 (25 mM acetate buffer solution). The membrane sensor manifested a good selectivity toward europium(III) ions with respect to other trivalent metals (iron, chromium and aluminium) and lanthanide(III) ions (lanthanum, samarium, terbium and ytterbium), although a small positive interference of terbium(III) ions was observed. It provided a linear range from 1.9 × 10(-8) to 5.0 × 10(-6) M with a very low detection limit (5.8 × 10(-9) M) and sensitivity (8.57 × 10(-7) a.u. per M). The applicability of this sensing film has been demonstrated by analyzing different kinds of spiked water samples obtaining recovery percentages of 95-97%.

  2. Ultrafast fluorescence study of the effect of carboxylic and carboxylate substituents on the excited state properties of anthracene

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Córdoba, William [Escuela de Física, Universidad Nacional de Colombia Sede Medellín, A.A. 3840, Medellín (Colombia); Noria-Moreno, Raquel; Navarro, Pedro [Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, 04510 México, DF (Mexico); Peon, Jorge, E-mail: jpeon@unam.mx [Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, 04510 México, DF (Mexico)

    2014-01-15

    With the objective of understanding the interaction between carboxylic substituents and aromatic systems in electronically excited states, we have studied the photophysics of anthracene-9-carboxylic acid and its conjugate base through spectroscopic and computational approaches. We measured the emission spectrum evolution with femtosecond resolution observing that the formation of the relaxed fluorescent state of the acid corresponds to a red shifting of the emission which takes place within the first picosecond after excitation, a time-scale defined by the solvent response (acetone). For the case of the anthracene-9-carboxylate system, the spectral evolution is practically absent, indicating a lack of relaxation of the substituent orientation in the S{sub 1} state. Computational work at the time-dependent density functional theory level, considering the novel state-specific formalism, indicates that for anthracene-9-carboxylic acid, the first electronically excited state evolves from a structure with a nearly 60° dihedral angle between the carboxylic and aromatic systems, to a relaxed structure with a nearly 30° angle. On the other hand, the calculations show that for the salt, the carboxylate group remains decoupled from the aromatic system both in the ground and fluorescent state, remaining in both states at nearly 90°. Our results elucidate that the emission spectra of the acid and conjugate base are defined by the degree of interaction between the carboxylic (or carboxylate) group and the aromatic system. Such interactions are drastically different from the formal charge present in the carboxylate ion. -- Highlights: • Understanding of the interaction between carboxylic substituents and aromatic systems in electronically excited states. • Elucidation of the excited state dynamics of 9-ACA and its conjugated base in acetone solutions. • The spectral evolution time-scale of the aromatic acid and its salt depends on the solvation dynamics. • The

  3. Europium (III) and americium (III) stability constants with humic acid

    Energy Technology Data Exchange (ETDEWEB)

    Torres, R.A.; Choppin, G.R.

    1984-01-01

    The stability constants for tracer concentrations of Eu(III) and Am(III) complexes with a humic acid extracted from a lake-bottom sediment were measured using a solvent extraction system. The organic extractant was di(2-ethylhexyl)-phosphoric acid in toluene while the humate aqueous phase had a constant ionic strength of 0.1 M (NaClO/sub 4/). Aqueous humic acid concentrations were monitored by measuring uv-visible absorbances at approx.= 380 nm. The total carboxylate capacity of the humic acid was determined by direct potentiometric titration to be 3.86 +- 0.03 meq/g. The humic acid displayed typical characteristics of a polyelectrolyte - the apparent pKsub(a), as well as the calculated metal ion stability constants increased as the degree of ionization (..cap alpha..) increased. The binding data required a fit of two stability constants, ..beta../sub 1/ and ..beta../sub 2/, such that for Eu, log ..beta../sub 1/ = 8.86 ..cap alpha.. + 4.39, log ..beta../sub 2/ = 3.55 ..cap alpha.. + 11.06 while for Am, log ..beta../sub 1/ = 10.58 ..cap alpha.. + 3.84, log ..beta../sub 2/ = 5.32 ..cap alpha.. + 10.42. With hydroxide, carbonate, and humate as competing ligands, the humate complex associated with the ..beta../sub 1/ constant is calculated to be the dominant species for the trivalent actinides and lanthanides under conditions present in natural waters.

  4. Di-μ-methacrylato-bis[diaquabis(methacrylatoeuropium(III] methacrylic acid disolvate

    Directory of Open Access Journals (Sweden)

    Zhi-Guo Zheng

    2008-01-01

    Full Text Available In the title centrosymmetric complex, [Eu2(C4H5O26(H2O4]·2C4H6O2, the unique EuIII cation is coordinated by seven carboxylate O atoms from four methacrylate ligands and two water molecules in a slightly disorted tricapped trigonal–prismatic environment. Two EuIII ions are bridged by carboxylate groups, forming a dinuclear complex. The formula unit also contains two molecules of methacrylic acid. In the crystal structure, molecules are linked via intermolecular O—H...O hydrogen bonds, forming one-dimensional chains propagating along the b-axis direction

  5. Electron and ligand transfer reactions between cyclometallated platinum(II) compounds and thallium(III) carboxylates

    NARCIS (Netherlands)

    Koten, G. van; Ploeg, A.F.M.J. van der; Vrieze, K.

    1982-01-01

    Reaction of trans-[(2-Me{2}NCH{2}C{6}H{4}{2}Pt}I{}I{] with Tl}I{}I{}I{(O{2}CR){3} (R = Me, i-Pr) gave direct elimination of Tl}I{(O{2}CR) and formation of the oxidative addition product [(2-Me{2}NCH{2}C{6}H{4}){2}Pt}I{}V{ (O{2}CR){2}], in two isomeric forms. A structure with the carbon ligands in

  6. Terbium to Quantum Dot FRET Bioconjugates for Clinical Diagnostics: Influence of Human Plasma on Optical and Assembly Properties

    Directory of Open Access Journals (Sweden)

    Niko Hildebrandt

    2011-10-01

    Full Text Available Förster resonance energy transfer (FRET from luminescent terbium complexes (LTC as donors to semiconductor quantum dots (QDs as acceptors allows extraordinary large FRET efficiencies due to the long Förster distances afforded. Moreover, time-gated detection permits an efficient suppression of autofluorescent background leading to sub-picomolar detection limits even within multiplexed detection formats. These characteristics make FRET-systems with LTC and QDs excellent candidates for clinical diagnostics. So far, such proofs of principle for highly sensitive multiplexed biosensing have only been performed under optimized buffer conditions and interactions between real-life clinical media such as human serum or plasma and LTC-QD-FRET-systems have not yet been taken into account. Here we present an extensive spectroscopic analysis of absorption, excitation and emission spectra along with the luminescence decay times of both the single components as well as the assembled FRET-systems in TRIS-buffer, TRIS-buffer with 2% bovine serum albumin, and fresh human plasma. Moreover, we evaluated homogeneous LTC-QD FRET assays in QD conjugates assembled with either the well-known, specific biotin-streptavidin biological interaction or, alternatively, the metal-affinity coordination of histidine to zinc. In the case of conjugates assembled with biotin-streptavidin no significant interference with the optical and binding properties occurs whereas the histidine-zinc system appears to be affected by human plasma.

  7. Evidence of mass exchange between inside and outside of sonoluminescing bubble in aqueous solution of terbium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Jinfu, E-mail: liang.shi2007@163.com [School of Physics and Electronic Science, Guizhou Normal University, Guiyang 550001 (China); Chen, Weizhong, E-mail: wzchen@nju.edu.cn [The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093 (China); Wang, Xun; Yang, Jing; Chen, Zhan [The Key Laboratory of Modern Acoustics, Ministry of Education, Institution of Acoustics, Nanjing University, Nanjing 210093 (China)

    2016-12-16

    Highlights: • Time-resolved spectra of SBSL were obtained for Tb{sup 3+} ions emission lines. • Mass exchange between inside and outside of SL bubble was probed via Tb{sup 3+} ions lines. • The argon rectification hypothesis was tested by time-resolved spectra of SBSL. • The rate of mass exchange inside an SBSL bubble increases with increasing sound pressure. - Abstract: Spectra of single-bubble sonoluminescence (SBSL) were obtained for Tb{sup 3+} ions emission lines from bubbles in an aqueous solution of terbium chloride (TbCl{sub 3}). The spectra provide experimental evidence to prove that an air bubble driven by strong ultrasound will not eventually become a rectified pure argon bubble, which is not as predicted by the argon rectification hypothesis. The time-resolved spectra of SBSL show a mass exchange of material such as Tb{sup 3+} ions between the inside and outside of the bubble. With increasing sound pressure, the rate of mass exchange and the SBSL intensity increases.

  8. Micelle enhanced and terbium sensitized spectrofluorimetric determination of danofloxacin in milk using molecularly imprinted solid phase extraction

    Science.gov (United States)

    Kaur, Kuldeep; Saini, Shivender Singh; Malik, Ashok Kumar; Singh, Baldev

    2012-10-01

    An efficient molecularly imprinted solid phase extraction (MISPE)-spectrofluorimetric method was developed to sensitively determine danofloxacin (DAN) in milk samples. Solid phase extraction procedure using MISPE cartridges was first performed on milk samples and then spectrofluorimetric determination was done at 546 nm using an excitation wavelength of 285 nm in presence of terbium and sodium dodecyl benzene sulfonate (SDBS). It was found that SDBS significantly enhanced the fluorescence intensity of the DAN-Tb3+ complex. Various factors affecting the fluorescence intensity of DAN-Tb3+-SDBS system were studied and conditions were optimized. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of DAN over the range of 8.4 × 10-9-3.4 × 10-7 mol L-1 with a correlation coefficient of 0.9996. The detection limit was determined as 2.0 × 10-9 mol L-1 and the limit of quantification was determined as 6.5 × 10-9 mol L-1. The MISPE-spectrofluorimetric procedure was successfully applied to the determination of DAN in milk samples. The method is simple, rapid, sensitive and allows interference free determination of DAN in complex fluorescent matrices like milk. The method can be used to determine whether the DAN residues in milk exceed MRLs or not.

  9. Study of quantum dot based on tin/yttrium mixed oxide doped with terbium to be used as biomarker

    Energy Technology Data Exchange (ETDEWEB)

    Paganini, Paula P.; Felinto, Maria Claudia F.C.; Kodaira, Claudia A., E-mail: paulapaganini@usp.b, E-mail: mfelinto@ipen.b, E-mail: claudiakodaira@yahoo.co [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Brito, Hermi F., E-mail: hefbrito@iq.usp.b [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica. Lab. de Elementos do Bloco f; Nunes, Luiz Antonio O., E-mail: luizant@ifsc.usp.b [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Fisica. Dept. de Fisica e Informatica

    2009-07-01

    Quantum dots (semiconductors nanocrystals) have brought a promising field to develop a new generation of luminescent biomarkers. The use of lanthanides ions as luminescent markers has many advantages, for example a security method, low cost, high specificity and also the luminescence can be promptly measured with high sensibility and accuracy. These luminescent dots are functionalized with biomolecules. For the luminophore particle to be connect with biologicals molecules (for example covalent antibody) is necessary a previous chemical treatment to modify luminophore particle surface and this process is called functionalization. A prior chemical treatment with changes on the surface luminophore particle is necessary to couple the luminophore to biological molecules. This process can be used as coating which can protect these particles from being dissolved by acid as well as provide functional groups for biological conjugation. This work presents a photoluminescence study of nanoparticles based on tin/yttrium mixed oxides doped with terbium (SnO{sub 2}/Y{sub 2}O{sub 3}:Tb{sup 3+}), synthesized by coprecipitation method. The nanoparticles were submitted to thermal treatment and characterized by X-Ray Powder Diffraction (XRD) that showed cassiterite phase formation and the influence of thermal treatment on nanoparticles structures. These nanoparticles going to be functionalized with a natural polysaccharide (chitosan) in order to form microspheres. These microspheres going to be irradiated with gamma radiation to sterilization and it can be evaluated if the nanoparticles are resistant to irradiation and they do not lose functionality with this process. (author)

  10. Carboxyl-functionalized magnetic microparticle carrier for isolation and identification of DNA in dairy products

    Energy Technology Data Exchange (ETDEWEB)

    Horak, Daniel [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovskeho Sq. 2, 162 06 Prague 6 (Czech Republic)]. E-mail: horak@imc.cas.cz; Rittich, Bohuslav [Masaryk University Brno, Tvrdeho 14, 602 00 Brno (Czech Republic)]. E-mail: rittich@sci.muni.cz; Spanova, Alena [Masaryk University Brno, Tvrdeho 14, 602 00 Brno (Czech Republic)]. E-mail: spanova@sci.muni.cz

    2007-04-15

    Magnetite nanoparticles about 14nm in diameter were obtained by chemical coprecipitation of Fe(II) and Fe(III) salts with aqueous ammonia in the presence of poly(ethylene glycol) (PEG). Magnetic poly(glycidyl methacrylate) (PGMA) microspheres about 1{mu}m in diameter were prepared by dispersion polymerization of GMA in aqueous ethanol in the presence of PEG-coated magnetite nanoparticles. The microspheres were hydrolyzed and carboxyl groups introduced by oxidation with KMnO{sub 4}. The particles reversibly bound bacterial DNA of Bifidobacterium and Lactobacillus genera in the presence of high concentrations of PEG 6000 and sodium chloride from crude cell lysates of various dairy products (butter milk, cheese, yoghurt, probiotic tablets) or from cell lyophilisates. The presence of Bifidobacterium and Lactobacillus DNA in samples was confirmed by PCR amplification.

  11. Conjugates of 1'-Aminoferrocene-1-carboxylic Acid and Proline: Synthesis, Conformational Analysis and Biological Evaluation

    Directory of Open Access Journals (Sweden)

    Monika Kovačević

    2014-08-01

    Full Text Available Our previous studies showed that alteration of dipeptides Y-Fca-Ala-OMe (III into Y-Ala-Fca-OMe (IV (Y = Ac, Boc; Fca = 1'-aminoferrocene-1-carboxylic acid significantly influenced their conformational space. The novel bioconjugates Y-Fca-Pro-OMe (1, Y = Ac; 2, Y = Boc and Y-Pro-Fca-OMe (3, Y = Boc; 4, Y = Ac have been prepared in order to investigate the influence of proline, a well-known turn-inducer, on the conformational properties of small organometallic peptides with an exchanged constituent amino acid sequences. For this purpose, peptides 1–4 were subjected to detailed spectroscopic analysis (IR, NMR, CD spectroscopy in solution. The conformation of peptide 3 in the solid state was determined. Furthermore, the ability of the prepared conjugates to inhibit the growth of estrogen receptor-responsive MCF-7 mammary carcinoma cells and HeLa cervical carcinoma cells was tested.

  12. Carboxyl-functionalized magnetic microparticle carrier for isolation and identification of DNA in dairy products

    Science.gov (United States)

    Horák, Daniel; Rittich, Bohuslav; Španová, Alena

    2007-04-01

    Magnetite nanoparticles about 14 nm in diameter were obtained by chemical coprecipitation of Fe(II) and Fe(III) salts with aqueous ammonia in the presence of poly(ethylene glycol) (PEG). Magnetic poly(glycidyl methacrylate) (PGMA) microspheres about 1 μm in diameter were prepared by dispersion polymerization of GMA in aqueous ethanol in the presence of PEG-coated magnetite nanoparticles. The microspheres were hydrolyzed and carboxyl groups introduced by oxidation with KMnO4. The particles reversibly bound bacterial DNA of Bifidobacterium and Lactobacillus genera in the presence of high concentrations of PEG 6000 and sodium chloride from crude cell lysates of various dairy products (butter milk, cheese, yoghurt, probiotic tablets) or from cell lyophilisates. The presence of Bifidobacterium and Lactobacillus DNA in samples was confirmed by PCR amplification.

  13. Hydrogenation of carboxylic acids with a homogeneous cobalt catalyst.

    Science.gov (United States)

    Korstanje, Ties J; van der Vlugt, Jarl Ivar; Elsevier, Cornelis J; de Bruin, Bas

    2015-10-16

    The reduction of esters and carboxylic acids to alcohols is a highly relevant conversion for the pharmaceutical and fine-chemical industries and for biomass conversion. It is commonly performed using stoichiometric reagents, and the catalytic hydrogenation of the acids previously required precious metals. Here we report the homogeneously catalyzed hydrogenation of carboxylic acids to alcohols using earth-abundant cobalt. This system, which pairs Co(BF4)2·6H2O with a tridentate phosphine ligand, can reduce a wide range of esters and carboxylic acids under relatively mild conditions (100°C, 80 bar H2) and reaches turnover numbers of up to 8000. Copyright © 2015, American Association for the Advancement of Science.

  14. Pyrazine Carboxylic Acid Derivatives of Dichlorobis(Cyclopentadienyltitanium(IV

    Directory of Open Access Journals (Sweden)

    Satish Chandra Dixit

    2012-07-01

    Full Text Available Reactions of dichlorobis(cyclopentadienyltitanium(IV with pyrazine carboxylic acids viz. 2-pyrazine carboxylic acid (2-PzCH, 5-methyl-2-pyrazine carboxylic acid (MPzCH and 2,3-pyrazine dicarboxylic acid (2,3-PzDCH2 were carried out in different stoichiometric ratios. Complexes of the type Cp2Ti(2-PzCCl , Cp2Ti(2-PzC2 ,Cp2Ti(MPzCCl,Cp2Ti(MPzC2, Cp2Ti(2,3-PzDCHCl and Cp2Ti(2,3-PzDCH2 were obtained. These newly synthesized complexes were characterized on the basis of elemental analyses, electrical conductance, magnetic moment and spectral data.

  15. Transition Metal Catalyzed Synthesis of Carboxylic Acids, Imines, and Biaryls

    DEFF Research Database (Denmark)

    Santilli, Carola; Madsen, Robert

    Dehydrogenative synthesis of carboxylic acids catalyzed by a ruthenium N- heterocycliccarbene complex. A new methodology for the synthesis of carboxylic acids from primary alcohols and hydroxide has been developed. The reaction is catalyzed by the ruthenium N-heterocycliccarbene complex [RuCl2(Ii......Pr)(p-cymene)] where dihydrogen is generated as the only by-product (Scheme i). The dehydrogenative reaction is performed in toluene, which allows for a simple isolation of the products by precipitation followed by extraction. Various substituted benzyl alcohols smoothly undergo the transformation. The fast conversion...... to the carboxylic acids can be explained by the involvement of a competing Cannizzaro reaction. The scope of the dehydrogenation was further extended to linear and branched saturated aliphatic alcohols, although longer reaction times are necessary to ensure complete substrate conversions. The kinetic isotope effect...

  16. Synthesis of lithium ferrites from polymetallic carboxylates

    Directory of Open Access Journals (Sweden)

    STEFANIA STOLERIU

    2008-10-01

    Full Text Available Lithium ferrite was prepared by the thermal decomposition of three polynuclear complex compounds containing as ligands the anions of malic, tartaric and gluconic acid: (NH42[Fe2.5Li0.5(C4H4O53(OH4(H2O2]×4H2O (I, (NH46[Fe2.5Li0.5(C4H4O63(OH8]×2H2O (II and (NH42[Fe2.5Li0.5(C6H11O73(OH7] (III. The polynuclear complex precursors were characterized by chemical analysis, IR and UV–Vis spectra, magnetic measurements and thermal analysis. The obtained lithium ferrites were characterized by XRD, scanning electron microscopy, IR spectra and magnetic measurements. The single α-Li0.5Fe2.5O4 phase was obtained by thermal decomposition of the tartarate complex annealed at 700 °C for 1 h. The magnetization value ≈ 50 emu g-1 is lower than that obtained for the bulk lithium ferrite due to the nanostructural character of the ferrite. The particle size was smaller than 100 nm.

  17. Properties of the Carboxylate ion exchange resins; Karboxylatjonbytarmassans egenskaper

    Energy Technology Data Exchange (ETDEWEB)

    Allard, Bert; Dario, Maarten [Oerebro Univ. (Sweden); Boren, Hans [Linkoepings Univ. (Sweden); Torstenfelt, Boerje [Swedpower, Stockholm (Sweden); Puigdomenech, Ignasi; Johansson, Claes [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2002-09-01

    Weakly acidic, carboxylic resin has been selected, together with strong base anion resins, for water purification at the Forsmark 1 and 2 reactors. For the strong (but not the weak) ion exchange resin the Nuclear Power Inspectorate has given permission to dispose the spent resins in the SFR 1 (the Final Repository for Radioactive Operational Waste). This report gives a review of the carboxylic resins and comes to the conclusion that the resins are very stable and that there should not exist any risks for increased leaching of radionuclides from SFR 1 if these resins are disposed (compared to the strong resins)

  18. Biotin Carboxyl Carrier Protein in Barley Chloroplast Membranes

    DEFF Research Database (Denmark)

    Kannangara, C. G.; Jense, C J

    1975-01-01

    Biotin localized in barley chloroplast lamellae is covalently bound to a single protein with an approximate molecular weight of 21000. It contains one mole of biotin per mole of protein and functions as a carboxyl carrier in the acetyl-CoA carboxylase reaction. The protein was obtained by solubil...... by solubilization of the lamellae in phenol/acetic acid/8 M urea. Feeding barley seedlings with [14C]-biotin revealed that the vitamin is not degraded into respiratory substrates by the plant, but is specifically incorporated into biotin carboxyl carrier protein....

  19. Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillation-based polymer optical fibre sensor for real time monitoring of radiation dose in oncology

    Science.gov (United States)

    Lewis, E.; O'Keeffe, S.; Grattan, M.; Hounsell, A.; McCarthy, D.; Woulfe, P.; Cronin, J.; Mihai, L.; Sporea, D.; Santhanam, A.; Agazaryan, N.

    2014-05-01

    A PMMA based plastic optical fibre sensor for use in real time radiotherapy dosimetry is presented. The optical fibre tip is coated with a scintillation material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb), which fluoresces when exposed to ionising radiation (X-Ray). The emitted visible light signal penetrates the sensor optical fibre and propagates along the transmitting fibre at the end of which it is remotely monitored using a fluorescence spectrometer. The results demonstrate good repeatability, with a maximum percentage error of 0.5% and the response is independent of dose rate.

  20. The role of carboxylic acids in TALSQueak separations

    Energy Technology Data Exchange (ETDEWEB)

    Braley, Jenifer C.; Carter, Jennifer C.; Sinkov, Sergey I.; Nash, Ken L.; Lumetta, Gregg J.

    2012-04-13

    Recent reports have indicated TALSPEAK-type separations chemistry can be improved through the replacement of bis-2-ethyl(hexyl) phosphoric acid (HDEHP) and diethylenetriamine-N,N,N,N,N-pentaacetic acid (DTPA) with the weaker reagents 2-ethyl(hexyl) phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) and N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), respectively. This modified TALSPEAK has been provided with an adjusted acronym of TALSQueak (Trivalent Actinide Lanthanide Separation using Quicker Extractants and Aqueous Komplexes). Among several benefits, TALSQueak chemistry provides more rapid phase transfer kinetics, is less reliant on carboxylic acids to mediate lanthanide extraction and allows a simplified thermodynamic description of the separations process that generally requires only parameters available in the literature to describe metal transfer. This manuscript focuses on the role of carboxylic acids in aqueous ternary (M-HEDTA-carboxylate) complexes, americium/lanthanide separations, and extraction kinetics. Spectrophotometry (UV-vis) of the Nd hypersensitive band indicates the presence of aqueous ternary species (K111 = 1.83 {+-} 0.01 at 1.0 M ionic strength, Nd(HEDTA) + Lac <-> Nd(HEDTA)Lac). Varying the carboxylic acid does not have a significant impact on Ln/Am separations or extraction kinetics. TALSqueak separations come to equilibrium in five minutes at the conventional operational pH of 3.6 using only 0.1 M total lactate or citrate.

  1. Intracomplex compounds of vanadyl with carboxylic acid hydrazides

    Energy Technology Data Exchange (ETDEWEB)

    Musaev, Z.M.; Usmankhodzhaeva, Ya.S.; Khodzhaev, O.F. (AN Uzbekskoj SSR, Tashkent. Inst. Khimii)

    1984-07-01

    Intracomplex vanadyl (2) compounds with some carboxylic acid hydrazides (HL) of the VOL/sub 2/xnH/sub 2/O composition, are prepared. Using IR absorption spectra of complexes, it is established that hydrazides are connected with a vanadyl ion in the deprotonated inidoalcohol form through an oxygen atom a nitrogen atom of aminogroup.

  2. Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

    African Journals Online (AJOL)

    NICO

    an average speed of 6.8 m s–1. Average temperature was 26.8 ... balance balance Mettler Toledo MX5 (reading precision 1 µg). Before weighing, the filters ..... Table 2 Correlation coefficients for PM mass, carboxylates, selected ions and wind speed in PM2.5 (upper triangle) and PM10 fractions (lower triangle) in Morogoro.

  3. Carboxylic ester hydrolases in mitochondria from rat skeletal muscle

    DEFF Research Database (Denmark)

    Kirkeby, S; Moe, D; Zelander, T

    1990-01-01

    A mitochondrial pellet, prepared from rat skeletal muscle, contained a number of carboxylic ester hydrolase isoenzymes. The esterases which split alpha-naphthyl acetate were organophosphate sensitive, whereas two out of three indoxyl acetate hydrolysing enzymes were resistant to both organophosph...

  4. Photodecarboxylative Cyclizations of ω-Phthalimido-para-phenoxy Carboxylates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ae Rhan; Lee, Younsik; Yoo, Dong Jin [Chonbuk National Univ., Jeonju (Korea, Republic of); Cho, Hyunseung [Seonam Univ., Namwon (Korea, Republic of)

    2012-10-15

    The chemistry of electronically-excited phthalimides is dictated by electron and/or hydrogen transfer reactions. The photochemistry of phthalimides has been intensively studied, and numerous synthetically useful transformations with high chemical and quantum yields have been developed. 3 Among the synthetic applications, intra- and intermolecular photodecarboxylation (PDC) of ω-phthalimidoalkyl carboxylates has been developed by Griesbeck and coworkers as a versatile pathway to medium- and large-ring heterocycles. Model reactions were further realized on macro- and micro-scales. We recently described PDC cyclizations of ω-phthalimidoalkynoates to produce macrocyclic alkynes with ring-sizes up to 17. In recent study, we expanded the portfolio of this reaction and investigated the photochemistry of related aryl-linked phthalimides in Scheme 1. Based on these approaches, we demonstrated that ω-phthalimido-ortho/meta-phenoxy carboxylates undergo efficient PDC cyclizations. While the yields of ω-phthalimido-ortho-phenoxy carboxylates steadily decreased with increasing chain-length and the maximum yield of the 6-membered product was obtained in 75%, the yields of meta-phenoxy carboxylates steadily increased with increasing chain-length and the extended 16-membered product was subsequently obtained in 48% yield.

  5. An anionic two-dimensional indium carboxylate framework derived ...

    Indian Academy of Sciences (India)

    1385–1391. c Indian Academy of Sciences. An anionic two-dimensional indium carboxylate framework derived from a pseudo C3-symmetric semi-flexible tricarboxylic acid. PRATAP VISHNOI, ALOK CH KALITA and RAMASWAMY MURUGAVEL. ∗. Department of Chemistry, Indian Institute of Technology Bombay, Powai, ...

  6. Sodium borohydride reduction of aromatic carboxylic acids via ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 118; Issue 5. Sodium borohydride reduction of aromatic carboxylic acids via methyl esters. Aamer Saeed Zaman Ashraf. Volume 118 ... Author Affiliations. Aamer Saeed1 Zaman Ashraf1. Department of Chemistry, Quaid-I-Azam University 45320, Islamabad, Pakistan ...

  7. Cyclodextrin derivatives with cyanohydrin and carboxylate groups as artificial glycosidases

    DEFF Research Database (Denmark)

    Bols, Mikael; Ortega-Caballero, Fernando

    2006-01-01

    Two cyclodextrin derivatives (1 and 2) were prepared in an attempt to create glycosidase mimics with a general acid catalyst and a nucleophilic carboxylate group. The catalysts 1 and 2 were found to catalyse the hydrolysis of 4-nitrophenyl beta-D-glucopyranoside at pH 8.0, but rapidly underwent...

  8. Different carboxylic acid homodimers in self-assemblies of adducts ...

    Indian Academy of Sciences (India)

    understand dislodging process of a dimeric assembly. Our anticipation was also based on our earlier obser- vation where we obtained packing polymorphs of the. (3-carboxymethoxy-naphthalen-2-yloxy)acetic acid,50 which is also a molecule comprised of linkages with carboxylic acid groups with intervening methylene.

  9. Ovalbumin with Glycated Carboxyl Groups Shows Membrane-Damaging Activity

    Directory of Open Access Journals (Sweden)

    Ching-Chia Tang

    2017-02-01

    Full Text Available The aim of the present study was to investigate whether glycated ovalbumin (OVA showed novel activity at the lipid-water interface. Mannosylated OVA (Man-OVA was prepared by modification of the carboxyl groups with p-aminophenyl α-dextro (d-mannopyranoside. An increase in the number of modified carboxyl groups increased the membrane-damaging activity of Man-OVA on cell membrane-mimicking vesicles, whereas OVA did not induce membrane permeability in the tested phospholipid vesicles. The glycation of carboxyl groups caused a notable change in the gross conformation of OVA. Moreover, owing to their spatial positions, the Trp residues in Man-OVA were more exposed, unlike those in OVA. Fluorescence quenching studies suggested that the Trp residues in Man-OVA were located on the interface binds with the lipid vesicles, and their microenvironment was abundant in positively charged residues. Although OVA and Man-OVA showed a similar binding affinity for lipid vesicles, the lipid-interacting feature of Man-OVA was distinct from that of OVA. Chemical modification studies revealed that Lys and Arg residues, but not Trp residues, played a crucial role in the membrane-damaging activity of Man-OVA. Taken together, our data suggest that glycation of carboxyl groups causes changes in the structural properties and membrane-interacting features of OVA, generating OVA with membrane-perturbing activities at the lipid-water interface.

  10. Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

    African Journals Online (AJOL)

    NICO

    on the earth's radiation balance by scattering incoming solar radiation, which counteracts global warming.3 More attention has been paid to carboxylic acids due to ..... Environ., 2007, 41(10), 2036–2048. 3 Intergovernmental Panel on Climate Change (IPCC). IPCC fourth assessment report, Contribution of Working Group I, ...

  11. Page 1 Ultrasonic absorption in carboxylic acids 46; annular rubber ...

    Indian Academy of Sciences (India)

    Figure 1a shows that the measured ultrasonic absorption for the oxalic acid dihydrate, benzoic acid and succinic acid increases with increase in the concentration of the solute, reaches a maximum (the concentration at which the absorption maximum occurs is. Figure 1. Absorption vs concentration of carboxylic acids in ...

  12. catalysed ortho-carboxylation of acetanilide with CO

    Indian Academy of Sciences (India)

    Abstract. The mechanism of palladium(II)-catalysed carboxylation of acetanilide with CO has been investi- gated using density functional theory calculation done at the B3LYP/6-31G(d, p)(SDD for Pd) level of theory. Solvent effects on these reactions have been explored by calculation that included a polarizable continuum.

  13. Synthesis of first row transition metal carboxylate complexes by ring ...

    Indian Academy of Sciences (India)

    holysis as well as for hydrolysis reactions of esters. Metal ions are known to catalyse such reactions13,14 and certain metal catalysed ring opening reactions are used as model catalyst for carboxypeptidase A.15 To make such reactions catalytic by a metal ion the inter- mittent metal carboxylate complex formed through ring.

  14. Synthesis of new series of 4, 5-dihydroisoxazole-5-carboxylate ...

    Indian Academy of Sciences (India)

    A new series of 4,5-dihydroisoxazole-5-carboxylate derivatives were synthesized via [3+2] cycloaddition reaction ... The synthesized derivatives were characterized by Mass, IR and NMR Spectroscopy and their mesomorphic behavior were studied using ..... Potential for Excellence (UPE), UGC for the financial support and ...

  15. Novel Lactate Transporters from Carboxylic Acid-Producing Rhizopus

    Science.gov (United States)

    The fungus Rhizopus is frequently used for fermentative production of lactic acid, but little is known about the mechanisms or proteins for transporting this carboxylic acid. Since transport of the lactate anion across the plasma membrane is critical to prevent acidification of the cytoplasm, we ev...

  16. Light dependence of carboxylation capacity for C3 photosynthesis models

    Science.gov (United States)

    Photosynthesis at high light is often modelled by assuming limitation by the maximum capacity of Rubisco carboxylation at low carbon dioxide concentrations, by electron transport capacity at higher concentrations, and sometimes by triose-phosphate utilization rate at the highest concentrations. Pho...

  17. Synthesis of new series of 4, 5-dihydroisoxazole-5-carboxylate ...

    Indian Academy of Sciences (India)

    A new series of 4,5-dihydroisoxazole-5-carboxylate derivatives were synthesized via [3+2] cycloaddition reaction between ethyl acrylate and nitrile oxide generated in situ in presence of Chloramine-T. The synthesized derivatives were characterized by Mass, IR and NMR Spectroscopy and their mesomorphic behavior were ...

  18. Influence of carboxylic acid type on microstructure and magnetic properties of polymeric complex sol–gel driven NiFe{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hessien, M.M. [Materials Science & Engineering Group, Department of Chemistry, Faculty of Science, Taif University (Saudi Arabia); Advanced Materials Dept, Central Metallurgical Research and Development Institute (CMRDI), P.O. Box: 87, Helwan, Cairo (Egypt); Mostafa, Nasser Y., E-mail: nmost69@yahoo.com [Materials Science & Engineering Group, Department of Chemistry, Faculty of Science, Taif University (Saudi Arabia); Department of Chemistry, Faculty of Science, Suez Canal University, Ismailia (Egypt); Abd-Elkader, Omar H. [Department of Zoology, Science College, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Electron Microscope and Thin Films Department, National Research Center (NRC), El-Behooth Street, Dokki, Cairo 12622 (Egypt)

    2016-01-15

    Citric, oxalic and tartaric acids were used for synthesis of NiFe{sub 2}O{sub 4} using polymeric complex precursor route. The dry precursor gels were calcined at various temperatures (400–1100 °C) for 2 h. All carboxylic acids produce iron-deficient NiFe{sub 2}O{sub 4} with considerable amount of α-Fe{sub 2}O{sub 3} at 400 °C. Increase in the annealing temperature caused reaction of α-Fe{sub 2}O{sub 3} with iron-deficient ferrite phase. The amount of initially formed α-Fe{sub 2}O{sub 3} is directly correlated with stability constant and inversely correlated with the decomposition temperature of Fe(III) carboxylate precursors. In case of tartaric acid precursor, single phase of the ferrite was obtained at 450 °C. However, in case of oxalic acid and citric acid precursors, single phase ferrite was obtained at 550 °C and 700 °C, respectively. The lattice parameters were increased with increasing annealing temperature and with decreasing the amount of α-Fe{sub 2}O{sub 3}. Maximum saturation magnetization (55 emu/g) was achieved using tartaric acid precursor annealed at 1100 °C. - Highlights: • Citric, oxalic and tartaric acids were used for synthesis of NiFe{sub 2}O{sub 4}. • Carboxylic acid type affects the produced powders. • At low temperatures all carboxylic acids produce iron-deficient NiFe{sub 2}O{sub 4} and α-Fe{sub 2}O{sub 3}. • α-Fe{sub 2}O{sub 3} is correlated with the decomposition of Fe(III) carboxylate precursors.

  19. Molecular Recognition of Cobalt(III)-ligated Peptides by Serine Proteases: The Role of Electrostatic Effects

    DEFF Research Database (Denmark)

    Bagger, Sven; Wagner, Kim

    1998-01-01

    A series of peptides with a positively charged cobalt(III)-complex group attached to the carboxylate terminal was synthesized. The behaviour of these metallopeptides as acceptor nucleophiles in acyl transfer reactions catalyzed by the three serine proteases bovine pancreatic à-chymotrypsin, porcine...

  20. Toward functional carboxylate-bridged diiron protein mimics: achieving structural stability and conformational flexibility using a macrocylic ligand framework.

    Science.gov (United States)

    Do, Loi H; Lippard, Stephen J

    2011-07-13

    A dinucleating macrocycle, H(2)PIM, containing phenoxylimine metal-binding units has been prepared. Reaction of H(2)PIM with [Fe(2)(Mes)(4)] (Mes = 2,4,6-trimethylphenyl) and sterically hindered carboxylic acids, Ph(3)CCO(2)H or Ar(Tol)CO(2)H (2,6-bis(p-tolyl)benzoic acid), afforded complexes [Fe(2)(PIM)(Ph(3)CCO(2))(2)] (1) and [Fe(2)(PIM)(Ar(Tol)CO(2))(2)] (2), respectively. X-ray diffraction studies revealed that these diiron(II) complexes closely mimic the active site structures of the hydroxylase components of bacterial multicomponent monooxygenases (BMMs), particularly the syn disposition of the nitrogen donor atoms and the bridging μ-η(1)η(2) and μ-η(1)η(1) modes of the carboxylate ligands at the diiron(II) centers. Cyclic voltammograms of 1 and 2 displayed quasi-reversible redox couples at +16 and +108 mV vs ferrocene/ferrocenium, respectively. Treatment of 2 with silver perchlorate afforded a silver(I)/iron(III) heterodimetallic complex, [Fe(2)(μ-OH)(2)(ClO(4))(2)(PIM)(Ar(Tol)CO(2))Ag] (3), which was structurally and spectroscopically characterized. Complexes 1 and 2 both react rapidly with dioxygen. Oxygenation of 1 afforded a (μ-hydroxo)diiron(III) complex [Fe(2)(μ-OH)(PIM)(Ph(3)CCO(2))(3)] (4), a hexa(μ-hydroxo)tetrairon(III) complex [Fe(4)(μ-OH)(6)(PIM)(2)(Ph(3)CCO(2))(2)] (5), and an unidentified iron(III) species. Oxygenation of 2 exclusively formed di(carboxylato)diiron(III) compounds, a testimony to the role of the macrocylic ligand in preserving the dinuclear iron center under oxidizing conditions. X-ray crystallographic and (57)Fe Mössbauer spectroscopic investigations indicated that 2 reacts with dioxygen to give a mixture of (μ-oxo)diiron(III) [Fe(2)(μ-O)(PIM)(Ar(Tol)CO(2))(2)] (6) and di(μ-hydroxo)diiron(III) [Fe(2)(μ-OH)(2)(PIM)(Ar(Tol)CO(2))(2)] (7) units in the same crystal lattice. Compounds 6 and 7 spontaneously convert to a tetrairon(III) complex, [Fe(4)(μ-OH)(6)(PIM)(2)(Ar(Tol)CO(2))(2)] (8), when treated with excess H

  1. CCDC 1410946: Experimental Crystal Structure Determination : catena-[dimethylammonium tris(mu-naphthalene-1,4-dicarboxylato)-tetrakis(mu-hydroxo)-triaqua-tri-terbium(iii) unknown solvate

    KAUST Repository

    Xue, Dongxu

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  2. Changing Single-Molecule Magnet Properties of a Windmill-Like Distorted Terbium(III) α-Butoxy-Substituted Phthalocyaninato Double-Decker Complex by Protonation/Deprotonation.

    Science.gov (United States)

    Horii, Yoji; Horie, Yusuke; Katoh, Keiichi; Breedlove, Brian K; Yamashita, Masahiro

    2018-01-16

    Synthesis, structures, and magnetic properties of α-butoxy-substituted phthalocyaninato double-decker complexes Tb(α-obPc)2 (1-) (α-obPc: dianion of 1,4,8,11,15,18,22,25-octa(n-butoxy)phthalocyaninato) with protonated (1H), deprotonated (1[HDBU]), and diprotonated forms (1H2+) are discussed. X-ray analysis was used to confirm the position of the proton in 1H, and it was revealed that the protonation induced asymmetric distortion in 1H. In contrast, 1[HDBU] was distorted in a highly symmetric windmill-like fashion. 1H is arranged in a slipped column array in the crystal packing, whereas 1[HDBU] is arranged in a one-dimensional fashion, in which the magnetic easy axes of 1[HDBU] lie along the same line. From direct-current (dc) magnetic measurements, ferromagnetic Tb-Tb interactions occur in both 1H and 1[HDBU], and magnetic hysteresis was observed. However, the area of the magnetic hysteresis in 1[HDBU] is larger than that in 1H, meaning that magnetic relaxation time (τ) is longer in 1[HDBU]. In addition, the results of alternating-current magnetic measurements in a zero dc magnetic field indicate that τ of 1[HDBU] is longer as compared to 1H. In other words, protonation/deprotonation affects not only the molecular structures and crystal packing but also the single-molecule magnet properties.

  3. Compact all-fiber optical Faraday components using 65-wt%-terbium-doped fiber with a record Verdet constant of -32 rad/(Tm).

    Science.gov (United States)

    Sun, L; Jiang, S; Marciante, J R

    2010-06-07

    A compact all-fiber Faraday isolator and a Faraday mirror are demonstrated. At the core of each of these components is an all-fiber Faraday rotator made of a 4-cm-long, 65-wt%-terbium-doped silicate fiber. The effective Verdet constant of the terbium-doped fiber is measured to be -32 rad/(Tm), which is 27 x larger than that of silica fiber. This effective Verdet constant is the largest value measured to date in any fiber and is 83% of the Verdet constant of commercially available crystal used in bulk optics-based isolators. Combining the all-fiber Faraday rotator with fiber polarizers results in a fully fusion spliced all-fiber isolator whose isolation is measured to be 19 dB. Combining the all-fiber Faraday rotator with a fiber Bragg grating results in an all-fiber Faraday mirror that rotates the polarization state of the reflected light by 88 +/- 4 degrees .

  4. Resonance Raman examination of the electronic excited states of glycylglycine and other dipeptides: Observation of a carboxylate{yields}amide charge transfer transition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.G.; Li, P.; Holtz, J.S.W.; Chi, Z.; Pajcini, V.; Asher, S.A. [Univ. of Pittsburgh, PA (United States); Kelly, L.A. [Brookhaven National Lab., Upton, NY (United States)

    1996-10-09

    We have examined the UV resonance Raman and the VUV absorption spectra of aqueous glycylglycine and other dipeptides. We observe strong resonance Raman enhancement of the amide I, II, and III bands and the amide C{sub {alpha}}H bending mode in a manner similar to that we observed previously with excitation within the {pi}{yields}{pi}{sup *} transition of N-methylacetamide. However, in addition, we observe strong resonance Raman enhancement of the ca. 1400 cm{sup -1} symmetric COO{sup -} stretching vibration, whose 206.5 nm Raman cross section is increased 20-fold compared to that of the carboxylate in sodium acetate, for example. Addition of a methylene spacer between the amide and carboxylate groups causes the resonance Raman enhancement of this symmetric COO{sup -} stretch to disappear. The UV resonance Raman excitation profiles, the Raman depolarization ratio dispersion, and the VUV absorption spectra of glycylglycine and other dipeptides demonstrate the existence of a new 197 nm charge transfer band which involves electron transfer from a nonbonding carboxylate orbital to the amide-like {pi}{sup *} orbital. This transition occurs at the penultimate carboxylate end of all peptides and proteins. 18 refs., 9 figs., 3 tabs.

  5. Biologically relevant mono- and di-nuclear manganese II/III/IV complexes of mononegative pentadentate ligands

    DEFF Research Database (Denmark)

    Baffert, Carole; Collomb, Marie-Nöelle; Deronzier, Alain

    2003-01-01

    ,2-diamine) have been prepared. The crystal structure of the Mn(II)-aqua complex of 1, shows it to be dimeric via (mu-kappaO)-bridging through one carboxylate oxygen atom of each of the two ligands. The non-coordinated carboxylate oxygen atoms are H-bonded to the water ligands on the adjacent Mn ion...... were characterised by UV-visible spectroscopy, ESI mass spectrometry and cyclic voltammetry. In addition, III-IV and II-III species were electrochemically generated. Thus the new mononegative pentadentate ligand systems display significant flexibility in the range of Mn oxidation states and species...

  6. Americium(iii) and europium(iii) complex formation with lactate at elevated temperatures studied by spectroscopy and quantum chemical calculations.

    Science.gov (United States)

    Barkleit, Astrid; Kretzschmar, Jerome; Tsushima, Satoru; Acker, Margret

    2014-08-07

    Thermodynamic parameters for the complex formation of Am(iii) and Eu(iii) with lactate were determined with UV-vis and time-resolved laser-induced fluorescence spectroscopy (TRLFS) in a temperature range between 25 and 70 °C. The reaction enthalpy decreased with increasing ionic strength. ATR FT-IR and NMR spectroscopy in combination with density functional theory (DFT) calculations revealed structural details of the Eu(iii) lactate 1 : 1 complex: a chelating coordination mode of the lactate with a monodentate binding carboxylate group and the hydroxyl group being deprotonated.

  7. Self-assembled carboxylate complexes of zinc, nickel and copper

    Science.gov (United States)

    Deka, Kaustavmoni; Barooah, Nilotpal; Sarma, Rupam Jyoti; Baruah, Jubaraj B.

    2007-02-01

    A metallo-organic hybrid acid namely tetra-aquo bis-4-carboxy- N-phthaloylglycinato zinc(II) dihydrate is prepared and characterised. In this complex the hydrogen bonding by free carboxylic acid group and π-π interactions between the rings in crystal lattice contributes to the formation of self-assembled structure. A monomeric nickel complex from 2-carbomethoxy benzoic acid ( L2H) and pyridine [Ni( L2)(py) 3(H 2O) 2] L2 is prepared (where py = pyridine). This complex has ionic as well as monodentate carboxylates. It forms self-assembly by C-H⋯π as well as hydrogen-bonding interactions. The 2-carbomethoxy benzoic acid ( L2H) forms dimeric copper complex [Cu 2( L2) 4(H 2O) 2]2H 2O which has an extended chain structure through hydrogen-bond interactions.

  8. Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

    Directory of Open Access Journals (Sweden)

    Roman Matthessen

    2014-10-01

    Full Text Available The near-unlimited availability of CO2 has stimulated a growing research effort in creating value-added products from this greenhouse gas. This paper presents the trends on the most important methods used in the electrochemical synthesis of carboxylic acids from carbon dioxide. An overview is given of different substrate groups which form carboxylic acids upon CO2 fixation, including mechanistic considerations. While most work focuses on the electrocarboxylation of substrates with sacrificial anodes, this review considers the possibilities and challenges of implementing other synthetic methodologies. In view of potential industrial application, the choice of reactor setup, electrode type and reaction pathway has a large influence on the sustainability and efficiency of the process.

  9. Propensity of salicylamide and ethenzamide cocrystallization with aromatic carboxylic acids.

    Science.gov (United States)

    Przybyłek, Maciej; Ziółkowska, Dorota; Mroczyńska, Karina; Cysewski, Piotr

    2016-03-31

    The cocrystallization of salicylamide (2-hydroxybenzamide, SMD) and ethenzamide (2-ethoxybenzamide, EMD) with aromatic carboxylic acids was examined both experimentally and theoretically. The supramolecular synthesis taking advantage of the droplet evaporative crystallization (DEC) technique was combined with powder diffraction and vibrational spectroscopy as the analytical tools. This led to identification of eleven new cocrystals including pharmaceutically relevant coformers such as mono- and dihydroxybenzoic acids. The cocrystallization abilities of SMD and EMD with aromatic carboxylic acids were found to be unexpectedly divers despite high formal similarities of these two benzamides and ability of the R2,2(8) heterosynthon formation. The source of diversities of the cocrystallization landscapes is the difference in the stabilization of possible conformers by adopting alternative intramolecular hydrogen boding patterns. The stronger intramolecular hydrogen bonding the weaker affinity toward intermolecular complexation potential. The substituent effects on R2,2(8) heterosynthon properties are also discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. CARBOXYLIC ACIDS OF HERB OF THYMUS CRETACEUS KLOK. ET SCHOST

    Directory of Open Access Journals (Sweden)

    V. N. Bubenchikova

    2014-01-01

    Full Text Available We have studied carboxylic acids of the herb of Thymus cretaceus Klok. et Schost which is widespread on a territory of some regions (Belgorod, Voronezh. The study was carried out using gas-liquid chromatography at Agilent Technologies 6890 chromatographer with massspectrometric detector 5973 N. Acids concentration was calculated by means of inner standard.We have established that carboxylic acids of Thymus cretaceus are represented by 34 compounds. Palmitic (1779.02 mg/kg, behenic (1084.15 mg/kg, levulinic (986.24 mg/kg and linoleic acids (678.82 mg/kg predominate among fatty acids; citric (9835.14 mg/kg, malonic (447.91 mg/kg and oxalic acids (388.32 mg/kg predominate among organic acids; andferulic acid predominate amongphenolcarbonic acids.

  11. Dimerization of Carboxylic Acids: An Equation of State Approach

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Kontogeorgis, Georgios; Panayiotou, Costas

    2017-01-01

    The association term of the nonrandom hydrogen bonding theory, which is an equation of state model, is extended to describe the dimerization of carboxylic acids in binary mixtures with inert solvents and in systems of two different acids. Subsequently, the model is applied to describe the excess...... enthalpies and the vapor-liquid equilibrium of relevant binary mixtures containing low molecular weight organic acids. The model sheds light on the interplay of intermolecular interactions through the calculation of the various contributions to the mixing enthalpies, namely from hydrogen bonding and non......-hydrogen bonding (dipolar, induced polar or dispersive) interactions. According to model predictions, the acid molecules are so strongly associated that the addition of inert solvents to carboxylic acids with small carbon numbers at ambient temperature does not dramatically alter their degree of association...

  12. Identification of Key Residues for Enzymatic Carboxylate Reduction

    Directory of Open Access Journals (Sweden)

    Holly Stolterfoht

    2018-02-01

    Full Text Available Carboxylate reductases (CARs, E.C. 1.2.1.30 generate aldehydes from their corresponding carboxylic acid with high selectivity. Little is known about the structure of CARs and their catalytically important amino acid residues. The identification of key residues for carboxylate reduction provides a starting point to gain deeper understanding of enzymatic carboxylate reduction. A multiple sequence alignment of CARs with confirmed activity recently identified in our lab and from the literature revealed a fingerprint of conserved amino acids. We studied the function of conserved residues by multiple sequence alignments and mutational replacements of these residues. In this study, single-site alanine variants of Neurospora crassa CAR were investigated to determine the contribution of conserved residues to the function, expressability or stability of the enzyme. The effect of amino acid replacements was investigated by analyzing enzymatic activity of the variants in vivo and in vitro. Supported by molecular modeling, we interpreted that five of these residues are essential for catalytic activity, or substrate and co-substrate binding. We identified amino acid residues having significant impact on CAR activity. Replacement of His 237, Glu 433, Ser 595, Tyr 844, and Lys 848 by Ala abolish CAR activity, indicating their key role in acid reduction. These results may assist in the functional annotation of CAR coding genes in genomic databases. While some other conserved residues decreased activity or had no significant impact, four residues increased the specific activity of NcCAR variants when replaced by alanine. Finally, we showed that NcCAR wild-type and mutants efficiently reduce aliphatic acids.

  13. 2-Oxo-1,2-dihydroquinoline-4-carboxylic acid monohydrate

    Directory of Open Access Journals (Sweden)

    Yassir Filali Baba

    2016-06-01

    Full Text Available In the title compound, C10H7NO3·H2O, O—H...O hydrogen bonds involving the carboxyl groups, the keto groups and the lattice water molecules form stepped sheets approximately parallel to {010} which are tied together by pairwise N—H...O interactions. The asymmetric unit contains two independent quinolone derivatives and two water molecules, one of which is disordered over two positions, of equal occupancy.

  14. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    Directory of Open Access Journals (Sweden)

    Hao Wang

    2015-08-01

    Full Text Available In this study, fluorescent nitrogen-doped carbon dots (NCDs were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  15. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao; Wang, Yun; Dai, Xiao; Zou, Guifu, E-mail: kqzhang@suda.edu.cn, E-mail: zouguifu@suda.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Gao, Peng; Zhang, Ke-Qin, E-mail: kqzhang@suda.edu.cn, E-mail: zouguifu@suda.edu.cn; Du, Dezhuang [National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123 (China); Guo, Jun [Testing and Analysis Center, Soochow University, Suzhou 215123 (China)

    2015-08-01

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  16. Carboxylic acid-functionalized SBA-15 nanorods for gemcitabine delivery

    Energy Technology Data Exchange (ETDEWEB)

    Bahrami, Zohreh; Badiei, Alireza, E-mail: abadiei@khayam.ut.ac.ir [University of Tehran, School of Chemistry, College of Science (Iran, Islamic Republic of); Ziarani, Ghodsi Mohammadi [Alzahra University, Research Laboratory of Pharmaceutical (Iran, Islamic Republic of)

    2015-03-15

    The present study deals with the functionalization of mesoporous silica nanoparticles as drug delivery systems. Mono, di, and tri amino-functionalized SBA-15 nanorods were synthesized by post-grafting method using (3-aminopropyl) triethoxysilane, N-(2-aminoethyl-)3- aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino) ethylamino] propyl trimethoxysilane, respectively. The carboxylic acid derivatives of the amino-functionalized samples were obtained using succinic anhydride. Tminopropyltrimethoxysilanehe obtained modified materials were investigated as matrixes for the anticancer drug (gemcitabine) delivery. The prepared samples were characterized by SAXS, N{sub 2} adsorption/desorption, SEM, transmission electron microscopy, thermogravimetric analysis, and FTIR and UV spectroscopies. The adsorption and release properties of all samples were studied. It was revealed that the adsorption capacity and release behavior of gemcitabine were highly dependent on the type of the introduced functional groups. The carboxylic acid-modified samples have higher loading content, due to the strong interaction with gemcitabine. The maximum content of deposited drug in the modified SBA-15 nanorods is close to 40 wt%. It was found that the surface functionalization leads toward significant decrease of the drug release rate. The carboxylic acid-functionalized samples have slower release rate in contrast with the amino-functionalized samples.

  17. Carboxylic acid-functionalized SBA-15 nanorods for gemcitabine delivery

    Science.gov (United States)

    Bahrami, Zohreh; Badiei, Alireza; Ziarani, Ghodsi Mohammadi

    2015-03-01

    The present study deals with the functionalization of mesoporous silica nanoparticles as drug delivery systems. Mono, di, and tri amino-functionalized SBA-15 nanorods were synthesized by post-grafting method using (3-aminopropyl) triethoxysilane, N-(2-aminoethyl-)3- aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino) ethylamino] propyl trimethoxysilane, respectively. The carboxylic acid derivatives of the amino-functionalized samples were obtained using succinic anhydride. Tminopropyltrimethoxysilanehe obtained modified materials were investigated as matrixes for the anticancer drug (gemcitabine) delivery. The prepared samples were characterized by SAXS, N2 adsorption/desorption, SEM, transmission electron microscopy, thermogravimetric analysis, and FTIR and UV spectroscopies. The adsorption and release properties of all samples were studied. It was revealed that the adsorption capacity and release behavior of gemcitabine were highly dependent on the type of the introduced functional groups. The carboxylic acid-modified samples have higher loading content, due to the strong interaction with gemcitabine. The maximum content of deposited drug in the modified SBA-15 nanorods is close to 40 wt%. It was found that the surface functionalization leads toward significant decrease of the drug release rate. The carboxylic acid-functionalized samples have slower release rate in contrast with the amino-functionalized samples.

  18. Functionalization of carbon nanotube by carboxyl group under radial deformation

    Energy Technology Data Exchange (ETDEWEB)

    Lara, Ivi Valentini [Pós-Graduação em Física, Universidade Federal de Santa Maria, UFSM, 97105-900 Santa Maria, RS (Brazil); Zanella, Ivana [Área de Ciências Tecnológicas, Centro Universitário Franciscano, 97010-032 Santa Maria, RS (Brazil); Fagan, Solange Binotto, E-mail: ivanazanella@gmail.com [Área de Ciências Tecnológicas, Centro Universitário Franciscano, 97010-032 Santa Maria, RS (Brazil)

    2014-01-15

    Highlights: • Structural and the electronic properties of carboxylated (5,5) single-walled carbon nanotubes (SWNT) under pressure. • sp{sup 3} hybridization induced by the functionalization and/or deformation of SWNT. • Functionalization of SWNT by –COOH under pressure for nanobiotechnological application. - Abstract: The dependence of the structural and the electronic properties of functionalized (5, 5) single-walled carbon nanotubes (SWNT) were investigated through ab initio density functional simulations when the carboxyl group is bonded on the flatter or curved regions. Radial deformations result in diameter decrease of up to 20 per cent of the original size, which was the limit reduction that maintains the SWNT functionalized structure. Changes on the electronic structure were observed due to the symmetry break of the SWNT caused by both the carboxyl group and the C–C bond distortions resulted by the radial deformation. It is observed that the functionalization process is specially favored by the sp{sup 3} hybridization induced on the more curved region of the deformed SWNT.

  19. Synthesis and fluorescence study of phenylcoumarin/cyanophenylbenzocoumarin-3-carboxylates

    Directory of Open Access Journals (Sweden)

    Hosanagara N. Harishkumar

    2012-01-01

    Full Text Available The absorption and fluorescence spectra of phenylcoumarin and cyanophenylbenzocoumarin-3-carboxylates 6a-f and 9a-e have been investigated in chloroform, acetonitrile and ethanol. The substituting groups with varying electron donating ability such as N,N-diethyl amine and morpholine at 7-position, in phenylcoumarin-3-carboxylate 6a-f exhibits fluorescence at a longer wavelength i.e. 420-460 nm in chloroform and 460-504 nm in acetonitrile. However the morpholine derivatives 6f-j did not show fluorescence in chloroform. In another series of cyanophenylbenzocoumarin-3-carboxylates 9a-e, the compound 9c exhibits fluorescence at 546 nm in ethanol and 256 nm in acetonitrile, and lower emission wavelength i.e. 356 nm in chloroform. Further the compounds 6e , 9b, 9d and 9e exhibited high quantum yield in ethanol i.e., Φ F = 0.79, 0.70, 0.80 and 0.74 respectively compare to Rhodamine B ( Φ F = 0.24 in ethanol.

  20. Role of carboxylate side chains in the cation Hofmeister series.

    Science.gov (United States)

    Kherb, Jaibir; Flores, Sarah C; Cremer, Paul S

    2012-06-28

    Thermodynamic and surface-specific spectroscopic investigations were carried with an elastin-like polypeptide (ELP) containing 16 aspartic acid residues. The goal was to explore the role of the carboxylate moieties in hydrophobic collapse and related Hofmeister effects. Experiments were conducted with a series of monovalent and divalent metal chloride salts. Both phase transition temperature and spectroscopic data demonstrated that the divalent cations showed relatively strong association to the carboxylate sites on the biopolymer with K(d) values in the range of 1 to 10 mM. The ordering of the divalent series was: Zn(2+) > Ca(2+) > Ba(2+) > Sr(2+) > Mg(2+). Monovalent cations displayed weaker binding which ranged from 78 mM for NH(4)(+) to 345 mM for Cs(+). The order for this series was: NH(4)(+) > Li(+) > Na(+) > NMe(4)(+) > K(+) > Rb(+) ≥ Cs(+). These results are in general agreement with the notion that strongly hydrated cations bind more tightly to carboxylate groups than do weakly hydrated cations. Moreover, the data for the monovalent series was partially consistent with the law of matching water affinity, although Li(+) and NH(4)(+) did not follow the model. The series for the divalent cations did not appear to obey the law of matching water affinity at all.

  1. Visible and NIR photoluminescence properties of a series of novel lanthanide-organic coordination polymers based on hydroxyquinoline-carboxylate ligands.

    Science.gov (United States)

    Gai, Yan-Li; Xiong, Ke-Cai; Chen, Lian; Bu, Yang; Li, Xing-Jun; Jiang, Fei-Long; Hong, Mao-Chun

    2012-12-17

    A series of novel two-dimensional (2D) lanthanide coordination polymers with 4-hydroxyquinoline-2-carboxylate (H(2)hqc) ligands, [Ln(Hhqc)(3)(H(2)O)](n)·3nH(2)O (Ln = Eu (1), Tb (2), Sm (3), Nd (4), and Gd (5)) and [Ln(Hhqc)(ox)(H(2)O)(2)](n) (Ln = Eu (6), Tb (7), Sm (8), Tm (9), Dy (10), Nd (11), Yb (12), and Gd (13); H(2)ox = oxalic acid), have been synthesized under hydrothermal conditions. Complexes 1-5 are isomorphous, which can be described as a two-dimensional (2D) hxl/Shubnikov network based on Ln(2)(CO(2))(4) paddle-wheel units, and the isomorphous complexes 6-13 feature a 2D decker layer architecture constructed by Ln-ox infinite chains cross-linked alternatively by bridging Hhqc(-) ligands. The room-temperature photoluminescence spectra of complexes Eu(III) (1 and 6), Tb(III) (2 and 7), and Sm(III) (3 and 8) exhibit strong characteristic emissions in the visible region, whereas Nd(III) (4 and 11) and Yb(III) (12) complexes display NIR luminescence upon irradiation at the ligand band. Moreover, the triplet state of H(2)hqc matches well with the emission level of Eu(III), Tb(III), and Sm(III) ions, which allows the preparation of new optical materials with enhanced luminescence properties.

  2. Six new coordination polymers constructed by 3-carboxyl-5-oxycarboxymethylpyridinio-1-carboxylate: Crystal structures, topologies, photoluminescent and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Hong-Yan [Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China); Dazhou Vocational and Technical College, 448 Xujiabei Road, Sishuan 635000 (China); Han, Min-Min; Jiang, Xian-Rong; Jiang, Zhan-Guo [Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China); Feng, Yun-Long, E-mail: sky37@zjnu.cn [Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China)

    2013-06-01

    Six new two-dimensional (2D) coordination polymers, [ML(H₂O)₃]ₙ (M=Zn (1), Cd (2), Mn (3), Co (4)), [CdL(H₂O)]ₙ} (5), [CdL(4,4´-bipy)]ₙ·nH₂O (6), (H₂L=3-carboxyl-5-oxycarboxymethylpyridinio-1-carboxylate, 4,4´-bipy=4,4´-bipyridine), have been hydrothermally synthesized and characterized by single crystal X-ray diffraction analyses, IR spectra, and thermogravimetric analyses. 1, 2, 3, 4 are isostructural and feature a binodal (4,6)-connected topology with left- and right-handed helical chains with a pitch of 9.9560 Å. 5 can be topologically presented as an uninodal 6-connected network if the hydrogen bonds are also considered. 6 is a binodal (3,5)-connected 2D layer network. The photoluminescent properties of 1, 2, 5, 6 and magnetic properties of 3, 4 have been studied and discussed. - Graphical abstract: The structural differences show that the ligand, the metal center, and the reaction conditions have great influence on the structure of the final assembly. Highlights: • A new asymmetric flexible tricarboxylate ligand of 3-carboxyl-5-oxycarboxymethylpyridinio-1-carboxylate was synthesized. • Six new two-dimensional (2D) coordination polymers have been hydrothermally obtained. • 1, 2, 3, 4 are isostructural and feature a binodal (4,6)-connected topology with left- and right-handed helical chains. • The photoluminescent properties of 1, 2, 5, 6 and magnetic properties of 3, 4 have been studied.

  3. Carboxyl-terminated butadiene-acrylonitrile-toughened epoxy/carboxyl-modified carbon nanotube nanocomposites: Thermal and mechanical properties

    Directory of Open Access Journals (Sweden)

    H. F. Xie

    2012-09-01

    Full Text Available Carboxyl-modified multi-walled carbon nanotubes (MWCNT–COOHs as nanofillers were incorporated into diglycidyl ether of bisphenol A (DGEBA toughened with carboxyl-terminated butadiene-acrylonitrile (CTBN. The carboxyl functional carbon nanotubes were characterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. Furthermore, cure kinetics, glass transition temperature (Tg, mechanical properties, thermal stability and morphology of DGEBA/CTBN/MWCNT–COOHs nanocomposites were investigated by differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, universal test machine, thermogravimetric analysis and scanning electron microscopy (SEM. DSC kinetic studies showed that the addition of MWCNT–COOHs accelerated the curing reaction of the rubber-toughened epoxy resin. DMA results revealed that Tg of rubber-toughened epoxy nanocomposites lowered with MWCNT–COOH contents. The tensile strength, elongation at break, flexural strength and flexural modulus of DGEBA/CTBN/MWCNT-COOHs nanocomposites were increased at lower MWCNT-COOH concentration. A homogenous dispersion of nanocomposites at lower MWCNT–COOH concentration was observed by SEM.

  4. Palladium-catalyzed C-H bond carboxylation of acetanilides: an efficient usage of N,N-dimethyloxamic acid as the carboxylate source.

    Science.gov (United States)

    Wu, Yinuo; Jiang, Cheng; Wu, Deyan; Gu, Qiong; Luo, Zhang-Yi; Luo, Hai-Bin

    2016-01-21

    N,N-Dimethyloxamic acid can be successfully employed as a carboxylate precursor in the palladium-catalyzed direct C-H carboxylation of acetanilides. The reaction proceeds smoothly under mild conditions over a broad range of substrates with high functional group tolerance, affording substituted N-acyl anthranilic acids in moderate to high yields.

  5. Antithrombin III blood test

    Science.gov (United States)

    ... medlineplus.gov/ency/article/003661.htm Antithrombin III blood test To use the sharing features on this page, ... a protein that helps control blood clotting. A blood test can determine the amount of AT III present ...

  6. Adsorption of Eu(III) onto roots of water hyacinth

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, C.; Mielke, R.E.; Dimaquibo, D.; Curtis, A.J. [Northern Arizona Univ., Flagstaff, AZ (United States). Dept. of Chemistry; Dewitt, J.G. [San Francisco State Univ., San Francisco, CA (United States)

    1999-05-01

    The water hyacinth (Eichhornia crassipes) has drawn attention as a plant capable of removing pollutants, including toxic metals, from water. The authors are interested in the capacity of the water hyacinth to remediate aquatic environments that have been contaminated with the lanthanide metal, europium Eu(III). Using scanning electron microscopy (SEM) they have been able to determine that Eu(III) is adsorbed onto the surface of the roots from water and that the highest concentration of Eu(III) is on the root hairs. X-ray absorption spectroscopy (XAS) techniques were used to speciate the Eu(III) adsorbed onto the surface of the roots. The XAS data for Eu-contaminated water hyacinth roots provides evidence of a Eu-oxygen environment and establishes that Eu(III) is coordinated to 10--11 oxygen atoms at a distance of 2.44 {angstrom}. This likely involves binding of Eu(III) to the root via carboxylate groups and hydration of Eu(III) at the root surface.

  7. SORPTION OF Au(III BY Saccharomyces cerevisiae BIOMASS

    Directory of Open Access Journals (Sweden)

    Amaria Amaria

    2010-07-01

    Full Text Available Au(III sorption by S. cerevisiae biomass extracted from beer waste industry was investigated. Experimentally, the sorption was conducted in batch method. This research involved five steps: 1 identification the functional groups present in the S. cerevisiae biomass by infrared spectroscopic technique, 2 determination of optimum pH, 3 determination of the sorption capacity and energy, 4 determination of the sorption type by conducting desorption of sorbed Au(III using specific eluents having different desorption capacity such as H2O (van der Waals, KNO3 (ion exchange, HNO3 (hydrogen bond, and tiourea (coordination bond, 5 determination of effective eluents in Au(III desorption by partial desorption of sorbed Au(III using thiourea, NaCN and KI. The remaining Au(III concentrations in filtrate were analyzed using Atomic Absorption Spectrophotometer. The results showed that: 1 Functional groups of S. cerevisiae biomass that involved in the sorption processes were hydroxyl (-OH, carboxylate (-COO- and amine (-NH2, 2 maximum sorption was occurred at pH 4, equal to 98.19% of total sorption, 3 The sorption capacity of biomass was 133.33 mg/g (6.7682E-04 mol/g and was involved sorption energy 23.03 kJ mol-1, 4 Sorption type was dominated by coordination bond, 5 NaCN was effective eluent to strip Au(III close to 100%.   Keywords: sorption, desorption, S. cerevisiae biomass, Au(III

  8. Luminescence and Magnetic Properties of Two Three-Dimensional Terbium and Dysprosium MOFs Based on Azobenzene-4,4′-Dicarboxylic Linker

    Directory of Open Access Journals (Sweden)

    Belén Fernández

    2016-02-01

    Full Text Available We report the in situ formation of two novel metal-organic frameworks based on terbium and dysprosium ions using azobenzene-4,4′-dicarboxylic acid (H2abd as ligand, synthesized by soft hydrothermal routes. Both materials show isostructural three-dimensional networks with channels along a axis and display intense photoluminescence properties in the solid state at room temperature. Textural properties of the metal-organic frameworks (MOFs have been fully characterized although no appreciable porosity was obtained. Magnetic properties of these materials were studied, highlighting the dysprosium material displays slightly frequency-dependent out of phase signals when measured under zero external field and under an applied field of 1000 Oe.

  9. (2S,4R-4-Fluoropyrrolidinium-2-carboxylate

    Directory of Open Access Journals (Sweden)

    David B. Hobart Jr

    2012-08-01

    Full Text Available The crystal structure of the title compound, C5H8FNO2, at 100 K, displays intermolecular N—H...O hydrogen bonding between the ammonium and carboxylate groups as a result of its zwitterionic nature in the solid state. The five-membered ring adopts an envelope conformation with the C atom at the 3-position as the flap. The compound is of interest with respect to the synthesis and structural properties of synthetic collagens. The absolute structure was determined by comparison with the commercially available material.

  10. Large-scale cathodic carboxylation of copper surfaces

    OpenAIRE

    Simonet, Jacques

    2017-01-01

    International audience; Large scale carboxylation of copper can easily be achieved by redn. of CO2 solubilised in aprotic polar solvents in the presence of tetramethylammonium salts (TMeA+ X-). Carbon dioxide could be inserted into the metal matrix (presumably in the form of the carbon dioxide anion radical) at high surface concns. (up to 10- 7 mol cm- 2), most probably organized in multi-layers. With significant amts. of electricity (> 0.1 × 10- 2 C cm- 2), this cathodic procedure leads to a...

  11. Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

    African Journals Online (AJOL)

    The results showed that mean mass concentration of PM2.5 and PM10 were 13 ± 3.5 μg m–3 and 16 ± 2.3 μg m–3, respectively. Mean concentrations of the total carboxylates were 23.7±6.5 ngm–3 in PM2.5 and 36.4 ± 12 ngm–3 in PM10 whereas total water-soluble inorganic ions were 448±88 ngm–3 and 646± 214 ...

  12. Separation and determination of some carboxylic acids by capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Sladkov, V.; Fourest, B

    2006-07-01

    Separation and determination of some organic acids, mono-carboxylic (formic and acetic), dicarboxylic (oxalic and tartaric), tricarboxylic (citric) acids and aromatic acids (phtalic, benzoic, mellitic and trimellitic), by capillary electrophoresis are reviewed. The method development parameters, such as separation and injection mode, are discussed. Special attention is paid to the comparison of different detection types (spectroscopic and electrochemical). The optimisation of the carrier electrolyte composition (choice of carrier electrolyte, effect of pH, ionic strength, electro-osmotic flow modifier) is treated. Different additives (alkali-earth and transition metal ions, cyclodextrins and alcohol), which are often used for improving organic acid separation, are also considered. (authors)

  13. (2S,4R-4-Ammonio-5-oxopyrrolidine-2-carboxylate

    Directory of Open Access Journals (Sweden)

    Krzysztof Kaczmarek

    2010-04-01

    Full Text Available In the crystal structure of the title compound, C5H8N2O3, the molecules exist in the zwitterionic form. The pyrrolidine ring adopts an envelope conformation with the unsubstituted endocyclic C atom situated at the flap. The other four endocyclic atoms are coplanar with the exocyclic carbonyl O atom, with an r.m.s. deviation from the mean plane of 0.06 Å. The carboxylate substituent is located axially, while the ammonium group occupies an equatorial position. In the crystal structure, the molecules are linked through N—H...O hydrogen bonds, forming a three-dimensional network.

  14. Luminescent triarylboron-functionalized zinc carboxylate metal-organic framework.

    Science.gov (United States)

    Blight, Barry A; Guillet-Nicolas, Rémy; Kleitz, Freddy; Wang, Rui-Yao; Wang, Suning

    2013-02-18

    A luminescent triarylboron ligand functionalized with three carboxylic groups has been synthesized and fully characterized. Its use in boron-containing metal-organic frameworks (B-MOFs) has been demonstrated by the synthesis and isolation of a Zn(II)B-MOF compound (B-MOF-1). The crystals of B-MOF-1 belong to the cubic space group F432 with 8-fold interpenetrated networks and ∼21% void space. B-MOF-1 exhibits blue fluorescence and is capable of modest gas sorption of N(2), argon, and CO(2).

  15. Poly[[tetraaquatetrakis[μ3-5-(pyridine-4-carboxamidoisophthalato]cobalt(IIdiholmium(III] tetrahydrate

    Directory of Open Access Journals (Sweden)

    Yi-Fang Deng

    2011-11-01

    Full Text Available In the centrosymmetric polymeric title compound, {[CoHo2(C14H8N2O54(H2O4]·4H2O}n, the HoIII ion is coordinated by one water molecule and four 5-(pyridine-4-carboxamidoisophthalate (L ligands in a distorted square-antiprismatic arrangement. The CoII ion, located on an inversion center, is coordinated by two pyridine N atoms, two carboxylate O atoms and two water molecules in a distorted octahedral geometry. One L ligand bridges two Ho ions and one Co ion through two carboxylate groups and one pyridine N atom. The other L ligand bridges two Ho ions and one Co ion through two carboxylate groups, while the uncoordinated pyridine N atom accepts a hydrogen bond from an adjacent coordinated water molecule. Extensive O—H...O, N—H...O and O—H...N hydrogen bonding is present in the crystal.

  16. Poly[diaqua-μ-oxalato-μ-pyrazine-2-carboxylato-lanthanum(III

    Directory of Open Access Journals (Sweden)

    Qun-Hui Meng

    2009-01-01

    Full Text Available In the title complex, [La(C5H3N2O2(C2O4(H2O2]n, the LaIII ion is coordinated by one N and three O atoms from two pyrazine-2-carboxylate ligands, by four O atoms from two oxalate ligands and by two O atoms of two water molecules, displaying a distorted bicapped square-antiprismatic geometry. The carboxylate groups of pyrazine-2-carboxylate and oxalate ligands link the lanthanum metal centres, forming layers parallel to (10overline{1}. The layers are further connected by intermolecular O—H...O and N—H...O hydrogen-bonding interactions, forming a three-dimensional supramolecular network.

  17. Zeolite-Y entrapped Ru(III and Fe(III complexes as heterogeneous catalysts for catalytic oxidation of cyclohexane reaction

    Directory of Open Access Journals (Sweden)

    Chetan K. Modi

    2017-02-01

    Full Text Available Catalysis is probably one of the greatest contributions of chemistry to both economic growth and environmental protection. Herein we report the catalytic behavior of zeolite-Y entrapped Ru(III and Fe(III complexes with general formulae [M(VTCH2·2H2O]+-Y and [M(VFCH2·2H2O]+-Y [where, VTCH = vanillin thiophene-2-carboxylic hydrazone and VFCH = vanillin furoic-2-carboxylic hydrazone] over the oxidation of cyclohexane forming cyclohexanone and cyclohexanol. The samples were corroborated by various physico-chemical techniques. These zeolite-Y based complexes are stable and recyclable under current reaction conditions. Amongst them, [Ru(VTCH2⋅2H2O]+-Y showed higher catalytic activity (41.1% with cyclohexanone (84.6% selectivity.

  18. Tetrakis(μ2-2-phenoxypropionato-κ3O,O′:O′;κ3O:O,O′;κ4O:O′-bis[(1,10-phenanthroline-κ2N,N′(2-phenoxypropionato-κ2O,O′gadolinium(III

    Directory of Open Access Journals (Sweden)

    Guo-Liang Zhao

    2011-10-01

    Full Text Available In the centrosymmetric binuclear title complex, [Gd2(C9H9O36(C12H8N22], the two Gd(III ions are linked by four 2-phenoxypropionate (L groups in bi- and tridentate bridging modes. Each GdIII ion is nine-coordinated by one 1,10-phenanthroline molecule, one bidentate chelating carboxylate group and four bridging carboxylate groups in a distorted GdN2O7 monocapped square-antiprismatic geometry.

  19. Integrated process for preparing a carboxylic acid from an alkane

    Science.gov (United States)

    Benderly, Abraham [Elkins Park, PA; Chadda, Nitin [Radnor, PA; Sevon, Douglass [Fairless Hills, PA

    2011-12-20

    The present invention relates to an integrated process for producing unsaturated carboxylic acids from the corresponding C.sub.2-C.sub.4 alkane. The process begins with performance of thermally integrated dehydrogenation reactions which convert a C.sub.2-C.sub.4 alkane to its corresponding C.sub.2-C.sub.4 alkene, and which involve exothermically converting a portion of an alkane to its corresponding alkene by oxidative dehydrogenation in an exothermic reaction zone, in the presence of oxygen and a suitable catalyst, and then feeding the products of the exothermic reaction zone to an endothermic reaction zone wherein at least a portion of the remaining unconverted alkane is endothermically dehydrogenated to form an additional quantity of the same corresponding alkene, in the presence of carbon dioxide and an other suitable catalyst. The alkene products of the thermally integrated dehydrogenation reactions are then provided to a catalytic vapor phase partial oxidation process for conversion of the alkene to the corresponding unsaturated carboxylic acid or nitrile. Unreacted alkene and carbon dioxide are recovered from the oxidation product stream and recycled back to the thermally integrated dehydrogenation reactions.

  20. Reductive Carboxylation of Propionate to Butyrate in Methanogenic Ecosystems

    Science.gov (United States)

    Tholozan, J. L.; Samain, E.; Grivet, J. P.; Moletta, R.; Dubourguier, H. C.; Albagnac, G.

    1988-01-01

    During the batch degradation of sodium propionate by the anaerobic sludge from an industrial digestor, we observed a significant amount of butyrate formation. Varying the initial propionate concentrations did not alter the ratio of maximal butyrate accumulation to initial propionate concentration within a large range. By measuring the decrease in the radioactivity of [1-14C]butyrate during propionate degradation, we estimated that about 20% of the propionate was converted to butyrate. Labeled butyrate was formed from [1-14C]propionate with the same specific radioactivity, suggesting a possible direct pathway from propionate to butyrate. We confirmed this hypothesis by nuclear magnetic resonance studies with [13C]propionate. The results showed that [1-13C]-, [2-13C]-, and [3-13C]propionate were converted to [2-13C]-, [3-13C]-, and [4-13C]butyrate, respectively, demonstrating the direct carboxylation on the carboxyl group of propionate without randomization of the other two carbons. In addition, we observed an exchange reaction between C-2 and C-3 of the propionate, indicating that acetogensis may proceed through a randomizing pathway. The physiological significance and importance of various metabolic pathways involved in propionate degradation are discussed, and an unusual pathway of butyrate synthesis is proposed. PMID:16347557

  1. Biocompatibility studies of polyacrylonitrile membranes modified with carboxylated polyetherimide

    Energy Technology Data Exchange (ETDEWEB)

    Senthilkumar, S.; Rajesh, S.; Jayalakshmi, A.; Mohan, D., E-mail: mohantarun@gmail.com

    2013-10-15

    Poly (ether-imide) (PEI) was carboxylated and used as the hydrophilic modification agent for the preparation of polyacrylonitrile (PAN) membranes. Membranes were prepared with different blend compositions of PAN and CPEI by diffusion induced precipitation. The modified membranes were characterized by thermo gravimetric analysis (TGA), mechanical analysis, scanning electron microscopy (SEM) and contact angle measurement to understand the influence of CPEI on the properties of the membranes. The biocompatibility studies exhibited reduced plasma protein adsorption, platelet adhesion and thrombus formation on the modified membrane surface. The complete blood count (CBC) results of CPEI incorporated membranes showed stable CBC values and significant decrease in the complement activation were also observed. In addition to good cytocompatibility, monocytes cultured on these modified membranes exhibited improved functional profiles in 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Thus it could be concluded that PAN/CPEI membranes with excellent biocompatibility can be useful for hemodialysis. Highlights: • Carboxylated PEI was prepared and utilized as hydrophilic modification agent. • CPEI incorporated into PAN to improved biocompatibility and cyto compatibility • Biocompatibility of membranes was correlated with morphology and hydrophilicity. • Antifouling studies of the PAN/CPEI membranes was studied by BSA as model foulant.

  2. Nonwoven Carboxylated Agarose-Based Fiber Meshes with Antimicrobial Properties.

    Science.gov (United States)

    Forget, Aurelien; Arya, Neha; Randriantsilefisoa, Rotsiniaina; Miessmer, Florian; Buck, Marion; Ahmadi, Vincent; Jonas, Daniel; Blencowe, Anton; Shastri, V Prasad

    2016-12-12

    Hydrogel forming polysaccharides, such as the seaweed derived agarose, are well suited for wound dressing applications as they have excellent cell and soft tissue compatibility. For wound dressings, fibrous structure is desirable as the high surface area can favor adsorption of wound exudate and promote drug delivery. Although electrospinning offers a straightforward means to produce nonwoven fibrous polymeric structures, processing agarose and its derivatives into fibers through electrospinning is challenging as it has limited solubility in solvents other than water. In this study we describe the processing of carboxylated agarose (CA) fibers with antibacterial properties by electrospinning from a solution of the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([Bmim] + Cl - ) possessing antimicrobial properties. The extent of carboxylation was found to impact fiber diameter, mesh elastic modulus, fiber swelling, and the loading and release of IL. IL-bearing CA fibers inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa, bacteria commonly found in wound exudate. In sum, nonwoven CA fibers processed from IL are promising as biomaterials for wound dressing applications.

  3. Reinforcing carbon fixation: CO2 reduction replacing and supporting carboxylation.

    Science.gov (United States)

    Cotton, Charles Ar; Edlich-Muth, Christian; Bar-Even, Arren

    2017-08-10

    Carbon dioxide enters the biosphere via one of two mechanisms: carboxylation, in which CO2 is attached to an existing metabolite, or reduction, in which CO2 is converted to formate or carbon monoxide before further assimilation. Here, we focus on the latter mechanism which usually receives less attention. To better understand the possible advantages of the 'reduction-first' approach, we compare the two general strategies according to the kinetics of the CO2-capturing enzymes, and the resource consumption of the subsequent pathways. We show that the best CO2 reducing enzymes can compete with the best carboxylases. We further demonstrate that pathways that fix CO2 by first reducing it to formate could have an advantage over the majority of their carboxylation-only counterparts in terms of ATP-efficiency and hence biomass yield. We discuss and elaborate on the challenges of implementing 'reduction-first' pathways, including the thermodynamic barrier of CO2 reduction. We believe that pathways based on CO2 reduction are a valuable addition to nature's arsenal for capturing inorganic carbon and could provide promising metabolic solutions that have been previously overlooked. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  4. Understanding potential exposure sources of perfluorinated carboxylic acids in the workplace

    National Research Council Canada - National Science Library

    Kaiser, Mary A; Dawson, Barbara J; Barton, Catherine A; Botelho, Miguel A

    2010-01-01

    This paper integrates perspectives from analytical chemistry, environmental engineering, and industrial hygiene to better understand how workers may be exposed to perfluorinated carboxylic acids when...

  5. A series of 3D lanthanide frameworks constructed from aromatic multi-carboxylate ligand: structural diversity, luminescence and magnetic properties.

    Science.gov (United States)

    Feng, Xun; Ling, Xun-Li; Liu, Lang; Song, Hong-Liang; Wang, Li-Ya; Ng, Seik-Weng; Su, Bei Ya

    2013-07-28

    Reactions of lanthanide(III) nitrates with multi-donor carboxylate ligand in the presence of oxalate anion afforded four new lanthanide coordination polymers with three dimensional (3D) frameworks, namely, {[Ln2(DPPA)2(μ2-C2O4)(H2O)2]·2H2O}n (Ln = Nd (1), Sm (2)) and [Ln2(HDPPA)2(DPPA)2]n (Ln = Tb (3), Yb (4)), (H3DPPA = 3-(4-hydroxyl pyridinium-1-yl) phthalic acid and H2C2O4 = oxalic acid). Compounds 1 and 2 are isostructural and isomorphous, featuring oxalate pillared binodal (4,5)-connected porous 3D framework with intersected 1D channels, in which the coordinated and lattice waters are accommodated. The complexes 3 and 4 are also isostructural, but featuring a (4,6)-connected 3D network based on a rectangular window composed of {Ln(HDPPA)}(+) extended anion chains, further interlinked by DPPA. The Tb(III) analogue exhibits intense characteristic green photoluminescence employing DPPA as an antenna. While Sm(III) compound 2 mainly involves ligand-to-ligand charge transfer. Variable-temperature susceptibility analyses of complexes 1 (Nd), 2 (Sm) and 3 (Tb) revealed that depopulation of the Stark levels together with weak antiferromagnetic interactions between the lanthanide ions lead to a continuous decrease in χ(M)T when the samples are cooled from 300 to 2 K.

  6. Six new coordination polymers constructed by 3-carboxyl-5-oxycarboxymethylpyridinio-1-carboxylate: Crystal structures, topologies, photoluminescent and magnetic properties

    Science.gov (United States)

    Yuan, Hong-Yan; Han, Min-Min; Jiang, Xian-Rong; Jiang, Zhan-Guo; Feng, Yun-Long

    2013-06-01

    Six new two-dimensional (2D) coordination polymers, [ML(H2O)3]n (M=Zn (1), Cd (2), Mn (3), Co (4)), [CdL(H2O)]n (5), [CdL(4,4'-bipy)]n·nH2O (6), (H2L=3-carboxyl-5-oxycarboxymethylpyridinio-1-carboxylate, 4,4'-bipy=4,4'-bipyridine), have been hydrothermally synthesized and characterized by single crystal X-ray diffraction analyses, IR spectra, and thermogravimetric analyses. 1, 2, 3, 4 are isostructural and feature a binodal (4,6)-connected topology with left- and right-handed helical chains with a pitch of 9.9560 Å. 5 can be topologically presented as an uninodal 6-connected network if the hydrogen bonds are also considered. 6 is a binodal (3,5)-connected 2D layer network. The photoluminescent properties of 1, 2, 5, 6 and magnetic properties of 3, 4 have been studied and discussed.

  7. The Conversion of 1-(Malonylamino)cyclopropane-1-Carboxylic Acid to 1-Aminocyclopropane-1-Carboxylic Acid in Plant Tissues.

    Science.gov (United States)

    Jiao, X Z; Philosoph-Hadas, S; Su, L Y; Yang, S F

    1986-06-01

    Since 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), the major conjugate of 1-aminocyclopropane-1-carboxylic acid (ACC) in plant tissues, is a poor ethylene producer, it is generally thought that MACC is a biologically inactive end product of ACC. In the present study we have shown that the capability of watercress (Nasturtium officinale R. Br) stem sections and tobacco (Nicotiana tabacum L.) leaf discs to convert exogenously applied MACC to ACC increased with increasing MACC concentrations (0.2-5 millimolar) and duration (4-48 hours) of the treatment. The MACC-induced ethylene production was inhibited by CoCl(2) but not by aminoethoxyvinylglycin, suggesting that the ACC formed is derived from the MACC applied, and not from the methionine pathway. This was further confirmed by the observation that radioactive MACC released radioactive ACC and ethylene. A cell-free extract, which catalyzes the conversion of MACC to ACC, was prepared from watercress stems which were preincubated with 1 millimolar MACC for 24 hours. Neither fresh tissues nor aged tissues incubated without external MACC exhibited enzymic activity, confirming the view that the enzyme is induced by MACC. The enzyme had a K(m) of 0.45 millimolar for MACC and showed maximal activity at pH 8.0 in the presence of 1 millimolar MnSO(4). The present study indicates that high MACC levels in the plant tissue can induce to some extent the capability to convert MACC to ACC.

  8. The Conversion of 1-(Malonylamino)cyclopropane-1-Carboxylic Acid to 1-Aminocyclopropane-1-Carboxylic Acid in Plant Tissues 1

    Science.gov (United States)

    Jiao, Xin-Zhi; Philosoph-Hadas, Sonia; Su, Ling-Yuan; Yang, Shang Fa

    1986-01-01

    Since 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), the major conjugate of 1-aminocyclopropane-1-carboxylic acid (ACC) in plant tissues, is a poor ethylene producer, it is generally thought that MACC is a biologically inactive end product of ACC. In the present study we have shown that the capability of watercress (Nasturtium officinale R. Br) stem sections and tobacco (Nicotiana tabacum L.) leaf discs to convert exogenously applied MACC to ACC increased with increasing MACC concentrations (0.2-5 millimolar) and duration (4-48 hours) of the treatment. The MACC-induced ethylene production was inhibited by CoCl2 but not by aminoethoxyvinylglycin, suggesting that the ACC formed is derived from the MACC applied, and not from the methionine pathway. This was further confirmed by the observation that radioactive MACC released radioactive ACC and ethylene. A cell-free extract, which catalyzes the conversion of MACC to ACC, was prepared from watercress stems which were preincubated with 1 millimolar MACC for 24 hours. Neither fresh tissues nor aged tissues incubated without external MACC exhibited enzymic activity, confirming the view that the enzyme is induced by MACC. The enzyme had a Km of 0.45 millimolar for MACC and showed maximal activity at pH 8.0 in the presence of 1 millimolar MnSO4. The present study indicates that high MACC levels in the plant tissue can induce to some extent the capability to convert MACC to ACC. PMID:16664869

  9. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden

    1975-01-01

    The selection rules for the linear couplings between magnons and phonons propagating in the c direction of a simple basal-plane hcp ferromagnet are determined by general symmetry considerations. The acoustic-optical magnon-phonon interactions observed in the heavy-rare-earth metals have been expl...... by Liu. The coupled magnon—transverse-phonon system for the c direction of Tb is analyzed in detail, and the strengths of the couplings are deduced as a function of wave vector by combining the experimental studies with the theory....

  10. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden; Bjerrum Møller, Hans

    1975-01-01

    The energies of spin waves propagating in the c direction of Tb have been studied by inelastic neutron scattering, as a function of a magnetic field applied along the easy and hard directions in the basal plane, and as a function of temperature. From a general spin Hamiltonian, consistent...... with the symmetry, we deduce the dispersion relation for the spin waves in a basal-plane ferromagnet. This phenomenological spin-wave theory accounts for the observed behavior of the magnon energies in Tb. The two q⃗-dependent Bogoliubov components of the magnon energies are derived from the experimental results...

  11. Photo-control of the magnetic properties of Dy(III) and Ho(III) homometal coordination polymers bridged by a diarylethene ligand.

    Science.gov (United States)

    Cosquer, Goulven; Morimoto, Masakazu; Irie, Masahiro; Fetoh, Ahmed; Breedlove, Brian K; Yamashita, Masahiro

    2015-04-07

    Two-dimensional Dy(III) and Ho(III) homometal coordination polymers containing the photochromic ligand 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluorocyclopentene (DTE) with the general formula [Ln2(DTE)3(bipyridine)2(H2O)2]n (Ln = Dy and Ho) were obtained, and the magnetic properties of their open (Dy-o and Ho-o) and closed forms (Dy-c and Ho-c) were investigated. The Dy complexes exhibited slow magnetic relaxation without an external dc field. The magnetic properties of the Dy complexes were irreversibly affected by the conformation of the ligand.

  12. tert-Butyl 3-[2,2-bis-(ethoxy-carbon-yl)vin-yl]-2-bromo-methyl-1H-indole-1-carboxyl-ate.

    Science.gov (United States)

    Thenmozhi, M; Kavitha, T; Dhayalan, V; Mohanakrishnan, A K; Ponnuswamy, M N

    2009-10-17

    In the title compound, C(22)H(26)BrNO(6), the indole ring system is planar [maximum deviation 0.029 (2) Å]. The tert-butyl bound carboxyl-ate group forms a dihedral angle of 17.54 (8)° with the indole ring system. In the crystal, mol-ecules are linked into centrosymmetric R(2) (2)(10) dimers by paired C-H⋯O hydrogen bonds.

  13. rac-4-Carbamoylpiperidinium cis-2-carboxycyclohexane-1-carboxylate

    Directory of Open Access Journals (Sweden)

    Graham Smith

    2012-03-01

    Full Text Available In the title racemic salt, C6H13N2O+·C8H11O4−, formed from the reaction of cis-cyclohexane-1,2-dicarboxylic anhydride with isonipecotamide, the cations are linked into duplex chain substructures through both centrosymmetric cyclic head-to-head `amide motif' hydrogen-bonding associations [graph set R22(8] and `side-by-side' R22(14 associations. The anions are incorporated into the chains through cyclic R43(10 interactions involving amide and piperidinium N—H...Ocarboxyl hydrogen bonds which, together with inter-anion carboxylic acid O—H...Ocarboxyl hydrogen bonds, give a two-dimensional layered structure extending along (011.

  14. Improved preparation of halopropyl bridged carboxylic ortho esters

    Directory of Open Access Journals (Sweden)

    Richard J. Petroski

    2008-10-01

    Full Text Available Bridged ortho esters of 3-halopropyl carboxylic acids were prepared by esterification of 3-methyl-3-hydroxymethyloxetane with 3-bromopropionyl chloride and pyridine in dry THF, followed by rearrangement with boron trifluoroetherate, to afford 1-(2-bromoethyl-4-methyl-2,6,7-trioxabicyclo[2,2,2]-octane. The 1-(2-iodoethyl-4-methyl-2,6,7-trioxabicyclo[2,2,2]-octane analogue could not be prepared directly by halogen exchange of 1-(2-bromoethyl-4-methyl-2,6,7-trioxabicyclo[2,2,2]-octane but could be prepared by halogen exchange of the (3-methyloxetan-3-ylmethyl 3-bromopropanoate with a mixture of sodium iodide and anhydrous sodium sulfate in acetone, followed by rearrangement with boron trifluoroetherate.

  15. Carboxylated nitrile butadiene rubber/hybrid filler composites

    Directory of Open Access Journals (Sweden)

    Ahmad Mousa

    2012-08-01

    Full Text Available The surface properties of the OSW and NLS are measured with the dynamic contact-angle technique. The x-ray photoelectron spectroscopy (XPS of the OSW reveals that the OSW possesses various reactive functional groups namely hydroxyl groups (OH. Hybrid filler from NLS and OSW were incorporated into carboxylated nitrile rubber (XNBR to produce XNBR hybrid composites. The reaction of OH groups from the OSW with COOH of the XNBR is checked by attenuated total reflectance spectra (ATR-IR of the composites. The degree of curing ΔM (maximum torque-minimum torque as a function of hybrid filler as derived from moving die rheometer (MDR is reported. The stress-strain behavior of the hybrid composites as well as the dynamic mechanical thermal analysis (DMTA is studied. Bonding quality and dispersion of the hybrid filler with and in XNBR are examined using scanning-transmission electron microscopy (STEM in SEM.

  16. Temporal changes in carboxylate content of ryegrass with stepwise change in nutrition

    NARCIS (Netherlands)

    Dijkshoorn, W.; Lathwell, D.J.; Wit, de C.T.

    1968-01-01

    A detailed scheme of carboxylate formation and retention by plant tissues as a result of ion uptake and utilization is given. By means of discontinuities in the supply with nutrient ions, carboxylate retention by the tissues of perennial ryegrass was followed as a function of growth. It was found

  17. Development of technology for fabrication of lithium CPS on basis of CNT-reinforced carboxylic fabric

    Energy Technology Data Exchange (ETDEWEB)

    Tazhibayeva, Irina, E-mail: tazhibayeva@ntsc.kz [Institute of Atomic Energy, National Nuclear Center of RK, Kurchatov (Kazakhstan); Baklanov, Viktor; Ponkratov, Yuriy [Institute of Atomic Energy, National Nuclear Center of RK, Kurchatov (Kazakhstan); Abdullin, Khabibulla [Institute of Experimental and Theoretical Physics of Kazakh National University, Almaty (Kazakhstan); Kulsartov, Timur; Gordienko, Yuriy; Zaurbekova, Zhanna [Institute of Atomic Energy, National Nuclear Center of RK, Kurchatov (Kazakhstan); Lyublinski, Igor [JSC «Red Star», Moscow (Russian Federation); NRNU «MEPhI», Moscow (Russian Federation); Vertkov, Alexey [JSC «Red Star», Moscow (Russian Federation); Skakov, Mazhyn [Institute of Atomic Energy, National Nuclear Center of RK, Kurchatov (Kazakhstan)

    2017-04-15

    Highlights: • Preliminary study of carboxylic fabric wettability with liquid lithium is presented. • Preliminary studies of carboxylic fabric wettability with liquid lithium consist in carrying out of experiments at temperatures 673,773 and 873 К in vacuum during long time. • A scheme of experimental device for manufacturing of lithium CPS and matrix filling procedure with liquid lithium are presented. • The concept of lithium limiter with CPS on basis of CNT-reinforced carboxylic fabric is proposed. - Abstract: The paper describes the analysis of liquid lithium interaction with materials based on carbon, the manufacture technology of capillary-porous system (CPS) matrix on basis of CNT-reinforced carboxylic fabric. Preliminary study of carboxylic fabric wettability with liquid lithium is presented. The development of technology includes: microstructural studies of carboxylic fabric before its CNT-reinforcing; validation of CNT-reinforcing technology; mode validation of CVD-method for CNT synthesize; study of synthesized carbon structures. Preliminary studies of carboxylic fabric wettability with liquid lithium consist in carrying out of experiments at temperatures 673, 773 and 873 К in vacuum during long time. The scheme of experimental device for manufacturing of lithium CPS and matrix filling procedure with liquid lithium are presented. The concept of lithium limiter with CPS on basis of CNT-reinforced carboxylic fabric is proposed.

  18. Vitamin K-dependent carboxylation of matrix gla protein influences the risk of calciphylaxis

    Science.gov (United States)

    Matrix Gla protein (MGP) is a potent inhibitor of vascular calcification. The ability of MGP to inhibit calcification requires the activity of a vitamin K-dependent enzyme, which mediates MGP carboxylation. We investigated how MGP carboxylation influences the risk of calciphylaxis in adult patients ...

  19. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    Science.gov (United States)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  20. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Science.gov (United States)

    2010-07-01

    ... metal salts. 721.4663 Section 721.4663 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under this...

  1. Visible and near-infrared intense luminescence from water-soluble lanthanide [Tb(III), Eu(III), Sm(III), Dy(III), Pr(III), Ho(III), Yb(III), Nd(III), Er(III)] complexes.

    Science.gov (United States)

    Quici, Silvio; Cavazzini, Marco; Marzanni, Giovanni; Accorsi, Gianluca; Armaroli, Nicola; Ventura, Barbara; Barigelletti, Francesco

    2005-02-07

    The synthesis of a new ligand (1) containing a single phenanthroline (phen) chromophore and a flexibly connected diethylenetriamine tetracarboxylic acid unit (DTTA) as a lanthanide (Ln) coordination site is reported [1 is 4-[(9-methyl-1,10-phenantrol-2-yl)methyl]-1,4,7-triazaheptane-1,1,7,7-tetraacetic acid]. From 1, an extended series of water-soluble Ln.1 complexes was obtained, where Ln is Eu(III), Tb(III), Gd(III), Sm(III), Dy(III), Pr(III), Ho(III), Yb(III), Nd(III), and Er(III). The stoichiometry for the association was found 1:1, with an association constant K(A) > or = 10(7) s(-1) as determined by employing luminescence spectroscopy. The luminescence and photophysical properties of the series of lanthanide complexes were investigated in both H2O and D2O solutions. High efficiencies for the sensitized emission, phi(se), in air-equilibrated water were observed for the Ln.1 complexes of Eu(III) and Tb(III) in the visible region (phi(se) = 0.24 and 0.15, respectively) and of Sm(III), Dy(III), Pr(III), Ho(III), Yb(III), Nd(III), and Er(III) in the vis and/or near-infrared region [phi(se) = 2.5 x 10(-3), 5 x 10(-4), 3 x 10(-5), 2 x 10(-5), 2 x 10(-4), 4 x 10(-5), and (in D2O) 4 x 10(-5), respectively]. For Eu.1 and Tb.1, luminescence data for water and deuterated water allowed us to estimate that no solvent molecules (q) are bound to the ion centers (q = 0). Luminescence quenching by oxygen was investigated in selected cases.

  2. AND Dy(III)

    African Journals Online (AJOL)

    userpc

    SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION AND BIOLOGICAL. ACTIVITIES OF Sm(III) AND Dy(III) COMPLEXES WITH SCHIFF BASE DERIVED FROM. 2-HYDROXY-1-NAPHTHALDEHYDE AND 2-AMINOBENZOIC ACID. 1Bashir, S.S. and Abdulhadi, A. 1Department of Chemistry, Rabi'u Musa Kwankwaso ...

  3. Luminescent hybrid lanthanide sulfates and lanthanide sulfonate-carboxylates with 1,10-phenanthroline involving in-situ oxidation of 2-mercaptonbenzoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Jie-Cen [College of Chemistry, Fuzhou University, Fuzhou 350002 (China); Wan, Fang [College of Chemistry, Fuzhou University, Fuzhou 350002 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Sun, Yan-Qiong, E-mail: sunyq@fzu.edu.cn [College of Chemistry, Fuzhou University, Fuzhou 350002 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen, Yi-Ping [College of Chemistry, Fuzhou University, Fuzhou 350002 (China)

    2015-01-15

    A series of lanthanide sulfates and lanthanide sulfonate-carboxylates, [Ln{sub 2}(phen){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O){sub 2}]{sub n} (I:Ln=Nd(1a), Sm(1b), Eu(1c), phen=1,10-phenanthroline) and [Ln(phen)(2-SBA)(BZA)]{sub n} (II: Ln=Sm(2a), Eu(2b), Dy(2c), 2-SBA=2-sulfobenzoate, BZA=benzoate) have been hydrothermally synthesized from lanthanide oxide, 2-mercaptonbenzoic acid with phen as auxiliary ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, TG analyses and luminescence spectroscopy. Interestingly, SO{sub 4}{sup 2−} anions in I came from the in situ deep oxidation of thiol groups of 2-mercaptonbenzoic acid while 2-sulfobenzoate and benzoate ligands in II from the middle oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. Compounds I are organic–inorganic hybrid lanthanide sulfates, which have rare one-dimensional column-like structures. Complexes II are binuclear lanthanide sulfonate-carboxylates with 2-sulfobenzoate and benzoate as bridges and 1,10-phenanthroline as terminal. Photoluminescence studies reveal that complexes I and II exhibit strong lanthanide characteristic emission bands in the solid state at room temperature. - Graphical abstract: Lanthanide sulfates and lanthanide sulfonate-carboxylates have been hydrothermally synthesized. Interestingly, sulfate anions, 2-sulfobenzoate and benzoate ligands came from the in situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. - Highlights: • In situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. • The organic–inorganic hybrid lanthanide sulfates with one-dimensional column-like structure. • The dinuclear lanthanide sulfonate-carboxylates. • The emission spectra exhibit the characteristic transition of {sup 5}D{sub 0}→{sup 7}F{sub J} (J=0–4) of the Eu(III)

  4. Iron(III)–siderophore coordination chemistry: Reactivity of marine siderophores

    OpenAIRE

    Butler, Alison; Theisen, Roslyn M.

    2010-01-01

    Two remarkable features of many siderophores produced by oceanic bacteria are the prevalence of an α-hydroxy-carboxylic acid functionality either in the form of the amino acid β-hydroxy aspartic acid or in the form of citric acid, as well as the predominance of amphiphilic siderophores. This review will provide an overview of the photoreactivity that takes place when siderophores containing β-hydroxy aspartic acid and citric acid are coordinated to iron(III). This photoreactivity raises quest...

  5. Synthesis, crystal structures, luminescent and magnetic properties of homodinuclear lanthanide complexes with a flexible tripodal carboxylate ligand.

    Science.gov (United States)

    Zhang, Ai-Jiang; Wang, Ya-Wen; Dou, Wei; Dong, Ming; Zhang, Yan-Ling; Tang, Yu; Liu, Wei-Sheng; Peng, Yu

    2011-03-28

    Six new homodinuclear lanthanide(III) complexes with a flexible tripodal carboxylate ligand (H(3)L), of formulae [Ln(2)L(2)(DMF)(4)]·4DMF (Ln = La (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), DMF = N, N-Dimethylformamide) have been synthesized. Among them, 1, 2, 3, 4, 6 were characterized by single-crystal X-ray diffraction, which crystallized in the monoclinic space group P2(1)/n with a = 13.309(2) Å, b = 27.404(4) Å, c = 16.686(3) Å, β = 105.115(2) and V = 5875.2(17) Å(3) for 1, a = 13.3016(5) Å, b = 27.1952(12) Å, c = 16.6339(7) Å, β = 105.030(2) and V = 5811.3(4) Å(3) for 2, a = 13.2797(10) Å, b = 27.072(2) Å, c = 16.6564(13) Å, β = 104.9390(10) and V = 5785.7(8) Å(3) for 3, a = 13.2855(3) Å, b = 27.0074(6) Å, c = 16.6357(3) Å, β = 104.9790(10) and V = 5766.2(2) Å(3) for 4, a = 13.2837(5) Å, b = 26.9105(10) Å, c = 16.6066(6) Å, β = 104.917(2) and V = 5736.3(4) Å(3) for 6. The crystal structures reveal that these complexes are isostructural, and molecules are connected from 0D to 3D supramolecular structures by hydrogen bonds. All of them were characterized by elemental analysis, IR spectroscopy, XRD and TGA. Unusually, non-luminescent Tb(III) complex was obtained. The photophysical property of the Eu(III) complex and the magnetic property of Gd(III) complex are investigated and discussed in detail.

  6. catena-Poly[[aqua(4-ethylbenzoic acid-κOlanthanum(III]-tri-μ-4-ethylbenzoato

    Directory of Open Access Journals (Sweden)

    Juan Yang

    2010-02-01

    Full Text Available The reaction of lanthanum nitrate and 4-ethylbenzoic acid (EBAH in aqueous solution yielded the title polymer, [La(C9H9O23(C9H10O2(H2O]n. The asymmetric unit contains one LaIII atom, three 4-ethylbenzoate (EBA ligands, one neutral EBAH ligand and one coordinated water molecule. Each LaIII ion is eight-coordinated by six O atoms from six bridging-bidentate EBA ligands, one O atom from a monodentate EBAH ligand and one water O atom in a distorted bicapped trigonal-prismatic geometry. The adjacent LaIII ions are linked by the carboxylate groups of EBA ligands in a bridging-bidetate coordination mode, resulting in an infinite chain structure along the c axis. O—H...O hydrogen-bonding interactions involving the water molecules, carboxylate groups and carboxyl H atoms are formed within the one-dimensional polymer. One of the ethyl groups is disordered over two positions with occupancies of 0.717 (7 and 0.283 (7.

  7. Dioxygen activation by nonheme iron enzymes with the 2-His-1-carboxylate facial triad that generate high-valent oxoiron oxidants.

    Science.gov (United States)

    Kal, Subhasree; Que, Lawrence

    2017-04-01

    The 2-His-1-carboxylate facial triad is a widely used scaffold to bind the iron center in mononuclear nonheme iron enzymes for activating dioxygen in a variety of oxidative transformations of metabolic significance. Since the 1990s, over a hundred different iron enzymes have been identified to use this platform. This structural motif consists of two histidines and the side chain carboxylate of an aspartate or a glutamate arranged in a facial array that binds iron(II) at the active site. This triad occupies one face of an iron-centered octahedron and makes the opposite face available for the coordination of O2 and, in many cases, substrate, allowing the tailoring of the iron-dioxygen chemistry to carry out a plethora of diverse reactions. Activated dioxygen-derived species involved in the enzyme mechanisms include iron(III)-superoxo, iron(III)-peroxo, and high-valent iron(IV)-oxo intermediates. In this article, we highlight the major crystallographic, spectroscopic, and mechanistic advances of the past 20 years that have significantly enhanced our understanding of the mechanisms of O2 activation and the key roles played by iron-based oxidants.

  8. Synthesis and biological activity of acetates of copper (II and iron (III for the control of Aedes aegypti (Diptera: Culicidae

    Directory of Open Access Journals (Sweden)

    Jéssica V. Nardeli

    2012-06-01

    Full Text Available This work aimed to the synthesis of basic acetates of Cu (II and Fe(III against larvae of Aedes aegypti and Gram negative and Gram positive. The transition metal ions Cu (II and Fe (III have bactericidal activity and are toxic to Aedes aegypti larvae in the eggs and larval stages of initial, precludes the eggs hatch and slow reproductive cycle of the insect. The theme investigates the importance of carboxyl groups in complex formation, transport and cellular internalization of the toxic ions. It is known that the bactericide or insecticide activity is due to metal ions and Cu (IIor Fe (III.

  9. Synthesis, crystal structure and electrochemical and DNA binding studies of oxygen bridged-copper(II) carboxylate

    Science.gov (United States)

    Iqbal, Muhammad; Ali, Saqib; Tahir, Muhammad Nawaz; Muhammad, Niaz; Shah, Naseer Ali; Sohail, Manzar; Pandarinathan, Vedapriya

    2015-08-01

    A new binuclear O-bridged Cu(II) complex with 4-chlorophenyl acetate and 2,2‧-bipyridine has been synthesized and characterized using FT-IR, powder and single crystal XRD and electrochemical solution studies. The results revealed that the two penta-coordinated Cu(II) centers are linked by two carboxylate ligands in end-on bonding fashion. The coordination geometry is slightly distorted square pyramidal (SP) with bridging oxygen atoms occupying the apical position and other ligands lying in the equatorial plane. The striking difference in Cu-O bond distance of the bridging oxygen atom in the complex may be responsible for the SP geometry of Cu(II) ion. The complex gave rise to metal centered irreversible electro-activity where one electron Cu(II)/Cu(III) oxidation process and a single step two electron Cu(II)/Cu(0) reduction process was observed. The redox processes were found predominantly adsorption controlled. The values of diffusion coefficient and heterogeneous rate constant for oxidation process were 6.98 × 10-7 cm2 s-1 and 4.60 × 10-5 cm s-1 while the corresponding values for reduction were 5.30 × 10-8 cm2 s-1 and 5.41 × 10-6 cm s-1, respectively. The formal potential and charge transfer coefficient were also calculated. The DNA-binding ability was explored through cyclic voltammetry and UV-Visible spectroscopy. Diminution in the value of Do for oxidation indicated the binding of the complex with DNA corresponding to Kb = 8.58 × 104 M-1. UV-Visible spectroscopy yielded ε = 49 L mol-1 cm-1 and Kb = 2.96 × 104 M-1. The data of both techniques support each other. The self-induced redox activation of the complex, as indicated by cyclic voltammetry heralds its potential applications in redox catalysis and anticancer activity.

  10. Thermal stability of carboxylic acid functionality in coal; Sekitanchu ni sonzaisuru karubokishiruki no netsubunkai kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsumi, Y.; Aida, T. [Kinki University, Osaka (Japan). Faculty of Engineering

    1996-10-28

    Carboxyl in coal was focused in discussing its pyrolytic behavior while tracking change of its absolute amount relative to the heating temperatures. A total of four kinds of coals, consisting of two kinds brown coals, sub-bituminous coal and bituminous coal were used. Change in the absolute amount of carboxyl due to heating varies with coalification degree. Decomposition starts in the bituminous coal from around 300{degree}C, and is rapidly accelerated when 400{degree}C is exceeded. Carboxyls in brown coals exist two to three times as much as those in bituminous and sub-bituminous coals, of which 40% is decomposed at a temperature as low as about 300{degree}C. Their pyrolytic behavior at temperatures higher than 400{degree}C resembles that of the bituminous coal. Carboxyls consist of those easy to decompose and difficult to decompose. Aromatic and aliphatic carboxylic acids with simple structure are stable at temperatures lower than 300{degree}C, and decompose abruptly from about 400{degree}C, hence their behavior resembles that of carboxyls in bituminous and sub-bituminous coals. Structure of low-temperature decomposing carboxyls in brown coals is not known, but it is assumed that humic acid originated from natural materials remains in the structure. 4 refs., 3 figs., 1 tab.

  11. NNDSS - Table III. Tuberculosis

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table III. Tuberculosis - 2017.This Table includes total number of cases reported in the United States, by region and by states, in accordance with the...

  12. Pseudo Class III malocclusion

    National Research Council Canada - National Science Library

    Al-Hummayani, Fadia M

    2016-01-01

    .... This case report represents a none traditional treatment modality to treat deep anterior crossbite in an adult pseudo class III malocclusion complicated by severely retruded, supraerupted upper and lower incisors...

  13. Synthesis and photoluminescence properties of cerium-doped terbium-yttrium aluminum garnet phosphor for white light-emitting diodes applications

    Science.gov (United States)

    Wang, Jun; Han, Tao; Lang, Tianchun; Tu, Mingjing; Peng, Lingling

    2015-11-01

    Cerium-doped terbium-yttrium aluminum garnet phosphors were synthesized using the solid-state reaction method. The crystalline phase, morphology, and photoluminescence properties were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), and fluorescence spectrophotometer, respectively. The XRD results indicate that with an increase of the amount of x (Tb3+), all of the samples have a pure garnet crystal structure without secondary phases. The SEM images reveal that the samples are composed of sphere-like crystallites, which exhibit different degrees of agglomeration. The luminescent properties of Ce ions in )Al5O12∶Ce0.1 have been studied, and it was found that the emission band shifted toward a longer wavelength. The redshift is attributed to the lowering of the 5d energy level centroid of Ce, which can be explained by the nephelauxetic effect and compression effect. These phosphors were coated on blue light-emitting diode (LED) chips to fabricate white light-emitting diodes (WLEDs), and their color-rendering indices, color temperatures, and luminous efficiencies were measured. As a consequence of the addition of Tb, the blue LED pumped )Al5O12∶Ce0.1 phosphors WLEDs showed good optical properties.

  14. Study on the fluorescent enhancement effect in terbium-gadolinium-protein-sodium dodecyl benzene sulfonate system and its application on sensitive detection of protein at nanogram level.

    Science.gov (United States)

    Sun, Changxia; Yang, Jinghe; Wu, Xia; Liu, Shufang; Su, Benyu

    2004-08-01

    The co-luminescence effect in a terbium-gadolinium-protein-sodium dodecyl benzene sulfonate (SDBS) system is reported here. Based on it, the sensitive quantitative analysis of protein at nanogram levels is established. The co-luminescence mechanism is studied using fluorescence, resonance light scattering (RLS), absorption spectroscopy and NMR measurement. It is considered that protein could be unfolded by SDBS, then a efficacious intramolecular fluorescent energy transfer occurs from unfolded protein to rare earth ions through SDBS acting as a "transfer bridge" to enhance the emission fluorescence of Tb3+ in this ternary complex of Tb-SDBS-BSA, where energy transfer from protein to SDBS by aromatic ring stacking is the most important step. Cooperating with the intramolecular energy transfer above is the intermolecular energy transfer between the simultaneous existing complexes of both Tb3+ and Gd3+. The fluorescence quantum yield is increased by an energy-insulating sheath, which is considered to be another reason for the resulting enhancement of the fluorescence. Förster theory is used to calculate the distribution of enhancing factors and has led to a greater understanding of the mechanisms of energy transfer.

  15. Coordination modes of bridge carboxylates in dinuclear manganese compounds determine their catalase-like activities.

    Science.gov (United States)

    Jiang, Xiaojun; Liu, Hui; Zheng, Bing; Zhang, Jingyan

    2009-10-28

    To explore the role of bridge carboxylate coordination modes on the catalase-like activities of dinuclear manganese compounds, [Mn(II)2(bpmapa)2(H2O)2](ClO4)2 (1), [Mn(II)2(pbpmapa)2(H2O)2](ClO4)2 (2), and [Mn(II)2(bpmaa)2(H2O)3](ClO4)2 (3) (bpmapa = [bis(2-pyridylmethyl)amino]propionic acid, pbpmapa = alpha-phenyl-beta-[bis(2-pyridylmethyl)amino]propionic acid, and bpmaa = [bis(2-pyridylmethyl)amino]acetic acid), in which Mn(II)-Mn(II) centers have a similar coordination sphere but different carboxylate-Mn bridging modes have been synthesized and structurally characterized by single X-ray diffraction, UV-visible, IR, and EPR spectroscopies, and their catalase-like activities were investigated. Studies of their catalytic activities and the influence of the nitrogenous bases on their catalytic activities indicated that the carboxylate-Mn coordination mode was crucial in H2O2 deprotonation, and eventually in H2O2 disproportionation. Compound 1 with a bidentate carboxylate bridge showed higher catalase-like activity than 2 and 3, in which the carboxylate groups have a monodentate bridging mode. The deprotonation ability of the carboxylate anion was determined by the O-C-O angle and the distance between the weakly bound oxygen of the bridging carboxylate to the manganese ion. The smaller the angle, and the shorter the distance, the stronger the basicity that the carboxylate anion exhibits. The bidentate mu-1,1 bridging coordination mode functionally mimicked the glutamate residues at the manganese catalase active site. Our results suggested that increasing the basicity of the bridging carboxylate ligand of the catalase model compounds will increase their deprotonation ability and lead to more active catalase mimics.

  16. Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors

    Science.gov (United States)

    Uznanski, Pawel; Zakrzewska, Joanna; Favier, Frederic; Kazmierski, Slawomir; Bryszewska, Ewa

    2017-03-01

    A comparative study of amine and silver carboxylate adducts [R1COOAg-2(R2NH2)] (R1 = 1, 7, 11; R2 = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, 13C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies (1H and 13C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism.

  17. Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors

    Energy Technology Data Exchange (ETDEWEB)

    Uznanski, Pawel, E-mail: puznansk@cbmm.lodz.pl; Zakrzewska, Joanna [Centre of Molecular and Macromolecular Studies, PAS (Poland); Favier, Frederic, E-mail: fredf@univ-montp2.fr [Université Montpellier II, ICGM - UMR5253- Equipe AIME (France); Kazmierski, Slawomir; Bryszewska, Ewa [Centre of Molecular and Macromolecular Studies, PAS (Poland)

    2017-03-15

    A comparative study of amine and silver carboxylate adducts [R{sub 1}COOAg-2(R{sub 2}NH{sub 2})] (R{sub 1} = 1, 7, 11; R{sub 2} = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, {sup 13}C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies ({sup 1}H and {sup 13}C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism.

  18. Photophysics of indole-2-carboxylic acid (I2C) and indole-5-carboxylic acid (I5C): heavy atom effect.

    Science.gov (United States)

    Kowalska-Baron, Agnieszka; Gałęcki, Krystian; Wysocki, Stanisław

    2013-12-01

    In this study the effect of carboxylic group substitution in the 2 and 5 position of indole ring on the photophysics of the parent indole chromophore has been studied. The photophysical parameters crucial in triplet state decay mechanism of aqueous indole-2-carboxylic acid (I2C) and indole-5-carboxylic acid (I5C) have been determined applying our previously proposed methodology based on the heavy atom effect and fluorescence and phosphorescence decay kinetics [Kowalska-Baron et al., 2012]. The determined time-resolved phosphorescence spectra of I2C and I5C are red-shifted as compared to that of the parent indole. This red-shift was especially evident in the case of I2C and may indicate the possibility of hydrogen bonded complex formation incorporating carbonyl CO, the NH group of I2C and, possibly, surrounding water molecules. The possibility of the excited state charge transfer process and the subsequent electronic charge redistribution in such a hydrogen bonded complex may also be postulated. The resulting stabilization of the I2C triplet state is manifested by its relatively long phosphorescence lifetime in aqueous solution (912 μs). The relatively short phosphorescence lifetime of I5C (56 μs) may be the consequence of more effective ground-state quenching of I5 C triplet state. This hypothesis may be strengthened by the significantly larger value of the determined rate constant of I5C triplet state quenching by its ground-state (4.4 × 10(8)M(-1)s(-1)) as compared to that for indole (6.8 × 10(7)M(-1)s(-1)) and I2C (2.3 × 10(7)M(-1)s(-1)). The determined bimolecular rate constant for triplet state quenching by iodide [Formula: see text] is equal to 1 × 10(4)M(-1)s(-1); 6 × 10(3)M(-1)s(-1) and 2.7 × 10(4)M(-1)s(-1) for indole, I2 C and I5 C, respectively. In order to obtain a better insight into iodide quenching of I2C and I5C triplet states in aqueous solution, the temperature dependence of the bimolecular rate constants for iodide quenching of the

  19. Photophysics of indole-2-carboxylic acid (I2C) and indole-5-carboxylic acid (I5C): Heavy atom effect

    Science.gov (United States)

    Kowalska-Baron, Agnieszka; Gałęcki, Krystian; Wysocki, Stanisław

    2013-12-01

    In this study the effect of carboxylic group substitution in the 2 and 5 position of indole ring on the photophysics of the parent indole chromophore has been studied. The photophysical parameters crucial in triplet state decay mechanism of aqueous indole-2-carboxylic acid (I2C) and indole-5-carboxylic acid (I5C) have been determined applying our previously proposed methodology based on the heavy atom effect and fluorescence and phosphorescence decay kinetics [Kowalska-Baron et al., 2012]. The determined time-resolved phosphorescence spectra of I2C and I5C are red-shifted as compared to that of the parent indole. This red-shift was especially evident in the case of I2C and may indicate the possibility of hydrogen bonded complex formation incorporating carbonyl Cdbnd O, the NH group of I2C and, possibly, surrounding water molecules. The possibility of the excited state charge transfer process and the subsequent electronic charge redistribution in such a hydrogen bonded complex may also be postulated. The resulting stabilization of the I2C triplet state is manifested by its relatively long phosphorescence lifetime in aqueous solution (912 μs). The relatively short phosphorescence lifetime of I5C (56 μs) may be the consequence of more effective ground-state quenching of I5C triplet state. This hypothesis may be strengthened by the significantly larger value of the determined rate constant of I5C triplet state quenching by its ground-state (4.4 × 108 M-1 s-1) as compared to that for indole (6.8 × 107 M-1 s-1) and I2C (2.3 × 107 M-1 s-1). The determined bimolecular rate constant for triplet state quenching by iodide kqT1 is equal to 1 × 104 M-1 s-1; 6 × 103 M-1 s-1 and 2.7 × 104 M-1 s-1 for indole, I2C and I5C, respectively. In order to obtain a better insight into iodide quenching of I2C and I5C triplet states in aqueous solution, the temperature dependence of the bimolecular rate constants for iodide quenching of the triplet states has been expressed in

  20. Remote carboxylation of halogenated aliphatic hydrocarbons with carbon dioxide

    Science.gov (United States)

    Juliá-Hernández, Francisco; Moragas, Toni; Cornella, Josep; Martin, Ruben

    2017-05-01

    Catalytic carbon-carbon bond formation has enabled the streamlining of synthetic routes when assembling complex molecules. It is particularly important when incorporating saturated hydrocarbons, which are common motifs in petrochemicals and biologically relevant molecules. However, cross-coupling methods that involve alkyl electrophiles result in catalytic bond formation only at specific and previously functionalized sites. Here we describe a catalytic method that is capable of promoting carboxylation reactions at remote and unfunctionalized aliphatic sites with carbon dioxide at atmospheric pressure. The reaction occurs via selective migration of the catalyst along the hydrocarbon side-chain with excellent regio- and chemoselectivity, representing a remarkable reactivity relay when compared with classical cross-coupling reactions. Our results demonstrate that site-selectivity can be switched and controlled, enabling the functionalization of less-reactive positions in the presence of a priori more reactive ones. Furthermore, we show that raw materials obtained in bulk from petroleum processing, such as alkanes and unrefined mixtures of olefins, can be used as substrates. This offers an opportunity to integrate a catalytic platform en route to valuable fatty acids by transforming petroleum-derived feedstocks directly.

  1. nematicidal carboxylic acids and aldehydes from Melia azedarach fruits.

    Science.gov (United States)

    Ntalli, Nikoletta G; Vargiu, Simona; Menkissoglu-Spiroudi, Urania; Caboni, Pierluigi

    2010-11-10

    Melia azedarach is a species gaining scientific interest mostly concerning its range of biological activities against agricultural target pests. The nematicidal melia methanol extract (MME) obtained from the fruits, acting against the phytonematode Meloidogyne incognita , is herein reported to contain hexadecanoic, acetic, and hexanoic acids as well as furfural, 5-hydroxymethylfurfural, 5-methylfurfural, and furfurol. All compounds were tested individually for nematicidal activity against the nematode second-stage juveniles, in paralysis experiments. The nematicidal activity was studied both after nematodes' immersion in treatment solutions and after exposure to test substance vapors. Clear dose and time response relationships were established at the dose ranges of 31.2-500 and 1-100 μg/mL, concerning the aldehydes and carboxylic acids, respectively, implementing analogous predominance of nematicidal activity. Nevertheless, no synergistic effects were observed in respective mixture interaction bioassays among furfural, 5-hydroxymethylfurfural, 5-methylfurfural, and furfurol. Furfural was the most active bionematicidal compound reported herein for the first time as a natural constituent of M. azedarach.

  2. Effects of Carboxylates on the Performance of Zn Electrode

    Directory of Open Access Journals (Sweden)

    Yongli Li

    2016-07-01

    Full Text Available Zinc is widely used as a negative electrode material for batteries due to its excellent electrochemical properties. Zinc is prone to corrosion and the formation of zinc dendrites cause short circuits of the battery, which leads to reduced battery capacity and shortens the battery’s life, hindering its use in weak acidic electrolytes (for example, aqueous Zn-polyaniline batteries. The effects of carboxylates (sodium formate, sodium acetate, sodium propionate, sodium butyrate, sodium valerate, disodium malonate, and disodium succinate and their concentrations on zinc electrode performance were studied with electrochemical methods to improve the zinc electrode activity for long-life Zn-polyaniline batteries. It was found that the ability of inhibiting corrosion of the zinc electrode is better in the aqueous electrolyte containing 0.2 M disodium malonate. The charge/discharge performance of a Zn-polyaniline battery electrodeposited with polyaniline on a carbon substrate is carried out in the aqueous electrolyte. the results show that the initial discharge specific capacity of the polyaniline in the Zn-polyaniline battery is as high as 131.1 mAh·g−1, and maintains a discharge specific capacity of 114.8 mAh·g−1 and a coulombic efficiency over 92% after 100 cycles at a charge/discharge current density of 1 A·g−1 in the voltage range of 1.5–0.7 V.

  3. Biohydrogen and carboxylic acids production from wheat straw hydrolysate.

    Science.gov (United States)

    Chandolias, Konstantinos; Pardaev, Sindor; Taherzadeh, Mohammad J

    2016-09-01

    Hydrolyzed wheat straw was converted into carboxylic acids and biohydrogen using digesting bacteria. The fermentations were carried out using both free and membrane-encased thermophilic bacteria (55°C) at various OLRs (4.42-17.95g COD/L.d), in semi-continuous conditions using one or two bioreactors in a series. The highest production of biohydrogen and acetic acid was achieved at an OLR of 4.42g COD/L.d, whilst the highest lactic acid production occurred at an OLR of 9.33g COD/L.d. Furthermore, the bioreactor with both free and membrane-encased cells produced 60% more lactic acid compared to the conventional, free-cell bioreactor. In addition, an increase of 121% and 100% in the production of acetic and isobutyric acid, respectively, was achieved in the 2nd-stage bioreactor compared to the 1st-stage bioreactor. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Structural and thermal properties of carboxylic acid functionalized polythiophenes

    Directory of Open Access Journals (Sweden)

    Ariane de França Mescoloto

    2014-01-01

    Full Text Available Polythiophenes functionalized with polar groups at the end of side-chain have emerged as an alternative method to obtain good compatibility between this class of conjugated polymers and electron acceptor compounds. The aim is to prevent phase segregation and to improve the efficiency of the polythiophene technological devices. However, homopolymers synthesized from thiophene rings with high polar groups at the end of the side-chain, such as hydroxyl and carboxylic acid groups, are poorly soluble in common volatile organic solvents. We report on a systematic preparation of copolymers of 3-hexylthiophene (HT and thiophene-3-acetic acid (TAA, using different feed ratios. The chemical structures of the copolymers were confirmed by FTIR and ¹H-NMR. The TAA content in these copolymers were 33, 38 and 54 mol %. HPSEC results did not show any remarkable correlation with TAA contents in the copolymers. In contrast, the thermal analyses showed a decrease in the thermal stability and an increase in rigidity of their backbones, for the copolymers with high amounts of TAA. The solubility and optical property of copolymers were also related to the TAA contents. Thus, the properties of these copolymers can be modulated by a simple control of feed ratio of TAA in the copolymerization.

  5. Electrosynthesis and comparative studies on carboxyl-functionalized polythiophene derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Toth, Peter S.; Janaky, Csaba; Hiezl, Zoltan [Department of Physical Chemistry and Materials Science, University of Szeged, Aradi V. Sq. 1., Szeged H-6720 (Hungary); Visy, Csaba, E-mail: visy@chem.u-szeged.h [Department of Physical Chemistry and Materials Science, University of Szeged, Aradi V. Sq. 1., Szeged H-6720 (Hungary)

    2011-04-01

    Electrochemical synthesis of a novel carboxylic acid functionalized polythiophene - poly(3-thiophene-butyric-acid), PTBA - has been realized. Its morphology, electrochemical, spectral and conducting properties have been compared to those of poly(3-thiophene-acetic-acid), PTAA, which is widely used to immobilise both bioactive molecules and inorganic nanoparticles. According to scanning electron microscopic (SEM) images, the difference in the real and geometric surface area of the modified electrodes is much more expressed in the case of PTBA. Both the symmetry of the cyclic voltammograms and the concurrent, sustained optical changes proved that this polymer possesses an improved and more stable redox activity. According to simultaneously performed in situ ac. impedance and UV-Vis measurements, both films could be uniformly transformed between the insulating and conducting forms, but PTAA exhibited some degradation. The development of the conducting state during the redox switching of both thiophene derivative polymers proved to be primarily connected to the formation of di-cationic species. The electrochemical quartz crystal microbalance (EQCM) results evidenced also differences between the two polymers, which difference can be interpreted by assuming the more expressed effect of the deprotonation-connected (self-) doping process in PTAA. The results confirm that the new conducting polymer, PTBA is much more convenient for being considered as the polymer matrix of practically applicable composites.

  6. Preparation and evaluation of some amide ether carboxylate surfactants

    Directory of Open Access Journals (Sweden)

    M.M.A. El-Sukkary

    2012-06-01

    Full Text Available A homologous series of new mild surfactants, namely: Alkyl amide ether carboxylates surfactants (AEC RCO–NHCH2CH2O (CH2CH2O6CH2COONa, were synthesized by esterification, amidation, ethoxylation and carboxymethylation reaction steps of fatty acids (Lauric, Myristic, palmitic, stearic, oleic or linoleic. The chemical structures of the prepared compounds were confirmed using different spectroscopic techniques, FTIR spectroscopy, mass spectra and HNMR. The surface properties including surface and interfacial tensions, foaming height, emulsification power, calcium ion stability, stability to hydrolysis and critical micelle concentration (cmc were determined. The study of their surface properties showed their stability in hard water and in acidic and alkaline media. These compounds have high calcium ion stability. The low foaming power could have an application in the dyeing auxiliary industry. The lower values of the interfacial tension values indicate the ability of using these surfactants in several applications as corrosion inhibitors and biocides. The data revealed various advantages and potentials as a main surfactant as well as co- surfactants.

  7. Synthetic routes to ruthenium (ii) species containing carboxylate-functionalized 2,2`-bipyridine ligands

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, T.; Patterson, A.; Keene, F.R. [James Cook University, Townsville, QLD (Australia). School of Biomedical and Molecular Sciences

    1998-12-31

    Two methods are reported for the incorporation of carboxylate substituents on polypyridyl ligands coordinated to ruthenium(ll) centres. In the first, a precursor complex is synthesized with ethoxycarbonyl groups which are subsequently base-hydrolysed to produce the carboxylate in high yield (-CO{sub 2}Et{yields} -CO{sub 2}H). In the second method, ruthenyl species were used to chemically catalyse the electochemical oxidation of methyl substituents on the ligands of a precursor complex to produce the target carboxylate species (-CH{sub 3} {yields} -CO{sub 2}H). Copyright (1998) CSIRO Australia 21 refs., 1 tab., 1 fig.

  8. A solid state and solution NMR study of the tautomerism in hydroxyquinoline carboxylic acids.

    Science.gov (United States)

    Gudat, Dietrich; Nycz, Jacek E; Polanski, Jaroslaw

    2008-01-01

    Some hydroxyquinoline carboxylic acids and their conjugate acids and bases were characterized by 13C and 15N NMR spectroscopy in solution and in the solid state. Differences in 13C and, in particular, 15N chemical shift patterns allow to distinguish between individual tautomers and confirm the presence of zwitterionic species in the solid state. Solution NMR spectra in dimethyl sulfoxide (DMSO) show effects resulting as a consequence of dynamic exchange and suggest the presence of an equilibrium mixture of hydroxyquinoline carboxylic acid and zwitterionic hydroxyquinolinium carboxylate tautomers.

  9. Carboxylated Capped Carbon Nanotubes Interacting with Nimesulide Molecules: Applied Electric Fields Effects

    Directory of Open Access Journals (Sweden)

    Vivian Machado de Menezes

    2015-01-01

    Full Text Available Interactions of carboxylated capped carbon nanotubes with nimesulide molecules under electric fields were investigated by ab initio simulations. Repulsive forces between the nimesulide molecules and the carboxyl group of the carbon nanotubes, except for the nimesulide radical configuration, were observed. To keep the original molecule in the pristine form, electric fields with different intensities were applied, where changes in the behavior of the interactions between the molecules were noticed. It was shown that the intensity of the interaction between the nimesulide and the hydrophilic carboxylated capped carbon nanotube can be modulated by the action of the external electric fields making promising systems for drug delivery applications.

  10. Chiral metal-organic frameworks bearing free carboxylic acids for organocatalyst encapsulation.

    Science.gov (United States)

    Liu, Yan; Xi, Xiaobing; Ye, Chengcheng; Gong, Tengfei; Yang, Zhiwei; Cui, Yong

    2014-12-08

    Two chiral carboxylic acid functionalized micro- and mesoporous metal-organic frameworks (MOFs) are constructed by the stepwise assembly of triple-stranded heptametallic helicates with six carboxylic acid groups. The mesoporous MOF with permanent porosity functions as a host for encapsulation of an enantiopure organic amine catalyst by combining carboxylic acids and chiral amines in situ through acid-base interactions. The organocatalyst-loaded framework is shown to be an efficient and recyclable heterogeneous catalyst for the asymmetric direct aldol reactions with significantly enhanced stereoselectivity in relative to the homogeneous organocatalyst. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Ligand Torsion Triggered Two Robust Fe-Tetratopic Carboxylate Frameworks with Enhanced Gas Uptake and Separation Performance.

    Science.gov (United States)

    Zhang, Jian-Wei; Hu, Man-Cheng; Li, Shu-Ni; Jiang, Yu-Cheng; Zhai, Quan-Guo

    2017-05-11

    By regulating the tetratopic carboxylate ligands, two robust Fe-MOFs (MOF=Metal-organic framework) comprising trigonal prismatic building blocks under a DMA/DMSO/HBF4 solvent system, namely, [(CH3 )2 NH2 ][Fe(II)3 (OH)(BPTC)1.5 (DMSO)3 ] (SNNU-60) and [Fe(III) Fe(II)2 (OH)(ABTC)1.5 (DMSO)3 ] (SNNU-61) (BPTC=3,3',5,5'-biphenyltetracarboxylic acid, ABTC=3,3',5,5'-azobenzenetetracarboxylic acid, SNNU=Shaanxi Normal University) have been successfully synthesized. The torsions between the benzene groups of the ligands result in two MOFs exhibiting completely different (4,6)-connected frameworks, which represent the only two MOF types constructed by [M3 (O/OH)(COO)6 ] trimeric building units and quadrilateral tetratopic carboxylate linkers until now. The robust Fe-MOFs SNNU-60 and SNNU-61 both exhibit high thermal/chemical stability, permanent microporosity, and excellent gas uptake capability for H2 , CO2 , C2 H2 , and C2 H4 under 1 bar. SNNU-60 in particular displays very high C2 H2 capture under low pressure (85 cm(3)  cm(-3) at 0.15 bar and 298 K), which is among the top C2 H2 uptake MOF materials. Also, these two Fe-MOFs display high separation for CO2 and C2 -hydrocarbons over CH4 . Significantly, thanks to the high stability, suitable pore size, open Fe sites, and ion skeleton, SNNU-60 has extremely high C2 H2 /CH4 selectivity (83.6, 298 K), which surpasses most MOFs reported so far under the same conditions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Second-sphere tethering of rare-earth ions to cucurbit[6]uril by iminodiacetic acid involving carboxylic group encapsulation.

    Science.gov (United States)

    Thuéry, Pierre

    2010-10-04

    The reaction of rare-earth nitrates with iminodiacetic acid (H(2)IDA) in the presence of cucurbit[6]uril (CB6) in water at room temperature yields a family of isomorphous complexes, [M(H(2)IDA)(NO(3))(H(2)O)(6)](NO(3))(2)·CB6·14H(2)O with M = Y (1), Ce (2), Nd (3), Eu (4), Dy (5), Er (6), Tm (7), and Yb (8). In these compounds, the trivalent metal ion is bound to one nitrate ion, six water molecules, and one zwitterionic H(2)IDA molecule. The latter is further partly included in the CB6 cavity, with the ammonium group forming two hydrogen bonds with oxygen atoms of one portal. The uncoordinated carboxylic group is thus encapsulated in CB6 and hydrogen-bonded to the other portal via a water molecule. CB6 is a second-sphere ligand in these complexes, but direct bonding of the metal ion to CB6 can be enforced by using a ligand more deeply imbedded in the cavity, such as 2-pyridylacetate (PA) in [Eu(PA)(CB6)(NO(3))(H(2)O)(5)](NO(3))·10H(2)O (11). When the reaction with H(2)IDA is performed with Lu(III) or Cu(II), no metal complex is isolated, but the inclusion compounds [(H(3)IDA)(2)(CB6)](NO(3))(2)·xH(2)O with x = 6 (9) or 8 (10) are obtained instead, in which the two H(3)IDA(+) cations are attached to the CB6 portals by ammonium-carbonyl hydrogen bonds and are linked to one another inside the cavity by hydrogen bonding between the carboxylic groups. These complexes are compared to that comprising a dicarboxylic acid devoid of an ammonium functionality, [(H(2)AZ)(CB6)]·6H(2)O (12), where H(2)AZ is azelaic acid. The metal ion complexes 1-8 and the organic complexes 9 and 10 display the unprecedented feature of inclusion of carboxylic groups inside the CB6 cavity, with the CB6/acid stoichiometry and the finer details of the host-guest interactions being dependent on the presence of the metal ion.

  13. r-VKORC1 expression in factor IX BHK cells increases factor IX carboxylation but is limited by saturation of another carboxylation component or by a shift in the rate limiting step†

    Science.gov (United States)

    Hallgren, Kevin W.; Qian, Wen; Yakubenko, Anna V.; Runge, Kurt W.; Berkner, Kathleen L.

    2008-01-01

    Carboxylation of vitamin K-dependent (VKD) proteins is required for their activity and depends upon reduced vitamin K generated by vitamin K oxidoreductase (VKOR) and a redox protein that regenerates VKOR activity. VKD protein carboxylation is inefficient in mammalian cells, and to understand why carboxylation becomes saturated we developed an approach that directly measures intracellular VKD protein carboxylation. Analysis of factor IX (fIX)-expressing BHK cells indicated that slow fIX egress from the endoplasmic reticulum and preferential secretion of the carboxylated form contribute to secreted fIX being more fully-carboxylated. The analysis also revealed the first reported in vivo VKD protein turnover, which was 14-fold faster than occurs in vitro, suggesting facilitation of this process in vivo. r-VKORC1 expression increased the rate of fIX carboxylation and extent of carboxylated fIX ~2-fold, which shows that carboxylation is the rate-limiting step in fIX turnover and which was surprising because turnover in vitro is limited by release of carboxylated fIX. Interestingly, the increases were significantly less than the amount of VKOR overexpression (15-fold). However, when cell extracts were tested in single turnover experiments in vitro, where redox protein is functionally substituted by dithiothreitol, VKOR overexpression increased the fIX carboxylation rate 14-fold, showing r-VKORC1 is functional for supporting fIX carboxylation. These data indicate that the effect of VKOR overexpression is limited in vivo, possibly because a carboxylation component like the redox protein becomes saturated or because another step is now rate-limiting. The studies illustrate the complexity of carboxylation and potential importance of component stoichiometry to overall efficiency. PMID:16634640

  14. Sodium borohydride reduction of aromatic carboxylic acids via ...

    Indian Academy of Sciences (India)

    Unknown

    C J, Jung S H, Kishi Y, Matelich M C, Ireland R E,. Armstrong J D III, Lebreton J, Meissner R S and. Rizzacasa M A 1993 J. Am. Chem. Soc. 115 7152. 12. Brown H C and Subba Rao B C 1955 J. Am. Chem. Soc. 77 3164. 13. Guida W C, Entreken E E and Guida A R 1984 J. Org. Chem. 49 3024. 14. Daluge S M, Martin M T, ...

  15. Water-Soluble and Highly Luminescent Europium(III) Complexes with Favorable Photostability and Sensitive pH Response Behavior.

    Science.gov (United States)

    Wei, Chen; Wei, Huibo; Yan, Weibo; Zhao, Zifeng; Cai, Zelun; Sun, Boxun; Meng, Zhaosha; Liu, Zhiwei; Bian, Zuqiang; Huang, Chunhui

    2016-10-17

    Two highly luminescent and water-soluble Eu(III) complexes, Eu1 and Eu2, based on novel carboxyl-functionalized 1,5-naphthyridine derivatives 8-hydroxy-1,5-naphthyridine-2-carboxylic acid (H2L1) and 7-cyano-8-hydroxy-1,5-naphthyridine-2-carboxylic acid (H2L2), respectively, are designed and synthesized. The crystal structure of Eu2 indicates that the central Eu(III) ion is nine-coordinated by three tridentate ligands (O^N^O). Both Eu1 and Eu2 show strong luminescence in aqueous solution with quantum yields (lifetimes) of 28% (1.1 ms) and 14% (0.76 ms), respectively. The chelates display unique UV-light stability in solution and remain highly emissive after 100 min of strong UV irradiation (∼300 W·m-2 at 345 nm). Moreover, they exhibit reversible luminescence intensity changes with varied pH values, and the response mechanism is investigated. "Turn-on" of the Eu(III) emission upon increasing pH is realized by ligand structure change from keto to enol anion form, resulting in red-shifted absorption band and suppressed quenching from solvents and N-H vibration upon deprotonating. The results show that these novel Eu(III) complexes are quite intriguing for potential application as bioimaging agents and pH probes.

  16. Quantum chemical investigation of the thermal pyrolysis reactions of the carboxylic group in a brown coal model.

    Science.gov (United States)

    Liu, Shengyu; Zhang, Zhiqiang; Wang, Huifang

    2012-01-01

    Different reaction pathways of the carboxylic group in a brown coal model were investigated by applying density function quantum chemical theory, examining the possible cross-linking and decomposition reactions between the hydrogen bonded carboxylic group-carboxylic group and the carboxylic group-hydroxyl group during the thermal pyrolysis process. The results show that bimolecular dehydration and decarboxylation of hydrogen bonded carboxylic groups have distinctly lower activation barriers and therefore, proceed preferentially at low temperature. The esterification reaction between the hydrogen bonded carboxylic group and hydroxyl group, together with unimolecular decarboxylation of isolated single carboxylic groups were also possible at moderate temperature. Aryl-aryl coupling is thought to occur via radical pyrolysis and recombination at relatively high temperature.

  17. Plastic scintillators with high loading of one or more metal carboxylates

    Science.gov (United States)

    Cherepy, Nerine; Sanner, Robert Dean

    2016-01-12

    In one embodiment, a material includes at least one metal compound incorporated into a polymeric matrix, where the metal compound includes a metal and one or more carboxylate ligands, where at least one of the one or more carboxylate ligands includes a tertiary butyl group, and where the material is optically transparent. In another embodiment, a method includes: processing pulse traces corresponding to light pulses from a scintillator material; and outputting a result of the processing, where the scintillator material comprises at least one metal compound incorporated into a polymeric matrix, the at least one metal compound including a metal and one or more carboxylate ligands, where at least one of the one or more carboxylate ligands has a tertiary butyl group, and where the scintillator material is optically transparent and has an energy resolution at 662 keV of less than about 20%.

  18. Enrichment of Nanodiamond Surfaces with Carboxyl Groups for Doxorubicin Loading and Release

    Science.gov (United States)

    Astuti, Y.; Saputra, F. D.; Wuning, S.; Arnelli; Bhaduri, G.

    2017-02-01

    In their pristine state, nanodiamond crystals produced via detonation techniques containing several functional groups present on the surface including amine, amide, alcohol, carbonyl, and carboxyl. These functional groups facilitate nanodiamond to interact drugs so as to nanodiamond is potential for medical application such as drug delivery. Even though research on t he use of nanodiamond for this application has been conducted widely, research on the effect of enrichment of nanodiamond surface with carboxyl functional groups for drug loading and release has not been explored extensively. Therefore, in this paper, the effect of carboxyl-terminated nanodiamond (ND-COOH) on drug loading and release will be presented. The enrichment of nanodiamond with carboxyl groups was undertaken by treating nanodiamond with sulphuric acid and nitric acid. The results show that the doxorubicin (DOX) loading and release efficiencies of ND pristine are higher than that of ND-COOH.

  19. Pyrazole carboxamides and carboxylic acids as protein kinase inhibitors in aberrant eukaryotic signal transduction

    DEFF Research Database (Denmark)

    Persson, Tobias; Yde, Christina W.; Rasmussen, Jakob Ewald

    2007-01-01

    Densely functionalised pyrazole carboxamides and carboxylic acids were synthesised in an expedient manner through saponification and transamidation, respectively, of ester-functionalised pyrazoles. This synthetic protocol allowed for three diversifying steps in which appendages on the pyrazole sc...

  20. Simple and Convenient Synthesis of Esters from Carboxylic Acids and Alkyl Halides Using Tetrabutylammonium Fluoride

    National Research Council Canada - National Science Library

    Matsumoto, Kouichi; Shimazaki, Hayato; Miyamoto, Yu; Shimada, Kazuaki; Haga, Fumi; Yamada, Yuki; Miyazawa, Hirotsugu; Nishiwaki, Keiji; Kashimura, Shigenori

    2014-01-01

    A simple and convenient method has been developed for the synthesis of esters from the corresponding carboxylic acids and alkyl halides by using a stoichiometric amount of tetrabutylammonium fluoride (Bu4NF) as the base...

  1. Preferential Interaction of Na+ over K+ to Carboxylate-functionalized Silver Nanoparticles

    Science.gov (United States)

    Elucidating mechanistic interactions between specific ions (Na+/ K+) and nanoparticle surfaces to alter particle stability in polar media has received little attention. We investigated relative preferential binding of Na+ and K+ to carboxylate-functionalized silver nanoparticles ...

  2. Effect of the cement type on compatibility with carboxylate superplasticisers

    Directory of Open Access Journals (Sweden)

    Bundyra-Oracz, G.

    2011-06-01

    Full Text Available An empirical study was conducted to gain a fuller understanding of the interactions taking place in cementsuperplasticiser systems. To this end, two clinkers of known chemical and phase composition were prepared in this study to gain insight into such interactions. One contained no tricalcium aluminate (C1, while the other had a 9% C3A content (C2. These clinkers were ground to approximately 340 m2/kg and blended with gypsum only or gypsum and Klein compound (3CaO·3Al2O3·CaSO4 (1, 2. Sufficient compound was added to C1 to ensure the formation of about the same amount of ettringite after 0.5 and 1 h of hydration as found in cement C2 + gypsum. The admixture used was a carboxylate superplasticiser. Rheology measurements showed that while paste yield stress was correlated to ettringite formation, no such simple relationship was observed for plastic viscosity. Plastic viscosity depended on the total hydrates formed, i.e., not only as ettringite but also as C-S-H gel. The findings revealed that in clinkers with very low sulfate and potassium contents, the rheology of carboxylate-containing cement paste is primarily controlled by ettringite formation.

    En el presente trabajo se ha realizado un estudio empírico con el objetivo de profundizar en el conocimiento de las interacciones del sistema cemento-superplastificante. Con este fin, se prepararon dos clínkeres con una composición química y de fases conocida: el primero (C1 sin aluminato tricálcico y el segundo (C2 con un contenido en C3A del 9%. Ambos se molieron hasta obtener una superficie específica aproximada de 340 m2/kg y se emplearon con dos adiciones: yeso y el compuesto de Klein (3CaO·3Al2O3·CaSO4 (1, 2. Se añadió la cantidad necesaria del compuesto de Klein a C1 para garantizar la formación, tras 0,5 y 1ª h. de hidratación, de aproximadamente la misma cantidad de etringita en dicho

  3. Lutetium(III cyclotetraphosphate

    Directory of Open Access Journals (Sweden)

    Aïcha Mbarek

    2010-06-01

    Full Text Available Single crystals of the title compound, tetralutetium(III tris(cyclotetraphosphate, Lu4(P4O123, were obtained by solid-state reaction. The cubic structure is isotypic with its AlIII and ScIII analogues and is built up from four-membered (P4O124− phosphate ring anions (overline{4} symmetry, isolated from each other and further linked through isolated LuO6 octahedra (.3. symmetry via corner sharing. Each LuO6 octahedron is linked to six (P4O124− rings, while each (P4O124− ring is linked to eight LuO6 octahedra.

  4. III-V microelectronics

    CERN Document Server

    Nougier, JP

    1991-01-01

    As is well known, Silicon widely dominates the market of semiconductor devices and circuits, and in particular is well suited for Ultra Large Scale Integration processes. However, a number of III-V compound semiconductor devices and circuits have recently been built, and the contributions in this volume are devoted to those types of materials, which offer a number of interesting properties. Taking into account the great variety of problems encountered and of their mutual correlations when fabricating a circuit or even a device, most of the aspects of III-V microelectronics, from fundamental p

  5. Spectrophotometric tool for the determination of the total carboxylate content in proteins; Molar extinction coefficient of the enol ester from Woodward's reagent K reacted with protein carboxylates

    NARCIS (Netherlands)

    Kosters, H.A.; Jongh, de H.H.J.

    2003-01-01

    A number of relevant properties of Woodward's reagent K have been determined, such as the stability of the reactant and the optimal reaction conditions of the reactant with protein carboxylates. A Woodward's reagent K stock solution was stable at 4 C for prolonged time, whereas upon storage at 22 C,

  6. Spectrophotometric tool for the determination of the total carboxylate content in proteins; molar extinction coefficient of the enol ester from Woodward's reagent K reacted with protein carboxylates

    NARCIS (Netherlands)

    Kosters, H.A.; Jongh, H.H.J.de

    2003-01-01

    A number of relevant properties of Woodward's reagent K have been determined, such as the stability of the reactant and the optimal reaction conditions of the reactant with protein carboxylates. A Woodward's reagent K stock solution was stable at 4°C for prolonged time, whereas upon storage at 22°C,

  7. Self-diffusion coefficients of the trivalent f-element ion series in dilute and moderately dilute aqueous solutions: A comparative study between europium, gadolinium, terbium and berkelium

    Science.gov (United States)

    Rafik, Besbes; Noureddine, Ouerfelli; Abderabbou, Abdelmanef; Habib, Latrous

    2010-03-01

    We have continued the studies on the trivalent ions of the 4f and 5f elements. In this paper, we compare the transport properties (self-diffusion coefficient) of the trivalent aquo ions over two ranges of concentrations (0 — 2×10-3M) and (2×10-3 — 1.5M). Self-diffusion coefficients, D, of the trivalent f-element aquo ion series have been determined in aqueous background electrolytes of Gd(NO3)3 and Nd(ClO4)3, at pH=2.5 (HNO3, HClO4) and at 25°C using the open-end capillary method (O.E.C.M.). This method measures the transportation time of ions across a fixed distance. In this paper, we complete a measurement of self-diffusion coefficient for terbium. We optimized the pH to avoid hydrolysis, ion-pairing and complexation of the trivalent 4f and 5f ions. The variation of D versus √C is not linear for dilute solutions (0 — 2×10-3M) and quasi-linear in moderate concentrations (C<=1.5 M). Similar behavior was observed for Tb, as compared with those for Bk, Eu and Gd. We complete the comparison variation of D/D° versus √C for all studied 4f and 5f elements from concentration 0 to 1.5M and we obtained the same variation with √C for all studied elements. All 4f and 5f elements studied follow the Nernst-Hartley expression.

  8. Terbium-based time-gated Förster resonance energy transfer imaging for evaluating protein-protein interactions on cell membranes.

    Science.gov (United States)

    Lindén, Stina; Singh, Manish Kumar; Wegner, K David; Regairaz, Marie; Dautry, François; Treussart, François; Hildebrandt, Niko

    2015-03-21

    Fluorescence imaging of cells and subcellular compartments is an essential tool to investigate biological processes and to evaluate the development and progression of diseases. In particular, protein-protein interactions can be monitored by Förster resonance energy transfer (FRET) between two proximal fluorophores that are attached to specific recognition biomolecules such as antibodies. We investigated the membrane expression of E- and N-cadherins in three different cell lines used as model systems to study epithelial to mesenchymal transition (EMT) and a possible detection of circulating tumour cells (CTCs). EMT is a key process in cancer metastasis, during which epithelial markers (such as E-cadherin) are down-regulated in the primary tumour whereas mesenchymal markers (such as N-cadherin) are up-regulated, leading to enhanced cell motility, intravasation, and appearance of CTCs. Various FRET donor-acceptor pairs and protein recognition strategies were utilized, in which Lumi4-Tb terbium complexes (Tb) and different organic dyes were conjugated to several distinct E- and N-cadherin-specific antibodies. Pulsed excitation of Tb at low repetition rates (100 Hz) and time-gated (TG) imaging of both the Tb-donor and the dye-acceptor photoluminescence (PL) allowed efficient detection of the EMT markers as well as FRET in the case of sufficient donor-acceptor proximity. Efficient FRET was observed only between two E-cadherin-specific antibodies and further experiments indicated that these antibodies recognized the same E-cadherin molecule, suggesting a limited accessibility of cadherins when they are clustered at adherens junctions. The investigated Tb-to-dye FRET systems provided reduced photobleaching compared to the AlexaFluor 488-568 donor-acceptor pair. Our results demonstrate the applicability and advantages of Tb-based TG FRET for efficient and stable imaging of antibody-antibody interactions on different cell lines. They also reveal the limitations of

  9. A broad G protein-coupled receptor internalization assay that combines SNAP-tag labeling, diffusion-enhanced resonance energy transfer, and a highly emissive terbium cryptate acceptor

    Directory of Open Access Journals (Sweden)

    Angélique eLEVOYE

    2015-11-01

    Full Text Available Although G protein-coupled receptor (GPCR internalization has long been considered a major aspect of the desensitization process that tunes ligand responsiveness, internalization is also involved in receptor resensitization and signaling, as well as the ligand scavenging function of some atypical receptors. Internalization thus contributes to the diversity of GPCR-dependent signaling, and its dynamics and quantification in living cells has generated considerable interest. We developed a robust and sensitive assay to follow and quantify ligand-induced and constitutive GPCR internalization but also receptor recycling in living cells. This assay is based on diffusion-enhanced resonance energy transfer (DERET between cell surface GPCRs labeled with a luminescent terbium cryptate donor and a fluorescein acceptor present in the culture medium. GPCR internalization results in a quantifiable reduction of energy transfer. This method yields a high signal-to-noise ratio due to time-resolved measurements. For various GPCRs belonging to different classes, we demonstrated that constitutive and ligand-induced internalization could be monitored as a function of time and ligand concentration, thus allowing accurate quantitative determination of kinetics of receptor internalization but also half-maximal effective or inhibitory concentrations of compounds. In addition to its selectivity and sensitivity, we provided evidence that DERET-based internalization assay is particularly suitable for characterizing biased ligands. Furthermore, the determination of a Z’-factor value of 0.45 indicates the quality and suitability of DERET-based internalization assay for high-throughput screening (HTS of compounds that may modulate GPCRs internalization.

  10. Metallothionein (MT)-III

    DEFF Research Database (Denmark)

    Carrasco, J; Giralt, M; Molinero, A

    1999-01-01

    Metallothionein-III is a low molecular weight, heavy-metal binding protein expressed mainly in the central nervous system. First identified as a growth inhibitory factor (GIF) of rat cortical neurons in vitro, it has subsequently been shown to be a member of the metallothionein (MT) gene family a...

  11. BANANAS III (ARTIC

    African Journals Online (AJOL)

    Fr. Ikenga

    Key words: Cross-Retaliation, Justiciability, EC-Bananas III, Countermeasure. 1. Introduction. The World Trade Organisation (WTO) as an international legal personality regulates the World. Trading System to ensure smooth, free, fair and predictable flow of international trade. It is. “the only International Organisation dealing ...

  12. Cobalt(III) complex

    Indian Academy of Sciences (India)

    Administrator

    . 2 radicals ... Crystal structure of the complex was determined by X-ray diffraction and is reported elsewhere. 5. The complex is stable towards hydrolysis at least for 10 h as checked by its ..... served in Co(III) aquo-ammonia complexes where.

  13. Supramolecular architectures in the salt trimethoprimium ferrocene-1-carboxylate and the cocrystal 4-amino-5-chloro-2,6-dimethylpyrimidine-ferrocene-1-carboxylic acid (1/1).

    Science.gov (United States)

    Swinton Darious, Robert; Thomas Muthiah, Packianathan; Perdih, Franc

    2017-09-01

    In the salt trimethoprimium ferrocenecarboxylate [systematic name: 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium ferrocene-1-carboxylate], (C14H19N4O3)[Fe(C5H5)(C6H4O2)], (I), of the antibacterial compound trimethoprim, the carboxylate group interacts with the protonated aminopyrimidine group of trimethoprim via two N-H...O hydrogen bonds, generating a robust R2(2)(8) ring motif (heterosynthon). However, in the cocrystal 4-amino-5-chloro-2,6-dimethylpyrimidine-ferrocene-1-carboxylic acid (1/1), [Fe(C5H5)(C6H5O2)]·C6H8ClN3, (II), the carboxyl-aminopyrimidine interaction [R2(2)(8) motif] is absent. The carboxyl group interacts with the pyrimidine ring via a single O-H...N hydrogen bond. The pyrimidine rings, however, form base pairs via a pair of N-H...N hydrogen bonds, generating an R2(2)(8) supramolecular homosynthon. In salt (I), the unsubstituted cyclopentadienyl ring is disordered over two positions, with a refined site-occupation ratio of 0.573 (10):0.427 (10). In this study, the two five-membered cyclopentadienyl (Cp) rings of ferrocene are in a staggered conformation, as is evident from the C...Cg...Cg...C pseudo-torsion angles, which are in the range 36.13-37.53° for (I) and 22.58-23.46° for (II). Regarding the Cp ring of the minor component in salt (I), the geometry of the ferrocene ring is in an eclipsed conformation, as is evident from the C...Cg...Cg...C pseudo-torsion angles, which are in the range 79.26-80.94°. Both crystal structures are further stabilized by weak π-π interactions.

  14. Crystallographic Location and Mutational Analysis of Zn and Cd Inhibitory Sites and Role of Lipidic Carboxylates in Rescuing Proton Path Mutants in Cytochrome c Oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Ling; Mills, Denise A.; Hiser, Carrie; Murphree, Anna; Garavito, R. Michael; Ferguson-Miller, Shelagh; Hosler, Jonathan (MSU); (UMMC)

    2009-01-15

    Cytochrome c oxidase (CcO) transfers protons from the inner surface of the enzyme to the buried O{sub 2} reduction site through two different pathways, termed K and D, and from the outer surface via an undefined route. These proton paths can be inhibited by metals such as zinc or cadmium, but the sites of inhibition have not been established. Anomalous difference Fourier analyses of Rhodobacter sphaeroides CcO crystals, with cadmium added, reveal metal binding sites that include the proposed initial proton donor/acceptor of the K pathway, Glu-101 of subunit II. Mutant forms of CcO that lack Glu-101{sub II} (E101A and E101A/H96A) exhibit low activity and eliminate metal binding at this site. Significant activity is restored to E101A and E101A/H96A by adding the lipophilic carboxylic compounds, arachidonic acid and cholic acid, but not by their non-carboxylic analogues. These amphipathic acids likely provide their carboxylic groups as substitute proton donors/acceptors in the absence of Glu-101{sub II}, as previously observed for arachidonic acid in mutants that alter Asp-132{sub I} of the D pathway. The activity of E101A/H96A is still inhibited by zinc, but this remaining inhibition is nearly eliminated by removal of subunit III, which is known to alter the D pathway. The results identify the Glu-101/His-96 site of subunit II as the site of metal binding that inhibits the uptake of protons into the K pathway and indicate that subunit III contributes to zinc binding and/or inhibition of the D pathway. By removing subunit III from E101A/H96A, thereby eliminating zinc inhibition of the uptake of protons from the inner surface of CcO, we confirm that an external zinc binding site is involved in inhibiting the backflow of protons to the active site.

  15. Poly[[aqua(μ2-oxalato(μ2-2-oxidopyridinium-3-carboxylatoholmium(III] monohydrate

    Directory of Open Access Journals (Sweden)

    Hui-Lan Zhu

    2009-10-01

    Full Text Available In the title complex, {[Ho(C2O4(C6H4NO3(H2O]·(H2O}n, the HoIII ion is coordinated by three O atoms from two 2-oxidopyridinium-3-carboxylate ligands, four O atoms from two oxalate ligands and one water molecule in a distorted bicapped trigonal-prismatic geometry. The 2-oxidopyridinium-3-carboxylate and oxalate ligands link the HoIII ions into a layer in (100. These layers are further connected by intermolecular O—H...O hydrogen bonds involving the coordinated water molecules to assemble a three-dimensional supramolecular network. The uncoordinated water molecule is involved in N—H...O and O—H...O hydrogen bonds within the layer.

  16. Structural basis for substrate recognition in the salicylic acid carboxyl methyltransferase family.

    Science.gov (United States)

    Zubieta, Chloe; Ross, Jeannine R; Koscheski, Paul; Yang, Yue; Pichersky, Eran; Noel, Joseph P

    2003-08-01

    Recently, a novel family of methyltransferases was identified in plants. Some members of this newly discovered and recently characterized methyltransferase family catalyze the formation of small-molecule methyl esters using S-adenosyl-L-Met (SAM) as a methyl donor and carboxylic acid-bearing substrates as methyl acceptors. These enzymes include SAMT (SAM:salicylic acid carboxyl methyltransferase), BAMT (SAM:benzoic acid carboxyl methyltransferase), and JMT (SAM:jasmonic acid carboxyl methyltransferase). Moreover, other members of this family of plant methyltransferases have been found to catalyze the N-methylation of caffeine precursors. The 3.0-A crystal structure of Clarkia breweri SAMT in complex with the substrate salicylic acid and the demethylated product S-adenosyl-L-homocysteine reveals a protein structure that possesses a helical active site capping domain and a unique dimerization interface. In addition, the chemical determinants responsible for the selection of salicylic acid demonstrate the structural basis for facile variations of substrate selectivity among functionally characterized plant carboxyl-directed and nitrogen-directed methyltransferases and a growing set of related proteins that have yet to be examined biochemically. Using the three-dimensional structure of SAMT as a guide, we examined the substrate specificity of SAMT by site-directed mutagenesis and activity assays against 12 carboxyl-containing small molecules. Moreover, the utility of structural information for the functional characterization of this large family of plant methyltransferases was demonstrated by the discovery of an Arabidopsis methyltransferase that is specific for the carboxyl-bearing phytohormone indole-3-acetic acid.

  17. Diastereoselective Synthesis of Symmetrical and Unsymmetrical Tetrahydropyridines Catalyzed by Bi(III) Immobilized on Triazine Dendrimer Stabilized Magnetic Nanoparticles.

    Science.gov (United States)

    Asadi, Beheshteh; Landarani-Isfahani, Amir; Mohammadpoor-Baltork, Iraj; Tangestaninejad, Shahram; Moghadam, Majid; Mirkhani, Valiollah; Amiri Rudbari, Hadi

    2017-06-12

    Unsymmetrical 1,2,5,6-tetrahydropyridine-3-carboxylates were obtained for the first time from a five-component Fe 3 O 4 @TDSN-Bi(III)-catalyzed reaction of aryl aldehydes, aryl amines, and ethyl acetoacetate. This magnetically separable catalyst enabled the selective incorporation of two different aryl amines or two different aryl aldehydes into the product, and provided excellent yields, short reaction times, mild reaction conditions, satisfactory catalyst recyclability, and low catalyst loading.

  18. Photoluminescent calcium azolium carboxylates with diversified calcium coordination geometry and thermal stability.

    Science.gov (United States)

    Suresh, Paladugu; Babu, Chatla Naga; Sampath, Natarajan; Prabusankar, Ganesan

    2015-04-28

    Despite the popularity and versatility of transition-metal–azolium carboxylate coordination polymers, there are very few examples of group 2 complexes supported by azolium carboxylate ligands in the literature, and there are none featuring luminescent calcium azolium carboxylates. New ionic calcium coordination networks, {[Ca2(L(1))2(H2O)4](Br)4·6H2O}∞ (1), {[(L(3))2Ca(H2O)2]2(Br)2}∞ (3), {[(L(4))2Ca(H2O)2]2(Br)2}∞ (4), and {[(L(5))2Ca3(Na)(H2O)9(Cl)](Br)6·2H2O}∞ (5) along with binuclear {[Ca2(L(2))2(H2O)9](Br)4·4H2O} (2), and trinuclear {[(L(6))2Ca3(H2O)9](Br)6} (6) were isolated from the reaction between the corresponding azolium carboxylates and calcium carbonate in aqueous solution. 1–6 were characterized by FT-IR, NMR, TGA, UV-vis, fluorescence and single crystal X-ray diffraction techniques. Interestingly, the first tetra-cationic binuclear calcium 2 was isolated using L(2)H2Br2 and hexa-cationic trinuclear calcium 6 was isolated using L(6)H3Br3. The 3D coordination polymers 1 and 4 were derived with the help of L(1)H2Br2 and L(4)H2Br2, respectively, through Br···H hydrogen bonding. The 3D MOF 3 with rhomboidal channels was constructed using L(3)H2Br2, where the channel size is about 4.8 × 2.9 nm. 5 was isolated as a rare 1D coordination polymer. The choice of azolium carboxylates in these solids not only changes the topology of the network but also affects the chemistry exhibited by the network. Calcium azolium carboxylate assemblies 1–4 and 6 exhibit interesting solid-state photoluminescence properties, driven by azolium carboxylate ligands. Variation of the bridging chromophore produced significant effects on the fluorescence properties. 1–4 and 6 represent the first examples of luminescent calcium azolium carboxylate complexes. As can be seen in the six metal–organic assemblies presented in this report, a combination of carboxylate groups and steric hindrance affects the topology and physical properties of the resultant solids.

  19. Calculus III essentials

    CERN Document Server

    REA, Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Calculus III includes vector analysis, real valued functions, partial differentiation, multiple integrations, vector fields, and infinite series.

  20. Phosphorescent emissions of phosphine copper(I) complexes bearing 8-hydroxyquinoline carboxylic acid analogue ligands

    Energy Technology Data Exchange (ETDEWEB)

    Małecki, Jan G., E-mail: gmalecki@us.edu.pl [Department of Crystallography, Institute of Chemistry, University of Silesia, Szkolna 9 street, 40-006 Katowice (Poland); Łakomska, Iwona, E-mail: iwolak@chem.umk.pl [Department of Chemistry, Nicolaus Copernicus University, Toruń (Poland); Maroń, Anna [Department of Crystallography, Institute of Chemistry, University of Silesia, Szkolna 9 street, 40-006 Katowice (Poland); Szala, Marcin [Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice (Poland); Fandzloch, Marzena [Department of Chemistry, Nicolaus Copernicus University, Toruń (Poland); Nycz, Jacek E., E-mail: jacek.nycz@us.edu.pl [Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice (Poland)

    2015-05-15

    The pseudotetrahedral complexes of [Cu(PPh{sub 3}){sub 2}(L)], where L=8-hydroxy-2-methylquinoline-7-carboxylic acid (1), 8-hydroxy-2,5-dimethylquinoline-7-carboxylic acid (2) or 5-chloro-8-hydroxy-2-methylquinoline-7-carboxylic acid (3) have been synthesized and structurally characterized by X-ray crystallography. Their properties have been examined through combinations of IR, NMR, electronic absorption spectroscopy and cyclic voltammetry. The complexes exhibit extraordinary photophysical properties. Complex (1) in solid state exhibits an emission quantum yield of 4.67% and an excited life time of 1.88 ms (frozen DCM solution up to 6.7 ms). When dissolved in a coordinating solvent (acetonitrile) the charge transfer emission was quenched on a microsecond scale. - Highlights: • Synthesis of copper(I) complexes with 8-hydroxyquinoline carboxylic acid ligands. • Very long lived phosphorescent copper(I) complexes. • [Cu(PPh{sub 3}){sub 2}(L)] where L=8-hydroxy-2-methylquinoline-7-carboxylic acid luminesce in the solid state exhibits extremely long lifetime on millisecond scale (1.9 ms). • In frozen MeOH:EtOH solution lifetime increases to 7 ms. • Quantum efficiency equal to 4.7%.

  1. Contributions to reversed-phase column selectivity: III. Column hydrogen-bond basicity.

    Science.gov (United States)

    Carr, P W; Dolan, J W; Dorsey, J G; Snyder, L R; Kirkland, J J

    2015-05-22

    Column selectivity in reversed-phase chromatography (RPC) can be described in terms of the hydrophobic-subtraction model, which recognizes five solute-column interactions that together determine solute retention and column selectivity: hydrophobic, steric, hydrogen bonding of an acceptor solute (i.e., a hydrogen-bond base) by a stationary-phase donor group (i.e., a silanol), hydrogen bonding of a donor solute (e.g., a carboxylic acid) by a stationary-phase acceptor group, and ionic. Of these five interactions, hydrogen bonding between donor solutes (acids) and stationary-phase acceptor groups is the least well understood; the present study aims at resolving this uncertainty, so far as possible. Previous work suggests that there are three distinct stationary-phase sites for hydrogen-bond interaction with carboxylic acids, which we will refer to as column basicity I, II, and III. All RPC columns exhibit a selective retention of carboxylic acids (column basicity I) in varying degree. This now appears to involve an interaction of the solute with a pair of vicinal silanols in the stationary phase. For some type-A columns, an additional basic site (column basicity II) is similar to that for column basicity I in primarily affecting the retention of carboxylic acids. The latter site appears to be associated with metal contamination of the silica. Finally, for embedded-polar-group (EPG) columns, the polar group can serve as a proton acceptor (column basicity III) for acids, phenols, and other donor solutes. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Prevalence of type III secretion system in effective biocontrol pseudomonads.

    Science.gov (United States)

    Almario, Juliana; Gobbin, Davide; Défago, Geneviève; Moënne-Loccoz, Yvan; Rezzonico, Fabio

    2014-05-01

    Functional type III secretion system (T3SS) genes are needed for effective biocontrol of Pythium damping-off of cucumber by Pseudomonas fluorescens KD, but whether biocontrol Pseudomonas strains with T3SS genes display overall a higher plant-protecting activity is unknown. The assessment of 198 biocontrol fluorescent pseudomonads originating from 60 soils worldwide indicated that 32% harbour the ATPase-encoding T3SS gene hrcN, which was most often found in tomato isolates. The hrcN(+) biocontrol strains (and especially those also producing 2,4-diacetylphloroglucinol and displaying 1-aminocyclopropane-1-carboxylate deaminase activity) displayed higher plant-protecting ability in comparison with hrcN(-) biocontrol strains, both in the Pythium/cucumber and Fusarium/cucumber pathosystems. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  3. Anaerobic Fermentation for Production of Carboxylic Acids as Bulk Chemicals from Renewable Biomass.

    Science.gov (United States)

    Wang, Jufang; Lin, Meng; Xu, Mengmeng; Yang, Shang-Tian

    Biomass represents an abundant carbon-neutral renewable resource which can be converted to bulk chemicals to replace petrochemicals. Carboxylic acids have wide applications in the chemical, food, and pharmaceutical industries. This chapter provides an overview of recent advances and challenges in the industrial production of various types of carboxylic acids, including short-chain fatty acids (acetic, propionic, butyric), hydroxy acids (lactic, 3-hydroxypropionic), dicarboxylic acids (succinic, malic, fumaric, itaconic, adipic, muconic, glucaric), and others (acrylic, citric, gluconic, pyruvic) by anaerobic fermentation. For economic production of these carboxylic acids as bulk chemicals, the fermentation process must have a sufficiently high product titer, productivity and yield, and low impurity acid byproducts to compete with their petrochemical counterparts. System metabolic engineering offers the tools needed to develop novel strains that can meet these process requirements for converting biomass feedstock to the desirable product.

  4. The fate of the carboxyl oxygens during D-proline reduction by clostridial proline reductase.

    Science.gov (United States)

    Arkowitz, R A; Dhe-Paganon, S; Abeles, R H

    1994-06-01

    D-Proline is converted to 5-amino valeric acid by D-proline reductase. This conversion involves the reductive cleavage of the alpha-carbon-nitrogen bond. We have examined the fate of the carboxyl oxygen atoms during conversion of D-proline to delta-NH2-valeric acid. 18O atoms from the carboxyl group of D-proline are not lost during conversion to product. In contrast, in the conversion of glycine to acetyl phosphate by glycine reductase a carboxyl oxygen atom is lost to solvent. An intermediate acyl-enzyme is found during the reduction of glycine. We conclude that the reduction of proline proceeds without the formation of an acyl enzyme intermediate.

  5. Carboxylic acid functionalization of halloysite nanotubes for sustained release of diphenhydramine hydrochloride

    Science.gov (United States)

    Zargarian, S. Sh.; Haddadi-Asl, V.; Hematpour, H.

    2015-05-01

    Halloysite nanotubes (HNT) (cylindrical shape with external diameter and length in the range of 30-80 nm and 0.2-1 µm, respectively) were functionalized with 3-aminopropyltriethoxysilane (APTES) from hydroxyl groups by a coupling reaction. Subsequently, maleic anhydride was attached to the APTES moieties to yield carboxylic acid-functionalized HNT. Loading and subsequent release of a model drug molecule diphenhydramine hydrochloride (DPH) on modified and unmodified nanotubes were investigated. Morphology of HNT was studied by electron microscopy. Successful attachment of APTES and carboxylic acid groups to halloysite and drug loading were evaluated by Fourier transform infrared spectroscopy. The amount of surface modification and drug adsorption capacity were calculated via thermogravimetric analysis. The ordered crystal structure of loaded drug was evaluated by X-ray diffraction. UV-Visible spectrophotometer was used to study drug release from modified and unmodified samples. Carboxylated halloysite exhibits higher loading capacity and prolonged release of DPH as compared to that of the natural halloysite.

  6. Water-enhanced solubility of carboxylic acids in organic solvents and its applications to extraction processes

    Energy Technology Data Exchange (ETDEWEB)

    Starr, John N. [Univ. of California, Berkeley, CA (United States)

    1991-11-01

    The solubilities of carboxylic acids in certain organic solvents increase remarkably with an increasing amount of water in the organic phase. This phenomenon leads to a novel extract regeneration process in which the co-extracted water is selectively removed from an extract, and the carboxylic acid precipitates. This approach is potentially advantageous compared to other regeneration processes because it removes a minor component of the extract in order to achieve a large recovery of acid from the extract. Carboxylic acids of interest include adipic acid, fumaric acid, and succinic acid because of their low to moderate solubilities in organic solvents. Solvents were screened for an increase in acid solubility with increased water concentration in the organic phase. Most Lewis-base solvents were found to exhibit this increased solubility phenomena. Solvents that have a carbonyl functional group showed a very large increase in acid solubility. 71 refs., 52 figs., 38 tabs.

  7. Synthesis, structural investigations, and anti-cancer activity of new methyl indole-3-carboxylate derivatives

    Science.gov (United States)

    Niemyjska, Maria; Maciejewska, Dorota; Wolska, Irena; Truszkowski, Paweł

    2012-10-01

    Two new methyl indole-3-carboxylate derivatives: methyl 1-(3'-indolylmethane)-indole-3-carboxylate (1), and methyl 1-(1'-benzenosulfonyl-3'-indolylmethane)-indole-3-carboxylate (2) were synthesized. They are interesting as the analogs of 3,3'-diindolylmethane, which is intensively tested as a potent antitumor agent. Their solid-state structure was characterized using 13C CP/MAS NMR or X-ray diffraction measurements. Molecular modeling was used as a help in the structure elucidation. The solid-state NMR spectroscopy showed only one stable conformer of 1, but the X-ray diffraction results indicate that compound 2 crystallizes in the triclinic space group P-1 with two molecules, A and B, in the asymmetric unit. Both compounds inhibited the growth of melanoma, renal and breast cancers cell lines.

  8. Isotope-Encoded Carboxyl Group Footprinting for Mass Spectrometry-Based Protein Conformational Studies

    Science.gov (United States)

    Zhang, Hao; Liu, Haijun; Blankenship, Robert E.; Gross, Michael L.

    2016-01-01

    We report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded "heavy" and "light" GEE are used to label separately the two states of the orange carotenoid protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the "heavy" and "light" peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting.

  9. CO 2 and CO utilization: radiation-induced carboxylation of aqueous chloroacetic acid to malonic acid

    Science.gov (United States)

    Getoff, Nikola

    2003-07-01

    CO 2 and CO in addition to HCOOH/HCOO - can be used to produce the carboxylating radical rad COOH/ rad COO - under the influence of ionizing radiation. The carboxylation of ClCH 2COOH/ClCH 2COO - to malonic acid/malonate was studied at the pH range 2-7. A maximum yield G(malonic acid)=85 at pH=3 was observed by using 5×10 -2 mol dm -3 ClCH 2COOH, 1×10 -2 mol dm -3 HCOOH and 1×10 -3 mol dm -3 CO at a dose of 4.8 kGy. Oxalic and succinic acids were found as byproducts. The yield of the formed Cl - ions passes two maxima, at pH=3 ( G=7.5) and 7 ( G=15). Reaction mechanisms for the carboxylation process are presented.

  10. Identification of new non-carboxylic acid containing inhibitors of aldose reductase.

    Science.gov (United States)

    Maccari, Rosanna; Ciurleo, Rosella; Giglio, Marco; Cappiello, Mario; Moschini, Roberta; Corso, Antonella Del; Mura, Umberto; Ottanà, Rosaria

    2010-06-01

    Non-carboxylic acid containing bioisosteres of (5-arylidene-2,4-dioxothiazolidin-3-yl)acetic acids, which are active as aldose reductase (ALR2) inhibitors, were designed by replacing the carboxylic group with the trifluoromethyl ketone moiety. The in vitro evaluation of the ALR2 inhibitory effects of these trifluoromethyl substituted derivatives led to the identification of two inhibitors effective at low micromolar doses. It was further confirmed that a carboxylic chain on N-3 of the thiazolidinedione scaffold is a determining requisite to obtain the highest efficacy levels; however, it is not essential for the interaction with the target enzyme and it can be replaced by different polar groups, thus obtaining less ionised or unionised inhibitors.

  11. On the one pot syntheses of chromeno[4,3-b]pyridine-3-carboxylate and chromeno[3,4-c]pyridine-3-carboxylate and dihydropyridines

    Energy Technology Data Exchange (ETDEWEB)

    Navarrete-Encina, Patricio A.; Vega-Retter, Christian, E-mail: pnavarre@vtr.ne [Universidad de Chile, Santiago (Chile). Facultad de Ciencias Quimicas y Farmaceuticas. Lab. de Sintesis Organica y Fisicoquimica; Salazar, Ricardo; Perez, Karina; Squella, Juan A.; Nunez-Vergara, Luis J. [Universidad de Chile, Santiago (Chile). Fac. de Ciencias Quimicas y Farmaceuticas. Lab. de Bioelectroquimica

    2010-07-01

    Substituted chromenos, dihydropyridines and pyridines have been important in the syntheses of compounds having interesting pharmacological properties. Therefore, we found of interest to synthesize chromenopyridines and chromeno dihydropyridines (i.e., fused chromeno and dihydropyridine or pyridine rings) to further study their biological activity. Here, we propose one-pot syntheses for substituted ethyl-2,4-dimethyl-5-oxo-5H-chromeno[4,3-b]pyridine-3-carboxylates, ethyl-2,4-dimethyl-5-oxo-5H-chromeno[3,4-c]pyridine-3-carboxylates and their respective 1,4-dihydropyridines based on a modified Hantzsch pyridine synthesis using 2-hydroxyaryl aldehydes, with electron withdrawing and electron donating groups on the phenyl ring, as starting reactants. Sixteen compounds were synthesized by the described method and fully characterized. An average yield of 37% was obtained for the different derivatives. (author)

  12. (1H-Benzimidazole-5-carboxylic acid-κN3(1H-benzimidazole-6-carboxylic acid-κN3silver(I perchlorate

    Directory of Open Access Journals (Sweden)

    Li Ma

    2011-04-01

    Full Text Available The reaction of 1H-benzimidazole-5-carboxylic acid with silver nitrate in the presence of perchloric acid under hydrothermal conditions yielded the title complex, [Ag(C8H6N2O22]ClO4, which comprises of an [Ag(C8H6N2O22] mononuclear cation and a perchlorate anion. The AgI ion is coordinated by two N atoms from two different neutral 1H-benzimidazole-5-carboxylic acid ligands with an N—Ag—N bond angle of 163.21 (14°, forming an [Ag(C8H6N2O22] mononuclear cation. Although both ligands in the mononuclear cation are monodentate with one N atom coordinated to the metal ion, they are different: one is N3 coordinated to the Ag I ion and the N1 atom protonated, the other with the N1 coordinated to the Ag I ion and the N3 atom protonated (and thus formally a 1H-benzimidazole-6-carboxylic acid rather than a 1H-benzimidazole-5-carboxylic acid ligand. The planes of the two planar ligands are roughly perpendicular, making a dihedral angle of 84.97 (2°. The packing of the ions is stablized by extensive O—H...O, N—H...O and C—H...O hydrogen bonds, and by remote Ag...O interactions [3.002 (3, 3.581 (5 and 3.674 (5 Å].

  13. Controlled Electrochemical Carboxylation of Graphene To Create a Versatile Chemical Platform for Further Functionalization

    DEFF Research Database (Denmark)

    Bjerglund Pedersen, Emil; Kongsfelt, Mikkel S.; Shimizu, Kyoko

    An electrochemical approach is introduced for the versatile carboxylation of multilayered graphene in 0.1 M Bu4NBF4/MeCN. First, the graphene substrate is negatively charged at −1.9 V vs. Ag/AgI to allow for intercalation of Bu4N+. In the second step, the strongly activated and nucleophilic graph...... in a multi-layered but expanded structure accessible for functionalization. On a more general level, this approach will provide a versatile way of forming new hybrid materials based on intimate bond coupling to graphene via carboxylate groups....

  14. Facile synthesis of α-hydroxy carboxylic acids from the corresponding α-amino acids

    DEFF Research Database (Denmark)

    Stuhr-Hansen, Nicolai; Padrah, Shahrokh; Strømgaard, Kristian

    2014-01-01

    An effective and improved procedure is developed for the synthesis of α-hydroxy carboxylic acids by treatment of the corresponding protonated α-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located α to a carboxylic acid function in order...... to undergo initial diazotization and successive hydroxylation, since neither β-amino acids nor acid derivatives such as esters and amides undergo hydroxylations. The method is successfully applied for the synthesis of 18 proteinogenic amino acids....

  15. Silver-Catalyzed Dehydrogenative Synthesis of Carboxylic Acids from Primary Alcohols

    DEFF Research Database (Denmark)

    Ghalehshahi, Hajar Golshadi; Madsen, Robert

    2017-01-01

    A simple silver-catalyzed protocol has been developed for the acceptorless dehydrogenation of primary alcohols into carboxylic acids and hydrogen gas. The procedure uses 2.5 % Ag2 CO3 and 2.5-3 equiv of KOH in refluxing mesitylene to afford the potassium carboxylate which is then converted...... into the acid with HCl. The reaction can be applied to a variety of benzylic and aliphatic primary alcohols with alkyl and ether substituents, and in some cases halide, olefin, and ester functionalities are also compatible with the reaction conditions. The dehydrogenation is believed to be catalyzed by silver...

  16. Production of alpha-hydroxy carboxylic acids and esters from higher sugars using tandem catalyst systems

    Energy Technology Data Exchange (ETDEWEB)

    Orazov, Marat; Davis, Mark E.

    2017-11-07

    The present disclosure is directed to methods and composition used in the preparation of alpha-hydroxy carboxylic acids and esters from higher sugars using a tandem catalyst system comprising retro-aldol catalysts and Lewis acid catalysts. In some embodiments, these alpha-hydroxy carboxylic acids may be prepared from pentoses and hexoses. The retro-aldol and Lewis catalysts may be characterized by their respective ability to catalyze a 1,2-carbon shift reaction and a 1,2-hydride shift reaction on an aldose or ketose substrate.

  17. catena-Poly[[diaqua[μ2-4-(4-carboxyphenoxybenzoato](μ2-4,4′-oxydibenzoatopraseodymium(III] monohydrate

    Directory of Open Access Journals (Sweden)

    Ping Li

    2013-11-01

    Full Text Available In the title compound, {[Pr(C14H8O5(C14H9O5(H2O2]·H2O}n, the PrIII cation is eight-coordinated by six carboxyl O atoms from both a monoanionic 4-(4-carboxyphenoxybenzoate and a dianionic 4,4′-oxydibenzoate ligand (four bridging with two from a bidentate chelate interaction, and two O-atom donors from water molecules. A single water molecule of solvation is also present. The complex units are linked through carboxyl O:O′ bridges giving a two-dimensional sheet polymer lying parallel to (001. An overall three-dimensional network structure is generated through intermolecular carboxylic acid and water O—H...O hydrogen bonds and weak C—H...O interactions.

  18. Phosphorescence quantum yield determination with time-gated fluorimeter and Tb(III)-acetylacetonate as luminescence reference

    Energy Technology Data Exchange (ETDEWEB)

    Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Fakultät für Physik, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg (Germany)

    2013-03-29

    Highlights: ► Procedure for absolute phosphorescence quantum yield measurement is described. ► Experimental setup for absolute luminescence quantum yield standard calibration. ► Tb(acac){sub 3} proposed as phosphorescence quantum yield reference standard. ► Luminescence quantum yield of Tb(acac){sub 3} in cyclohexane measured. ► Luminescence lifetime of Tb(acac){sub 3} in cyclohexane measured. - Abstract: Phosphorescence quantum yield measurements of fluorescent and phosphorescent samples require the use of time-gated fluorimeters in order to discriminate against the fluorescence contribution. As reference standard a non-fluorescent luminescent compound is needed for absolute phosphorescence quantum yield determination. For this purpose the luminescence behavior of the rare earth chelate terbium(III)-acetylacetonate (Tb(acac){sub 3}) was studied (determination of luminescence quantum yield and luminescence lifetime). The luminescence quantum yield of Tb(acac){sub 3} was determined by using an external light source and operating the fluorimeter in chemo/bioluminescence mode with a fluorescent dye (rhodamine 6G in methanol) as reference standard. A procedure is developed for absolute luminescence (phosphorescence) quantum yield determination of samples under investigation with a time-gated fluorimeter using a non-fluorescent luminescent compound of known luminescence quantum yield and luminescence lifetime.

  19. Hydrothermal synthesis and crystal structure of a new lanthanum(III coordination polymer with fumaric acid

    Directory of Open Access Journals (Sweden)

    Hayet Anana

    2015-05-01

    Full Text Available The title compound, poly[diaquatris(μ4-but-2-enedioato(μ2-but-2-enedioic aciddilanthanum(III], [La2(C4H2O43(C4H4O4(H2O2]n, was synthesized by the reaction of lanthanum chloride pentahydrate with fumaric acid under hydrothermal conditions. The asymmetric unit comprises an LaIII cation, one and a half fumarate dianions (L2−, one a half-molecule of fumaric acid (H2L and one coordinated water molecule. Each LaIII cation has the same nine-coordinate environment and is surrounded by eight O atoms from seven distinct fumarate moieties, including one protonated fumarate unit and one water molecule in a distorted tricapped trigonal–prismatic environment. The LaO8(H2O polyhedra centres are edge-shared through three carboxylate bridges of the fumarate ligand, forming chains in three dimensions to construct the MOF. The crystal structure is stabilized by O—H...O hydrogen-bond interactions between the coordinated water molecule and the carboxylate O atoms, and also between oxygen atoms of fumaric acid

  20. Quantification of carboxyl groups in carbodiimide cross-linked collagen sponges.

    Science.gov (United States)

    Everaerts, Frank; Torrianni, Mark; Hendriks, Marc; Feijen, Jan

    2007-12-15

    Glutaraldehyde (GA) fixation of bioprosthetic tissue is a well adapted technique, with commercial products on the market for almost 40 years. Amine groups present in tissue react with GA to form different types of cross-links. An estimation of the degree of cross-linking of the tissue can be obtained by measuring the concentration of residual amine groups, which is frequently carried out with the 2,4,6 trinitrobenzene sulphonic acid (TNBS) assay. Cross-linked tissue and collagen matrices are usually further characterized by determining their physical properties (such as the shrinkage temperature), biological properties (such as resistance to enzymatic degradation), and mechanical properties before in vivo evaluation takes place. In an effort to improve the properties of cross-linked tissue and collagen, alternative cross-linking methods have been developed. One of these methods is based on the use of water soluble carbodiimides (CDI). It is generally accepted that this cross-linking method leads only to the formation of amide linkages between tissue carboxyl and amine groups. Therefore, until recently the TNBS assay was also used to determine the degree of cross-linking of CDI cross-linked tissue and collagen. However, it cannot be excluded that after activation of carboxyl groups of tissue and collagen by CDI, these groups can react with other nucleophiles (like hydroxyl groups) present in the matrix. To obtain a better insight in the degree of cross-linking of CDI cross-linked matrices a reliable assay for quantification of residual carboxyl groups is required. Up to now such an assay was not available. In this study a new assay to determine residual carboxyl groups in CDI cross-linked collagen matrices is presented. Reconstituted dermal bovine collagen matrices (RDBC) were cross-linked with a water soluble CDI and N-hydroxysuccinimide (NHS) and residual carboxyl groups were labeled using 5-bromomethyl fluorescein. Subsequently, the fluorescent label was released

  1. IDENTIFICATION AND QUANTIFICATION OF AEROSOL POLAR OXYGENATED COMPOUNDS BEARING CARBOXYLIC AND/OR HYDROXYL GROUPS. 1. METHOD DEVELOPMENT

    Science.gov (United States)

    In this study, a new analytical technique was developed for the identification and quantification of multi-functional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) ...

  2. Carboxylated polymers functionalized by cyclodextrins for the stabilization of highly efficient rhodium(0) nanoparticles in aqueous phase catalytic hydrogenation.

    Science.gov (United States)

    Noël, Sébastien; Léger, Bastien; Herbois, Rudy; Ponchel, Anne; Tilloy, Sébastien; Wenz, Gerhard; Monflier, Eric

    2012-11-21

    Rhodium(0) nanoparticles stabilized by a polymer containing carboxylate and β-cyclodextrin moieties have high stability and catalytic activity for aqueous hydrogenation reactions of olefins and aromatic substrates. This catalytic system can be recycled and reused without loss of activity. These high catalytic performances can be attributed to conjugated electrostatic interactions (carboxylate groups) and steric interactions (polymer structure and β-cyclodextrin moiety).

  3. Role of apparent pKa of carboxylic acids in lipase-catalyzed esterifications in biphasic systems

    NARCIS (Netherlands)

    Dominguez de Maria, Pablo; Fernandez-Alvaro, Elena; ten Kate, Antoon; Bargeman, Gerrald

    2009-01-01

    Lipase-catalyzed esterifications in biphasic media (heptane–water, 1:1) were conducted by using Thermomyces lanuginosus lipase (TLL) as biocatalyst. Different carboxylic acids (from acetic to lauric) were thus esterified with 1-butanol at different pH values (2–10). For all carboxylic acids tested,

  4. Solvent-Free Esterification of Carboxylic Acids Using Supported Iron Oxide Nanoparticles as an Efficient and Recoverable Catalyst

    Directory of Open Access Journals (Sweden)

    Fatemeh Rajabi

    2016-07-01

    Full Text Available Supported iron oxide nanoparticles on mesoporous materials (FeNP@SBA-15 have been successfully utilized in the esterification of a variety carboxylic acids including aromatic, aliphatic, and long-chain carboxylic acids under convenient reaction conditions. The supported catalyst could be easily recovered after reaction completion and reused several times without any loss in activity after up to 10 runs.

  5. Quantum chemical investigation of the primary thermal pyrolysis reactions of the sodium carboxylate group in a brown coal model.

    Science.gov (United States)

    Li, Jian; Zhang, Baisheng; Zhang, Zhiqiang; Yan, Kefeng; Kang, Lixun

    2014-12-01

    The primary pyrolysis mechanisms of the sodium carboxylate group in sodium benzoate-used as a model compound of brown coal-were studied by performing quantum chemical computations using B3LYP and the CBS method. Various possible reaction pathways involving reactions such as unimolecular and bimolecular decarboxylation and decarbonylation, crosslinking, and radical attack in the brown coal matrix were explored. Without the participation of reactive radicals, unimolecular decarboxylation to release CO2 was calculated to be the most energetically favorable primary reaction pathway at the B3LYP/6-311+G (d, p) level of theory, and was also found to be more energetically favorable than decarboxylation of an carboxylic acid group. When CBS-QBS results were included, crosslinking between the sodium carboxylate group and the carboxylic acid and the decarboxylation of the sodium carboxylate group (catalyzed by the phenolic hydroxyl group) were found to be possible; this pathway competes with unimolecular decarboxylation of the sodium carboxylate group. Provided that H and CH3 radicals are present in the brown coal matrix and can access the sodium carboxylate group, accelerated pyrolysis of the sodium carboxylate group becomes feasible, leading to the release of an Na atom or an NaCO2 radical at the B3LYP/6-311+G (d, p) or CBS-QB3 level of theory, respectively.

  6. Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexes

    KAUST Repository

    Zhang, Tao

    2014-01-01

    Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by metal-carboxylate complexation. It is unknown whether this process is effective for all carboxylates or selective to special molecule structures. In this work, the selectivity was confirmed using O3/(CuO/CeO2) and six distinct ozone-resistant probe carboxylates (i.e., acetate, citrate, malonate, oxalate, pyruvate and succinate). Among these probe compounds, pyruvate, oxalate, and citrate were readily degraded following the rate order of oxalate>citrate>pyruvate, while the degradation of acetate, malonate, and succinate was not promoted. The selectivity was independent on carboxylate group number of the probe compounds and solution pH. Competitive degradation was observed for carboxylate mixtures following the preference order of citrate, oxalate, and finally pyruvate. The competitive degradation was ascribed to competitive adsorption on the catalyst surface. It was revealed that the catalytically degradable compounds formed bidentate chelating or bridging complexes with surface copper sites of the catalyst, i.e., the active sites. The catalytically undegradable carboxylates formed monodentate complexes with surface copper sites or just electrostatically adsorbed on the catalyst surface. The selectivity, relying on the structure of surface metal-carboxylate complex, should be considered in the design of catalytic ozonation process. © 2013 Elsevier B.V.

  7. Poly[diaqua(μ-oxalato(μ-2-oxidopyridinium-3-carboxylatopraseodymium(III

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available In the title complex, [Pr(C6H4NO3(C2O4(H2O2]n, each PrIII ion is coordinated by eight O atoms from two 2-oxynicotinate ligands, two oxalate ligands and two water molecules, displaying a distorted bicapped square-antiprismatic geometry. The carboxylate groups link adjacent praseodymium metal centres, forming layers parallel to the bc plane. The crystal packing is stabilized by intermolecular O—H...O and N—H...O hydrogen bonds.

  8. Carboxylate-assisted C(sp³)-H activation in olefin metathesis-relevant ruthenium complexes.

    Science.gov (United States)

    Cannon, Jeffrey S; Zou, Lufeng; Liu, Peng; Lan, Yu; O'Leary, Daniel J; Houk, K N; Grubbs, Robert H

    2014-05-07

    The mechanism of C-H activation at metathesis-relevant ruthenium(II) benzylidene complexes was studied both experimentally and computationally. Synthesis of a ruthenium dicarboxylate at a low temperature allowed for direct observation of the C-H activation step, independent of the initial anionic ligand-exchange reactions. A first-order reaction supports an intramolecular concerted metalation-deprotonation mechanism with ΔG(‡)(298K) = 22.2 ± 0.1 kcal·mol(-1) for the parent N-adamantyl-N'-mesityl complex. An experimentally determined ΔS(‡) = -5.2 ± 2.6 eu supports a highly ordered transition state for carboxylate-assisted C(sp(3))-H activation. Experimental results, including measurement of a large primary kinetic isotope effect (k(H)/k(D) = 8.1 ± 1.7), agree closely with a computed six-membered carboxylate-assisted C-H activation mechanism where the deprotonating carboxylate adopts a pseudo-apical geometry, displacing the aryl ether chelate. The rate of cyclometalation was found to be influenced by both the electronics of the assisting carboxylate and the ruthenium ligand environment.

  9. Effects of intermediate metabolite carboxylic acids of TCA cycle on Microcystis with overproduction of phycocyanin.

    Science.gov (United States)

    Bai, Shijie; Dai, Jingcheng; Xia, Ming; Ruan, Jing; Wei, Hehong; Yu, Dianzhen; Li, Ronghui; Jing, Hongmei; Tian, Chunyuan; Song, Lirong; Qiu, Dongru

    2015-04-01

    Toxic Microcystis species are the main bloom-forming cyanobacteria in freshwaters. It is imperative to develop efficient techniques to control these notorious harmful algal blooms (HABs). Here, we present a simple, efficient, and environmentally safe algicidal way to control Microcystis blooms, by using intermediate carboxylic acids from the tricarboxylic acid (TCA) cycle. The citric acid, alpha-ketoglutaric acid, succinic acid, fumaric acid, and malic acid all exhibited strong algicidal effects, and particularly succinic acid could cause the rapid lysis of Microcystis in a few hours. It is revealed that the Microcystis-lysing activity of succinic acid and other carboxylic acids was due to their strong acidic activity. Interestingly, the acid-lysed Microcystis cells released large amounts of phycocyanin, about 27-fold higher than those of the control. On the other hand, the transcription of mcyA and mcyD of the microcystin biosynthesis operon was not upregulated by addition of alpha-ketoglutaric acid and other carboxylic acids. Consider the environmental safety of intermediate carboxylic acids. We propose that administration of TCA cycle organic acids may not only provide an algicidal method with high efficiency and environmental safety but also serve as an applicable way to produce and extract phycocyanin from cyanobacterial biomass.

  10. Improved chlorine tolerance of a polyvinyl pyrrolidone-polysulfone membrane enabled by carboxylated carbon nanotubes.

    Science.gov (United States)

    Xie, Pengchao; de Lannoy, Charles-François; Ma, Jun; Wang, Zongping; Wang, Songlin; Li, Jingjing; Wiesner, Mark R

    2016-11-01

    Chemical cleaning of membranes may be limited by the tolerance of some polymeric membranes to chlorine. In this work we show that modification of a polyvinyl pyrrolidone-polysulfone (PVP-PSF) membrane with carboxylated carbon nanotubes (CNTs) leads to greater chlorine tolerance of the membrane along with smoothing the surface roughness and improving some membrane properties including permeability, hydrophilicity and antifouling ability. In comparison with PVP-PSF membrane, incorporating carboxylated CNTs reduced the release of organic matter from the membrane and caused less decrease in hydrophilicity, permeability and BSA rejection. After chlorine treatment of a conventional PVP-PSF membrane, an infrared absorbance peak around 1670 cm-1, representing the vibration of the amide bond in the PVP, decreased significantly and two smaller peaks at around 1725 and 1775 cm-1 were observed. The percentage of C-Cl (2p) in the PVP-PSF membrane was about 2.8 times greater than that of the carboxylated CNT-composite PVP-PSF (CNT-PVP-PSF) membrane after chlorine exposure, suggesting greater chlorine tolerance of CNT-PVP-PSF membrane. In comparison with PVP-PSF membrane, the formation of toxic chlorinated byproducts during chlorination of organic matter released from CNT-PVP-PSF membrane was much lower. The improvement of tolerance to chlorine is attributed to stabilization of the polymer through hydrogen bonding between polymer and carboxylated CNTs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. The Cannabinoid Type-1 Receptor Carboxyl-Terminus, More Than Just a Tail

    Science.gov (United States)

    Stadel, Rebecca; Ahn, Kwang H.; Kendall, Debra A.

    2011-01-01

    The cannabinoid type-1 (CB1) receptor is a G protein-coupled receptor (GPCR) that binds the main active ingredient of marijuana, Δ9-tetrahydrocannabinol, and has been implicated in several disease states, including drug addiction, anxiety, depression, obesity, and chronic pain. In the two decades since the discovery of CB1, studies at the molecular level have centered on the transmembrane core. This interest has now expanded as we discover that other regions of CB1, including the CB1 carboxyl-terminus, have critical structures that are important for CB1 activity and regulation. Following the recent description of the three dimensional structure of the full-length CB1 carboxyl-terminal tail (Ahn et al., Biopolymers (2009) 91: 565–573), several residues and structural motifs including two α-helices (termed H8 and H9) have been postulated to interact with common GPCR accessory proteins, such as G-proteins and β-arrestins. This discourse will focus on the CB1 carboxyl-terminus; our current understanding of the structural features of this region, evidence for its interaction with proteins, and the impact of structure on the binding and regulatory function of CB1 accessory proteins. The involvement of the carboxyl-terminus in the receptor life cycle including activation, desensitization, and internalization will be highlighted. PMID:21244428

  12. Formation of biologically relevant carboxylic acids during the gamma irradiation of acetic acid

    Science.gov (United States)

    Negron-Mendoza, A.; Ponnamperuma, C.

    1976-01-01

    Irradiation of aqueous solutions of acetic acid with gamma rays produced several carboxylic acids in small yield. Their identification was based on the technique of gas chromatography combined with mass spectrometry. Some of these acids are Krebs Cycle intermediates. Their simultaneous formation in experiments simulating the primitive conditions on the earth suggests that metabolic pathways may have had their origin in prebiotic chemical processes.

  13. Li-Carboxylate Anode Structure-Property Relationships from Molecular Modeling

    KAUST Repository

    Burkhardt, Stephen E.

    2013-01-22

    The full realization of a renewable energy strategy hinges upon electrical energy storage (EES). EES devices play a key role in storing energy from renewable sources (which are inherently intermittent), to efficient transmission (e.g., grid load-leveling), and finally into the electrification of transportation. Organic materials represent a promising class of electrode active materials for Li-ion and post-Li-ion batteries. Organics consist of low-cost, lightweight, widely available materials, and their properties can be rationally tuned using the well-established principles of organic chemistry. Within the class of organic EES materials, carboxylates distinguish themselves for Li-ion anode materials based on their observed thermal stability, rate capability, and high cyclability. Further, many of the carboxylates studied to date can be synthesized from renewable or waste feedstocks. This report begins with a preliminary molecular density-functional theory (DFT) study, in which the calculated molecular properties of a set of 12 known Li-ion electrode materials based on carboxylate and carbonyl redox couples are compared to literature data. Based on the agreement between theoretical and experimental data, an expanded study was undertaken to identify promising materials and establish design principles for anodes based on Li-carboxylate salts. Predictive computational studies represent an important step forward for the identification of organic anode materials. © 2012 American Chemical Society.

  14. Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil

    Science.gov (United States)

    Long-term effectiveness of biochar for heavy metal stabilization depends upon biochar’s sorptive property and recalcitrance in soil. To understand the role of carboxyl functional groups on heavy metal stabilization, cottonseed hull biochar and flax shive steam activated biochar having low O/C ratio...

  15. Carboxylic acid functional group analysis using constant neutral loss scanning-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Dron, Julien [Laboratoire de Chimie et Environnement, Marseille Universites (case 29), 3 place Victor Hugo, 13331 Marseille Cedex 3 (France)], E-mail: julien.dron@up.univ-mrs.fr; Eyglunent, Gregory; Temime-Roussel, Brice; Marchand, Nicolas; Wortham, Henri [Laboratoire de Chimie et Environnement, Marseille Universites (case 29), 3 place Victor Hugo, 13331 Marseille Cedex 3 (France)

    2007-12-12

    The present study describes the development of a new analytical technique for the functional group determination of the carboxylic moiety using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS/MS) operated in the constant neutral loss scanning (CNLS) mode. Carboxylic groups were first derivatized into their corresponding methyl esters by reacting with BF{sub 3}/methanol mix and the reaction mixture was then directly injected into the APCI chamber. The loss of methanol (m/z = 32 amu) resulting from the fragmentation of the protonated methyl esters was then monitored. Applying this method together with a statistical approach to reference mixtures containing 31 different carboxylic acids at randomly calculated concentrations demonstrated its suitability for quantitative functional group measurements with relative standard deviations below 15% and a detection limit of 0.005 mmol L{sup -1}. Its applicability to environmental matrices was also shown through the determination of carboxylic acid concentrations inside atmospheric aerosol samples. To the best of our knowledge, it is the first time that the tandem mass spectrometry was successfully applied to functional group analysis, offering great perspectives in the characterization of complex mixtures which are prevailing in the field of environmental analysis as well as in the understanding of the chemical processes occurring in these matrices.

  16. Carboxylate-bridged dinuclear manganese systems - From catalases to oxidation catalysis

    NARCIS (Netherlands)

    de Boer, Johannes W.; Browne, Wesley R.; Feringa, Ben L.; Hage, Ronald

    2007-01-01

    Dinuclear manganese based enzymes engage in processes as diverse as amino acid hydrolysis and hydrogen peroxide disproportionation. Despite the mechanistic diversity displayed by this class of enzymes, a common feature is the presence of carboxylate residues, which serve to bridge the manganese

  17. Effect of thermal stabilizers (Ba/Cd/Zn metal salts carboxylate and ...

    African Journals Online (AJOL)

    The study of the photodegradation of unstabilized and stabilized PVC films has been performed by means of artificial UV light. Eight (8) mixtures of PVC have been prepared by compounding PVC powder with two kinds of stabilizers at varied concentrations. The two stabilizers used are namely Ba/Cd/Zn carboxylate and ...

  18. Effect of thermal stabilizers (Ba/Cd/Zn metal salts carboxylate and ...

    African Journals Online (AJOL)

    carboxylic acids, α and β chloroketones, α and α' dichloroketones, acid chlorides, ester groups, peracids, peresters unsaturated ketones and lactones [4, 9 - 11]. Elsewhere, it was demonstrated that the addition of stabilizers to PVC affects both the kinetic of the carbonyl groups formation and the types of oxidation products ...

  19. Substituted Amides of Pyrazine-2-carboxylic acids: Synthesis and Biological Activity

    Directory of Open Access Journals (Sweden)

    Katarina Kralova

    2002-03-01

    Full Text Available Condensation of 6-chloro-, 5-tert-butyl- or 6-chloro-5-tert-butylpyrazine-2-carboxylic acid chloride with ring substituted anilines yielded a series of amides, which were tested for their in vitro antimycobacterial, antifungal and photosynthesis-inhibiting activities. The highest antituberculotic activity (72% inhibition against Mycobacterium tuberculosis and the highest lipophilicity (log P = 6.85 were shown by the 3,5-bistrifluoromethylphenyl amide of 5-tert-butyl-6-chloropyrazine-2-carboxylic acid (2o. The 3-methylphenyl amides of 6-chloro- and 5-tert-butyl-6-chloro-pyrazine-2-carboxylic acid (2d and 2f exhibited only a poor in vitro antifungal effect (MIC = 31.25-500 μmol·dm-3 against all strains tested, although the latter was the most active antialgal compound (IC50 = 0.063 mmol·dm-3. The most active inhibitor of oxygen evolution rate in spinach chloroplasts was the (3,5-bis-trifluoromethylphenylamide of 6-chloropyrazine-2-carboxylic acid (2m, IC50 = 0.026 mmol·dm-3.

  20. Preparation of mono- and diacetyl 4,4′-dimethylbiphenyl and their corresponding carboxylic acids

    DEFF Research Database (Denmark)

    Titinchi, Salam J.J.; Kamounah, Fadhil S.; Abbo, Hanna S.

    2007-01-01

    dimethylbiphenyls. In chloroalkane or carbon disulfide solvent, the yields of isomers were in the order: 2 -> 3-; in nitromethane 3-isomer predominated. On the other hand diacetylation of the hydrocarbon gave only the 2,3′-diacetyl isomer. The mono- and di-ketones are converted to the corresponding carboxylic acids...

  1. Effect of hydrogen and carbon dioxide on carboxylic acids patterns in mixed culture fermentation

    NARCIS (Netherlands)

    Arslan, D.; Steinbusch, K.J.J.; Diels, L.; Wever, De H.; Buisman, C.J.N.; Hamelers, H.V.M.

    2012-01-01

    This study investigated the carboxylate spectrum from mixed culture fermentation of three organic waste streams after supplying 2 bar hydrogen and carbon dioxide or a mixture of these two gases to the headspace. Under any modified headspace, propionate production was ceased and butyrate, caproate

  2. Preparation and assessment of carboxylate polyelectrolyte as draw solute for forward osmosis.

    Science.gov (United States)

    Cui, Hongtao; Zhang, Hanmin; Jiang, Wei; Yang, Fenglin

    2017-12-11

    Reverse draw solute diffusion not only reduces the water flux in forward osmosis (FO), but also contaminates the feed solution and eventually increases the regeneration cost of draw solution. In the present study, a new polyelectrolyte was synthesized as FO draw solute to address this problem. Acrylic acid and sodium p-styrenesulfonate monomers with hydrophilic group were used to fabricate carboxylate polyelectrolyte through free radical polymerization reaction. Results demonstrated that the osmotic pressure of carboxylate polyelectrolyte solution had a good linear relationship with concentration, and the viscosity of 0.18 g/mL solution was less than 5.4 cP. Active layer facing draw solution produced the initial water flux of 11.77 LMH and active layer facing feed solution yielded the initial water flux of 6.68 LMH when the concentration of draw solution was 0.18 g/mL. The reverse solute flux was around 1 gMH, and specific reverse solute flux of 0.18 g/mL carboxylate polyelectrolyte draw solution was 0.11 g/L which was much lower than that of traditional inorganic salts. Finally, diluted draw solution was regenerated via ultrafiltration, and the recovery efficiency of 94.78% was achieved. So, carboxylate polyelectrolyte can be suitable draw solute for FO.

  3. Exploring the reductive capacity of Pyrococcus furiosus : the reduction of carboxylic acids and pyridine nucleotides

    NARCIS (Netherlands)

    Ban, van den E.C.D.

    2001-01-01

    This Ph.D. project started in 1997 and its main goal was to obtain insight in the reductive capacity of the hyperthermophilic archaeon Pyrococcus furiosus . The research was focused on the biocatalytic reduction of carboxylic

  4. New co-crystal and salt form of sulfathiazole with carboxylic acid and ...

    Indian Academy of Sciences (India)

    ... Refresher Courses · Symposia · Live Streaming. Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 5. New co-crystal and salt form of sulfathiazole with carboxylic acid and amide. Ranita Samanta Shipra Kanaujia C Malla Reddy. Special issue on Chemical Crystallography Volume 126 Issue 5 September ...

  5. Influence of kraft pulping on carboxylate content of softwood kraft pulps

    Science.gov (United States)

    Zheng Dang; Thomas Elder; Arthur J. Ragauskas

    2006-01-01

    This study characterizes changes in fiber charge, which is the carboxylate content of fibers, for two sets of kraft pulps: (1) conventional laboratory cooked loblolly pine kraft pulps and (2) conventional pulping (CK) versus low solids pulping (LS) pulps. Laboratory kraft pulping of loblolly pine was carried out to study the influence of pulping conditions, including...

  6. 4-(Dimethylamino)pyridine-catalysed iodolactonisation of γ,δ-unsaturated carboxylic acids.

    Science.gov (United States)

    Meng, Chuisong; Liu, Zhihui; Liu, Yuxiu; Wang, Qingmin

    2015-06-28

    4-(Dimethylamino)pyridine functioned as an excellent catalyst for iodolactonisation reactions of γ,δ-unsaturated carboxylic acids, affording γ-lactones, δ-lactones, or both under neutral conditions at room temperature. The effects of substrate structures on the iodolactonisation were investigated, and a catalytic mechanism is proposed.

  7. Carboxylic Acids as Directing Groups for C-H Bond Functionalization.

    Science.gov (United States)

    Pichette Drapeau, Martin; Gooßen, Lukas J

    2016-12-23

    The selective transformation of C-H bonds is one of the most desirable approaches to creating complexity from simple building blocks. Several directing groups are efficient in controlling the regioselectivity of catalytic C-H bond functionalizations. Among them, carboxylic acids are particularly advantageous, since they are widely available in great structural diversity and at low cost. The carboxylate directing groups can be tracelessly cleaved or may serve as the anchor point for further functionalization through decarboxylative couplings. This Minireview summarizes the substantial progress made in the last few years in the development of reactions in which carboxylate groups direct C-H bond functionalizations with formation of C-C, C-O, C-N, or C-halogen bonds at specific positions. It is divided into sections on C-C, C-O, C-N, and C-halogen bond formation, each of which is subdivided by reactions and product classes. Particular emphasis is placed on methods that enable multiple derivatizations by combining carboxylate-directed C-H functionalization with decarboxylative couplings. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Synthesis of N-acylurea derivatives from carboxylic acids and N,N ...

    Indian Academy of Sciences (India)

    Synthesis of N-acylurea derivatives from carboxylic acids and. N,N -dialkyl carbodiimides in water. ALI RAMAZANIa,∗, FATEMEH ZEINALI NASRABADIb, ARAM REZAEIa,. MORTEZA ROUHANIc, HAMIDEH AHANKARd, PEGAH AZIMZADEH ASIABIa,. SANG WOO JOOe,∗. , KATARZYNA SLEPOKURAf and TADEUSZ LISf.

  9. Construction of molecular rectangles with titanium-oxo clusters and rigid aromatic carboxylate ligands.

    Science.gov (United States)

    Ding, Qing-Rong; Liu, Jin-Xiu; Narayanam, Nagaraju; Zhang, Lei; Zhang, Jian

    2017-11-28

    Four rectangular molecular architectures have been successfully constructed using {Ti5O7} clusters as inorganic vertical edges and bridging aromatic carboxylates as horizontal edges. The introduced organic ligands show a strong influence on the light absorption behaviors of the obtained hybrid complexes.

  10. Oxymatrinium tetrachloridoferrate(III

    Directory of Open Access Journals (Sweden)

    Xiong He

    2012-02-01

    Full Text Available The asymmetric unit of the title compound, (C15H25N2O2[FeCl4], contains a tetrachloridoferrate(III anion and a oxymatrinium cation [oxymatrine is (4R,7aS,13aR,13bR,13cS-dodecahydro-1H,5H,10H-dipyrido[2,1-f:3′,2′,1′-ij][1,6]naphthyridin-10-one 4-oxide]. The conformation of oxymatrine is similar to that of matrine with one ring having a half-chair conformation, while the others have chair conformations. Chiral chains of cations along the c axis are formed by O—H...O hydrogen bonds.

  11. Ammonium diphosphitoindate(III

    Directory of Open Access Journals (Sweden)

    Farida Hamchaoui

    2013-04-01

    Full Text Available The crystal structure of the title compound, NH4[In(HPO32], is built up from InIII cations (site symmetry 3m. adopting an octahedral environment and two different phosphite anions (each with site symmetry 3m. exhibiting a triangular–pyramidal geometry. Each InO6 octahedron shares its six apices with hydrogen phosphite groups. Reciprocally, each HPO3 group shares all its O atoms with three different metal cations, leading to [In(HPO32]− layers which propagate in the ab plane. The ammonium cation likewise has site symmetry 3m.. In the structure, the cations are located between the [In(HPO32]− layers of the host framework. The sheets are held together by hydrogen bonds formed between the NH4+ cations and the O atoms of the framework.

  12. Selective Sensing of Fe(3+) and Al(3+) Ions and Detection of 2,4,6-Trinitrophenol by a Water-Stable Terbium-Based Metal-Organic Framework.

    Science.gov (United States)

    Cao, Li-Hui; Shi, Fang; Zhang, Wen-Min; Zang, Shuang-Quan; Mak, Thomas C W

    2015-10-26

    A water-stable luminescent terbium-based metal-organic framework (MOF), {[Tb(L1 )1.5 (H2 O)]⋅3 H2 O}n (Tb-MOF), with rod-shaped secondary building units (SBUs) and honeycomb-type tubular channels has been synthesized and structurally characterized by single-crystal X-ray diffraction. The high green emission intensity and the microporous nature of the Tb-MOF indicate that it can potentially be used as a luminescent sensor. In this work, we show that Tb-MOF can selectively sense Fe(3+) and Al(3+) ions from mixed metal ions in water through different detection mechanisms. In addition, it also exhibits high sensitivity for 2,4,6-trinitrophenol (TNP) in the presence of other nitro aromatic compounds in aqueous solution by luminescence quenching experiments. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Prediction of phase equilibrium and hydration free energy of carboxylic acids by Monte Carlo simulations.

    Science.gov (United States)

    Ferrando, Nicolas; Gedik, Ibrahim; Lachet, Véronique; Pigeon, Laurent; Lugo, Rafael

    2013-06-13

    In this work, a new transferable united-atom force field has been developed to predict phase equilibrium and hydration free energy of carboxylic acids. To take advantage of the transferability of the AUA4 force field, all Lennard-Jones parameters of groups involved in the carboxylic acid chemical function are reused from previous parametrizations of this force field. Only a unique set of partial electrostatic charges is proposed to reproduce the experimental gas phase dipole moment, saturated liquid densities and vapor pressures. Phase equilibrium properties of various pure carboxylic acids (acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid) and one diacid (1,5-pentanedioic) are studied through Monte Carlo simulations in the Gibbs ensemble. A good accuracy is obtained for pure compound saturated liquid densities and vapor pressures (average deviation of 2% and 6%, respectively), as well as for critical points. The vaporization enthalpy is, however, poorly predicted for short acids, probably due to a limitation of the force field to correctly describe the significant dimerization in the vapor phase. Pressure-composition diagrams for two binary mixtures (acetic acid + n-butane and propanoic acid + pentanoic acid) are also computed with a good accuracy, showing the transferability of the proposed force field to mixtures. Hydration free energies are calculated for three carboxylic acids using thermodynamic integration. A systematic overestimation of around 10 kJ/mol is observed compared to experimental data. This new force field parametrized only on saturated equilibrium properties appears insufficient to reach an acceptable precision for this property, and only relative hydration free energies between two carboxylic acids can be correctly predicted. This highlights the limitation of the transferability feature of force fields to properties not included in the parametrization database.

  14. Vitamin K-Dependent Carboxylation of Matrix Gla Protein Influences the Risk of Calciphylaxis.

    Science.gov (United States)

    Nigwekar, Sagar U; Bloch, Donald B; Nazarian, Rosalynn M; Vermeer, Cees; Booth, Sarah L; Xu, Dihua; Thadhani, Ravi I; Malhotra, Rajeev

    2017-06-01

    Matrix Gla protein (MGP) is a potent inhibitor of vascular calcification. The ability of MGP to inhibit calcification requires the activity of a vitamin K-dependent enzyme, which mediates MGP carboxylation. We investigated how MGP carboxylation influences the risk of calciphylaxis in adult patients receiving dialysis and examined the effects of vitamin K deficiency on MGP carboxylation. Our study included 20 patients receiving hemodialysis with calciphylaxis (cases) and 20 patients receiving hemodialysis without calciphylaxis (controls) matched for age, sex, race, and warfarin use. Cases had higher plasma levels of uncarboxylated MGP (ucMGP) and carboxylated MGP (cMGP) than controls. However, the fraction of total MGP that was carboxylated (relative cMGP concentration = cMGP/[cMGP + uncarboxylated MGP]) was lower in cases than in controls (0.58±0.02 versus 0.69±0.03, respectively; P=0.003). In patients not taking warfarin, cases had a similarly lower relative cMGP concentration. Each 0.1 unit reduction in relative cMGP concentration associated with a more than two-fold increase in calciphylaxis risk. Vitamin K deficiency associated with lower relative cMGP concentration in multivariable adjusted analyses (β=-8.99; P=0.04). In conclusion, vitamin K deficiency-mediated reduction in relative cMGP concentration may have a role in the pathogenesis of calciphylaxis. Whether vitamin K supplementation can prevent and/or treat calciphylaxis requires further study. Copyright © 2017 by the American Society of Nephrology.

  15. Floral Benzenoid Carboxyl Methyltransferases: From in Vitro to in Planta Function

    Energy Technology Data Exchange (ETDEWEB)

    Effmert,U.; Saschenbrecker, S.; Ross, J.; Negre, F.; Fraser, C.; Noel, J.; Dudareva, N.; Piechulla, B.

    2005-01-01

    Benzenoid carboxyl methyltransferases synthesize methyl esters (e.g., methyl benzoate and methyl salicylate), which are constituents of aromas and scents of many plant species and play important roles in plant communication with the surrounding environment. Within the past five years, eleven such carboxyl methyltransferases were isolated and most of them were comprehensively investigated at the biochemical, molecular and structural level. Two types of enzymes can be distinguished according to their substrate preferences: the SAMT-type enzymes isolated from Clarkia breweri, Stephanotis floribunda, Antirrhinum majus, Hoya carnosa, and Petunia hybrida, which have a higher catalytic efficiency and preference for salicylic acid, while BAMT-type enzymes from A. majus, Arabidopsis thaliana, Arabidopsis lyrata, and Nicotiana suaveolens prefer benzoic acid. The elucidation of C. breweri SAMT's three-dimensional structure allowed a detailed modelling of the active sites of the carboxyl methyltransferases and revealed that the SAM binding pocket is highly conserved among these enzymes while the methyl acceptor binding site exhibits some variability, allowing a classification into SAMT-type and BAMT-type enzymes. The analysis of expression patterns coupled with biochemical characterization showed that these carboxyl methyltransferases are involved either in floral scent biosynthesis or in plant defense responses. While the latter can be induced by biotic or abiotic stress, the genes responsible for floral scent synthesis exhibit developmental and rhythmic expression pattern. The nature of the product and efficiency of its formation in plants depend on the availability of substrates, the catalytic efficiency of the enzyme toward benzoic acid and/or salicylic acid, and the transcriptional, translational, and post-translational regulation at the enzyme level. The biochemical properties of benzenoid carboxyl methyltransferases suggest that the genes involved in plant defenses

  16. Semiconducting III-V compounds

    CERN Document Server

    Hilsum, C; Henisch, Heinz R

    1961-01-01

    Semiconducting III-V Compounds deals with the properties of III-V compounds as a family of semiconducting crystals and relates these compounds to the monatomic semiconductors silicon and germanium. Emphasis is placed on physical processes that are peculiar to III-V compounds, particularly those that combine boron, aluminum, gallium, and indium with phosphorus, arsenic, and antimony (for example, indium antimonide, indium arsenide, gallium antimonide, and gallium arsenide).Comprised of eight chapters, this book begins with an assessment of the crystal structure and binding of III-V compounds, f

  17. 1,4,10,13-Tetra-oxa-7,16-diazo-nia-cyclo-octa-decane bis-(1H-pyrrole-2-carboxyl-ate).

    Science.gov (United States)

    Zeng, Fanglei; Yin, Zhenming

    2013-01-01

    In the title salt, C12H28N2O4 (2+)·2C5H4NO2 (-), the 1,4,10,13-tetra-oxa-7,16-di-aza-cyclo-octa-decane dication possesses inversion symmetry. In the crystal, the pyrrole-carboxyl-ate anions are linked via pairs of N-H⋯O hydrogen bonds, forming inversion dimers. These dimers are linked by the dications, via N-H⋯O hydrogen bonds, forming chains propagating along [110].

  18. Proteomics computational analyses suggest that the bornavirus glycoprotein is a class III viral fusion protein (γ penetrene

    Directory of Open Access Journals (Sweden)

    Garry Robert F

    2009-09-01

    Full Text Available Abstract Background Borna disease virus (BDV is the type member of the Bornaviridae, a family of viruses that induce often fatal neurological diseases in horses, sheep and other animals, and have been proposed to have roles in certain psychiatric diseases of humans. The BDV glycoprotein (G is an extensively glycosylated protein that migrates with an apparent molecular mass of 84,000 to 94,000 kilodaltons (kDa. BDV G is post-translationally cleaved by the cellular subtilisin-like protease furin into two subunits, a 41 kDa amino terminal protein GP1 and a 43 kDa carboxyl terminal protein GP2. Results Class III viral fusion proteins (VFP encoded by members of the Rhabdoviridae, Herpesviridae and Baculoviridae have an internal fusion domain comprised of beta sheets, other beta sheet domains, an extended alpha helical domain, a membrane proximal stem domain and a carboxyl terminal anchor. Proteomics computational analyses suggest that the structural/functional motifs that characterize class III VFP are located collinearly in BDV G. Structural models were established for BDV G based on the post-fusion structure of a prototypic class III VFP, vesicular stomatitis virus glycoprotein (VSV G. Conclusion These results suggest that G encoded by members of the Bornavirdae are class III VFPs (gamma-penetrenes.

  19. Cyanide toxicokinetics: the behavior of cyanide, thiocyanate and 2-amino-2-thiazoline-4-carboxylic acid in multiple animal models.

    Science.gov (United States)

    Bhandari, Raj K; Oda, Robert P; Petrikovics, Ilona; Thompson, David E; Brenner, Matthew; Mahon, Sari B; Bebarta, Vikhyat S; Rockwood, Gary A; Logue, Brian A

    2014-05-01

    Cyanide causes toxic effects by inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cytotoxic anoxia, and can eventually lead to death. Cyanide exposure can be verified by direct analysis of cyanide concentrations or analyzing its metabolites, including thiocyanate (SCN(-)) and 2-amino-2-thiazoline-4-carboxylic acid (ATCA) in blood. To determine the behavior of these markers following cyanide exposure, a toxicokinetics study was performed in three animal models: (i) rats (250-300 g), (ii) rabbits (3.5-4.2 kg) and (iii) swine (47-54 kg). Cyanide reached a maximum in blood and declined rapidly in each animal model as it was absorbed, distributed, metabolized and eliminated. Thiocyanate concentrations rose more slowly as cyanide was enzymatically converted to SCN(-). Concentrations of ATCA did not rise significantly above the baseline in the rat model, but rose quickly in rabbits (up to a 40-fold increase) and swine (up to a 3-fold increase) and then fell rapidly, generally following the relative behavior of cyanide. Rats were administered cyanide subcutaneously and the apparent half-life (t1/2) was determined to be 1,510 min. Rabbits were administered cyanide intravenously and the t1/2 was determined to be 177 min. Swine were administered cyanide intravenously and the t1/2 was determined to be 26.9 min. The SCN(-) t1/2 in rats was 3,010 min, but was not calculated in rabbits and swine because SCN(-) concentrations did not reach a maximum. The t1/2 of ATCA was 40.7 and 13.9 min in rabbits and swine, respectively, while it could not be determined in rats with confidence. The current study suggests that cyanide exposure may be verified shortly after exposure by determining significantly elevated cyanide and SCN(-) in each animal model and ATCA may be used when the ATCA detoxification pathway is significant.

  20. Amine-Mediated Enzymatic Carboxylation of Phenols Using CO2as Substrate Increases Equilibrium Conversions and Reaction Rates.

    Science.gov (United States)

    Pesci, Lorenzo; Gurikov, Pavel; Liese, Andreas; Kara, Selin

    2017-12-01

    A variety of strategies is applied to alleviate thermodynamic and kinetic limitations in biocatalytic carboxylation of metabolites in vivo. A key feature to consider in enzymatic carboxylations is the nature of the cosubstrate: CO 2 or its hydrated form, bicarbonate. The substrate binding and activation mechanism determine what the actual carboxylation agent is. Dihydroxybenzoic acid (de)carboxylases catalyze the reversible regio-selective ortho-(de)carboxylation of phenolics. These enzymes have attracted considerable attention in the last 10 years due to their potential in substituting harsh conditions typical of chemical carboxylations (100-200 °C, 5-100 bar) with, ideally, greener ones (20-40 °C, 1 bar). They are reported to use bicarbonate as substrate, needed in large excess to overcome thermodynamic and kinetic limitations. Therefore, CO 2 can be used as substrate by these enzymes only if it is converted into bicarbonate in situ. In this contribution, we report the simultaneous amine-mediated conversion of CO 2 into bicarbonate and the ortho-carboxylation of different phenolic molecules catalyzed by 2,3-dihydroxybenzoic acid (de)carboxylase from Aspergillus oryzae. Our results show that under the newly developed conditions a significant thermodynamic (up to twofold increase in conversion) and kinetic improvement (up to approx. fivefold increase in rate) of the biocatalytic carboxylation of catechol is achieved. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Inhibition by 1-aminocyclobutane-1-carboxylate of the activity of 1-aminocyclopropane-1-carboxylate oxidase obtained from senescing petals of carnation (Dianthus caryophyllus L.) flowers.

    Science.gov (United States)

    Kosugi, Y; Oyamada, N; Satoh, S; Yoshioka, T; Onodera, E; Yamada, Y

    1997-03-01

    We partially purified 1-aminocyclopropane-1-carboxylate (ACC) oxidase from senescing petals of carnation (Dianthus caryophyllus L. cv. Nora) flowers and investigated its general characteristics, and, in particular, the inhibition of its activity by ACC analogs. The enzyme had an optimum pH at 7-7.5 and required Fe2+, ascorbate and NaHCO3 for its maximal activity. The Km for ACC was calculated as 111-125 microM in the presence of NaHCO3. Its M(r) was estimated to be 35 and 36 kDa by gel-filtration chromatography on HPLC and SDS-PAGE, respectively, indicating that the enzyme exists in a monomeric form. These properties were in agreement with those reported previously with ACC oxidases from different plant tissues including senescing carnation petals. Among six ACC analogs tested, 1-aminocyclobutane-1-carboxylate (ACBC) inhibited most severely the activity of ACC oxidase from carnation petals. ACBC acted as a competitive inhibitor with the Ki of 20-30 microM. The comparison between the Km for ACC and the Ki for ACBC indicated that ACBC had an affinity which was ca. 5-fold higher than that of ACC. Whereas ACC inactivated carnation ACC oxidase in a time-dependent manner during incubation, ACBC did not cause the inactivation of the enzyme. Preliminary experiments showed that ACBC and its N-substituted derivatives delayed the onset of senescence in cut carnation flowers.

  2. PREFACE: Quantum Optics III

    Science.gov (United States)

    Orszag, M.; Retamal, J. C.; Saavedra, C.; Wallentowitz, S.

    2007-06-01

    All the 50 years of conscious pondering did not bring me nearer to an answer to the question `what is light quanta?'. Nowadays, every rascal believes, he knows it, however, he is mistaken. (A Einstein, 1951 in a letter to M Besso) Quantum optics has played a key role in physics in the last several decades. On the other hand, in these early decades of the information age, the flow of information is becoming more and more central to our daily life. Thus, the related fields of quantum information theory as well as Bose-Einstein condensation have acquired tremendous importance in the last couple of decades. In Quantum Optics III, a fusion of these fields appears in a natural way. Quantum Optics III was held in Pucón, Chile, in 27-30 of November, 2006. This beautiful location in the south of Chile is near the lake Villarrica and below the snow covered volcano of the same name. This fantastic environment contributed to a relaxed atmosphere, suitable for informal discussion and for the students to have a chance to meet the key figures in the field. The previous Quantum Optics conferences took place in Santiago, Chile (Quantum Optics I, 2000) and Cozumel, Mexico (Quantum Optics II, 2004). About 115 participants from 19 countries attended and participated in the meeting to discuss a wide variety of topics such as quantum-information processing, experiments related to non-linear optics and squeezing, various aspects of entanglement including its sudden death, correlated twin-photon experiments, light storage, decoherence-free subspaces, Bose-Einstein condensation, discrete Wigner functions and many more. There was a strong Latin-American participation from Argentina, Brazil, Chile, Colombia, Peru, Uruguay, Venezuela and Mexico, as well as from Europe, USA, China, and Australia. New experimental and theoretical results were presented at the conference. In Latin-America a quiet revolution has taken place in the last twenty years. Several groups working in quantum optics and

  3. Towards an interpretation of the mechanism of the actinides(III)/lanthanides(III) separation by synergistic solvent extraction with nitrogen-containing polydendate ligands; Vers une interpretation des mecanismes de la separation actinides(III)/lanthanides(III) par extraction liquide-liquide synergique impliquant des ligands polyazotes

    Energy Technology Data Exchange (ETDEWEB)

    Francois, N. [CEA/VALRHO - site de Marcoule, Dept. de Recherche en Retraitement et en Vitrification, (DRRV), 30 - Marcoule (France); Universite Henri Poincare, 54 - Vandoeuvre-les-Nancy (France)

    2000-07-01

    In the field of the separation of long-lived radionuclides from the wastes produced by nuclear fuel reprocessing, aromatic nitrogen-containing polydendate ligands are potential candidates for the selective extraction, alone or in synergistic mixture with acidic extractants, of trivalent actinides from trivalent lanthanides. The first part of this work deals with the complexation of trivalent f cations with various nitrogen-containing ligands (poly-pyridine analogues). Time-resolved laser-induced fluorimetry (TRLIF) and UV-visible spectrophotometry were used to determine the nature and evaluate the stability of each complex. Among the ligands studied, the least basic Me-Btp proved to be highly selective towards americium(III) in acidic solution. In the second part, two synergistic systems (nitrogen-containing polydendate ligand and lipophilic carboxylic acid) are studied and compared in regard to the extraction and separation of lanthanides(III) and actinides(III). TRLIF and gamma spectrometry allowed the nature of the extracted complexes and the optimal conditions of efficiency of both systems to be determined. Comparison between these different studies showed that the selectivity of complexation of trivalent f cations by a given nitrogen-containing polydendate ligand could not always be linked to the Am(III)Eu(III) selectivity reached in synergistic extraction. The latter depends on the 'balance' between the acid-basic properties on the one hand, and on the hard-soft characteristics on the other hand, of both components of synergistic system. (author)

  4. Perfluorooctanoic acid degradation in the presence of Fe(III) under natural sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dandan [Beijing Key Laboratory of Water Resource and Environmental Engineering, China University of Geosciences, Beijing 100083 (China); Xiu, Zongming [Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005 (United States); Liu, Fei [Beijing Key Laboratory of Water Resource and Environmental Engineering, China University of Geosciences, Beijing 100083 (China); Wu, Gang [Division of Hematology, Department of Internal Medicine, University of Texas-Medical School at Houston, Houston, TX 77030 (United States); Adamson, Dave; Newell, Charles [GSI Environmental Inc., Houston, TX 77098 (United States); Vikesland, Peter [Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Tsai, Ah-Lim [Division of Hematology, Department of Internal Medicine, University of Texas-Medical School at Houston, Houston, TX 77030 (United States); Alvarez, Pedro J., E-mail: alvarez@rice.edu [Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005 (United States)

    2013-11-15

    Highlights: • PFOA was photo-chemically decomposed in the presence of Fe(III) and natural sunlight. • An alternative reaction pathway involves hydroxyl radical as confirmed by EPR. • Common oxidant-persulfate increased PFOA defluorination extent. -- Abstract: Due to the high bond dissociation energy (BDE) of C-F bonds (116 kcal/mol), perfluorooctanoic acid (PFOA) is a highly recalcitrant pollutant. Herein, we demonstrate a novel method to decompose PFOA in the presence of sunlight and ferric iron (Fe(III)). Under such conditions, 97.8 ± 1.7% of 50 μM PFOA decomposed within 28 days into shorter-chain intermediates and fluoride (F{sup −}), with an overall defluorination extent of 12.7 ± 0.5%. No PFOA was removed under visible light, indicating that UV radiation is required for PFOA decomposition. Spectroscopic analysis indicates that the decomposition reaction is likely initiated by electron-transfer from PFOA to Fe(III), forming Fe(II) and an unstable organic carboxyl radical. An alternative mechanism for the formation of this organic radical involves hydroxyl radicals, detected by electron paramagnetic resonance (EPR). The observation that PFOA can be degraded by Fe(III) under solar irradiation provides mechanistic insight into a possibly overlooked natural attenuation process. Because Fe(III) is abundant in natural waters and sunlight is essentially free, this work represents a potentially important step toward the development of simple and inexpensive remediation strategies for PFOA-contaminated water.

  5. Carboxylate groups play a major role in antitumor activity of Ganoderma applanatum polysaccharide.

    Science.gov (United States)

    Sun, Xiaobo; Zhao, Chen; Pan, Wei; Wang, Jinping; Wang, Weijun

    2015-06-05

    In this paper, the structure difference between the polysaccharides isolated from fruit bodies (FGAP) and submerged fermentation system (SGAP) of Ganoderma applanatum was investigated by means of GPC, HPLC and IR, respectively. And their antitumor activities were evaluated against Sarcoma 180 in vivo. The results showed that FGAP and SGAP were typical polysaccharides with different molecular weights, monosaccharide components, and functional groups. Closely related to the distinct structures, FGAP exhibited a better antitumor activity than SGAP. Moreover, since FGAP contained carboxylate groups rather than SGAP, such groups were chemically introduced into SGAP (CSGAP) by carboxymethylation in order to identify their contribution to antitumor activity. The results demonstrated that the inhibition of CSGAP against Sarcoma 180 in vivo was significantly enhanced by comparison to the native SGAP and even higher than that of FGAP, suggesting that the carboxylate groups played a major role in antitumor activity of G. applanatum polysaccharide. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Synthesis, crystal structure, DNA binding and molecular docking studies of zinc(II) carboxylates

    Science.gov (United States)

    Muhammad, Niaz; Ikram, Muhammad; Wadood, Abdul; Rehman, Sadia; Shujah, Shaukat; Erum; Ghufran, Mehreen; Rahim, Shahnaz; Shah, Muzamil; Schulzke, Carola

    2018-02-01

    New zinc(II) carboxylate complexes [Zn(3-F-C6H4CH2COO)2]n (1), [Zn3(3-F-C6H4CH2COO)6(Phen)2] (2) and [Zn3(3-F-C6H4CH2COO)6(bipy)2] (3) were synthesized and characterized by atomic absorption, single crystal structural analysis and IR studies. Complex 1 crystallizes as a coordination polymer constituting a web of μ - η1,η1 carboxylate bridged tetrahedral zinc centers. Complexes 2 and 3 comprise trinuclear zinc centers with two terminal fivefold coordinated slightly distorted square-pyramidal and central sixfold coordinated octahedral zinc centers. The complexes were also assessed for their DNA binding ability by UV/- Vis spectroscopy and their behavior rationalized theoretically by molecular docking studies. A DNA binding study has shown groove binding interactions with the complexes.

  7. Carboxyl-rich plasma polymer surfaces in surface plasmon resonance immunosensing

    Science.gov (United States)

    Makhneva, Ekaterina; Obrusník, Adam; Farka, Zdeněk; Skládal, Petr; Vandenbossche, Marianne; Hegemann, Dirk; Zajíčková, Lenka

    2018-01-01

    Stable carboxyl-rich plasma polymers (PPs) were deposited onto the gold surface of surface plasmon resonance (SPR) chips under conditions that were chosen based on lumped kinetic model results. Carboxyl-rich films are of high interest for bio-applications thanks to their high reactivity, allowing the formation of covalent linkages between biomolecules and a surface. Accordingly, the monoclonal antibody, specific to human serum albumin (HSA), was immobilized and the performance of SPR immunosensors was evaluated by the immunoassay flow test. The developed sensors performed high level of stability and provided selective and high response to the HSA antigen solutions. The achieved results confirmed that the presented methodologies for the grafting of biomolecules on the gold surfaces have great potential for biosensing applications.

  8. Coupling of carboxylic groups onto the surface of polystyrene parts during fused filament fabrication

    Science.gov (United States)

    Nagel, Jürgen; Zimmermann, Philipp; Schubert, Oliver; Simon, Frank; Schlenstedt, Kornelia

    2017-11-01

    A method for the fabrication of polystyrene parts, modified with carboxylic groups during Fused Filament Fabrication (FFF), is being introduced. This method is based on the application of a thin layer of a reactive polymer carrying carboxylic groups on a substrate surface. A polystyrene film is printed on top of this layer. During contact between the hot melt and the reactive layer, a Friedel-Crafts type acylation using a green catalyst takes place, which attaches the reactive polymer to the polystyrene surface. The modified surface is homogeneous, hydrophilic and able to bind copper ions. The method could be used to fabricate unique parts of polystyrene with tailored surface functionalisation. It could be applied for laboratory use, e.g. for the manufacture of lab-on-a-chip devices.

  9. Supramolecular Coordination Assemblies Constructed From Multifunctional Azole-Containing Carboxylic Acids

    Directory of Open Access Journals (Sweden)

    Yuheng Deng

    2010-05-01

    Full Text Available This paper provides a brief review of recent progress in the field of metal coordination polymers assembled from azole-containing carboxylic acids and gives a diagrammatic summary of the diversity of topological structures in the resulting infinite metal-organic coordination networks (MOCNs. Azole-containing carboxylic acids are a favorable kind of multifunctional ligand to construct various metal complexes with isolated complexes and one, two and three dimensional structures, whose isolated complexes are not the focus of this review. An insight into the topology patterns of the infinite coordination polymers is provided. Analyzed topologies are compared with documented topologies and catalogued by the nature of nodes and connectivity pattern. New topologies which are not available from current topology databases are described and demonstrated graphically.

  10. Chemoselective Boron-Catalyzed Nucleophilic Activation of Carboxylic Acids for Mannich-Type Reactions.

    Science.gov (United States)

    Morita, Yuya; Yamamoto, Tomohiro; Nagai, Hideoki; Shimizu, Yohei; Kanai, Motomu

    2015-06-10

    The carboxyl group (COOH) is an omnipresent functional group in organic molecules, and its direct catalytic activation represents an attractive synthetic method. Herein, we describe the first example of a direct catalytic nucleophilic activation of carboxylic acids with BH3·SMe2, after which the acids are able to act as carbon nucleophiles, i.e. enolates, in Mannich-type reactions. This reaction proceeds with a mild organic base (DBU) and exhibits high levels of functional group tolerance. The boron catalyst is highly chemoselective toward the COOH group, even in the presence of other carbonyl moieties, such as amides, esters, or ketones. Furthermore, this catalytic method can be extended to highly enantioselective Mannich-type reactions by using a (R)-3,3'-I2-BINOL-substituted boron catalyst.

  11. The effect of zinc oxide nanoparticle morphology on activity in crosslinking of carboxylated nitrile elastomer

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available The aim of this work was to study the activity of several nanosized zinc oxides in the crosslinking of carboxylated nitrile elastomer (XNBR. In this article, we discuss the effect of zinc oxide nanoparticles with respect to their specific surface area, particle size and morphology (spheres, whiskers, and snowflakes on the crosslinking density and mechanical properties of vulcanisates. The morphology of nanoparticles considerably influences the activity of zinc oxide towards carboxylated nitrile rubber. As a crosslinking agent, zinc oxide with snowflake particles seems to be the most active. The application of nanosized zinc oxide allows the amount of ZnO to be reduced by almost 40%, as compared to vulcanisates containing microsized particles. Moreover, vulcanisates crosslinked with zinc oxide nanoparticles exhibit thermoplastic properties that enable this material to be recycled, which is very important from an ecological point of view.

  12. Carboxylated pillar[5]arene-coated gold nanoparticles with chemical stability and enzyme-like activity.

    Science.gov (United States)

    Park, Chiyoung; Jeong, Eun Sun; Lee, Kyung Joo; Moon, Hoi Ri; Kim, Kyoung Taek

    2014-10-01

    A facile synthesis of gold nanoparticles (AuNPs) covered with a multidentate macrocycle, carboxylated pillar[5]arene (CP), via a one-pot hydrothermal process is reported. The resulting AuNPs are highly stable against salts and pH variations, while their traditional counterparts are not stable at the same conditions. For the stabilization, multiple carboxylate groups of CP might contribute to electrostatic or steric stabilization. In addition, we found that CP-coated AuNPs exhibit greater peroxidase-like activity than citrate-stabilized AuNPs in the presence of silver cations. The system presented herein would provide a new scheme to fabricate unique sensory systems in combination with enzymes, which can bind to the pocket of CP. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Monitoring carboxylic acid formation in engine oils by liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Simon W.; Worsfold, Paul J. (Dept. of Environmental Sciences, Univ. of Plymouth (United Kingdom)); McKerrell, Euan H. (Shell Research Ltd., Thornton Research Centre, Chester (United Kingdom))

    1994-04-21

    Straight chain aliphatic carboxylic acids (C[sub 6]-C[sub 22]) were selectively derivatised in oxidised engine oils with the fluorescent label 9-anthracenemethanol after dialysis of the oils to remove polymeric additives, organometallic oxidation products and solid debris. The ester derivatives were separated by reversed-phase liquid chromatography and quantified using fluorescence detection ([lambda][sub ex]=251 nm; [lambda][sub em]=412 nm). Calibrations over the range 1-4 mg ml[sup -1] were linear (0.9987[<=]r[sup 2][<=]1.0000). The limit of detection (S/N=3) for octadecanoic acid was 85 [mu]g ml[sup -1] in n-heptane (4.3 ng on-column). Results showed that carboxylic acids are formed during the oxidation of oils in car engines and that their concentrations are directly related to the degree of oil degradation

  14. Synthesis of carboxyl superparamagnetic ultrasmall iron oxide (USPIO) nanoparticles by a novel flocculation-redispersion process

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Changming [Nano Biomedicine Research Center, Med-X Research Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Kou Geng [International Joint Cancer Institute, Second Military Medical University, Shanghai 200433 (China); Wang Xiaoliang [Nano Biomedicine Research Center, Med-X Research Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Wang Shuhui [International Joint Cancer Institute, Second Military Medical University, Shanghai 200433 (China); Gu Hongchen [Nano Biomedicine Research Center, Med-X Research Institute, Shanghai Jiao Tong University, Shanghai 200240 (China)], E-mail: hcgu@sjtu.edu.cn; Guo Yajun [International Joint Cancer Institute, Second Military Medical University, Shanghai 200433 (China)], E-mail: yjguo@smmu.edu.cn

    2009-09-15

    We report a novel flocculation-redispersion method to synthesize and purify the biocompatible superparamagnetic ultrasmall iron oxide (USPIO) nanoparticles coated with carboxyl dextran derivative. First, USPIO nanoparticles were synthesized and flocculated to form the large clusters through bridging effect of polyvinyl alcohol (PVA) during coprecipitation process. Then the flocculated USPIO was separated and purified from the solution conveniently through magnetic sedimentation. Finally, USPIO in the clusters were released again and well dispersed through electrostatic repelling effect of citric acid with the aid of ultrasonic. The dispersed carboxyl-functionalized USPIO was conjugated with the monoclonal antibodies. And it has been proved that the antibodies anchored on USPIO still retained their bioactivity after the conjugation. These results implied that the USPIO synthesized have good potential as active targeting molecular probe in biomedical application.

  15. Adsorption Profile of Basic Dye onto Novel Fabricated Carboxylated Functionalized Co-Polymer Nanofibers

    Directory of Open Access Journals (Sweden)

    Marwa F. Elkady

    2016-04-01

    Full Text Available Acrylonitrile-Styrene co-polymer was prepared by solution polymerization and fabricated into nanofibers using the electrospinning technique. The nanofiber polarization was enhanced through its surface functionalization with carboxylic acid groups by simple chemical modification. The carboxylic groups’ presence was dedicated using the FT-IR technique. SEM showed that the nanofiber attains a uniform and porous structure. The equilibrium and kinetic behaviors of basic violet 14 dye sorption onto the nanofibers were examined. Both Langmuir and Temkin models are capable of expressing the dye sorption process at equilibrium. The intraparticle diffusion and Boyd kinetic models specified that the intraparticle diffusion step was the main decolorization rate controlling the process.

  16. Predicting the maximum rate of carboxylation based on the coordination hypothesis of leaf resource allocation

    Science.gov (United States)

    Keenan, T. F.; Prentice, I. C.; Wang, H.; Wright, I. J.; Maire, V.; Dong, N.

    2015-12-01

    Photosynthetic traits in higher plants are known to vary with changes in climate and soil properties. These observed relationships have been included in land surface models through empirical equations, but a fundamental mechanistic understanding remains lacking, making spatial and temporal extrapolation difficult at best. Recent advances in the theory of optimal resource allocation provide a path through which to test hypotheses regarding the governing controls of various plant traits. Here, we propose an optimal theoretical underpinning, based on the coordination hypothesis, for spatial and temporal variations in the maximum rate of carboxylation, Vcmax, and test the theory using observations from 1500 species at 300 sites worldwide. Results suggest that variation in Vcmax can be explained through first-principles, based on the coordinated regulation of the balance of RuBP carboxylation and regeneration.

  17. Photo-Responsive Soft Ionic Crystals: Ion-Pairing Assemblies of Azobenzene Carboxylates.

    Science.gov (United States)

    Yamakado, Ryohei; Hara, Mitsuo; Nagano, Shusaku; Seki, Takahiro; Maeda, Hiromitsu

    2017-07-12

    This report delineates the design and synthesis of negatively charged azobenzene derivatives that form photo-responsive ion-pairing assemblies. The azobenzene carboxylates possessing aliphatic chains were prepared as photo-responsive anions that promote the formation of ion-pairing dimension-controlled assemblies, including mesophases, when used in conjunction with a tetrabutylammonium (TBA) cation. The photo-responsive properties of the ion pairs and the precursory carboxylic acids in the bulk state were examined by polarized optical microscopy (POM) and X-ray diffraction (XRD), demonstrating that liquid crystal (LC)-liquid and crystal-liquid phase transitions occurred, depending on the number and lengths of the aliphatic chains of each assembly. An ion pair exhibited photo-induced crystal-crystal phase transitions upon switching between two irradiation wavelengths (365/436 nm). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Lignosulfonates carboxylated with chloroacetic acid as additives in oil recovery processes involving chemical recovery agents

    Energy Technology Data Exchange (ETDEWEB)

    Kalfoglou, G.

    1981-05-19

    A process for producing petroleum from subterranean formations is disclosed wherein production from the formation is obtained by driving a fluid from an injection well to a production well. The process involves injecting via the injection well into the formation an aqueous solution of lignosulfonates carboxylated with chloroacetic acid as a sacrificial agent to inhibit the deposition of surfactant and/or polymer on the reservoir matrix. The process may best be carried out by injecting the lignosulfonates carboxylated with chloroacetic acid into the formation through the injection well mixed with either a polymer, a surfactant solution and/or a micellar dispersion. This mixture would then be followed by a drive fluid such as water to push the chemicals to the production well.

  19. [Synthesis and luminescence properties of ternary complexes of europium with aromatic carboxylic acid and acrylonitrile].

    Science.gov (United States)

    Guo, Dong-cai; Yi, Li-ming; Shu, Wan-gen; Zhang, Zhen-zhen; Zeng, Zhao-rong; Zhang, Xi-qian

    2006-11-01

    Five ternary complexes were synthesized from europium with aromatic carboxylic acid (p-methylbenzoic acid, methoxybenzoic acid, m-chlorobenzoic acid and benzoic acid, p-hydroxylbenzoic acid) and acrylonitrile, and characterized by means of elemental analysis, thermal analysis, FTIR spectra and UV spectra. The fluorescence spectra show that five ternary complexes have good luminescence properties, and the sequence of the ability of the aromatic carboxylic acids to transfer light energy to europium ion is as follows: p-methylbenzoic acid>benzoic acid>m-chlorobenzoic acid>p-hydroxylbenzoic acid>methoxybenzoic acid. Meanwhile, the ternary europium complexes containing a reactive ligand acrylonitrile will possibly have a potential application to the fabrication of bonding-type europium polymer luminescent materials.

  20. Fe(III)-promoted transformation of β-lactam antibiotics: Hydrolysis vs oxidation.

    Science.gov (United States)

    Chen, Jiabin; Wang, Ying; Qian, Yajie; Huang, Tianyin

    2017-08-05

    The widely used β-lactam antibiotics are susceptible to oxidative and/or hydrolytic degradation promoted by some metal ions (e.g., Cu(II)). Ferric ions (Fe(III)) are among the most common metal ions, but their role in the environmental transformation and fate of β-lactam antibiotics is still unknown. This study elucidates that Fe(III) can promote degradation of β-lactam antibiotics under environmental aquatic conditions. Degradation rate constants of ampicillin (AMP) linearly increased with increasing Fe(III) concentration, but were independent of AMP concentration when AMP was higher than Fe(III) concentration. Neutral pH was most favorable for Fe(III)-promoted degradation of AMP, and the promoted degradation was also significant in real surface water and wastewater matrix. Among the various β-lactam antibiotics, Fe(III)-promoted degradation of penicillins was faster than that of cephalosporins. Product analysis indicated that only two isomers of hydrolysis products were observed without detection of oxidation products. The Fe(III)-promoted degradation likely occurred via complexation of β-lactam antibiotics with carboxyl group and tertiary nitrogen, and then enhancing the hydrolytic cleavage of β-lactam ring. This study is among the first to identify the role of Fe(III) in the degradation of β-lactam antibiotics and elucidate the mechanism. The new findings indicate iron species are among the factors affecting the environmental fate of β-lactam antibiotics. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Synthesis and spectroscopic characterization of some lanthanide(III nitrate complexes of ethyl 2-[2-(1-acetyl-2-oxopropylazo]-4,5-dimethyl-3-thiophenecarboxyate

    Directory of Open Access Journals (Sweden)

    CHEMPAKAM JANARDHANAN ATHIRA

    2011-02-01

    Full Text Available Ethyl 2-[2-(1-acetyl-2-oxopropylazo]-4,5-dimethyl-3-thiophenecarboxyate was synthesized by coupling diazotized ethyl 2-amino-4,5-dimethylthiophene-3-carboxylate with acetylacetone. Based on various spectral studies and elemental analysis, an intramolecularly hydrogen-bonded azo-enol structural form was assigned for the ligand. This ligand is versatile in forming a series of lanthanide(III complexes, viz., lanthanum(III, cerium(III, praseodymium(III, neodymium(III, samarium(III and gadolinium(III, which were characterized through various spectral studies, elemental analysis, magnetic susceptibility measurements, molar conductance and thermal analysis. The spectral data revealed that the ligand acted as a neutral tridentate, coordinating to the metal ion through one of the azo nitrogen atoms, the ester carbonyl and the enolic oxygen of the acetylacetone moiety, without deprotonation. Molar conductance values adequately supported their non-electrolytic nature. The ligand and lanthanum(III complex were subjected to X-ray diffraction studies. In addition, the lanthanum(III complex underwent a facile transesterification reaction on refluxing with methanol for a long period. The thermal behaviour of the lanthanum(III complex was also examined

  2. Heterogeneous and homogeneous catalysis for the hydrogenation of carboxylic acid derivatives: history, advances and future directions.

    Science.gov (United States)

    Pritchard, James; Filonenko, Georgy A; van Putten, Robbert; Hensen, Emiel J M; Pidko, Evgeny A

    2015-06-07

    The catalytic reduction of carboxylic acid derivatives has witnessed a rapid development in recent years. These reactions, involving molecular hydrogen as the reducing agent, can be promoted by heterogeneous and homogeneous catalysts. The milestone achievements and recent results by both approaches are discussed in this Review. In particular, we focus on the mechanistic aspects of the catalytic hydrogenation and highlight the bifunctional nature of the mechanism that is preferred for supported metal catalysts as well as homogeneous transition metal complexes.

  3. DTA Studies on the Thermal Oxidation and Crosslinking Reactions of Carboxyl-Terminated Polybutadiene

    OpenAIRE

    Kishore, K; Verneker, Pai VR; Dharumaraj, Varghese G

    1984-01-01

    Studies on the thermal oxidation of carboxyl-terminated polybutadiene in the presence of antioxidants have been carried out by dynamic DTA. Bis-thioacetylacetonato nickel(II) compounds are found to be effective in inhibiting the air oxidation reaction in the polymer. The crosslinking reaction of the polymer through the double bonds present in the polymer molecule is desensitized by the antioxidants and the effect is more with N-phenyl-1-naphthylamine. An exothermic peak formed at $270^ \\circ ...

  4. Urinary and brain beta-carboline-3-carboxylates as potent inhibitors of brain benzodiazepine receptors.

    OpenAIRE

    Braestrup, C; Nielsen, M; Olsen, C E

    1980-01-01

    Benzodiazepines probably exert their anxiolytic, hypnotic, and anticonvulsant effects by interacting with brain-specific high-affinity benzodiazepine receptors. In searching for possible endogenous ligands for these receptors we have purified a compound 10(7)-fold from human urine by extractions, treatment with hot ethanol, and column chromatography. The compound was identified as beta-carboline-3-carboxylic acid ethyl ester (IIc) by mass spectrometry, NMR spectrometry, and synthesis; IIc was...

  5. The Cannabinoid Type-1 Receptor Carboxyl-Terminus, More Than Just a Tail

    OpenAIRE

    Stadel, Rebecca; Ahn, Kwang H.; Kendall, Debra A.

    2011-01-01

    The cannabinoid type-1 (CB1) receptor is a G protein-coupled receptor (GPCR) that binds the main active ingredient of marijuana, Δ9-tetrahydrocannabinol, and has been implicated in several disease states, including drug addiction, anxiety, depression, obesity, and chronic pain. In the two decades since the discovery of CB1, studies at the molecular level have centered on the transmembrane core. This interest has now expanded as we discover that other regions of CB1, including the CB1 carboxyl...

  6. Time and substrate dependent exudation of carboxylates by Lupinus albus L. and Brassica napus L.

    Science.gov (United States)

    Mimmo, Tanja; Hann, Stephan; Jaitz, Leonhard; Cesco, Stefano; Gessa, Carlo Emanuele; Puschenreiter, Markus

    2011-11-01

    Root exudates influence significantly physical, chemical and biological characteristics of rhizosphere soil. Their qualitative and quantitative composition is affected by environmental factors such as pH, soil type, oxygen status, light intensity, soil temperature, plant growth, nutrient availability and microorganisms. The aim of the present study was to assess the influence of growth substrate and plant age on the release of carboxylates from Lupinus albus L. and Brassica napus L. Both plant species were studied in continuously percolated microcosms filled with either sand, soil or sand + soil (1:1) mixture. Soil solution was collected every week at 7, 14, 21, 28 and 35 days after planting (DAP). Carboxylate concentrations were determined by reversed-phase liquid chromatography - electrospray ionization - time of flight mass spectrometry (LC-ESI-TOFMS). Oxalate, citrate, succinate, malate and maleate were detected in soil solutions of both plant species. Their concentrations were correlated with the physiological status of the plant and the growth substrate. Oxalate was the predominant carboxylate detected within the soil solution of B. napus plants while oxalate and citrate were the predominant ones found in the soil solutions of L. albus plants. The sampling determination of carboxylates released by plant roots with continuous percolation systems seems to be promising as it is a non-destructive method and allows sampling and determination of soluble low molecular weight organic compounds derived from root exudation as well as the concentration of soluble nutrients, which both might reflect the nutritional status of plants. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  7. Merging Photoredox and Nickel Catalysis: Decarboxylative Cross-Coupling of Carboxylic Acids with Vinyl Halides

    Science.gov (United States)

    2015-01-01

    Decarboxylative cross-coupling of alkyl carboxylic acids with vinyl halides has been accomplished through the synergistic merger of photoredox and nickel catalysis. This new methodology has been successfully applied to a variety of α-oxy and α-amino acids, as well as simple hydrocarbon-substituted acids. Diverse vinyl iodides and bromides give rise to vinylation products in high efficiency under mild, operationally simple reaction conditions. PMID:25521443

  8. Supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulphate on ...

    Indian Academy of Sciences (India)

    of β-acetamido ketones in good to excellent yields. Keywords. β-Acetamido ketones; L-pyrrolidine-2-carboxylic ..... significant effect on the outcome of reaction. Also, both. O. O. H. +. CH3CN, CH3COCl reflux. NHAc. O. (Cat.) N. H. HO3SO. COOH/SiO2. Cl. Cl. Scheme 2. Effect of catalyst on the outcome of the reaction.

  9. Electron polarizability of molecules of carboxylic acids and their dimers and trimers

    Science.gov (United States)

    Nazarov, A. P.; Barabanova, N. N.; Bogdanov, D. L.; Dadivanyan, A. K.

    2017-11-01

    Components of the tensor of the electron polarizability of molecules of carboxylic acids and their dimers and trimers with conjugated chemical bonds are calculated according the Hartree-Fock method. The dependences of a change in the anisotropy of polarizability on the average polarizability of a molecule and the number of electrons in a conjugated system are determined. An increase in the anisotropy of electron polarizability during the formation of intermolecular associates through hydrogen bonds is observed.

  10. Functional Oligomerization of the Saccharomyces cerevisiae Isoprenylcysteine Carboxyl Methyltransferase, Ste14p

    OpenAIRE

    Griggs, Amy M.; Hahne, Kalub; Hrycyna, Christine A.

    2010-01-01

    The isoprenylcysteine carboxyl methyltransferase (Icmt) from Saccharomyces cerevisiae, also designated Ste14p, is a 26-kDa integral membrane protein that contains six transmembrane spanning segments. This protein is localized to the endoplasmic reticulum membrane where it performs the methylation step of the CAAX post-translational processing pathway. Sequence analysis reveals a putative GXXXG dimerization motif located in transmembrane 1 of Ste14p, but it is not known whether Ste14p forms or...

  11. Tailored and integrated production of carboxylated cellulose nanocrystals (CNC) with nanofibrils (CNF) through maleic acid hydrolysis

    Science.gov (United States)

    Ruibin Wang; Liheng Chen; J.Y. Zhu; Rendang Yang

    2017-01-01

    This study demonstrates the feasibility of tailored and integrated production of carboxylated cellulose nanocrystals (CNC) with nanofibrils (CNF) from bleached pulp fibers through hydrolysis using a recyclable dicarboxylic acid. Hydrolysis experiments were conducted using ranges of 15–75 wt% maleic acid concentrations, 60–120°C temperatures, and 5–300 min reaction...

  12. SYNTHESIS OF FLAVANONE-6-CARBOXYLIC ACID DERIVATIVES FROM SALICYLIC ACID DERIVATIVE

    OpenAIRE

    Mardjan, Muhammad Idham Darussalam; Ambarwati, Retno; Matsjeh, Sabirin; Wahyuningsih, Tutik Dwi; Haryadi, Winarto

    2012-01-01

    Synthesis of flavanone-6-carboxylic acid derivatives had been conducted via the route of chalcone. The synthesis was carried out from salicylic acid derivative, i.e. 4-hydroxybenzoic acid, via esterification, Fries rearrangement, Claisen-Schmidt condensation and 1,4-nucleophilic addition reactions. Structure elucidation of products was performed using FT-IR, 1H-NMR, GC-MS and UV-Vis spectrometers. Reaction of 4-hydroxybenzoic acid with methanol catalyzed with sulfuric acid produced methyl 4-h...

  13. Carboxylic ionophores enhance the cytotoxic potency of ligand- and antibody-delivered ricin A chain

    Science.gov (United States)

    1984-01-01

    The highly selective cytotoxicity of site-directed ricin A chain conjugates can be potentiated by membrane-active carboxylic ionophores. The combined use of the two agents results in much faster inactivation of ribosomes and subsequent cell death and lysis. The potency of A chain cytotoxins is correspondingly increased by several orders of magnitude and cells that sparsely express the target antigen or receptor can be killed. PMID:6090575

  14. Carboxylic Terminated Thermo-Responsive Copolymer Hydrogel and Improvement in Peptide Release Profile

    Directory of Open Access Journals (Sweden)

    Zi-Kun Rao

    2018-02-01

    Full Text Available To improve the release profile of peptide drugs, thermos-responsive triblock copolymer poly (ε-caprolactone-co-p-dioxanone-b-poly (ethylene glycol-b-poly (ε-caprolactone-co-p-dioxanone (PECP was prepared and end capped by succinic anhydride to give its carboxylic terminated derivative. Both PCEP block copolymer and its end group modified derivative showed temperature-dependent reversible sol-gel transition in water. The carboxylic end group could significantly decrease the sol-gel transition temperature by nearly 10 °C and strengthen the gel due to enhanced intermolecular force among triblock copolymer chains. Furthermore, compared with the original PECP triblock copolymer, HOOC–PECP–COOH copolymer displayed a retarded and sustained release profile for leuprorelin acetate over one month while effectively avoiding the initial burst. The controlled release was believed to be related to the formation of conjugated copolymer-peptide pair by ionic interaction and enhanced solubility of drug molecules into the hydrophobic domains of the hydrogel. Therefore, carboxyl terminated HOOC–PECP–COOH hydrogel was a promising and well-exhibited sustained release carrier for peptide drugs with the advantage of being able to develop injectable formulation by simple mixing.

  15. Accumulation of n-alkanes and carboxylic acids in peat mounds

    Science.gov (United States)

    Gabov, D. N.; Beznosikov, V. A.; Gruzdev, I. V.; Yakovleva, E. V.

    2017-10-01

    The quantitative and qualitative compositions of n-alkanes and carboxylic acids have been identified, and the features of their vertical stratification in peat mound profiles of the forest-tundra zone of Komi Republic have been revealed. The composition of n-alkanes (structures with C23, C25, C27, C29, and C31) and carboxylic acids (C24, C26, and C28) and their proportions make it possible to determine changes in plant communities of peat mounds with time and can be used as markers for the degree of decomposition of organic matter. In cryogenic horizons, the contents of n-alkanes (mainly C23, C25, and C27) and carboxylic acids (C24, C26, and C28) significantly decrease because of the different botanic composition of cryogenic horizons (grass-woody residues) and seasonally thawing horizons (moss-subshrub residues) and the almost complete stopping of the equilibrium accumulation and transformation of organic compounds in permafrost.

  16. Carboxylic Acid Fullerene (C60) Derivatives Attenuated Neuroinflammatory Responses by Modulating Mitochondrial Dynamics.

    Science.gov (United States)

    Ye, Shefang; Zhou, Tong; Cheng, Keman; Chen, Mingliang; Wang, Yange; Jiang, Yuanqin; Yang, Peiyan

    2015-12-01

    Fullerene (C60) derivatives, a unique class of compounds with potent antioxidant properties, have been reported to exert a wide variety of biological activities including neuroprotective properties. Mitochondrial dynamics are an important constituent of cellular quality control and function, and an imbalance of the dynamics eventually leads to mitochondria disruption and cell dysfunctions. This study aimed to assess the effects of carboxylic acid C60 derivatives (C60-COOH) on mitochondrial dynamics and elucidate its associated mechanisms in lipopolysaccharide (LPS)-stimulated BV-2 microglial cell model. Using a cell-based functional screening system labeled with DsRed2-mito in BV-2 cells, we showed that LPS stimulation led to excessive mitochondrial fission, increased mitochondrial localization of dynamin-related protein 1 (Drp1), both of which were markedly suppressed by C60-COOH pretreatment. LPS-induced mitochondria reactive oxygen species (ROS) generation and collapse of mitochondrial membrane potential (ΔΨm) were also significantly inhibited by C60-COOH. Moreover, we also found that C60-COOH pretreatment resulted in the attenuation of LPS-mediated activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) signaling, as well as the production of pro-inflammatory mediators. Taken together, these findings demonstrated that carboxylic acid C60 derivatives may exert neuroprotective effects through regulating mitochondrial dynamics and functions in microglial cells, thus providing novel insights into the mechanisms of the neuroprotective properties of carboxylic acid C60 derivatives.

  17. Investigation of Carboxylic Acid-Neodymium Conversion Films on Magnesium Alloy

    Science.gov (United States)

    Cui, Xiufang; Liu, Zhe; Lin, Lili; Jin, Guo; Wang, Haidou; Xu, Binshi

    2015-01-01

    The new carboxylic acid-neodymium anhydrous conversion films were successfully prepared and applied on the AZ91D magnesium alloy surface by taking absolute ethyl alcohol as solvent and four kinds of soluble carboxylic acid as activators. The corrosion resistance of the coating was measured by potentiodynamic polarization test in 3.5 wt.% NaCl solution in pH 7.0. The morphology, structure, and constituents of the coating were observed by scanning electron microscope, energy dispersivespectrum, x-ray photoelectron spectrum, and Fourier infrared spectrometer. Results show that corrosion resistance properties of samples coated with four different anhydrous conversion films were improved obviously. The corrosion potential increased, corrosion current density decreased, and polarization resistance increased. Among these four kinds of conversion films the one added with phytic exhibits the best corrosion resistant property. The mechanism of anhydrous-neodymium conversion film formation is also analyzed in this paper. It reveals that the gadolinium conversion coating is mainly composed of stable Nd2O3, MgO, Mg(OH)2, and carboxylate of Nd. And that the sample surface is rich in organic functional groups.

  18. Preparation and Application of Carboxylated Graphene Oxide Sponge in Dye Removal

    Directory of Open Access Journals (Sweden)

    Lianqin Zhao

    2017-10-01

    Full Text Available Spongy graphene is a newly developed adsorbent of high performance for water treatment. Proper functionalization is an efficient approach to improve the adsorption capacity of graphene adsorbents. In this study, we prepared graphene oxide (GO, functionalized it with carboxyl groups to produce carboxylated GO (GO-COOH dispersion, and lyophilized the GO-COOH dispersion to obtain the GO-COOH sponge. The adsorption isotherm, kinetics, thermodynamics, influencing factors, and regeneration of the adsorption of dye methylene blue (MB on GO-COOH sponge were evaluated in batch experiments. The adsorption capacity of GO-COOH sponge was measured as 780 mg/g, which was nearly twice that of GO sponge (446 mg/g. The adsorption isotherm could be well described by the Freundlich model with a KF of 508 (L/mg1/n. The adsorption kinetic was nicely fitted by pseudo-first-order model with a k1 of 0.00157·min−1. In thermodynamics analysis, the negative ΔG indicated the spontaneous nature of adsorption on GO-COOH sponge. The adsorption process was endothermic and was driven by the increase of entropy. Higher pH benefited the removal of MB by GO-COOH sponge and the ionic strength had no meaningful effect. The regeneration was poor due to the strong electrostatic interaction between MB and the GO-COOH sponge. The results collectively suggested that carboxylation increased the adsorption performance of GO sponge.

  19. Graphene oxide and carboxylated graphene oxide: Viable two-dimensional nanolabels for lateral flow immunoassays.

    Science.gov (United States)

    Yu, Li; Li, Peiwu; Ding, Xiaoxia; Zhang, Qi

    2017-04-01

    Graphene oxide (GO) and carboxylated GO were used as labels for lateral flow immunoassays, instead of the conventionally used colloidal gold and colored latex labels. A sensor is demonstrated that enables fast screening for aflatoxin B 1 (AFB 1 ) as a model analyte using the antibody-GO complex as the recognition element. The visual limit of detection and cut-off value for AFB 1 are 0.3 and 1ng/mL, respectively. It is shown that GO and carboxylated GO are viable black labels for use in lateral flow assays, one typical advantage being the saving cost (compared to the use of colloidal gold). Qualitative results are achieved within 15min, and the analytical results were in good agreement with the reference LC MS/MS method. The method was successfully applied to the on-site determination of AFB 1 in agricultural products. In our perception, it opens new possibilities for the screening of other toxins by lateral flow immunoassays using GO and carboxylated GO as labels. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Gold nanostar-enhanced surface plasmon resonance biosensor based on carboxyl-functionalized graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Sun, Ying; Ma, Pinyi; Zhang, Di; Li, Shuo; Wang, Xinghua; Song, Daqian, E-mail: songdq@jlu.edu.cn

    2016-03-24

    A new high-sensitivity surface plasmon resonance (SPR) biosensor based on biofunctional gold nanostars (AuNSs) and carboxyl-functionalized graphene oxide (cGO) sheets was described. Compared with spherical gold nanoparticles (AuNPs), the anisotropic structure of AuNSs, which concentrates the electric charge density on its sharp tips, could enhance the local electromagnetic field and the electronic coupling effect significantly. cGO was obtained by a diazonium reaction of graphene oxide (GO) with 4-aminobenzoic acid. Compared with GO, cGO could immobilize more antibodies due to the abundant carboxylic groups on its surface. Testing results show that there are fairly large improvements in the analytical performance of the SPR biosensor using cGO/AuNSs-antigen conjugate, and the detection limit of the proposed biosensor is 0.0375 μg mL{sup −1}, which is 32 times lower than that of graphene oxide-based biosensor. - Highlights: • A sensitive and versatile SPR biosensor was constructed for detection of pig IgG. • Biofunctional gold nanostars were used to amplify the response signals. • The strategy employed carboxyl-functionalized graphene oxide as biosensing substrate. • The detection limit of the proposed biosensor is 32 times lower than that of graphene oxide-based biosensor.

  1. Statistical investigation of lead removal with various functionalized carboxylate ferroxane nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moattari, Rozita M.; Rahimi, Safoora [Polymer Research Lab., Department of Chemical Engineering, College of Engineering, Razi University, Kermanshah (Iran, Islamic Republic of); Rajabi, Laleh, E-mail: laleh.rajabii@gmail.com [Polymer Research Lab., Department of Chemical Engineering, College of Engineering, Razi University, Kermanshah (Iran, Islamic Republic of); Derakhshan, Ali Ashraf [Young Researchers Club, Kermanshah Branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of); Keyhani, Mohammad [Polymer Research Lab., Department of Chemical Engineering, College of Engineering, Razi University, Kermanshah (Iran, Islamic Republic of)

    2015-02-11

    Graphical abstract: - Highlights: • Four new carboxylate ferroxane nanostructures were synthesized and characterized. • Carboxylate ferroxanes were used as nanosorbents for lead removal. • Taguchi method was used to design the experiments. • Statistical analyses evaluated the three model responses [R%, Logit (R%), C{sub ratio}]. • Maleate ferroxane performed the best of the four nanosorbents studied. - Abstract: Four new types of carboxylate-ferroxane nanoparticles, namely; maleate ferroxane (MF), fumarateferroxane (FF), para-amino benzoate ferroxane (PABF) and para-hydroxy benzoate ferroxane (PHBF) were synthesized, characterized and used for lead removal from aqueous solutions. Lepidocrocite nanoparticles were also synthesized and characterized asa precursorforcarboxylate-ferroxanes. FTIR, SEM and DLS analysis characterized the synthesized samplesand final Pb(II) concentration were analysed using inductively coupled plasma atomic emission spectrometer. Performance evaluation of the nanoparticlesin adsorption process was achieved using Taguchi experimental design. Variables in adsorption process were initial pH, contact time, adsorbent dose, adsorbent typeand initial concentration of Pb{sup 2+} ions. The initial Pb(II) concentration was the most influential factor in the adsorption process among the five factors. Adsorption of lead was performed through two possible mechanisms; ion exchange and complex formation. Maleate ferroxane performed the best lead removal efficiency among the four types of ferroxane nanostructures studied. The adsorption kinetic data described well with a pseudo-second-order model and the equilibrium data fitted well to the Frendlich isotherm.

  2. Surface complexation of carboxylate adheres Cryptosporidium parvum öocysts to the hematite-water interface

    Science.gov (United States)

    Gao, X.; Metge, D.W.; Ray, C.; Harvey, R.W.; Chorover, J.

    2009-01-01

    The interaction of viable Cryptosporidium parvum öocysts at the hematite (α-Fe2O3)−water interface was examined over a wide range in solution chemistry using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Spectra for hematite-sorbed öocysts showed distinct changes in carboxylate group vibrations relative to spectra obtained in the absence of hematite, indicative of direct chemical bonding between carboxylate groups and Fe metal centers of the hematite surface. The data also indicate that complexation modes vary with solution chemistry. In NaCl solution, öocysts are bound to hematite via monodentate and binuclear bidentate complexes. The former predominates at low pH, whereas the latter becomes increasingly prevalent with increasing pH. In a CaCl2 solution, only binuclear bidentate complexes are observed. When solution pH is above the point of zero net proton charge (PZNPC) of hematite, öocyst surface carboxylate groups are bound to the mineral surface via outer-sphere complexes in both electrolyte solutions.

  3. Imidazolidene carboxylate bound MBPh4 complexes (M = Li, Na) and their relevance in transcarboxylation reactions.

    Science.gov (United States)

    Van Ausdall, Bret R; Poth, Nils F; Kincaid, Virginia A; Arif, Atta M; Louie, Janis

    2011-10-21

    Combination of 1,3-bis(2,6-diisopropylphenyl)imidazolum-2-carboxylate (IPrCO(2)) with the Lewis acids MBPh(4), where M = Li or Na, provided two separate complexes. The crystal structures of these complexes revealed that coordination to NaBPh(4) yielded a dimeric species, yet coordination of IPrCO(2) with LiBPh(4) yielded a monomeric species. Combination of 1,3-bis(2,4,6-trimethylphenyl)imidazolum-2-carboxylate (IMesCO(2)) with LiBPh(4) also afforded a dimeric species that was similar in global structure to that of the IPrCO(2)+NaBPh(4) dimer. In all three cases, the cation of the organic salt was coordinated to the oxyanion of the zwitterionic carboxylate. Thermogravimetric analysis of the crystals demonstrated that decarboxylation occurred at lower temperatures than the decarboxylation temperature of the parent NHC·CO(2) (NHC = N-heterocyclic carbene). Kinetic analysis of the transcarboxylation of IPrCO(2) to acetophenone with NaBPh(4) to yield sodium benzoylacetate was performed. First-order dependences were observed for IPrCO(2) and acetophenone, whereas zero -order dependence was observed for NaBPh(4). Direct dicarboxylation was observed when I(t)BuCO(2) was added to MeCN in the absence of added MBPh(4).

  4. Carboxylic acid functionalization of halloysite nanotubes for sustained release of diphenhydramine hydrochloride

    Energy Technology Data Exchange (ETDEWEB)

    Zargarian, S. Sh.; Haddadi-Asl, V., E-mail: haddadi@aut.ac.ir; Hematpour, H. [Amirkabir University of Technology, Department of Polymer Engineering and Color Technology (Iran, Islamic Republic of)

    2015-05-15

    Halloysite nanotubes (HNT) (cylindrical shape with external diameter and length in the range of 30–80 nm and 0.2–1 µm, respectively) were functionalized with 3-aminopropyltriethoxysilane (APTES) from hydroxyl groups by a coupling reaction. Subsequently, maleic anhydride was attached to the APTES moieties to yield carboxylic acid-functionalized HNT. Loading and subsequent release of a model drug molecule diphenhydramine hydrochloride (DPH) on modified and unmodified nanotubes were investigated. Morphology of HNT was studied by electron microscopy. Successful attachment of APTES and carboxylic acid groups to halloysite and drug loading were evaluated by Fourier transform infrared spectroscopy. The amount of surface modification and drug adsorption capacity were calculated via thermogravimetric analysis. The ordered crystal structure of loaded drug was evaluated by X-ray diffraction. UV–Visible spectrophotometer was used to study drug release from modified and unmodified samples. Carboxylated halloysite exhibits higher loading capacity and prolonged release of DPH as compared to that of the natural halloysite.

  5. On the formation of niacin (vitamin B3) and pyridine carboxylic acids in interstellar model ices

    Science.gov (United States)

    McMurtry, Brandon M.; Turner, Andrew M.; Saito, Sean E. J.; Kaiser, Ralf I.

    2016-06-01

    The formation of pyridine carboxylic acids in interstellar ice grains was simulated by electron exposures of binary pyridine (C5H5N)-carbon dioxide (CO2) ice mixtures at 10 K under contamination-free ultrahigh vacuum conditions. Chemical processing of the pristine ice and subsequent warm-up phase was monitored on line and in situ via Fourier transform infrared spectroscopy to probe for the formation of new radiation induced species. In the infrared spectra of the irradiated ice, bands assigned to nicotinic acid (niacin; vitamin B3; m-C5H4NCOOH) along with 2,3-, 2,5-, 3,4-, and 3,5-pyridine dicarboxylic acid (C5H3N(COOH)2) were unambiguously identified along with the hydroxycarbonyl (HOCO) radical. Our study suggests that the reactive pathway responsible for pyridine carboxylic acids formation involves a HOCO intermediate, which forms through the reaction of suprathermal hydrogen ejected from pyridine with carbon dioxide. The newly formed pyridinyl radical may then undergo radical-radical recombination with a hydroxycarbonyl radical to form a pyridine carboxylic acid.

  6. Design, Synthesis, Antimycobacterial Evaluation, and In Silico Studies of 3-(Phenylcarbamoyl-pyrazine-2-carboxylic Acids

    Directory of Open Access Journals (Sweden)

    Lucia Semelková

    2017-09-01

    Full Text Available Pyrazinamide, the first-line antitubercular drug, has been regarded the basic component of tuberculosis treatment for over sixty years. Researchers have investigated its effect on Mycobacterium tuberculosis for this long time, and as a result, new potential targets of pyrazinamide or its active form, pyrazinoic acid, have been found. We have designed and prepared 3-(phenyl-carbamoylpyrazine-2-carboxylic acids as more lipophilic derivatives of pyrazinoic acid. We also prepared methyl and propyl derivatives as prodrugs with further increased lipophilicity. Antimycobacterial, antibacterial and antifungal growth inhibiting activity was investigated in all prepared compounds. 3-[(4-Nitrophenylcarbamoyl]pyrazine-2-carboxylic acid (16 exerted high antimycobacterial activity against Mycobacterium tuberculosis H37Rv with MIC = 1.56 μg·mL−1 (5 μM. Propyl 3-{[4-(trifluoromethylphenyl]carbamoyl}pyrazine-2-carboxylate (18a showed also high antimycobacterial activity against Mycobacterium tuberculosis H37Rv with MIC = 3.13 μg·mL−1. In vitro cytotoxicity of the active compounds was investigated and no significant cytotoxic effect was observed. Based to structural similarity to known inhibitors of decaprenylphosphoryl-β-d-ribose oxidase, DprE1, we performed molecular docking of the prepared acids to DprE1. These in silico experiments indicate that modification of the linker connecting aromatic parts of molecule does not have any negative influence on the binding.

  7. Biotransformation of fluorophenyl pyridine carboxylic acids by the model fungus Cunninghamella elegans.

    Science.gov (United States)

    Palmer-Brown, William; Dunne, Brian; Ortin, Yannick; Fox, Mark A; Sandford, Graham; Murphy, Cormac D

    2017-09-01

    1. Fluorine plays a key role in the design of new drugs and recent FDA approvals included two fluorinated drugs, tedizolid phosphate and vorapaxar, both of which contain the fluorophenyl pyridyl moiety. 2. To investigate the likely phase-I (oxidative) metabolic fate of this group, various fluorinated phenyl pyridine carboxylic acids were incubated with the fungus Cunninghamella elegans, which is an established model of mammalian drug metabolism. 3. (19)F NMR spectroscopy established the degree of biotransformation, which varied depending on the position of fluorine substitution, and gas chromatography-mass spectrometry (GC-MS) identified alcohols and hydroxylated carboxylic acids as metabolites. The hydroxylated metabolites were further structurally characterised by nuclear magnetic resonance spectroscopy (NMR), which demonstrated that hydroxylation occurred on the 4' position; fluorine in that position blocked the hydroxylation. 4. The fluorophenyl pyridine carboxylic acids were not biotransformed by rat liver microsomes and this was a consequence of inhibitory action, and thus, the fungal model was crucial in obtaining metabolites to establish the mechanism of catabolism.

  8. Fluorescence Quenching of Two Coumarin-3-carboxylic Acids by Trivalent Lanthanide Ions.

    Science.gov (United States)

    Cisse, Lamine; Djande, Abdoulaye; Capo-Chichi, Martine; Delattre, François; Saba, Adama; Brochon, Jean-Claude; Sanouski, Serguei; Tine, Alphonse; Aaron, Jean-Jacques

    2017-03-01

    The effects of various trivalent lanthanide ions (acetates of Ce3+, Er3+, Eu3+, Nd3+) on the electronic absorption and fluorescence spectra of un-substituted coumarin-3-carboxylic acid (CCA) and 7-N,N-diethylamino-coumarin-3-carboxylic acid (DECCA) have been investigated in dimethylsulfoxide (DMSO) at room temperature. Depending on the lanthanide ion nature and concentration, significant spectral changes of absorption bands occurred for both coumarin derivatives. These spectral changes were attributed to the formation of ground-state complexes between the coumarin carboxylate derivatives and lanthanide ions. The fluorescence quenching of CCA and DECCA upon increasing the lanthanide ion concentration was studied. Different quantitative treatments, including the Stern-Volmer equation, the Perrin equation and a polynomial equation, were applied and compared in order to determine the nature of the quenching mechanisms for both coumarin derivatives. The results suggested the contribution of both dynamic and static quenching. Significant differences of CCA and DECCA fluorescence quenching efficiency were also observed, depending on the lanthanide ion. DECCA fluorescence lifetime measurements, performed in the absence and in the presence of Ln3+, confirmed a contribution of static quenching.

  9. On the formation of niacin (vitamin B3) and pyridine carboxylic acids in interstellar model ices

    Energy Technology Data Exchange (ETDEWEB)

    McMurtry, Brandon M.; Turner, Andrew M.; Saito, Sean E.J.; Kaiser, Ralf I. [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822 (United States); Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822 (United States)

    2016-06-15

    The formation of pyridine carboxylic acids in interstellar ice grains was simulated by electron exposures of binary pyridine (C{sub 5}H{sub 5}N)-carbon dioxide (CO{sub 2}) ice mixtures at 10 K under contamination-free ultrahigh vacuum conditions. Chemical processing of the pristine ice and subsequent warm-up phase was monitored on line and in situ via Fourier transform infrared spectroscopy to probe for the formation of new radiation induced species. In the infrared spectra of the irradiated ice, bands assigned to nicotinic acid (niacin; vitamin B3; m-C{sub 5}H{sub 4}NCOOH) along with 2,3-, 2,5-, 3,4-, and 3,5-pyridine dicarboxylic acid (C{sub 5}H{sub 3}N(COOH){sub 2}) were unambiguously identified along with the hydroxycarbonyl (HOCO) radical. Our study suggests that the reactive pathway responsible for pyridine carboxylic acids formation involves a HOCO intermediate, which forms through the reaction of suprathermal hydrogen ejected from pyridine with carbon dioxide. The newly formed pyridinyl radical may then undergo radical–radical recombination with a hydroxycarbonyl radical to form a pyridine carboxylic acid.

  10. Solution-processable carboxylate-capped CuO nanoparticles obtained by a simple solventless method

    Energy Technology Data Exchange (ETDEWEB)

    Estruga, Marc [Universitat Autonoma de Barcelona, Department of Chemistry (Spain); Roig, Anna; Domingo, Concepcion [CSIC, Institut de Ciencia de Materials de Barcelona (Spain); Ayllon, Jose A., E-mail: joseantonio.ayllon@uab.es [Universitat Autonoma de Barcelona, Department of Chemistry (Spain)

    2012-08-15

    Carboxylate-capped CuO nanoparticles were obtained via a simple solventless route, based on the thermal decomposition at 120 Degree-Sign C of solid precursors. The reaction mixture consisted of copper acetate monohydrate, acting as the CuO precursor, and different organic carboxylic acids (lauric, phenylvaleric or 3,6,9-trioxadecanoic acid) used as the capping agent. The proposed method, in good agreement with environmentally friendly practices, produced dry nanoparticles, thereby totally eliminating the need of washing, filtration, or other downstream steps. Transmission electron micrographs show crystalline roughly spherical CuO nanoparticles with average diameters between 3.1 and 5.5 nm depending on the capping ligand. The laurate-capped CuO nanoparticles showed a paramagnetic behaviour at room temperature, while a weak ferromagnetic component was detected at low temperature (<40 K). It was also proved that the chemical structure of the carboxylic acid tail enabled the straightforward dispersibility of nanoparticles in common solvents and assisted in the deposition of the material as thin films.

  11. Attenuated total reflectance Fourier-transform infrared spectroscopy of carboxylic acids adsorbed onto mineral surfaces

    Science.gov (United States)

    Kubicki, J. D.; Schroeter, L. M.; Itoh, M. J.; Nguyen, B. N.; Apitz, S. E.

    1999-09-01

    A suite of naturally-occurring carboxylic acids (acetic, oxalic, citric, benzoic, salicylic and phthalic) and their corresponding sodium salts were adsorbed onto a set of common mineral substrates (quartz, albite, illite, kaolinite and montmorillonite) in batch slurry experiments. Solution pH's of approximately 3 and 6 were used to examine the effects of pH on sorption mechanisms. Attenuated total reflectance Fourier-transform infrared (ATR FTIR) spectroscopy was employed to obtain vibrational frequencies of the organic ligands on the mineral surfaces and in solution. UV/visible spectroscopy on supernatant solutions was also employed to confirm that adsorption from solution had taken place for benzoic, salicylic and phthalic acids. Molecular orbital calculations were used to model possible surface complexes and interpret the experimental spectra. In general, the tectosilicates, quartz and albite feldspar, did not chemisorb (i.e., strong, inner-sphere adsorption) the carboxylate anions in sufficient amounts to produce infrared spectra of the organics after rinsing in distilled water. The clays (illite, kaolinite and montmorillonite) each exhibited similar ATR FTIR spectra. However, the illite sample used in this study reacted to form strong surface and aqueous complexes with salicylic acid before being treated to remove free Fe-hydroxides. Chemisorption of carboxylic acids onto clays is shown to be limited without the presence of Fe-hydroxides within the clay matrix.

  12. A relativistic density functional study of uranyl hydrolysis and complexation by carboxylic acids in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Rupashree Shyama

    2009-02-10

    In this work, the complexation of uranium in its most stable oxidation state VI in aqueous solution was studied computationally, within the framework of density functional (DF) theory. The thesis is divided into the following parts: Chapter 2 briefly summarizes the relevant general aspects of actinide chemistry and then focuses on actinide environmental chemistry. Experimental results on hydrolysis, actinide complexation by carboxylic acids, and humic substances are presented to establish a background for the subsequent discussion. Chapter 3 describes the computational method used in this work and the relevant features of the parallel quantum chemistry code PARAGAUSS employed. First, the most relevant basics of the applied density functional approach are presented focusing on relativistic effects. Then, the treatment of solvent effects, essential for an adequate modeling of actinide species in aqueous solution, will be introduced. At the end of this chapter, computational parameters and procedures will be summarized. Chapter 4 presents the computational results including a comparison to available experimental data. In the beginning, the mononuclear hydrolysis product of UO{sub 2}{sup 2+}, [UO{sub 2}OH]{sup +}, will be discussed. The second part deals with actinide complexation by carboxylate ligands. First of all the coordination number for uranylacetate will be discussed with respect to implications for the complexation of actinides by humic substances followed by the uranyl complexation of aromatic carboxylic acids in comparison to earlier results for aliphatic ones. In the end, the ternary uranyl-hydroxo-acetate are discussed, as models of uranyl humate complexation at ambient condition.

  13. SYNTHESIS OF FLAVANONE-6-CARBOXYLIC ACID DERIVATIVES FROM SALICYLIC ACID DERIVATIVE

    Directory of Open Access Journals (Sweden)

    Muhammad Idham Darussalam Mardjan

    2012-02-01

    Full Text Available Synthesis of flavanone-6-carboxylic acid derivatives had been conducted via the route of chalcone. The synthesis was carried out from salicylic acid derivative, i.e. 4-hydroxybenzoic acid, via esterification, Fries rearrangement, Claisen-Schmidt condensation and 1,4-nucleophilic addition reactions. Structure elucidation of products was performed using FT-IR, 1H-NMR, GC-MS and UV-Vis spectrometers. Reaction of 4-hydroxybenzoic acid with methanol catalyzed with sulfuric acid produced methyl 4-hydroxybenzoate in 87% yield. The acid-catalyzed-acetylation of the product using acetic anhydride gave methyl 4-acetoxybenzoate in 75% yield. Furthermore, solvent-free Fries rearrangement of methyl 4-acetoxybenzoate in the presence of AlCl3 produced 3-acetyl-4-hydroxybenzoic acid as the acetophenone derivatives in 67% yield. Then, Claisen-Schmidt condensation of the acetophenone and benzaldehyde derivatives of p-anisaldehyde and veratraldehyde in basic condition gave 2'-hydroxychalcone-5'-carboxylic acid derivatives  in 81 and 71 % yield, respectively. Finally, the ring closure reaction of the chalcone yielded the corresponding flavanone-6-carboxylic acids in 67 and 59% yield, respectively.

  14. Carboxylated magnetic nanoparticles as MRI contrast agents: Relaxation measurements at different field strengths

    Energy Technology Data Exchange (ETDEWEB)

    Jedlovszky-Hajdu, Angela, E-mail: angela.hajdu@net.sote.hu [Laboratory of Nanochemistry, Department of Biophysics and Radiation Biology, Semmelweis University, Nagyvarad Sq 4, H-1089 Budapest (Hungary); Tombacz, Etelka, E-mail: tombacz@chem.u-szeged.hu [Department of Physical Chemistry and Material Science, University of Szeged, Aradi Vt. Sq 1, Szeged 6720 (Hungary); Banyai, Istvan, E-mail: banyai.istvan@science.unideb.hu [Department of Colloid and Environmental Chemistry, University of Debrecen (Hungary); Babos, Magor, E-mail: babosmagor@yahoo.com [Euromedic Diagnostics Szeged Ltd., Semmelweis St 6, Szeged 6720 (Hungary); Palko, Andras, E-mail: palko@radio.szote.u-szeged.hu [Faculty of Medicine, Department of Radiology, University of Szeged (Hungary)

    2012-09-15

    At the moment the biomedical applications of magnetic fluids are the subject of intensive scientific interest. In the present work, magnetite nanoparticles (MNPs) were synthesized and stabilized in aqueous medium with different carboxylic compounds (citric acid (CA), polyacrylic acid (PAA), and sodium oleate (NaOA)), in order to prepare well stabilized magnetic fluids (MFs). The magnetic nanoparticles can be used in the magnetic resonance imaging (MRI) as contrast agents. Magnetic resonance relaxation measurements of the above MFs were performed at different field strengths (i.e., 0.47, 1.5 and 9.4 T) to reveal the field strength dependence of their magnetic responses, and to compare them with that of ferucarbotran, a well-known superparamagnetic contrast agent. The measurements showed characteristic differences between the tested magnetic fluids stabilized by carboxylic compounds and ferucarbotran. It is worthy of note that our magnetic fluids have the highest r2 relaxivities at the field strength of 1.5 T, where the most of the MRI works in worldwide. - Highlights: Black-Right-Pointing-Pointer Magnetic resonance relaxation measurements were done at different field strengths. Black-Right-Pointing-Pointer Results show characteristic differences between the tested carboxylated MFs. Black-Right-Pointing-Pointer r1 and r2 relaxivities depend on the thickness of the protecting layer. Black-Right-Pointing-Pointer MFs have high r2/r1 ratios at each magnetic field.

  15. Aptamer-Based Carboxyl-Terminated Nanocrystalline Diamond Sensing Arrays for Adenosine Triphosphate Detection

    Directory of Open Access Journals (Sweden)

    Evi Suaebah

    2017-07-01

    Full Text Available Here, we propose simple diamond functionalization by carboxyl termination for adenosine triphosphate (ATP detection by an aptamer. The high-sensitivity label-free aptamer sensor for ATP detection was fabricated on nanocrystalline diamond (NCD. Carboxyl termination of the NCD surface by vacuum ultraviolet excimer laser and fluorine termination of the background region as a passivated layer were investigated by X-ray photoelectron spectroscopy. Single strand DNA (amide modification was used as the supporting biomolecule to immobilize into the diamond surface via carboxyl termination and become a double strand with aptamer. ATP detection by aptamer was observed as a 66% fluorescence signal intensity decrease of the hybridization intensity signal. The sensor operation was also investigated by the field-effect characteristics. The shift of the drain current–drain voltage characteristics was used as the indicator for detection of ATP. From the field-effect characteristics, the shift of the drain current–drain voltage was observed in the negative direction. The negative charge direction shows that the aptamer is capable of detecting ATP. The ability of the sensor to detect ATP was investigated by fabricating a field-effect transistor on the modified NCD surface.

  16. (Benzoato-κ2O,O′(quinoline-2-carboxylato-κ2N,O(quinoline-2-carboxylic acid-κ2N,Omanganese(II

    Directory of Open Access Journals (Sweden)

    Nuno D. Martins

    2008-01-01

    Full Text Available The crystal structure of the title compound, [Mn(C7H5O2(C10H6NO2(C10H7NO2], contains manganese(II ions six-coordinated in a distorted octahedral environment. The equatorial plane is occupied by four O atoms, two from the carboxylate group of the benzoate ion, the other two from carboxylate/carboxyl groups of the quinaldate/quinaldic acid molecules. The axial positions are occupied by the N atoms of the quinoline ring systems. The metal ion lies on a twofold rotation axis that bisects the benzoate ligand; the quinaldate and quinaldic acid ligands are therefore equivalent by symmetry, and the carboxylate/carboxyl groups are disordered. The complexes are joined together by hydrogen bonds between the carboxylate/carboxyl groups of adjacent quinaldate/quinaldic acid molecules, forming zigzag chains that run along the c axis.

  17. High-level production of C-11-carboxyl-labeled amino acids. [For use in tumor and pancreatic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Washburn, L. C.; Sun, T. T.; Byrd, B. L.; Hayes, R. L.; Butler, T. A.; Callahan, A. P.

    1979-01-01

    Carbon-11-labeled amino acids have significant potential as agents for positron tomographic functional imaging. We have developed a rapid, high-temperature, high-pressure modification of the Buecherer--Strecker amino acid synthesis and found it to be quite general for the production of C-11-carboxyl-labeled neutral amino acids. Production of C-11-carboxyl-labeled DL-tryptophan requires certain modifications in the procedure. Twelve different amino acids have been produced to date by this technique. Synthesis and chromatographic purification require approximately 40 min, and C-11-carboxyl-labeled amino acids have been produced in yields of up to 425 mCi. Two C-11-carboxyl-labeled amino acids are being investigated clinically for tumor scanning and two others for pancreatic imaging. Over 120 batches of the various agents have been produced for clinical use over a three-year period.

  18. One-Pot Synthesis of Esters of Cyclopropane Carboxylic Acids via Tandem Vicarious Nucleophilic Substitution-Michael Addition Process.

    Science.gov (United States)

    Mąkosza, Mieczysław; Bester, Karol; Cmoch, Piotr

    2015-06-05

    α-Chlorocarbanions generated via base-induced vicarious nucleophilic substitution reaction of alkyl dichloroacetates with nitroarenes react with Michael acceptors to give esters of cyclopropane carboxylic acids substituted with p-nitroaromatic rings.

  19. Variations in the saturation magnetization of nanosized NiFe2O4 particles on adsorption of carboxylic acids

    Directory of Open Access Journals (Sweden)

    Ryo Kurosawa

    2014-03-01

    Full Text Available This work investigated magnetization changes in NiFe2O4 nanoparticles induced by the adsorption of a series of carboxylic acids. The application of formic acid resulted in a significant 8.6% decrease in the magnetization of NiFe2O4 nanoparticles at 18,000 Oe. With increasing carbon bond number in the saturated carboxylic acids, reductions in the magnetization of NiFe2O4 nanoparticles became around 4%. All unsaturated carboxylic acids produced approximately equivalent reductions in the magnetization, regardless of their double bond content. Based on these results, the observed NiFe2O4 magnetization changes appear to depend on either the polarity or the molecular size of the carboxylic acids and are believed to be caused by canting or pinning of spins in the vicinity of particle surfaces following adsorption of the acids.

  20. Nano-graphene oxide carboxylation for efficient bioconjugation applications: a quantitative optimization approach

    Energy Technology Data Exchange (ETDEWEB)

    Imani, Rana; Emami, Shahriar Hojjati, E-mail: semami@aut.ac.ir [Amirkabir University of Technology, Department of Biomedical Engineering (Iran, Islamic Republic of); Faghihi, Shahab, E-mail: shahabeddin.faghihi@mail.mcgill.ca, E-mail: sfaghihi@nigeb.ac.ir [National Institute of Genetic Engineering and Biotechnology, Tissue Engineering and Biomaterials Division (Iran, Islamic Republic of)

    2015-02-15

    A method for carboxylation of graphene oxide (GO) with chloroacetic acid that precisely optimizes and controls the efficacy of the process for bioconjugation applications is proposed. Quantification of COOH groups on nano-graphene oxide sheets (NGOS) is performed by novel colorimetric methylene blue (MB) assay. The GO is synthesized and carboxylated by chloroacetic acid treatment under strong basic condition. The size and morphology of the as-prepared NGOS are characterized by scanning electron microscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effect of acid to base molar ratio on the physical, chemical, and morphological properties of NGOS is analyzed by Fourier-transformed infrared spectrometry (FTIR), UV–Vis spectroscopy, X-ray diffraction (XRD), AFM, and zeta potential. For evaluation of bioconjugation efficacy, the synthesized nano-carriers with different carboxylation ratios are functionalized by octaarginine peptide sequence (R8) as a biomolecule model containing amine groups. The quantification of attached R8 peptides to graphene nano-sheets’ surface is performed with a colorimetric-based assay which includes the application of 2,4,6-Trinitrobenzene sulfonic acid (TNBS). The results show that the thickness and lateral size of nano-sheets are dramatically decreased to 0.8 nm and 50–100 nm after carboxylation process, respectively. X-ray analysis shows the nano-sheets interlaying space is affected by the alteration of chloroacetic acid to base ratio. The MB assay reveals that the COOH groups on the surface of NGOS are maximized at the acid to base ratio of 2 which is confirmed by FTIR, XRD, and zeta potential. The TNBS assay also shows that bioconjugation of the optimized carboxylated NGOS sample with octaarginine peptide is 2.5 times more efficient compared to bare NGOS. The present work provides evidence that treatment of GO by chloroacetic acid under an optimized condition would create a functionalized high

  1. Tetrakis(μ-2-phenoxypropionato-κ3O,O′:O′;κ3O:O,O′;κ4O:O′-bis[(1,10-phenanthroline-κ2N,N′(2-phenoxypropionato-κ2O,O′holmium(III

    Directory of Open Access Journals (Sweden)

    Guo-Liang Zhao

    2011-10-01

    Full Text Available The title compound, [Ho2(C9H9O36(C12H8N22], lies about a centre of symmetry and is comprised of six 2-phenoxypropionate (POPA anions and two 1,10-phenanthroline (phen ligands. The two HoIII ions are linked by four POPA groups utilizing both bi- and tridentate bridging modes to form an inversion-symmetric dimer. Each HoIII ion is nine-coordinate, with a chelating 1,10-phenanthroline molecule, one bidentate chelating carboxylate group, two bidentate bridging carboxylate groups and two tridentate bridging carboxylate groups in a distorted mono-capped square antiprism geometry. There are weak π–π aromatic interactions between the phen groups and aromatic rings of the POPA ligands [centroid–centroid distance = 3.829 (1 Å].

  2. Topological and Mutational Analysis of Saccharomyces cerevisiae Ste14p, Founding Member of the Isoprenylcysteine Carboxyl Methyltransferase Family

    OpenAIRE

    Romano, Julia D.; Michaelis, Susan

    2001-01-01

    Eukaryotic proteins that terminate in a CaaX motif undergo three processing events: isoprenylation, C-terminal proteolytic cleavage, and carboxyl methylation. In Saccharomyces cerevisiae, the latter step is mediated by Ste14p, an integral endoplasmic reticulum membrane protein. Ste14p is the founding member of the isoprenylcysteine carboxyl methyltransferase (ICMT) family, whose members share significant sequence homology. Because the physiological substrates of St...

  3. Access to Alkyl-Substituted Lactone via Photoredox-Catalyzed Alkylation/Lactonization of Unsaturated Carboxylic Acids.

    Science.gov (United States)

    Sha, Wanxing; Ni, Shengyang; Han, Jianlin; Pan, Yi

    2017-11-03

    An efficient photoredox-catalyzed alkylation/lactonization reaction of unsaturated carboxylic acids by using alkyl N-hydroxyphthalimide esters as alkylation reagents has been developed. Varieties of redox-active esters derived from aliphatic carboxylic acids were proved viable in this method, affording alkyl substituted lactones in moderate to good yields. This redox-neutral procedure features mild conditions and operational simplicity, which provides a new strategy for the synthesis of alkyl substituted lactones.

  4. Celestine III and the North

    DEFF Research Database (Denmark)

    Nielsen, Torben Kjersgaard

    2008-01-01

    Artiklen gennemgår pave Cølestin IIIs forhold til de nordiske kongeriger i perioden 1191-1198. Artiklen viser, at paven, som i forskningen traditionelt år har stået i skyggen af sin berømte, energiske og især: yngre efterfølger, Innocens III, har været på forkant med udviklingen i de nordiske rig...

  5. Genetics Home Reference: mucolipidosis III gamma

    Science.gov (United States)

    ... Home Health Conditions Mucolipidosis III gamma Mucolipidosis III gamma Printable PDF Open All Close All Enable Javascript ... view the expand/collapse boxes. Description Mucolipidosis III gamma is a slowly progressive disorder that affects many ...

  6. Multinuclear magnetic resonance study of the structure and dynamics of lanthanide(III) complexes of the bis(propylamide) of diethylenetriaminepentaacetic acid in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Geraldes, C.F.G.C.; Urbano, A.M. (Univ. of Coimbra (Portugal)); Hoefnagel, M.A.; Peters, J.A. (Delft Univ. of Technology (Netherlands))

    1993-05-26

    The structure and dynamics of the lanthanide(III) complexes of the bis(propylamide) of diethylenetriaminepentaacetate (DTPA-PA[sub 2]) in aqueous solution have been investigated by [sup 13]C and [sup 17]O NMR. With the use of the longitudinal [sup 13]C relaxation times of the Nd[sup III] complex it is shown that the organic ligand is bound to the lanthanide(III) ion in an octadentate fashion via the three nitrogens of the diethyenetriamine backbone, the three carboxylate groups, and the two amide oxygens. [sup 17]O NMR measurements show that the coordination sphere is completed by one water ligand. The inversion of the lanthanide-bound nitrogens is precluded, and therefore four diastereomeric pairs of isomers are possible for these complexes. Low-temperature [sup 13]C NMR spectra show that all these isomers occur in solution. Three dynamic processes have been identified by means of variable-temperature NMR measurements: (i) rapid rotations of the carboxylate groups, (ii) racemization at the middle N atom via interconversions between the two possible conformations of the ethylene bridges, and (iii) racemization at the terminal N atoms of the diethylenetriamine backbone via decoordination-inversion-coordination. The barriers of the interconversions between the enantiomers have been determined by line-shape analysis and from coalescence temperatures. A comparison is made with the Ln[sup III] diethylenetriaminepentaacetate (DTPA) complexes.

  7. Influence of humic substances on the removal of pentachlorophenol by a biomimetic catalytic system with a water-soluble iron(III)-porphyrin complex.

    Science.gov (United States)

    Fukushima, Masami; Sawada, Akira; Kawasaki, Mikio; Ichikawa, Hiroyasu; Morimoto, Kengo; Tatsumi, Kenji; Aoyama, Masakazu

    2003-03-01

    To investigate some basic aspects of soil remediation using biomimetic catalysts, the effects of humic substances (HSs) on the removal of xenobiotics, such as pentachlorophenol (PCP), were investigated. The use of a biomimetic catalytic system using tetra(p-sulfophenyl)porphine-iron(III) (Fe(III)-TPPS) and potassium monopersulfate (KHSO5) resulted in the disappearance of PCP, accompanied by dechlorination. In addition, this process was enhanced by the presence of several types of HSs. The degrees of enhancement (% delta(PCP)60) achieved by the presence of HSs from peat and compost soils were larger than those in the presence of other types of HSs (tropical peat, brown forest, and ando soils). In control experiments, no PCP disappearance and dechlorination were observed in the presence of only KHSO5, only Fe(III)-TPPS, or combinations of HSs and either KHSO5 or Fe(III)-TPPS. To better understand the role of added HS in enhancing or inhibiting PCP disappearance, correlations between the chemical parameters of the HSs and % delta(PCP)60 were investigated. The most effective HSs had lower carboxylic acid contents and lower degrees of unsaturation. The carboxylic acid content and degree of unsaturation increase with the extent of humification. Therefore, HSs of a lower degree of humification would be predicted to be more useful in enhancing the disappearance of PCP in an Fe(III)-TPPS/KHSO5 system.

  8. catena-Poly[[[tetrakis(μ-2-butenoatodicopper(II]-μ-2-butenoato-[diaqua(2-butenoatoholmium(III]-di-μ-2-butenoato-[diaqua(2-butenoatoholmium(III]-μ-2-butenoato] trihydrate

    Directory of Open Access Journals (Sweden)

    Mireille Perec

    2008-11-01

    Full Text Available The title compound {[Cu2Ho2(C4H5O210(H2O4]·3H2O}n, is a one-dimensional 3d/4f organic–inorganic hybrid complex, the HoIII member of the isotypic lanthanoid series with Ln = GdIII, ErIII and YIII. The structure shows an alternation of Cu2 and Ho2 dinuclear units bridged by the ligands and hydrogen bonds only. The chains are composed of Cu2 classical dinuclear η1:η1:μ2 fourfold bridges [Cu...Cu = 2.6417 (9 Å] and of Ho2 units bridged by two η2:η1:μ2 carboxylate units. This results in distorted square-based pyramidal CuO5 units and irregular HoO9 units. The alternating Cu2 and Ho2 units are bridged into linear arrays along the a axis by a set of one η2:η1:μ2 carboxylate O atom and two hydrogen bonds with Cu...Ho separations of 4.4883 (10 and 4.5086 (10 Å. The distance between adjacent chains, as calculated by the closest and furthest distances between two chains, covers the range 10–14 Å. The H atoms of the water molecules could not be located, but the O...O separations for these species suggest the presence of O—H...O hydrogen bonds.

  9. Complexation of actinides(III) and lanthanides(III) cations by tridentate nitrogen ligands; Complexation des cations actinides(III) et lanthanides(III) par des ligands azotes tridentates

    Energy Technology Data Exchange (ETDEWEB)

    Cordier, P.Y.; Francois, N.; Guillaneux, D.; Hill, C.; Madic, Ch. [CEA Valrho, (DCC/DRRV/SEMP), 30 - Marcoule (France); Illemassene, M. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire

    2000-07-01

    To understand the properties of some systems able to extract actinides (III) from lanthanides(III) selectively, the solution chemistry of lanthanide(III) and actinide(III) cations with poly-hetero-aromatic nitrogen-containing ligands was studied by Time-Resolved Laser Induced Fluorimetry (TRLIF) and UV-visible spectrophotometry, combined with chemo-metric methods. Three soft donor ligands (L) were selected for the study: 2,2':6;2{sup -}ter-pyridine (Tpy),4,6-tri-(pyridine-2-yl)-1,3,5-triazine (Tptz) and 2,6-bis-(5,6-dimethyl-1,2,4-triazine-3-yl)-pyridine (MeBtp). Tpy and Tptz exhibit moderate affinity (distribution ratio) and selectivity when used in the synergistic liquid-liquid extraction of americium(III) (with a lipophilic carboxylic acid). MeBtp is also very efficient, and extracts Am(III) with high selectivity; The TRLIF study analyzed the Eu(III) fluorescence emission spectrum. By analyzing the respective changes in the band intensities, and the lifetimes of the Eu(III) excited states, when the ligands were added in homogeneous phase, the following conclusions were drawn: - for Tpy and Tptz, only one EuL{sup 3+} complex species was detected, with a low symmetry in the first coordination sphere, and the Eu(III) hydration number (number of water molecules in the Eu(III) first sphere of coordination) in these complexes was found to be around 5-6; - for MeBtp, two species were detected, one with a low symmetry and a hydration number close to 5-6, the other with a high symmetry and almost completely dehydrated. This is indicative of the formation of the complexes: EuL{sup 3+} for L =Tpy and Tptz, and Eu(MeBtp){sup 3+} and Eu(MeBtp){sub 3}{sup 3+} in the case of MeBtp. The formation of these complexes, as well as the protonated ligands, was quantitatively studied using UV-visible spectrophotometry. In each case, the variation in the absorption spectrum of one species was monitored, while the concentration of the other was varied. The complex formation

  10. Rational design of carboxyl groups perpendicularly attached to a graphene sheet: a platform for enhanced biosensing applications.

    Science.gov (United States)

    Bonanni, Alessandra; Chua, Chun Kiang; Pumera, Martin

    2014-01-03

    Graphene oxide (GO)-based materials offer great potential for biofunctionalization with applications ranging from biosensing to drug delivery. Such biofunctionalization utilizes specific functional groups, typically a carboxyl moiety, as anchoring points for biomolecule. However, due to the fact that the exact chemical structure of GO is still largely unknown and poorly defined (it was postulated to consist of various oxygen-containing groups, such as epoxy, hydroxyl, carboxyl, carbonyl, and peroxy in varying ratios), it is challenging to fabricate highly biofunctionalized GO surfaces. The predominant anchoring sites (i.e., carboxyl groups) are mainly present as terminal groups on the edges of GO sheets and thus account for only a fraction of the oxygen-containing groups on GO. Herein, we suggest a direct solution to the long-standing problem of limited abundance of carboxyl groups on GO; GO was first reduced to graphene and consequently modified with only carboxyl groups grafted perpendicularly to its surface by a rational synthesis using free-radical addition of isobutyronitrile with subsequent hydrolysis. Such grafted graphene oxide can contain a high amount of carboxyl groups for consequent biofunctionalization, at which the extent of grafting is limited only by the number of carbon atoms in the graphene plane; in contrast, the abundance of carboxyl groups on "classical" GO is limited by the amount of terminal carbon atoms. Such a graphene platform embedded with perpendicularly grafted carboxyl groups was characterized in detail by X-ray photoelectron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy, and its application was exemplified with single-nucleotide polymorphism detection. It was found that the removal of oxygen functionalities after the chemical reduction enhanced the electron-transfer rate of the graphene. More importantly, the introduction of carboxyl groups promoted a more efficient immobilization of DNA probes on the

  11. Spectrophotometric and pH-Metric Studies of Ce(III, Dy(III, Gd(III,Yb(III and Pr(III Metal Complexes with Rifampicin

    Directory of Open Access Journals (Sweden)

    A. N. Sonar

    2011-01-01

    Full Text Available The metal-ligand and proton-ligand stability constant of Ce(III, Dy(III, Gd(III,Yb(III and Pr(III metals with substituted heterocyclic drug (Rifampicin were determined at various ionic strength by pH metric titration. NaClO4 was used to maintain ionic strength of solution. The results obtained were extrapolated to the zero ionic strength using an equation with one individual parameter. The thermodynamic stability constant of the complexes were also calculated. The formation of complexes has been studied by Job’s method. The results obtained were of stability constants by pH metric method is confirmed by Job’s method.

  12. Charge-Assisted Hydrogen-Bonded Networks of NH4+ and [Co(NH36]3+ with the New Linker Anion of 4-Phosphono-Biphenyl-4′-Carboxylic Acid

    Directory of Open Access Journals (Sweden)

    Christian Heering

    2016-02-01

    Full Text Available The new linker molecule 4-phosphono-biphenyl-4′-carboxylic acid (H2O3P-(C6H42-COOH, H3BPPA has been structurally elucidated in hydrogen-bonded networks with the ammonium cation NH4(H2BPPA(H3BPPA (1 and the hexaamminecobalt(III cation [Co(NH36](BPPA·4H2O (2. The protic O-H and N-H hydrogen atoms were found and refined in the low-temperature single-crystal X-ray structures. The hydrogen bonds in both structures are so-called charge-assisted; that is, the H-bond donor and/or acceptor carry positive and/or negative ionic charges, respectively. The H-bonded network in 1 consists of one formally mono-deprotonated 4-phosphonato-biphenyl-4′-carboxylic acid group; that is, a H2BPPA− anion and a neutral H3BPPA molecule, which together form a 3D hydrogen-bonded network. However, an almost symmetric resonance-assisted hydrogen bond (RAHB bond [O···H = 1.17 (3 and 1.26 (3 Å, O···H···O = 180 (3°] signals charge delocalization between the formal H2BPPA− anion and the formally neutral H3BPPA molecule. Hence, the anion in 1 is better formulated as [H2BPPA···H···H2BPPA]−. In the H-bonded network of 2 the 4-phosphonato-biphenyl-4′-carboxylic acid is triply deprotonated, BPPA3−. The [Co(NH36]3+ cation is embedded between H-bond acceptor groups, –COO− and –PO3− and H2O molecules. The incorporation of sixteen H2O molecules per unit cell makes 2 an analogue of the well-studied guanidinium sulfonate frameworks.

  13. Lanthanide(III) complexes are more active inhibitors of the Fenton reaction than pure ligands.

    Science.gov (United States)

    Martin, Jan; Mladěnka, Přemysl; Saso, Luciano; Kostova, Irena

    2016-03-01

    This study is an extension to our finding of direct anti-oxidant activities of lanthanide(III) complexes with the heterocyclic compound, 5-aminoorotic acid (AOA). In this experiment, we used AOA and coumarin-3-carboxylic acid as the two heterocyclic compounds with anti-oxidant potential, to produce the complexes with different lanthanides. Lanthanide(III) complexes were tested on the iron-driven Fenton reaction. The product of this reaction, the hydroxyl radical, was detected by HPLC. All complexes as well as their ligands had positive or neutral effect on the Fenton reaction but their behavior was different. Both pure ligands in low concentration ratio to iron were inefficient in contrast to some of their complexes. Complexes of neodymium, samarium, gadolinium, and partly of cerium blocked the Fenton reaction at very low ratios (in relation to iron) but the effect disappeared at higher ratios. In contrast, lanthanum complexes appeared to be the most promising. Both blocked the Fenton reaction in a dose-dependent manner. Lanthanide(III) complexes were proven to block the iron-driven production of the hydroxyl radical. Second, the lanthanide(III) element appears to be crucial for the anti-oxidant effect. Overall, lanthanum complexes may be promising direct anti-oxidants for future testing.

  14. Luminescent behavior of CdTe quantum dots: Neodymium(III) complex-capped nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Margarida S. [Centro de Geologia do Porto, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto (Portugal); Algarra, Manuel, E-mail: magonzal@fc.up.pt [Centro de Geologia do Porto, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto (Portugal); Jimenez-Jimenez, Jose; Rodriguez-Castellon, Enrique [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos s/n 29071, Malaga (Spain); Campos, Bruno B.; Esteves da Silva, Joaquim C.G. [Centro de Investigacao em Quimica (CIQ-UP), Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto (Portugal)

    2013-02-15

    A water soluble complex of neodymium(III) with CdTe quantum dots nanoparticles was synthesized. The obtained homogeneous solutions were characterized by fluorescence, X-ray photoelectron and energy dispersive X-ray spectroscopies. The effect of the refluxing time of the reaction on the fluorescence intensity and emission wavelength has been studied. It was found that the emission wavelength of the solutions of neodymium(III) complex capped CdTe QDs nanoparticles shifted from about 540 to 735 nm. For an emission wavelength of 668 nm, the most reproducible nanoparticles obtained, the pH effect over the fluorescence emission and its intensity were studied. The purified and lyophilized solid obtained was morphologically characterized by transmission electron microscopy (TEM). The quantitative composition was determined by fluorescence X-ray spectroscopy (EDAX) and the X-ray photoelectron analysis (XPS) confirmed the presence of neodymium(III) at the surface of the CdTe nanoparticles forming a complex with the carboxylate groups from 3-mercaptopropanoic acid of the CdTe QDs. Due to the optical behavior of this complex, it could be of potential interest as a light source in optical devices. - Highlights: Black-Right-Pointing-Pointer CdTe quantum dots nanoparticles. Black-Right-Pointing-Pointer Neodymium(III) complexed quantum dots. Black-Right-Pointing-Pointer Strong red fluorescent emission nanomaterial soluble in water.

  15. The START III bargaining space

    Energy Technology Data Exchange (ETDEWEB)

    Karas, T.H.

    1998-08-01

    The declining state of the Russian military and precarious Russian economic condition will give the US considerable advantages at the START III bargaining table. Taking the US-RF asymmetries into account, this paper discusses a menu of START III measures the US could ask for, and measures it could offer in return, in attempting to negotiate an equitable treaty. Measures the US might seek in a START III treaty include: further reductions in deployed strategic nuclear warheads, irreversibility of reductions through warhead dismantlement; beginning to bring theater nuclear weapons under mutual control, and increased transparency into the Russian nuclear weapons complex. The US may, however, wish to apply its bargaining advantages to attempting to achieve the first steps toward two long-range goals that would enhance US security: bringing theater nuclear weapons into the US-RF arms control arena, and increasing transparency into the Russian nuclear weapons complex. In exchange for measures relating to these objectives, the US might consider offering to Russia: Further strategic weapons reductions approaching levels at which the Russians believe they could maintain a degree of parity with the US; Measures to decrease the large disparities in potential deliver-system uploading capabilities that appear likely under current START II/START III scenarios; and Financial assistance in achieving START II/START III reductions as rapidly as is technically possible.

  16. Carboxylated molecules regulate magnesium content of amorphous calcium carbonates during calcification.

    Science.gov (United States)

    Wang, Dongbo; Wallace, Adam F; De Yoreo, James J; Dove, Patricia M

    2009-12-22

    With the realization that many calcified skeletons form by processes involving a precursor phase of amorphous calcium carbonate (ACC), a new paradigm for mineralization is emerging. There is evidence the Mg content in biogenic ACC is regulated by carboxylated (acidic) proteins and other macromolecules, but the physical basis for such a process is unknown. We test the hypothesis that ACC compositions express a systematic relationship to the chemistry of carboxyl-rich biomolecules. A series of inorganic control experiments were conducted to establish the dependence of Mg/Ca ratios in ACC on solution composition. We then determined the influence of a suite of simple carboxylated organic acids on Mg content. Molecules with a strong affinity for binding Ca compared with Mg promote the formation of Mg-enriched ACC that is compositionally equivalent to high-magnesium calcites and dolomite. Measurements show Mg/Ca ratios are controlled by a predictable dependence upon the binding properties of the organic molecules. The trend appears rooted in the conformation and electrostatic potential topology of each molecule, but dynamic factors also may be involved. The dependence suggests a physical basis for reports that specific sequences of calcifying proteins are critical to modulating mineralization. Insights from this study may provide a plausible explanation for why some biogenic carbonates and carbonaceous cements often contain higher Mg signatures than those that are possible by classical crystal growth processes. The findings reiterate the controls of microenvironment on mineralization and suggest an origin of compositional offsets, or vital effects, long recognized by the paleoclimate community.

  17. Carbon dioxide utilization via carbonate-promoted C-H carboxylation

    Science.gov (United States)

    Banerjee, Aanindeeta; Dick, Graham R.; Yoshino, Tatsuhiko; Kanan, Matthew W.

    2016-03-01

    Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO32-) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)—a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO32--promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.

  18. A short cross-linker activates human P-glycoprotein missing a catalytic carboxylate.

    Science.gov (United States)

    Loo, Tip W; Clarke, David M

    2017-12-01

    P-glycoprotein (P-gp) is an ATP-dependent drug pump that protects us from toxic agents and confers multidrug resistance. It has a tweezer-like structure with each arm consisting of a transmembrane domain (TMD) and a nucleotide-binding domain (NBD). Drug substrates bind to sites within the TMDs to activate ATPase activity by promoting a tweezer-like closing of the gap between the NBDs. The catalytic carboxylates may be critical for NBD movements because the E556Q(NBD1) or E1201Q(NBD2) mutation inhibited drug-stimulated ATPase activity. If the catalytic carboxylates were components of the mechanism to bring the NBDs together, then we predicted that insertion of a flexible cross-linker between the arms would increase ATPase activity of the mutants. We found that cross-linking (between L175C(TMD1) and N820C(TMD2)) with a short flexible cross-linker (7.8Å maximum) restored high levels of drug-stimulated ATPase activity of the E556Q or E1201Q mutants. Cross-linking with a longer cross-linker (22Å maximum) however, did not restore activity. Cross-linking could not rescue all ATPase deficient mutants. For example, cross-linking L175C/N820C with short or long cross-linkers did not activate the H-loop mutants H587A or H1232A or the Walker A K433M or K1076M mutants. The results suggest that the E556 and E1201 catalytic carboxylates are part of a spring-like mechanism that is required to facilitate movements between the open and closed conformations of P-gp during ATP hydrolysis. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Oxidation of carboxylic acids regenerates hydroxyl radicals in the unpolluted and nighttime troposphere.

    Science.gov (United States)

    da Silva, Gabriel

    2010-07-01

    The hydroxyl radical (OH) controls the removal of organic compounds from the troposphere. Atmospheric chemistry models significantly under-predict OH levels in unpolluted environments, implying that they are regenerated via some unknown mechanism(s). This work uses computational chemistry to demonstrate that the photochemical oxidation of alkyl carboxylic acids can efficiently regenerate the hydroxyl radical via unimolecular decomposition of alpha-carboxyalkylperoxy radicals. For acetic acid and propanoic acid the proposed mechanism is predicted to dominate in the unpolluted lower troposphere, and it may also operate to some extent in the mid to upper troposphere. Alkyl carboxylic acids are also predicted to act as a new source of nighttime OH throughout the planetary boundary layer, where OH levels are also under-predicted. The thermodynamic requirements for reactions of this class are discussed, and some candidate OH-reforming molecules particularly relevant to aromatic photooxidation are identified. Adopting a broader perspective, the alpha-carboxyalkyl radical precursors that react with O(2) to form the unstable alpha-carboxyalkylperoxy type radicals are also expected to form during combustion, in the interstellar medium, and from the gamma-irradiation of glycine and related amino acids, and the potential importance of this new chemistry in these environments is discussed. Master equation simulations suggest that alpha-carboxyalkyl + O(2) reactions provide a prompt OH source during the autoignition and combustion of biodiesel and other oxygenated biofuels, where carboxylic acids are formed as early stage oxidation products. Ketene combustion is also thought to proceed via these OH-reforming alpha-carboxyalkyl radicals. The in vivo formation of alpha-carboxyalkylperoxy radicals followed by oxidation to the highly reactive OH radical may induce oxidative stress in the human body, in a process initiated by gamma-rays. Finally, the reaction of ketenes with OH to

  20. Binding properties of solubilized gonadotropin-releasing hormone receptor: role of carboxylic groups

    Energy Technology Data Exchange (ETDEWEB)

    Hazum, E.

    1987-11-03

    The interaction of /sup 125/I-buserelin, a superactive agonist of gonadotropin-releasing hormone (GnRH), with solubilized GnRH receptor was studied. The highest specific binding of /sup 125/I-buserelin to solubilized GnRH receptor is evident at 4/sup 0/C, and equilibrium is reached after 2 h of incubation. The soluble receptor retained 100% of the original binding activity when kept at 4 or 22/sup 0/C for 60 min. Mono- and divalent cations inhibited, in a concentration-dependent manner, the binding of /sup 125/I-buserelin to solubilized GnRH receptor. Monovalent cations require higher concentrations than divalent cations to inhibit the binding. Since the order of potency with the divalent cations was identical with that of their association constants to dicarboxylic compounds, it is suggested that there are at least two carboxylic groups of the receptor that participate in the binding of the hormone. The carboxyl groups of sialic acid residues are not absolutely required for GnRH binding since the binding of /sup 125/I-buserelin to solubilized GnRH receptor was only slightly affected by pretreatment with neuraminidase and wheat germ agglutinin. The finding that polylysines stimulate luteinizing hormone (LH) release from pituitary cell cultures with the same efficacy as GnRH suggest that simple charge interactions can induce LH release. According to these results, the authors propose that the driving force for the formation of the hormone-receptor complex is an ionic interaction between the positively charged amino acid arginine in position 8 and the carboxyl groups in the binding site.

  1. Low-Molecular Weight Carboxylic Acids in Gas Phase in a Developing Megacity

    Science.gov (United States)

    Khwaja, H. A.; Saied, S.; Hussain, M. M.; Siddique, A.; Butts, C.; Kamran, S. S.; Khan, M. K.

    2013-12-01

    Carboxylic acids are amongst the plethora of pollutants that are currently ubiquitous in the environment. Molecular distributions of carboxylic acids have been studied in the atmosphere of the developing mega city Karachi, Pakistan. As a region the city is experiencing industrial and population growth at an unparallel rate. Karachi served as a great focal point to observe the effects of industrial development on a growing city and how it contributes to the progression of environmental pollution. Results indicate that acetic and formic acids are important components of the Karachi atmosphere. The most abundant acids, by a substantial margin, were acetic acid and formic acid, with concentrations of 0.70 - 14.2 ppb and 0.82 - 11.0 ppb, respectively. On the average acetic acid levels exceeded those of formic acid. Concentrations of propionic acid, pyruvic acid, and glyoxalic acid ranged 0.03 - 1.41, 0.01 - 0.28, and 0.02 - 0.14 ppb, respectively. The gaseous acids showed diurnal cycles, with higher mixing ratios during nighttime. Compared with other metropolitans in the world, the level of acetic and formic acid concentration of Karachi is much higher. The ratio of formic to acetic acid was used to distinguish primary sources from secondary sources. A mean ratio of 0.85 was found. A positive correlation (r = 0.65 - 0.94) was observed between the acid concentrations suggesting that they have similar sources. Carboxylic acid concentrations appear to arise both from direct emissions and from atmospheric oxidation of hydrocarbons.

  2. Organotin(IV) Carboxylates as Promising Potential Drug Candidates in the Field of Cancer Chemotherapy.

    Science.gov (United States)

    Sirajuddin, Muhammad; Ali, Saqib

    2016-01-01

    Medicinal inorganic chemistry plays an important role in exploring the properties of metal ions for the designing of new drugs. The field has been stimulated by the success of cis-platin, the world best selling anticancer drug and platinum complexes with reduced toxicity, oral activity and activity against resistant tumors are currently on clinical trial. The use of cis-platin is, however, severely limited by its toxic side-effects. This has stimulated chemists to employ different strategies in the development of new metal-based anticancer agents with different mechanisms of action. The discovery of new non-covalent interactions with the classical target, DNA, was the first developing step in the treatment of cancer. The use of organometallic compounds as a medicine is very common now a days because it offers potential advantages over the more common organic-based drugs. In this article we have highlighted the anticancer activity of the organotin(IV) carboxylates published in the last few years (from 2008 to 2016). In most cases they present lower IC50 values than those of cisplatin, which indicates their high activity against the cancer cell lines. The summarized data reveal that every year new organotin(IV) carboxylate complexes are synthesized with the aim of new anticancer agent with much better results than the than the corresponding activity of cis-platin or other clinically approved drugs. In addition to the advantages of high activity, compared to the platinum compound, tin complexes are much cheaper. Thus by using organotin carboxylate for clinical medicine, cost reduction, dosage reduction and effect enhancement will be reached. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Studies on carboxylated graphene oxide incorporated polyetherimide mixed matrix ultrafiltration membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kaleekkal, Noel Jacob, E-mail: noeljacob89@gmail.com [Membrane Laboratory, Department of Chemical Engineering, ACT, Anna University, Chennai, 600025 (India); Thanigaivelan, A., E-mail: thanichemstar@gmail.com [Membrane Laboratory, Department of Chemical Engineering, ACT, Anna University, Chennai, 600025 (India); Rana, Dipak, E-mail: rana@uottawa.ca [Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur Private, Ottawa, Ontario, K1N 6N5 (Canada); Mohan, D., E-mail: mohantarun@gmail.com [Membrane Laboratory, Department of Chemical Engineering, ACT, Anna University, Chennai, 600025 (India)

    2017-01-15

    In this work the graphene oxide prepared by the modified Hummers’ method was effectively carboxylated. These carboxylated graphene oxide (c-GO) microsheets was characterized by X-ray diffraction analysis, Raman shift, zeta potential, and their morphology was observed using a high resolution scanning/transmission electron microscopy. Polyetherimide mixed matrix membranes (MMMs) were fabricated by the non-solvent induced phase separation technique with varying concentration of this microsheet. The presence of these microsheets on the membrane surface was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy and could also be confirmed visually by optical images. The membranes were further characterized; they showed a greater water flux, higher porosity, and sufficient thermal stability. Incorporation of these microsheets improved the hydrophilicity of the membrane confirmed by the lower contact angle values, which in turn explained the lower interfacial free energy, the increase in work of adhesion, the higher solid-vapor free energy and the spreading coefficient. Membranes loaded with 0.3 wt% of c-GO showed a flux recovery of 94% and only a small flux decline even after 180 min of filtration of humic acid (HA) solution. The efficiency of these membranes in removal of HA, toxic metal ions was also investigated. The bacterial anti-adhesion property of c-GO in the membranes was also explored using Escherichia coli, as a model bio-foulant. The charge of the microsheets and their unique architecture imparts higher hydrophilicity and greater fouling resistance along with improved permeation flux when incorporated into the polymer matrix. - Highlights: • Novel membranes by incorporating carboxylated GO into polyetherimide matrix. • Modified membranes exhibited greater porosity, flux and high humic acid rejection. • Nanoplatelets improved the flux recovery ratio to >94%. • Liquid phase polymer based retention utilized for toxic heavy metal

  4. Chemical Derivatization of Peptide Carboxyl Groups for Highly Efficient Electron Transfer Dissociation

    Science.gov (United States)

    Frey, Brian L.; Ladror, Daniel T.; Sondalle, Samuel B.; Krusemark, Casey J.; Jue, April L.; Coon, Joshua J.; Smith, Lloyd M.

    2013-11-01

    The carboxyl groups of tryptic peptides were derivatized with a tertiary or quaternary amine labeling reagent to generate more highly charged peptide ions that fragment efficiently by electron transfer dissociation (ETD). All peptide carboxyl groups—aspartic and glutamic acid side-chains as well as C-termini—were derivatized with an average reaction efficiency of 99 %. This nearly complete labeling avoids making complex peptide mixtures even more complex because of partially-labeled products, and it allows the use of static modifications during database searching. Alkyl tertiary amines were found to be the optimal labeling reagent among the four types tested. Charge states are substantially higher for derivatized peptides: a modified tryptic digest of bovine serum albumin (BSA) generates ~90% of its precursor ions with z > 2, compared with less than 40 % for the unmodified sample. The increased charge density of modified peptide ions yields highly efficient ETD fragmentation, leading to many additional peptide identifications and higher sequence coverage (e.g., 70 % for modified versus only 43 % for unmodified BSA). The utility of this labeling strategy was demonstrated on a tryptic digest of ribosomal proteins isolated from yeast cells. Peptide derivatization of this sample produced an increase in the number of identified proteins, a >50 % increase in the sequence coverage of these proteins, and a doubling of the number of peptide spectral matches. This carboxyl derivatization strategy greatly improves proteome coverage obtained from ETD-MS/MS of tryptic digests, and we anticipate that it will also enhance identification and localization of post-translational modifications.

  5. Specific catalysis of asparaginyl deamidation by carboxylic acids: kinetic, thermodynamic, and quantitative structure-property relationship analyses.

    Science.gov (United States)

    Connolly, Brian D; Tran, Benjamin; Moore, Jamie M R; Sharma, Vikas K; Kosky, Andrew

    2014-04-07

    Asparaginyl (Asn) deamidation could lead to altered potency, safety, and/or pharmacokinetics of therapeutic protein drugs. In this study, we investigated the effects of several different carboxylic acids on Asn deamidation rates using an IgG1 monoclonal antibody (mAb1*) and a model hexapeptide (peptide1) with the sequence YGKNGG. Thermodynamic analyses of the kinetics data revealed that higher deamidation rates are associated with predominantly more negative ΔS and, to a lesser extent, more positive ΔH. The observed differences in deamidation rates were attributed to the unique ability of each type of carboxylic acid to stabilize the energetically unfavorable transition-state conformations required for imide formation. Quantitative structure property relationship (QSPR) analysis using kinetic data demonstrated that molecular descriptors encoding for the geometric spatial distribution of atomic properties on various carboxylic acids are effective determinants for the deamidation reaction. Specifically, the number of O-O and O-H atom pairs on carboxyl and hydroxyl groups with interatomic distances of 4-5 Å on a carboxylic acid buffer appears to determine the rate of deamidation. Collectively, the results from structural and thermodynamic analyses indicate that carboxylic acids presumably form multiple hydrogen bonds and charge-charge interactions with the relevant deamidation site and provide alignment between the reactive atoms on the side chain and backbone. We propose that carboxylic acids catalyze deamidation by stabilizing a specific, energetically unfavorable transition-state conformation of l-asparaginyl intermediate II that readily facilitates bond formation between the γ-carbonyl carbon and the deprotonated backbone nitrogen for cyclic imide formation.

  6. ZnO-coated carbon nanotubes: inter-diffusion of carboxyl groups and enhanced photocurrent generation.

    Science.gov (United States)

    Hung, Chia-I; Wen, Hua-Chiang; Lai, Yao-Cheng; Chang, Shih-Hsin; Chou, Wu-Ching; Hsu, Wen-Kuang

    2015-03-16

    ZnO is a defect-governed oxide and emits light at both visible and UV regimes. This work employs atomic layer deposition to produce oxide particles on oxygenated carbon nanotubes, and the composites only show emission profiles at short wavelengths. The quenching of defect-related emissions at long wavelengths is verified, owing to carboxyl diffusion into oxygen vacancies, and doping is supported by ZnCO3 formation in oxide lattice. Fully coated tubes display an increased photocurrent and the quantum efficiency increases by 22 % relative to the bare nanotubes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Dielectric properties of supramolecular ionic structures obtained from multifunctional carboxylic acids and amines

    DEFF Research Database (Denmark)

    Gonzalez, Lidia; Yu, Liyun; Hvilsted, Søren

    2014-01-01

    The dielectric properties of several supramolecular ionic polymers and networks, linked by the ammonium salts of hexamethylene diamine (HMDA), tris(2-aminoethyl)amine (TAEA), poly(propylene imine) (PPI) dendrimers and two short bis carboxymethyl ether-terminated poly(ethylene glycol)s (Di......), are investigated. Here the relative dielectric permittivities of the supramolecular ionic structures formed with the multifunctional carboxylic acids were lower than those from the supramolecular ionic structures formed with the two carboxymethyl ether-terminated poly(ethylene glycol)s....

  8. An Electrochemical Method for Carboxylic Ester Synthesis from N-Alkoxyamides.

    Science.gov (United States)

    Subramanian, Kripa; Yedage, Subhash L; Bhanage, Bhalchandra M

    2017-10-06

    An electrochemical method for the synthesis of carboxylic as well as hindered esters from N-alkoxyamides has been reported. The electrochemical reaction proceeds through constant current electrolysis (CCE) by taking advantage of the dual role of n-Bu4NI (TBAI) as the redox catalyst as well as the supporting electrolyte. Besides providing mild reaction conditions, the present protocol is free from external oxidants and conducting salts, thereby generating nitrogen as the nonhazardous side product. Additionally, the developed procedure is highly advantageous due to its short reaction time, wide substrate scope, and gram-scale synthesis.

  9. Carboxylic multi-walled carbon nanotubes as immobilized stationary phase in capillary electrochromatography.

    Science.gov (United States)

    Sombra, Lorena; Moliner-Martínez, Yolanda; Cárdenas, Soledad; Valcárcel, Miguel

    2008-09-01

    Carboxylic multi-walled carbon nanotubes (c-MWNT) have been immobilized into a fused-silica capillary for capillary electrochromatography. The c-MWNT were successfully incorporated after the silanization and coupling with glutaraldehyde on the inner surface of the capillary. The electrochromatographic features of the c-MWNT immobilized stationary phase have been evaluated for the analysis of different compounds of pharmaceutical interest. The results indicated high electrochromatographic resolution, good capillary efficiency and retention factors. In addition, highly reproducible results between runs, days and capillaries were obtained.

  10. Esterification of camphene over heterogeneous heteropoly acid catalysts: synthesis of isobornyl carboxylates.

    OpenAIRE

    Meireles, Augusto Luís Pereira de; Rocha, Kelly Alessandra da Silva; Kozhevnikov, Ivan V.; Goussevskaia, Elena Vitalievna

    2011-01-01

    Silica supported H3PW12O40 (PW), the strongest heteropoly acid in the Keggin series, is an active and environmentally friendly solid acid catalyst for liquid-phase esterification of camphene, a renewable biomass-based substrate, with C2, C4 and C6 short-chain fatty acids. The reaction provides isobornyl carboxylates, useful as fragrances, in virtually 100% selectivity and 80–90% yield. The reaction is equilibrium-controlled and occurs under mild conditions with a catalyst turnover number of u...

  11. Peptide Conjugates of Benzene Carboxylic Acids as Agonists and Antagonists of Amylin Aggregation.

    Science.gov (United States)

    Profit, Adam A; Vedad, Jayson; Desamero, Ruel Z B

    2017-02-15

    Human islet amyloid polypeptide (hIAPP), also known as amylin, is a 37 residue peptide hormone that is stored and co-secreted with insulin. hIAPP plays a pivotal role in type 2 diabetes and is the major component of amyloid deposits found in the pancreas of patients afflicted with the disease. The self-assembly of hIAPP and the formation of amyloid is linked to the death of insulin producing β-cells. Recent findings suggest that soluble hIAPP oligomers are the cytotoxic species responsible for β-cell loss whereas amyloid fibrils themselves may indeed be innocuous. Potential avenues of therapeutic intervention include the development of compounds that prevent hIAPP self-assembly as well as those that reduce or eliminate lag time and rapidly accelerate the formation of amyloid fibrils. Both of these approaches minimize temporal exposure to soluble cytotoxic hIAPP oligomers. Toward this end our laboratory has pursued an electrostatic repulsion approach to the development of potential inhibitors and modulators of hIAPP self-assembly. Peptide conjugates were constructed in which benzene carboxylic acids of varying charge were employed as electrostatic disrupting elements and appended to the N-terminal of the hIAPP22-29 (NFGAILSS) self-recognition sequence. The self-assembly kinetics of conjugates were characterized by turbidity measurements and the structure of aggregates probed by Raman and CD spectroscopy while the morphology was assessed using transmission electron microscopy. Several benzene carboxylic acid peptide conjugates failed to self-assemble and some were found to inhibit the aggregation of full-length amylin while others served to enhance the rate of amyloid formation and/or increase the yield of amyloid produced. Studies reveal that the geometric display of free carboxylates on the benzene ring of the conjugates plays an important role in the activity of conjugates. In addition, a number of free benzene carboxylic acids were found to modulate amylin self

  12. Computational Analysis of the CB1 Carboxyl-terminus in the Receptor-G Protein Complex

    OpenAIRE

    Shim, Joong-Youn; Khurana, Leepakshi; Kendall, Debra A.

    2016-01-01

    Despite the important role of the carboxyl-terminus (Ct) of the activated brain cannabinoid receptor one (CB1) in the regulation of G protein signaling, a structural understanding of interactions with G proteins is lacking. This is largely due to the highly flexible nature of the CB1 Ct that dynamically adapts its conformation to the presence of G proteins. In the present study, we explored how the CB1 Ct can interact with the G protein by building on our prior modeling of the CB1-Gi complex ...

  13. Controlled Electrochemical Carboxylation of Graphene To Create a Versatile Chemical Platform for Further Functionalization

    DEFF Research Database (Denmark)

    Bjerglund Pedersen, Emil; Kongsfelt, Mikkel; Shimizu, Kyoko

    2014-01-01

    , this electrochemical method offers a versatile procedure to make all graphene sheets in a multi-layered but expanded structure accessible for functionalization. On a more general level, this approach will provide a versatile way of forming new hybrid materials based on intimate bond coupling to graphene via......An electrochemical approach is introduced for the versatile carboxylation of multi-layered graphene in 0.1 M Bu4NBF4/MeCN. First, the graphene substrate (i.e., graphene chemically vapor-deposited on Ni) is negatively charged at -1.9 V versus Ag/AgI in a degassed solution to allow for intercalation...

  14. One-pot synthesis of pyrrole-2-carboxylates and -carboxamides via an electrocyclization/oxidation sequence.

    Science.gov (United States)

    Imbri, Dennis; Netz, Natalie; Kucukdisli, Murat; Kammer, Lisa Marie; Jung, Philipp; Kretzschmann, Annika; Opatz, Till

    2014-12-05

    An electrocyclic ring closure is the key step of an efficient one-pot method for the synthesis of pyrrole-2-carboxylates and -carboxamides from chalcones and glycine esters or amides. The 3,4-dihydro-2H-pyrrole intermediates generated in situ are oxidized to the corresponding pyrroles by stoichiometric oxidants or by catalytic copper(II) and air in moderate to high yields. A wide range of functional groups are tolerated, and further combination with an in situ bromination gives access to polyfunctional pyrrole scaffolds.

  15. Enantioselective Synthesis of Acyclic α-Quaternary Carboxylic Acid Derivatives through Iridium-Catalyzed Allylic Alkylation.

    Science.gov (United States)

    Shockley, Samantha E; Hethcox, J Caleb; Stoltz, Brian M

    2017-09-11

    The first highly enantioselective iridium-catalyzed allylic alkylation that provides access to products bearing an allylic all-carbon quaternary stereogenic center has been developed. The reaction utilizes a masked acyl cyanide (MAC) reagent, which enables the one-pot preparation of α-quaternary carboxylic acids, esters, and amides with a high degree of enantioselectivity. The utility of these products is further explored through a series of diverse product transformations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Synthesis and physicochemical properties of unsaturated trifluoromethylated sodium carboxylates in aqueous media.

    Science.gov (United States)

    Damas, Christine; Carcenac, Yvan; Abarbri, Mohamed; Coudert, Robert

    2013-04-01

    Structural modifications of unsaturated sodium carboxylate surfactants in terms of trifluoromethylation associated with the hydrocarbon chain length have been studied, the synthesis is described, and aggregation properties have been examined by conductimetry and vapor pressure osmometry between 30°C and 45°C. No strong effect of adding a CF3 group was observed on the Critical Micellar Concentrations. However, the thermodynamic study shows the specific effect exerted by the CF3 group through the enhancement of the entropic contribution. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Synthesis of carbon-13 labeled aldehydes, carboxylic acids, and alcohols via organoborane chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kabalka, G.W.; Delgado, M.C.; Kunda, U.S.; Kunda, S.A.

    1984-01-13

    The carbonylation of organoboranes using carbon-13 enriched carbon monoxide to produce labeled aldehydes in excellent yields is described. This same synthesis technique was tested for the production of labeled carboxylic acids with the incorporation of direct oxidation of the initial organoborane adduct; however, yields were not as good as those obtained with silver oxide oxidation of the aldehydes to produce acids. Since higher yields of carbon-13 labeled alcohols were obtained by reduction of the aldehyde with a borane reagent rather than the direct hydrolysis of the initially formed organoborane, the former method is recommended for the production of carbon-13 labeled alcohols.

  18. Dynamic and structural correlations in nanocomposites of silica with modified surface and carboxylated nitrile rubber.

    Science.gov (United States)

    Sala, Renata L; Oliveira Xavier, Tatielih P; Venâncio, Tiago; Arantes, Tatiane Moraes; Paranhos, Caio M; Camargo, Emerson R

    2016-03-15

    Distinct affinities between the organic and inorganic phases were observed in nanocomposites prepared through a colloidal route with carboxylated nitrile rubber and modified silica nanoparticles, which resulted in variable mechanical properties and improved thermal stability. Nanoparticles with modified surface affected the macromolecular arrangements of the elastomeric matrix, changing the final mechanical behavior of the nanocomposite, which could be predicted by the spin-lattice relaxation time measured by solid-state NMR. It was also possible to identify how each different nanoparticle affected the molecular dynamic of nanocomposite, correlating the dynamic-mechanical analysis with the NMR data of the saturated carbons of the elastomer. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Synthesis and Optical Properties of Pentamethine Cyanine Dyes With Carboxylic Acid Moieties

    Directory of Open Access Journals (Sweden)

    Tyler L Dost

    2017-05-01

    Full Text Available Cyanine dyes possessing carboxylic acid groups have been used in many different fields of study. The acid groups can act as handles for bioconjugation or as metal chelators. Several pentamethine cyanine dyes with propionic acid handles were synthesized and their optical properties were studied to determine their usefulness as fluorescent probes. The optical properties studies performed include the absorbance and emission maxima values as well as the calculation of quantum yield and molecular brightness levels. Molecular models were also calculated to help analyze the dyes’ behavior and were compared with similar dyes with varying alkyl chain lengths replacing the acid moieties.

  20. Synthesis and characterization of novel organotin carboxylate maleimide monomers and copolymers

    Directory of Open Access Journals (Sweden)

    2009-06-01

    Full Text Available Two novel tributyltin carboxylate maleimide monomers, tributyltin(maleimidoacetate and tributyltin(4-maleimidobenzoate, were synthesized by condensation reaction of maleimidoacetic acid or 4-maleimidobenzoic acid with bis(tributyltin oxide. Copolymerization of these monomers with styrene was carried in dioxane at 70°C using asobisisobutyronitrile as free radical initiator. The structures of monomers and copolymers were confirmed by FT-IR (Fourier Transform Infrared, 1H and 13C NMR (nuclear magnetic resonance spectroscopy and elemental analysis. The copolymers were characterized by solubility and thermal analysis.

  1. 5-Amino-1-phenyl-3-trifluoro?methyl-1H-pyrazole-4-carboxylic acid

    OpenAIRE

    Caruso, Francesco; Raimondi, Maria Valeria; Daidone, Giuseppe; Pettinari, Claudio; Rossi, Miriam

    2009-01-01

    In the title compound, C11H8F3N3O2, there are two molecules in the asymmetric unit wherein the phenyl rings make dihedral angles of 65.3 (2) and 85.6 (2)° with the pyrazole rings. In the crystal, pairs of molecules are held together by O—H...O hydrogen bonds between the carboxyl groups, forming a centrosymmetric dimer with an R22(8) motif. Intramolecular N—H...O interactions are also present.

  2. 5-Amino-1-phenyl-3-trifluoromethyl-1H-pyrazole-4-carboxylic acid

    Directory of Open Access Journals (Sweden)

    Francesco Caruso

    2009-09-01

    Full Text Available In the title compound, C11H8F3N3O2, there are two molecules in the asymmetric unit wherein the phenyl rings make dihedral angles of 65.3 (2 and 85.6 (2° with the pyrazole rings. In the crystal, pairs of molecules are held together by O—H...O hydrogen bonds between the carboxyl groups, forming a centrosymmetric dimer with an R22(8 motif. Intramolecular N—H...O interactions are also present.

  3. 5-Amino-1-phenyl-3-trifluoro­methyl-1H-pyrazole-4-carboxylic acid

    Science.gov (United States)

    Caruso, Francesco; Raimondi, Maria Valeria; Daidone, Giuseppe; Pettinari, Claudio; Rossi, Miriam

    2009-01-01

    In the title compound, C11H8F3N3O2, there are two mol­ecules in the asymmetric unit wherein the phenyl rings make dihedral angles of 65.3 (2) and 85.6 (2)° with the pyrazole rings. In the crystal, pairs of mol­ecules are held together by O—H⋯O hydrogen bonds between the carboxyl groups, forming a centrosymmetric dimer with an R 2 2(8) motif. Intra­molecular N—H⋯O inter­actions are also present. PMID:21577579

  4. High performance flexible pH sensor based on carboxyl-functionalized and DEP aligned SWNTs

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lu; Shao, Jinyou, E-mail: jyshao@mail.xjtu.edu.cn; Li, Xiangming; Zhao, Qiang; Nie, Bangbang; Xu, Chuan; Ding, Haitao

    2016-11-15

    Highlights: • The flexible chemiresistive pH sensor based on two-terminal microsensors eliminating the need for a reference electrode, is simple in structure and can be fabricated on a variety of substrates such as PET, PI and PVC. • SWNTs as an ideal one dimensional material are carboxyl-functionalized to make the pH sensor show high sensitivity and outstanding flexibility for practical applications. • DEP technique is used to manipulate and position SWNTs into appropriate locations and desired formations to improve the metal-nanotube interface and highly rapid detection of pH value, resulting in better overall device performance. • Mechanical bendability of the pH sensor, which arises from the combination of flexible PET substrates and SWNTs, offer a significant improvement for applications that are difficult or impossible to achieve with traditional sensors on rigid substrates. - Abstract: The detection and control of the pH is very important in many biomedical and chemical reaction processes. A miniaturized flexible pH sensor that is light weight, robust, and conformable is very important in many applications, such as multifunctional lab-on-a-chip systems or wearable biomedical devices. In this work, we demonstrate a flexible chemiresistive pH sensor based on dielectrophoresis (DEP) aligned carboxyl-functionalized single-walled carbon nanotubes (SWNTs). Decorated carboxyl groups can react with hydrogen (H{sup +}) and hydroxide (OH{sup −}) ions, enabling the sensor to be capable of sensing the pH. DEP is used to deposit well-organized and highly aligned SWNTs in desired locations, which improves the metal-nanotube interface and highly rapid detection of the pH, resulting in better overall device performance. When pH buffer solutions are dropped onto such SWNTs, the H{sup +} and OH{sup −} ions caninteract with the carboxyl groups and affect the generation of holes and electrons in the SWNTs, leading to resistance variations in the SWNTs. The results

  5. III-Nitride nanowire optoelectronics

    Science.gov (United States)

    Zhao, Songrui; Nguyen, Hieu P. T.; Kibria, Md. G.; Mi, Zetian

    2015-11-01

    Group-III nitride nanowire structures, including GaN, InN, AlN and their alloys, have been intensively studied in the past decade. Unique to this material system is that its energy bandgap can be tuned from the deep ultraviolet (~6.2 eV for AlN) to the near infrared (~0.65 eV for InN). In this article, we provide an overview on the recent progress made in III-nitride nanowire optoelectronic devices, including light emitting diodes, lasers, photodetectors, single photon sources, intraband devices, solar cells, and artificial photosynthesis. The present challenges and future prospects of III-nitride nanowire optoelectronic devices are also discussed.

  6. First Stars III Conference Summary

    Science.gov (United States)

    O'Shea, B. W.; McKee, C. F.; Heger, A.; Abel, T.

    2008-03-01

    The understanding of the formation, life, and death of Population III stars, as well as the impact that these objects had on later generations of structure formation, is one of the foremost issues in modern cosmological research and has been an active area of research during the past several years. We summarize the results presented at "First Stars III," a conference sponsored by Los Alamos National Laboratory, the Kavli Institute for Particle Astrophysics and Cosmology, and the Joint Institute for Nuclear Astrophysics. This conference, the third in a series, took place in July 2007 at the La Fonda Hotel in Santa Fe, New Mexico, U.S.A.

  7. Trichloridobis(ethyldiphenylphosphine(tetrahydrofuranmolybdenum(III

    Directory of Open Access Journals (Sweden)

    Tomasz Kruczyński

    2010-07-01

    Full Text Available In the mononuclear title compound, [MoCl3(C4H8O(C14H15P2], obtained by the reaction of trichlorotris(tetrahydrofuranmolybdenum(III and ethyldiphenylphosphine in tetrahydrofuran (THF solution, the MoIII atom is six-coordinated by one O atom of a THF molecule, two P atoms from two ethyldiphenylphosphine ligands and three Cl atoms in a distorted octahedral geometry. The C atoms of the THF molecule are disordered over two positions in a 0.55 (2:0.45 (2 ratio.

  8. Graphics Gems III IBM version

    CERN Document Server

    Kirk, David

    1994-01-01

    This sequel to Graphics Gems (Academic Press, 1990), and Graphics Gems II (Academic Press, 1991) is a practical collection of computer graphics programming tools and techniques. Graphics Gems III contains a larger percentage of gems related to modeling and rendering, particularly lighting and shading. This new edition also covers image processing, numerical and programming techniques, modeling and transformations, 2D and 3D geometry and algorithms,ray tracing and radiosity, rendering, and more clever new tools and tricks for graphics programming. Volume III also includes a

  9. Assembly of heterobimetallic Ni(II)-Ln(III) (Ln(III) = Dy(III), Tb(III), Gd(III), Ho(III), Er(III), Y(III)) complexes using a ferrocene ligand: slow relaxation of the magnetization in Dy(III), Tb(III) and Ho(III) analogues.

    Science.gov (United States)

    Chakraborty, Amit; Bag, Prasenjit; Rivière, Eric; Mallah, Talal; Chandrasekhar, Vadapalli

    2014-06-21

    A family of dinuclear 3d-4f heterobimetallic complexes [LNi(H2O)(μ-OAc)Ln(NO3)2]·CH3CN; {Ln = Dy(III) (1), Tb(III) (2), Ho(III) (3), Gd(III) (4), Er(III) (5), Y(III) (6)} have been synthesized by utilizing a ferrocene-based, dual compartmental ligand H2L. 1-6 are isostructural and crystallize in the triclinic (P1) space group. In these complexes Ni(II) is present in the inner coordination sphere of the dianionic [L](2-) ligand; Ln(III) is encapsulated in the outer coordination pocket. Ni(II) shows a 2N, 4O coordination environment in a distorted octahedral geometry, while the Ln(III) ion possesses a 9O coordination environment in a distorted tricapped trigonal prismatic geometry. ESI-MS studies suggest that the structural integrity of 1-6 is retained in solution. Electrochemical studies reveal that these complexes show a reversible one-electron response typical of the ferrocene motif along with an irreversible one-electron oxidation involving the Ni(II)/Ni(III) couple. Magnetic studies revealed the presence of ferromagnetic exchange coupling between Ni(II) and Ln(III) centers as shown by the increase of χMT value upon cooling below 50 K for compounds 1, 2, 4 and 5. Further, dynamic magnetic susceptibility measurements (1-3) confirm the absence of an out-of-phase (χ'') signal at zero dc fields. However, when these measurements were carried out at 1000 Oe dc field the χ'' signal was observed, although maxima could not be detected up to 2 K.

  10. One-pot synthesis of mesoporous silica nanocarriers with tunable particle sizes and pendent carboxylic groups for cisplatin delivery.

    Science.gov (United States)

    Gu, Jinlou; Liu, Jiapeng; Li, Yongsheng; Zhao, Wenru; Shi, Jianlin

    2013-01-08

    Mesoporous silica nanocarriers with tunable particle sizes and different loadings of pendent carboxylic groups were successfully prepared by a straightforward and reproducible strategy, in which carboxyethylsilanetriol sodium salt was co-condensed with tetraethoxyorthosilicate to introduce the carboxylic groups. The key in this strategy was to separate the synthesis process into two steps of the nuclei formation and particle growth. The uniform particle size and ordered structure of the synthesized nanocarriers were manifested by several techniques such as XRD, TEM, SEM, and BET. DLS measurement illustrated that nanocarriers could be well suspended in aqueous solution. The integration and content tunability of the carboxylic groups within mesoporous silica nanoparticles (MSNs) were verified by FT-IR and (29)Si NMR. The inherent carboxylic units on the obtained carboxylic group modified MSNs (MSNs-C) effectively enhanced the capture and tailored the release properties of the anticancer drug of cisplatin. The accumulation of drug in the HeLa cells was greatly enhanced due to the highly efficient platinum uptake efficiency transported by the synthesized nanocarriers. The drug encapsulated in the MSNs-C exhibited a higher antitumor activity than free cisplatin against both MCF-7 and HeLa cells.

  11. Diphenyl-benzo[1,3]dioxole-4-carboxylic acid pentafluorophenyl ester: a convenient catechol precursor in the synthesis of siderophore vectors suitable for antibiotic Trojan horse strategies.

    Science.gov (United States)

    Baco, Etienne; Hoegy, Françoise; Schalk, Isabelle J; Mislin, Gaëtan L A

    2014-02-07

    Catechols are components of many metal-chelating compounds, including siderophores that are naturally occurring iron(III) chelators excreted by microorganisms. Catechol derivatives are poorly soluble in organic media and the synthesis of catechol-containing molecules requires the use of protected catechol precursors with improved organic solubility. We therefore developed 2,2-diphenyl-benzo[1,3]dioxole-4-carboxylic acid pentafluorophenyl ester. This activated ester reacts with an amine functionalized scaffold to generate chelators in which the catechol functions are protected in the form of diphenyl-benzodioxole moieties. The catechol can subsequently be deprotected, at the end of the synthesis, with trifluoroacetic acid (TFA). This strategy was applied to the synthesis of two catechol compounds functionalized with a terminal propargyl extension. These two compounds were shown to promote iron uptake in Escherichia coli and Pseudomonas aeruginosa. These two compounds are suitable for use as vectors in antibiotic Trojan horse approaches, as they could be conjugated with azide-functionalized antibiotics using the Huisgen dipolar 1,3-cycloaddition.

  12. Timely management of developing class III malocclusion

    OpenAIRE

    M R Yelampalli; M R Rachala

    2012-01-01

    Timing of orthodontic treatment, especially for children with developing class III malocclusions, has always been somewhat controversial, and definitive treatment tends to be delayed for severe class III cases. Developing class III patients with moderate to severe anterior crossbite and deep bite may need early intervention in some selected cases. Class III malocclusion may develop in children as a result of an inherent growth abnormality, i.e. true class III malocclusion, or as a result of p...

  13. In Vitro Reactivity of Carboxylic Acid-CoA Thioesters with Glutathione

    DEFF Research Database (Denmark)

    Sidenius, Ulrik; Skonberg, Christian; Olsen, Jørgen

    2004-01-01

    was to investigate whether a correlation could be found between the structure of acyl-CoA thioesters and their reactivities toward the tripeptide, glutathione (ç- Glu-Cys-Gly).  The  acyl-CoA  thioesters  of  eight  carboxylic  acids  (ibuprofen,  clofibric  acid, indomethacin,  fenbufen,  tolmetin,  salicylic  acid......The chemical reactivity of acyl-CoA thioesters toward nucleophiles has been demonstrated in several recent studies. Thus, intracellularly formed acyl-CoAs of xenobiotic carboxylic acids may react covalently with endogenous proteins and potentially lead to adverse effects. The purpose of this study......,  2-phenoxypropionic  acid,  and  (4-chloro-2-methyl-phenoxy)acetic  acid  (MCPA))  were  synthesized,  and  each  acyl-CoA  (0.5  mM)  was incubated with glutathione (5.0 mM) in 0.1 M potassium phosphate (pH 7.4, 37 °C). All of the acyl-CoAs reacted with glutathione to form the respective acyl...

  14. Synthesis of tricyclic indole-2-carboxylic [correction of caboxylic] acids as potent NMDA-glycine antagonists.

    Science.gov (United States)

    Katayama, S; Ae, N; Nagata, R

    2001-05-18

    The practical synthesis of a series of tricyclic indole-2-carboxylic acids, 7-chloro-3-arylaminocarbonylmethyl-1,3,4,5-tetrahydrobenz[cd]indole-2-carboxylic acids, as a new class of potent NMDA-glycine antagonists is described. The synthetic route to the key intermediate 12a comprises a regioselective iodination of 4-chloro-2-nitrotoluene, modified Reissert indole synthesis, Jeffery's Heck-type reaction with allyl alcohol, Wittig-Horner-Emmons reaction, and iodination at the indole C-3 position. The key step in the route is an intramolecular cyclization of 12a to give the tricyclic indole structure. Two methods of cyclization, (1) an intramolecular radical cyclization of 12a and (2) a sequence of intramolecular Heck reaction of 12a followed by a 1,4-reduction, were performed. The resulting tricyclic indole diester 13a was selectively hydrolyzed to afford the desired tricyclic indole monocarboxylic acid 16 on a multihundred gram scale without any chromatographic purifications. Optical resolution of 16 to (-)-isomer 17 and (+)-isomer 18 was carried out, and the resulting isomers were derivatized, respectively. Evaluation of the optically active derivatives for affinity to the NMDA-glycine binding site using the radio ligand binding assay with [(3)H]-5,7-dichlorokynurenic acid revealed that the derivatives of (-)-isomer 17 were more potent than the others and that especially substituted anilide (-)-isomer 24 (K(i) = 0.8 nM) showed high affinity.

  15. Carboxylated-nanoncellulose as a template for the synthesis of silver nanoprism

    Science.gov (United States)

    Chook, Soon Wei; Yau, Shun Xiang; Chia, Chin Hua; Chin, Siew Xian; Zakaria, Sarani

    2017-11-01

    The features of templates, such as physical dimensions or functional groups, often affect the in situ growth process of nanoparticles. In this study, a rapid thermal synthesis method was adopted for the synthesis of Ag nanoprisms (AgNPRs) on cellulose nanofibrils (CNF), which were obtained via defibrillations of holocellulose. In comparison, holocellulose and pure cellulose also were used for the attempted synthesis of AgNPRs. The produced nanocomposites were examined for their optical and physical properties using ultraviolet-visible spectroscopy, transmission electron microscopy and X-ray diffraction. The results demonstrate that the reduced of the fibres into nanosize and carboxylate functional groups present on the cellulosic template affects the formation of AgNPRs, with which CNF is able to form AgNPRs. The surface-enhanced Raman scattering (SERS) activity of the CNF-AgNPRs composite was studied and exhibited a higher enhancement, compared to the spherical AgNPs-anchored CNF. The CNF prepared from carboxylated holocellulose not only served as nanoparticles support for the SERS application, it also facilitated the formation of AgNPRs that resulted in a better enhancement SERS signal.

  16. Omega-3 carboxylic acids monotherapy and combination with statins in the management of dyslipidemia

    Directory of Open Access Journals (Sweden)

    Benes LB

    2016-12-01

    Full Text Available Lane B Benes1, Nikhil S Bassi2, Michael H Davidson1 1Department of Medicine, Section of Cardiology, 2Department of Medicine, University of Chicago, Chicago, IL, USA Abstract: The 2013 American College of Cardiology/American Heart Association guidelines on cholesterol management placed greater emphasis on statin therapy given the well-established benefits in primary and secondary prevention of cardiovascular disease. Residual risk may remain after statin initiation, in part because of triglyceride-rich lipoprotein cholesterol. Several large trials have failed to show benefit with non-statin cholesterol-lowering medications in the reduction of cardiovascular events. Yet, subgroup analyses showed a benefit in those with hypertriglyceridemia and lower high-density lipoprotein cholesterol level, a high-risk pattern of dyslipidemia. This review discusses the benefits of omega-3 carboxylic acids, a recently approved formulation of omega-3 fatty acid with enhanced bioavailability, in the treatment of dyslipidemia both as monotherapy and combination therapy with a statin. Keywords: omega-3 carboxylic acids, non-HDL-C, hypertriglyceridemia, residual risk, statin

  17. Investigating the photostability of carboxylic acids exposed to Mars surface ultraviolet radiation conditions.

    Science.gov (United States)

    Stalport, F; Coll, P; Szopa, C; Cottin, H; Raulin, F

    2009-01-01

    The detection and identification of organic molecules on Mars are of primary importance to establish the existence of a possible ancient prebiotic chemistry or even biological activity. The harsh environmental conditions at the surface of Mars could explain why the Viking probes-the only efforts, to date, to search for organics on Mars-detected no organic matter. To investigate the nature, abundance, and stability of organic molecules that could survive such environmental conditions, we developed a series of experiments that simulate martian surface environmental conditions. Here, we present results with regard to the impact of solar UV radiation on various carboxylic acids, such as mellitic acid, which are of astrobiological interest to the study of Mars. Our results show that at least one carboxylic acid, mellitic acid, could produce a resistant compound-benzenehexacarboxylic acid-trianhydride (C(12)O(9))-when exposed to martian surface radiation conditions. The formation of such products could contribute to the presence of organic matter in the martian regolith, which should be considered a primary target for in situ molecular analyses during future surface missions.

  18. Stability study of ZnO nanoparticles in aqueous solutions of carboxylate anions

    Science.gov (United States)

    Godymchuk, Anna; Karepina, Elizaveta; Yunda, Elena; Lyamina, Galina; Kosova, Natalia; Kuznetsov, Denis

    2015-03-01

    The paper is devoted to the use of carboxylic acids and salts for the elaboration of stable suspensions of ZnO engineered nanoparticles (40 and 200 nm) in physiological media at pH 6-8. It was shown that the aggregation degree of ZnO-200 particles increases with the growth of carboxylic anion activity, e.g., at pH 7 in the row «Acetate--Citrate3--Oxalate2-» the average size of ZnO-200 particles in suspensions amounts to «169-523-770» nm, zeta potential-«35.9-19.9-+5.42 mV», respectively. The aggregation degree of ZnO-40 particles increases in the row «Citrate3--Acetate--Oxalate2-», at pH 7, the average size of ZnO-40 particles in suspension amounts to «50-121-430» nm, zeta potential-«-28.3-14.5-+2.3» mV, respectively. pH-impact was found to be size-dependent: there was a significantly less effect of pH on adsorption, dispersion, and electrokinetic properties of ZnO-40 particles when compared to ZnO-200 particles. The main reason for the difference between micro- and nanosized particles behavior is a change of the ratio of acidic, basic, and neutral Bronsted centers for particles of nanosized scale.

  19. Chemo-enzymatic epoxidation of olefins by carboxylic acid esters and hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Ruesch gen. Klaas, M.; Warwel, S. [Inst. for Biochemistry and Technology of Lipids, H.P. Kaufmanm-Inst., Federal Centre for Cereal, Potato and Lipid Research, Muenster (Germany)

    1998-12-31

    Ethylen and, recently, butadiene can be epoxidized directly with oxygen and for the epoxidation of propylene, the use of heterogeneous transition metals and organic peroxides (Halcon-Process) is the major player. But, beside from those notable exceptions, all other epoxidations, including large ones like the epoxidation of plant oils as PVC-stabilizers (about 200.000 t/year), are carried out with peroxy acids. Because mcpba is far to expensive for most applications, short chain peracids like peracetic acid are used. Being much less stable than mcpba and thus risky handled in large amounts and high concentrations, these peroxy acids were preferably prepared in-situ. However, conventional in-situ formation of peracids has the serious drawback, that a strong acid is necessary to catalyze peroxy acid formation from the carboxylic acid and hydrogen peroxide. The presence of a strong acid in the reaction mixture often results in decreased selectivity because of the formation of undesired by-products by opening of the oxirane ring. Therefore, we propose a new method for epoxidation based on the in-situ preparation of percarboxylic acids from carboxylic acid esters and hydrogen peroxide catalyzed by a commercial, immobilized lipase. (orig.)

  20. Alkenyl Carboxylic Acid: Engineering the Nanomorphology in Polymer-Polymer Solar Cells as Solvent Additive.

    Science.gov (United States)

    Zhang, Yannan; Yuan, Jianyu; Sun, Jianxia; Ding, Guanqun; Han, Lu; Ling, Xufeng; Ma, Wanli

    2017-04-19

    We have investigated a series of commercially available alkenyl carboxylic acids with different alkenyl chain lengths (trans-2-hexenoic acid (CA-6), trans-2-decenoic acid (CA-10), 9-tetradecenoic acid (CA-14)) for use as solvent additives in polymer-polymer non-fullerene solar cells. We systematically investigated their effect on the film absorption, morphology, carrier generation, transport, and recombination in all-polymer solar cells. We revealed that these additives have a significant impact on the aggregation of polymer acceptor, leading to improved phase segregation in the blend film. This in-depth understanding of the additives effect on the nanomorphology in all-polymer solar cell can help further boost the device performance. By using CA-10 with the optimal alkenyl chain length, we achieved fine phase separation, balanced charge transport, and suppressed recombination in all-polymer solar cells. As a result, an optimal power conversion efficiency (PCE) of 5.71% was demonstrated which is over 50% higher than that of the as-cast device (PCE = 3.71%) and slightly higher than that of devices with DIO treatment (PCE = 5.68%). Compared with widely used DIO, these halogen-free alkenyl carboxylic acids have a more sustainable processing as well as better performance, which may make them more promising candidates for use as processing additives in organic non-fullerene solar cells.