WorldWideScience

Sample records for 2,4-pentanedione

  1. The chemical processing of gas-phase carbonyl compounds by sulfuric acid aerosols: 2,4-pentanedione

    Science.gov (United States)

    Nozière, Barbara; Riemer, Daniel D.

    This work investigates the interactions between gas-phase carbonyl compounds and sulfuric acid aerosols. It focuses on understanding the chemical processes, giving a first estimate of their importance in the atmosphere, and suggesting directions for further investigations. The solubility and reactivity of a compound with a large enolization constant, 2,4-pentanedione, in water/sulfuric acid solutions 0-96 wt% have been investigated at room temperature using the bubble column/GC-FID technique. 2,4-pentanedione was found to undergo aldol condensation at acidities as low as 20 wt% H 2SO 4, that is, well in the tropospheric range of aerosol composition. In agreement with well-established organic chemical knowledge, this reaction resulted in changes of color of the solutions of potential importance for the optical properties of the aerosols. 2,4-pentanedione was also found to undergo retroaldol reaction, specific to dicarbonyl compounds, producing acetone and acetaldehyde. The Henry's law coefficient for 2,4-pentanedione was found to be a factor 5 larger than the one of acetone over the whole range of acidity, with a value in water of H (297 K)=(155±27) M atm -1. A chemical system is proposed to describe the transformations of carbonyl compounds in sulfuric acid aerosols. Aldol condensation is likely to be the most common reaction for these compounds, probably involving a large number of the ones present in the atmosphere and a wide range of aerosol compositions. The enolization constant contributes as a proportional factor to the rate constant for aldol condensation, and is shown in this work to contribute as an additive constant to the Henry's law coefficient. In addition to the many important aspects of these reactions illustrated in this work, the rate of aldol condensation was estimated to be potentially fast enough for the losses of some compounds in acidic aerosols to compete with their gas-phase chemistry in the atmosphere.

  2. Structure and vibrational assignment of the enol form of 1,1,1-trifluoro-2,4-pentanedione

    Science.gov (United States)

    Zahedi-Tabrizi, Mansoureh; Tayyari, Fariba; Moosavi-Tekyeh, Zainab; Jalali, Alireza; Tayyari, Sayyed Faramarz

    2006-10-01

    Molecular structure of 1,1,1-trifluoro-pentane-2,4-dione, known as trifluoro-acetylacetone (TFAA), has been investigated by means of Density Functional Theory (DFT) calculations and the results were compared with those of acetylacetone (AA) and hexafluoro-acetylacetone (HFAA). The harmonic vibrational frequencies of both stable cis-enol forms were calculated at B3LYP level of theory using 6-31G** and 6-311++G** basis sets. We also calculated the anharmonic frequencies at B3LYP/6-31G** level of theory for both stable cis-enol isomers. The calculated frequencies, Raman and IR intensities, and depolarization ratios were compared with the experimental results. The energy difference between the two stable cis-enol forms, calculated at B3LYP/6-311++G**, is only 5.89 kJ/mol. The observed vibrational frequencies and Raman and IR intensities are in excellent agreement with the corresponding values calculated for the most stable conformation, 2TFAA. According to the theoretical calculations, the hydrogen bond strength for the most stable conformer is 57 kJ/mol, about 9.5 kJ/mol less than that of AA and about 14.5 kJ/mol more than that of HFAA. These hydrogen bond strengths are consistent with the frequency shifts for OH/OD stretching and OH/OD out-of-plane bending modes upon substitution of CH 3 groups with CF 3 groups. By comparing the vibrational spectra of both theoretical and experimental data, it was concluded that 2TFAA is the dominant isomer.

  3. Substituent Effects on Keto-Enol Equilibria Using NMR Spectroscopy

    Science.gov (United States)

    Manbeck, Kimberly A.; Boaz, Nicholas C.; Bair, Nathaniel C.; Sanders, Allix M. S.; Marsh, Anderson L.

    2011-01-01

    In this extension to a classic physical chemistry experiment, students record the proton nuclear magnetic resonance spectra of the [beta]-diketones 2,4-pentanedione, 3-methyl-2,4-pentanedione, and 3-chloro-2,4-pentanedione to investigate the effect of substituents on keto-enol tautomerization equilibria. From the integrated intensities of keto and…

  4. Deposition of metal oxide films and nanostructures by methods derived from photochemical metal organic deposition

    OpenAIRE

    Xin ZHANG

    2009-01-01

    In this research, methods for the deposition of patterned films and nanostructures were developed from photochemical metal organic deposition (PMOD). Positive lithographic PMOD was demonstrated with films of titanium (IV) di-n-butoxide bis(2-ethylhexanoate) (Ti(OBun)2(eh)2), titanium (IV) diisopropoxide bis(2,4-pentanedionate), and zirconium (IV) di-n-butoxide bis(2,4-pentanedionate). The photochemistry of these complexes in films was studied by FTIR, AES, and XRD. Photo-induced reactivity an...

  5. Synthesis of two 14C-labeled catechol-o-methyltransferase inhibitors

    International Nuclear Information System (INIS)

    14C-labelled 3-(3,4-dihydroxy-5-nitrophenylmethylidene)-2,4-pentanedione and 14C-labelled E-N,N-diethyl-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide have been synthesized from [carbonyl-14C]vanillin. (author)

  6. Synthesis and Thermal Decomposition Mechanism Study of a Novel Iridium Precursor

    OpenAIRE

    Yan Xin; Ai Tao; Su Xinhua; Wang Zhenjun; Sun Guodong; Zhao Peng

    2016-01-01

    Ir(TFA)3 (TFA=1,1,1-trifluoro-2,4-pentanedionate) metal complexes with high purity was successfully synthesized. The metal complexes have been characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance spectroscopy. The volatility of metal complexes was studied by thermogravimetry analysis. And a possible decomposition mechanism was studied by mass spectroscopic analysis method. The novel iridium complexes can be severed as precursor in metalorganic chemical vapor ...

  7. Cobalt(II complexes of tetraazamacrocycles derived from b-diketones and diaminoalkanes

    Directory of Open Access Journals (Sweden)

    R. N. PRASAD

    2005-04-01

    Full Text Available Co(II complexes of the type [Co(L(NO32] (L = tetraazamacrocycle with 18 to 34-membered ring were synthesized by the template condensation of b-diketones, such as 2,4-pentanedione, 1-phenyl-1,3-butanedione or 1,3-diphenyl-1,3-propanedione, with diaminoalkanes. The complexes were characterized by elemental analyses, molar conductances and magnetic moments measurements, as well as infra red and electronic spectroscopy.

  8. Enzymatic synthesis of vitamin B6 precursor

    Directory of Open Access Journals (Sweden)

    Prlainović Nevena Ž.

    2013-01-01

    Full Text Available 3-Cyano-4-ethoxymethyl-6-methyl-2-pyridone is an important precursor in the synthesis of vitamin B6, obtained in the addition reaction between 2-cyanoacetamide and 1-ethoxy-2,4-pentanedione catalyzed by lipase from Candida rugosa (triacylglycerol ester hydrolases, EC 3.1.1.3. This work shows new experimental data and mathematical modeling of lipase catalyzed synthesis of 3-cyano-4-ethoxymethyl-6-methyl-2-pyridone, starting from 1-ethoxy-2,4-pentanedione and 2-cyanoacetamide. Kinetic measurements were done at 50 oC with enzyme concentration of 1.2 % w/v. Experimental results were fitted with two kinetic models: the ordered bi-ter and ping-pong bi-ter model, and the initial rates of the reaction were found to correlate best with a ping-pong bi-ter mechanism with inhibition by 2-cyanoacetamide. Obtained specificity constants indicated that lipase from C. rugosa had higher affinity towards 1-ethoxy-2,4-pentanedione and less bulky substrates. [Projekat Ministarstva nauke Republike Srbije, br. 172013, br. III 46010 and br. 172049

  9. Chemical solution deposition (CSD) of CeO2 and La2Zr2O7 buffer layers on cube textured NiW substrates

    International Nuclear Information System (INIS)

    We present results of crack free layers of CeO2 and La2Zr2O7 deposited by means of CSD on cube textured Ni-4 at.% W substrates. EBSD-data show histograms with very good inplane- and out-of-plane textures and were used to simulate the critical current density in the YBCO layer. The surface roughness, a sensitive feature for good deposition results, was analyzed with a profilometer. In the CSD process we applied, the 2, 4-pentanedionates of the metal cations in glacial acetic acid and methanol served as starting substances

  10. Energy transfer and light yield properties of a new highly loaded indium(III) β-diketonate organic scintillator system

    Science.gov (United States)

    Buck, C.; Hartmann, F. X.; Motta, D.; Schoenert, S.

    2007-02-01

    We present combined experimental and model studies of the light yield and energy transfer properties of a newly developed high light yield scintillator based on indium(III)-tris(2,4-pentanedionate) in a 2-(4-biphenyl)-5-phenyloxazole (BPO), methoxybenzene organic liquid; of interest to the detection of solar electron neutrino oscillations. Optical measurements are made to understand the energy transfer properties and a model is advanced to treat the unusual conditions of high metal and fluor loadings. Such scintillator types are of interest to the exploration of novel luminescent materials and the development of large-scale detectors for studying fundamental properties of naturally occurring neutrinos.

  11. A Facile Synthesis of New Monoazo Disperse Dyes Derived from 4-Hydroxyphenylazopyrazole-5-amines: Evaluation of Microwave Assisted Dyeing Behavior

    Directory of Open Access Journals (Sweden)

    Alya M. Al-Etaibi

    2012-11-01

    Full Text Available A series of new monoazo disperse dyes containing pyrazolopyrimidine moieties was synthesized by coupling malononitrile or 3-aminocrotononitrile with 4-hydroxy- benzenediazonium chloride. Treatment of the resulting products with hydrazine hydrate yields the corresponding 4-arylazoaminopyrazoles, which then react with either 2,4-pentanedione and enaminonitriles or aryl-substituted enaminoketones to give the target pyrazolopyrimidine monoazo disperse dyes. Structural assignments of the dyes were made using both NMR spectroscopic and X-ray crystallographic methods. A high temperature dyeing method, by microwave irradiation, was employed with polyester fabrics. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing and perspiration fastness levels.

  12. Aldol Condensation of Volatile Carbonyl Compounds in Acidic Aerosols

    Science.gov (United States)

    Noziere, B.; Esteve, W.

    2003-12-01

    Reactions of volatile organic compounds in acidic aerosols have been shown recently to be potentially important for organic aerosol formation and growth. Aldol condensation, the acid-catalyzed polymerization of carbonyl compounds, is a likely candidate to enhance the flux of organic matter from the gas phase to the condensed phase in the atmosphere. Until now these reactions have only been characterized for conditions relevant to synthesis (high acidities and liquid phase systems) and remote from atmospheric ones. In this work, the uptake of gas-phase acetone and 2,4\\-pentanedione by sulfuric acid solutions has been measured at room temperature using a Rotated Wetted Wall Reactor coupled to a Mass Spectrometer. The aldol condensation rate constants for 2,4\\-pentanedione measured so far for sulfuric acid solutions between 96 and 70 % wt. display a variation with acidity in agreement with what predicted in the organic chemical literature. The values of these constants, however, are much lower than expected for this compound, and comparable to the ones of acetone. Experiments are underway to complete this study to lower acidities and understand the discrepancies with the predicted reactivity.

  13. High performance of inverted polymer solar cells with cobalt oxide as hole-transporting layer

    Science.gov (United States)

    Wang, Xiangdong; Peng, Qing; Zhu, Weiguo; Lei, Gangtie

    2015-05-01

    Cobalt oxide (II, III) (CoOx) was inserted as efficient hole-transporting interlayer between the active layer and top electrode in inverted polymer solar cells (PSCs) with titanium (diisopropoxide) bis(2, 4-pentanedionate) (TIPD) as an electron selective layer. The work function of CoOx was measured by Kelvin probe and the device performances with different thicknesses of cobalt oxide were studied. The device with CoOx exhibited a remarkable improvement in power conversion efficiency compared with that without CoOx, which indicated that CoOx efficiently prevented the recombination of charge carriers at the organic/top electrode interface. The performance improvement was attributed to the fact that the CoOx thin film can module the Schottky barrier and form an ohmic contact at the organic/metal interface, which makes it a promising hole-transporting layer.

  14. Estimation of vapour pressure and partial pressure of subliming compounds by low-pressure thermogravimetry

    Indian Academy of Sciences (India)

    G V Kunte; Ujwala Ail; P K Ajikumar; A K Tyagi; S A Shivashankar; A M Umarji

    2011-12-01

    A method for the estimation of vapour pressure and partial pressure of subliming compounds under reduced pressure, using rising temperature thermogravimetry, is described in this paper. The method is based on our recently developed procedure to estimate the vapour pressure from ambient pressure thermogravimetric data using Langmuir equation. Using benzoic acid as the calibration standard, vapour pressure–temperature curves are calculated at 80, 160 and 1000 mbar for salicylic acid and vanadyl bis-2,4-pentanedionate, a precursor used for chemical vapour deposition of vanadium oxides. Using a modification of the Langmuir equation, the partial pressure of these materials at different total pressures is also determined as a function of temperature. Such data can be useful for the deposition of multi-metal oxide thin films or doped thin films by chemical vapour deposition (CVD).

  15. Performance improvement of polymer solar cells by using a solution processible titanium chelate as cathode buffer layer

    Science.gov (United States)

    Tan, Zhan'ao; Yang, Chunhe; Zhou, Erjun; Wang, Xiang; Li, Yongfang

    2007-07-01

    A solution processible titanium chelate, titanium (diisopropoxide) bis (2,4-pentanedionate) (TIPD), was used as the cathode buffer layer in the polymer solar cells (PSCs) based on the blend of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] and [6,6]-phenyl-C61-butyric acid methyl ester. Introducing TIPD buffer layer reduced the interface resistance between the active layer and Al electrode, leading to a lower device resistance. The power conversion efficiency of the PSC with TIPD buffer layer reached 2.52% under the illumination of AM1.5, 100mW/cm2, which is increased by 51.8% in comparison with that (1.66%) of the device without TIPD buffer layer under the same experimental conditions.

  16. The imidazole role in strontium beta-diketonate complexes formation.

    Science.gov (United States)

    Marchetti, Fabio; Pettinari, Claudio; Pettinari, Riccardo; Cingolani, Augusto; Gobetto, Roberto; Chierotti, Michele R; Drozdov, Andrei; Troyanov, Sergey I

    2006-04-01

    A selection of new strontium beta-diketonate derivatives (imH2)2[Sr2(beta-dike)6] [where imH = imidazole and beta-dike = tfac (tfacH = 1,1,1-trifluoro-2,4-pentanedione), tfbz (tfbzH = 1,1,1-trifluoro-4-phenyl-2,4-butanedione), or hfac (hfacH = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione)], [Sr2(tfac)4(Meim)2(H2O)2], (MeimH)2[Sr(beta-dike)4] (where Meim = 1-methylimidazole and beta-dike = tfbz or hfac), [Sr2(thd)4(imH)2(EtOH)], and [Sr2(thd)4(Meim)2(EtOH)] (where thdH = 2,2,6,6-tetramethyl-3,5-heptanedione) have been synthesized and fully characterized. (imH2)2[Sr2(beta-dike)6] and (MeimH)2[Sr(beta-dike)4] are di- and mononuclear Sr anionic complexes, respectively, while [Sr2(tfac)4(Meim)2(H2O)2], [Sr2(thd)4(imH)2(EtOH)], and [Sr2(thd)4(Meim)2(EtOH)] are neutral dinuclear molecular derivatives. The derivative (imH2)2[Sr2(hfac)6] slowly decomposes in solution under aerobic conditions, giving (imH2)2[Sr(H2O)2(tfa)3](tfa) (tfaH = trifluoroacetic acid), which is an ionic compound containing polynuclear anionic chains composed of Sr(H2O)2(tfa)3 units. When a deficiency of imH is employed, the thdH proligand forms not only the dinuclear derivative [Sr2(thd)4(imH)2(EtOH)] but also an additional product with the formula [Sr(thd)2(H2O)2(EtOH)], in which the Sr atom is seven-coordinated. A complete solid-state characterization has been accomplished by comparing X-ray and solid-state 13C NMR data. Elucidation of the H-bond interaction between the heterocyclic rings and metal complexes by cross-polarization magic-angle-spinning 15N NMR is also reported. PMID:16562964

  17. Europium incorporated into titanium oxide by the sol-gel method

    Directory of Open Access Journals (Sweden)

    Lucas Alonso Rocha

    2005-09-01

    Full Text Available In this work titanium sol was prepared from tetraethylorthotitanate (TEOT in ethanol, stabilized with beta-diketonate 2,4 pentanedione in molar ratio 1:1 homogenized by magnetic stirring, europium ion was add as structural probe. The xerogels were heat treated at 500, 750 and 1000 °C and the characterization was realized by x-ray diffraction (XRD, transmission electron microscopy (TEM, thermogravimetric analysis (TGA/DSC and photoluminescence (PL. The excitation spectra of Eu (III ion present maximum in 394 nm correspondent to 5L6 level and emission spectra present bands characteristic transitions arising from the 5 D0 -> 7F J (J = 0, 1, 2, 3, 4 manifolds to samples treat at 500 and 750 °C. The Eu (III emission disappear, when heated at 1000 °C, probably due to phase transition anatase to rutile and migrations of ions to the external surface that was proved by x-ray diffraction, transmission electronic microscopy and the thermogravimetric analyses of xerogels.

  18. Crystal structure, photoluminescence and electroluminescence of three bluish green light-emitting iridium complexes.

    Science.gov (United States)

    Xu, Qiu-Lei; Liang, Xiao; Jiang, Liang; Zhao, Yue; Zheng, You-Xuan

    2016-04-25

    Three bis-cyclometalated iridium complexes ((TPP)2Ir(acac), (TPP)2Ir(tpip) and (TPP)2Ir(pic)) with 2-(2-trifluoromethyl)pyrimidine-pyridine (TPP) as the main ligand, 2,4-pentanedionate (acac), tetraphenylimidodiphosphinate (tpip) and picolinate (pic) as the ancillary ligands, respectively, were prepared. Their photoluminescence and electrochemistry properties were investigated in detail, and (TPP)2Ir(tpip) was also examined by X-ray crystallography. These complexes show bluish green emission with a quantum efficiency of 11-14%. The organic light emitting diodes (OLEDs) with the structure of ITO/TAPC (1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane, 40 nm)/mCP (1,3-bis(9H-carbazol-9-yl)benzene, 10 nm)/Ir complex (8 wt%):PPO21 (3-(diphenylphosphoryl)-9-(4-(diphenylphosphoryl)phenyl)-9H-carbazole, 25 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) were fabricated to evaluate the potential application of these complexes. A (TPP)2Ir(tpip) emitter based device showed the best performance of a maximum current efficiency (ηc) value of 37.61 cd A(-1) and a maximum external quantum efficiency (EQE) of 13.7% with low efficiency roll-off. PMID:27030006

  19. Synthesis, Characterization and Biological Evaluation of Succinate Prodrugs of Curcuminoids for Colon Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Pornchai Rojsitthisak

    2011-02-01

    Full Text Available A novel series of succinyl derivatives of three curcuminoids were synthesized as potential prodrugs. Symmetrical (curcumin and bisdesmethoxycurcumin and unsymmetrical (desmethoxycurcumin curcuminoids were prepared through aldol condensation of 2,4-pentanedione with different benzaldehydes. Esterification of these compounds with a methyl or ethyl ester of succinyl chloride gave the corresponding succinate prodrugs in excellent yields. Anticolon cancer activity of the compounds was evaluated using Caco-2 cells. The succinate prodrugs had IC50 values in the 1.8–9.6 ��M range, compared to IC50 values of 3.3–4.9 μM for the parent compounds. Curcumin diethyl disuccinate exhibited the highest potency and was chosen for stability studies. Hydrolysis of this compound in phosphate buffer at pH 7.4 and in human plasma followed pseudo first-order kinetics. In phosphate buffer, the kobs and t1/2 for hydrolysis indicated that the compound was much more stable than curcumin. In human plasma, this compound was able to release curcumin, therefore our results suggest that succinate prodrugs of curcuminoids are stable in phosphate buffer, release the parent curcumin derivatives readily in human plasma, and show anti-colon cancer activity.

  20. Composition-dependent electrocatalytic activity of palladium-iridium binary alloy nanoparticles supported on the multiwalled carbon nanotubes for the electro-oxidation of formic acid.

    Science.gov (United States)

    Bao, Jianming; Dou, Meiling; Liu, Haijing; Wang, Feng; Liu, Jingjun; Li, Zhilin; Ji, Jing

    2015-07-22

    Surface-functionalized multiwalled carbon nanotubes (MWCNTs) supported Pd100-xIrx binary alloy nanoparticles (Pd100-xIrx/MWCNT) with tunable Pd/Ir atomic ratios were synthesized by a thermolytic process at varied ratios of bis(acetylacetonate) palladium(II) and iridium(III) 2,4-pentanedionate precursors and then applied as the electrocatalyst for the formic acid electro-oxidation. The X-ray diffraction pattern (XRD) and transmission electron microscope (TEM) analysis showed that the Pd100-xIrx alloy nanoparticles with the average size of 6.2 nm were uniformly dispersed on the MWCNTs and exhibited a single solid solution phase with a face-centered cubic structure. The electrocatalytic properties were evaluated through the cyclic voltammetry and chronoamperometry tests, and the results indicated that both the activity and stability of Pd100-xIrx/MWCNT were strongly dependent on the Pd/Ir atomic ratios: the best electrocatalytic performance in terms of onset potential, current density, and stability against CO poisoning was obtained for the Pd79Ir21/MWCNT. Moreover, compared with pure Pd nanoparticles supported on MWCNTs (Pd/MWCNT), the Pd79Ir21/MWCNT exhibited enhanced steady-state current density and higher stability, as well as maintained excellent electrocatalytic activity in high concentrated formic acid solution, which was attributed to the bifunctional effect through alloying Pd with transition metal. PMID:26132867

  1. A novel MOCVD strategy for the fabrication of cathode in a solid oxide fuel cell: Synthesis of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} films on YSZ electrolyte pellets

    Energy Technology Data Exchange (ETDEWEB)

    Toro, Roberta G., E-mail: rgtoro@unict.it [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy); Fiorito, Davide M.R.; Fragala, Maria E. [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy); Barbucci, Antonio; Carpanese, Maria P. [Dipartimento di Ingegneria Chimica e di Processo, Universita di Genova, and INSTM, UdR P.le Kennedy 1, I-16129 Genova (Italy); Malandrino, Graziella, E-mail: gmalandrino@dipchi.unict.it [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy)

    2010-12-01

    Porous La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSMO) films have been prepared by metal organic chemical vapor deposition (MOCVD) technique for solid oxide fuel cell (SOFC) applications. LSMO samples have been deposited on yttria-stabilized zirconia (YSZ) electrolyte pellets. The adopted in situ strategy involves a molten mixture consisting of the La(hfa){sub 3}.diglyme, Sr(hfa){sub 2}.tetraglyme, and Mn(tmhd){sub 3} [Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; diglyme = bis(2-methoxyethyl)ether; tetraglyme = 2,5,8,11,14-pentaoxapentadecane; Htmhd = 2,2,6,6-tetramethyl-3,5-heptandione] precursors. It has been shown that porous LSMO films can be obtained through an accurate tuning of processing parameters, which affect the nucleation and growth processes. The structural and compositional characterizations of these films, carried out by X-ray diffraction (XRD) and energy dispersive X-ray analysis, point to the formation of a single polycrystalline La{sub 0.8}Sr{sub 0.2}MnO{sub 3} phase. The field emission scanning electron microscopy (FE-SEM) images confirm the formation of porous films. To evaluate the electrochemical activity of the cathodic films, an investigation by impedance spectroscopy (IS) has been performed.

  2. Metal-assisted in situ formation of a tridentate acetylacetone ligand for complexation of fac-Re(CO)3+ for radiopharmaceutical applications.

    Science.gov (United States)

    Benny, Paul D; Fugate, Glenn A; Barden, Adam O; Morley, Jennifer E; Silva-Lopez, Elsa; Twamley, Brendan

    2008-04-01

    Reaction of [NEt4]2[ReBr3(CO)3] with 2,4-pentanedione (acac) yields a complex of the type fac-Re(acac)(OH2)(CO)3 (1) under aqueous conditions. 1 was further reacted with a monodentate ligand (pyridine) to yield a fac-Re(acac)(pyridine)(CO)3 complex (2). Complex 1 was found to react with primary amines to generate a Schiff base (imine) in aqueous solutions. When a mixed-nitrogen donor bidentate ligand, 2-(2-aminoethyl)pyridine, that has different coordination affinities for fac-Re(acac)(OH2)(CO)3 was utilized, a unique tridentate ligand was formed in situ utilizing a metal-assisted Schiff base formation to yield a complex fac-Re(CO)3(3[(2-phenylethyl)imino]-2-pentanone) (3). Tridentate ligand formation was found to occur only with the Re-coordinated acac ligand. Reactions of acac with fac-Re(CO)3Br(2-(2-aminoethyl)pyridine) (4) or a mixture of [NEt4]2[ReBr3(CO)3], acac, and 2-(2-aminoethyl)pyridine did not yield the formation of complex 3 in water. PMID:18298058

  3. X-ray Emission Spectroscopy to Study Ligand Valence Orbitals in Mn Coordination Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Smolentsev, Grigory; Soldatov, Alexander V; Messinger, Johannes; Merz, Kathrin; Weyhermuller, Thomas; Bergmann, Uwe; Pushkar, Yulia; Yano, Junko; Yachandra, Vittal K.; Glatzel, Pieter

    2009-03-02

    We discuss a spectroscopic method to determine the character of chemical bonding and for the identification of metal ligands in coordination and bioinorganic chemistry. It is based on the analysis of satellite lines in X-ray emission spectra that arise from transitions between valence orbitals and the metal ion 1s level (valence-to-core XES). The spectra, in connection with calculations based on density functional theory (DFT), provide information that is complementary to other spectroscopic techniques, in particular X-ray absorption (XANES and EXAFS). The spectral shape is sensitive to protonation of ligands and allows ligands, which differ only slightly in atomic number (e.g., C, N, O...), to be distinguished. A theoretical discussion of the main spectral features is presented in terms of molecular orbitals for a series of Mn model systems: [Mn(H2O)6]2+, [Mn(H2O)5OH]+, [Mn(H2O)5NH2]+, and [Mn(H2O)5NH3]2+. An application of the method, with comparison between theory and experiment, is presented for the solvated Mn2+ ion in water and three Mn coordination complexes, namely [LMn(acac)N3]BPh4, [LMn(B2O3Ph2)(ClO4)], and [LMn(acac)N]BPh4, where L represents 1,4,7-trimethyl-1,4,7-triazacyclononane, acac stands for the 2,4-pentanedionate anion, and B2O3Ph2 represents the 1,3-diphenyl-1,3-dibora-2-oxapropane-1,3-diolato dianion.

  4. Antiproliferative and cancer-chemopreventive properties of sulfated glycosylated extract derived from Leucaena leucocephala

    Directory of Open Access Journals (Sweden)

    Gamal-Eldeen Amira

    2007-01-01

    Full Text Available This work aimed to prove that simple chemical modification could provide new cancer chemopreventive and/or anticancer properties to the inactive extracted polysaccharide derived from Leucaena leucocephala . Polysaccharides were extracted from Leucaena leucocephala seeds and its 2,4-pentanedione-treated derivative (glycosylated form was prepared, which is further sulphated to give sulphated glycosylated form. Estimation of their anti-initiation activity, modulation of carcinogen metabolism, was indicated by the inhibition cytochrome P450 1A (CYP1A and the induction of glutathione-S-transferases (GSTs. Anti-proliferation activity was investigated by MTT assay against human hepatocarcinoma (HepG2, breast carcinoma (MCF-7 and lymphoblastic leukemia (1301. Apoptosis/necrosis and cell cycle were analyzed by flow cytometry. The results revealed that glycosylated form inhibited both CYP1A and GSTs, while sulphated glycosylated form not only inhibited CYP1A, but also induced the GSTs. Unlike GE, sulphated glycosylated form possessed a significant anti-proliferative activity against different cell lines. Analysis of HepG2 cell cycle phases demonstrated that glycosylated form led to a delay of G2/M-phase, while sulphated glycosylated form led to a concomitant arrest in S- and G2/M-phases. Investigation of apoptosis/necrosis ratio demonstrated that both of glycosylated form and sulphated glycosylated form induced HepG2 cell death by necrosis, but not apoptosis. Unmodified crude extract was neither active as cancer chemopreventive nor as anti-proliferative. In conclusion, chemical modification of Leucaena gum induced its cancer chemopreventive and anti-proliferative activities.

  5. An iron(II) diketonate–diamine complex as precursor for thin film fabrication by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bratvold, Jon E., E-mail: j.e.bratvold@kjemi.uio.no [Centre for Materials Science and Nanotechnology (SMN)/Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315 Oslo (Norway); Carraro, Giorgio [Department of Chemistry, University of Padova and INSTM, via F. Marzolo 1, I-35131 Padova (Italy); Barreca, Davide [CNR-IENI and INSTM, Department of Chemistry, University of Padova, via F. Marzolo 1, I-35131 Padova (Italy); Nilsen, Ola [Centre for Materials Science and Nanotechnology (SMN)/Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315 Oslo (Norway)

    2015-08-30

    Highlights: • First report of Fe(hfa){sub 2}TMEDA as precursor in ALD and MLD. • Hybrid organic–inorganic films with oxalic acid as co-reactant between 125 and 350 °C. • Surface saturation evidenced by quartz crystal microbalance (QCM) analysis. • XPS confirms complete preservation of Fe(II) from precursor to film. • Deposition of α-Fe{sub 2}O{sub 3} when using ozone as co-reactant. - Abstract: A new divalent Fe precursor has been explored for deposition of iron-containing thin films by atomic layer deposition and molecular layer deposition (ALD/MLD). The Fe(II) β-diketonate-diamine complex, Fe(hfa){sub 2}TMEDA, (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate, TMEDA = N,N,N′,N′-tetramethylethylenediamine) can be handled in air, and sublimation at 60 °C ensures a satisfactory vaporization rate. The reactivity of the precursor does not allow for direct reaction with water as co-reactant. Nevertheless, it reacts with carboxylic acids, resulting in organic–inorganic hybrid materials, and with ozone, yielding α-Fe{sub 2}O{sub 3}. The divalent oxidation state of iron was maintained during deposition when oxalic acid was used as co-reactant, demonstrating the first preservation of Fe(II) from precursor to film during an MLD process. A self-saturating growth mode was proven by in situ quartz crystal microbalance (QCM) measurements, and the films were further characterized by grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS)

  6. Harvard--MIT research program in short-lived radiopharmaceuticals

    International Nuclear Information System (INIS)

    This report describes progress on five projects. The first project showed a 1000 fold concentration of the cationic complex 99mTc (MIBI) in heart cell mitochondria vs heart cell cytoplasm, as determined by high resolution electron probe microanalysis. Additional technetium-99m based complexes are being developed and tested. The second project involves evaluating technetium acetylacteonates as potential indicators of cerebral blood flow. An intermediate in the synthesis of a technetium porphyrin complex has been synthesized; an oxotechnetium(V)-2,4-pentanedione complex has been prepared and is currently being characterized. The third project involves using radio labelled antibodies for diagnosis and treatment of cancer. An early discovery was that chloramine-T based iodination protocols resulted in a reversal of the charge on mouse lgGs. Immunoperoxidase-labelled monoclonal antibody MOv 18 was shown to bind specifically to the most frequent ovarian aderon carcinomas, and not to healthy tissue, making this antibody a good candidate for immunotherapy or immunodetection. Work on a specific immunotherapy protocol suffered a setback when one reagent, a 125I-biotin complex, proved to be unstable in vivo. The fourth project involves labelling antibodies with positron emitting radionuclides. Radiofluorination was accomplished through reductive alkylation of 18F-aldehyde, or pentafluorophenyl esters. Radioiodination was accomplished using alkyl-tin derivation exchange. The fifth project examined antibody modification for use in radioimmune imaging. Technetium-99m-labelled lgG was shown to be biologically equivalent to Indium-III-labelled lgG for imaging focal sites of inflamation. Also, Indium III labelling of small bioactive peptides was examined as a means of imaging important physiological processes. 44 refs., 2 figs

  7. Analysis of Redox Series of Unsymmetrical 1,4-Diamido-9,10-anthraquinone-Bridged Diruthenium Compounds.

    Science.gov (United States)

    Mandal, Abhishek; Hoque, Md Asmaul; Grupp, Anita; Paretzki, Alexa; Kaim, Wolfgang; Lahiri, Goutam Kumar

    2016-03-01

    The unsymmetrical diruthenium complexes [(bpy)2Ru(II)(μ-H2L(2-))Ru(III)(acac)2]ClO4 ([3]ClO4), [(pap)2RuII(μ-H2L(2-))Ru(III)(acac)2]ClO4 ([4]ClO4), and [(bpy)2Ru(II)(μ-H2L(2-))Ru(II)(pap)2](ClO4)2 ([5](ClO4)2) have been obtained by way of the mononuclear precursors [(bpy)2Ru(II)(H3L(-))]ClO4 ([1]ClO4) and [(pap)2Ru(II)(H3L(-))]ClO4 ([2]ClO4) (where bpy = 2,2′-bipyridine, pap = 2-phenylazopyridine, acac(-) = 2,4-pentanedionate, and H4L = 1,4-diamino-9,10-anthraquinone). Structural characterization by single-crystal X-ray diffraction and magnetic resonance (nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR)) were used to establish the oxidation state situation in each of the isolated materials. Cyclic voltammetry, EPR, and ultraviolet-visible-near-infrared (UV-vis-NIR) spectroelectrochemistry were used to analyze the multielectron transfer series of the potentially class I mixed-valent dinuclear compounds, considering the redox activities of differently coordinated metals, of the noninnocent bridge and of the terminal ligands. Comparison with symmetrical analogues [L2′Ru(μ-H2L)RuL2′](n) (where L′ = bpy, pap, or acac(-)) shows that the redox processes in the unsymmetrical dinuclear compounds are not averaged, with respect to the corresponding symmetrical systems, because of intramolecular charge rearrangements involving the metals, the noninnocent bridge, and the ancillary ligands. PMID:26887785

  8. 桥连双(酮亚胺)和双(二酮亚胺)及其铝配合物的合成与催化活性%Synthesis and Catalytic Activity of Aluminum Complexes Supported by Bis(β-ketimine) and Bis(β-diketimine) Ligands

    Institute of Scientific and Technical Information of China (English)

    黄庆东; 李春兰; 张宇; 崔立山; 朱百春; 义建军; 刘林; 郝海军

    2014-01-01

    Owing to its special physical and chemical properties as well as good coordination activity with transition metals, β-diketone-derived β-ketimines and β-diketimines have been extensively studied in recent years. In this work, five new bridged bis(β-ketimine)(1-5) and bis(β-diketimine) ligands(6,7) were syn-thesized by the condensation reaction of 3,3’-(1,4-phenylene) bis(2,4-pentanedione) with various anilines. Treatment of these ligands with AlMe3 afforded five new aluminum complexes(8-12). All these compounds were characterized via elemental analysis, 1 H NMR, 13 C NMR, ESI-MS and IR spectroscopy. Structures of two aluminium complexes were determined by the X-ray single-crystal diffraction analysis. The bridged β-keti-mine acted as a chelating N, O-bidentate ligand to the aluminium atom. Each aluminum atom showed a dis-torted tetrahedral coordination geometry. These aluminum complexes exhibited effective catalytic activity in the ring-opening polymerization of ε-caprolactone.%通过桥连双β-二酮类化合物与取代苯胺反应,合成了5个新的桥连双(β-单酮亚胺)化合物(1~5)和2个新的桥连双(β-二酮亚胺)化合物(6,7),它们与三甲基铝反应,得到了相应的3个双(β-酮亚胺基)二铝配合物(8~10)和2个双(β-二酮亚胺基)二铝配合物(11,12)。采用核磁共振、红外光谱和质谱等对这些化合物进行了表征,通过X射线单晶衍射分析证实了铝配合物的结构,并考察了这些铝配合物在ε-己内酯开环聚合反应中的催化活性。

  9. 基体匹配校正-顶空-气相色谱法测定食品塑料包装材料中挥发性有机物%Head-Space-GC Determination of Volatile Organic Compounds in Plastic Packaging Materials for Foodstuffs with Matrix Matching Calibration

    Institute of Scientific and Technical Information of China (English)

    程欲晓; 周宇艳; 马明

    2012-01-01

    Ten volatile organic compounds(VOC′s),i.e.,toluene,ethyl acetate,2,4-pentanedione,2-ethyl-1-hexanol,1-nanaldehyde,decanecarbaldehyde,dodecanacarbaldehyde,decane,octane and dodecane in soft plastic packaging materials were determined by head-space gas chromatography using matrix matching calibration to compensate the matrix interference.A representative portion of the sample(packaging film,ca.100 cm2) was taken and stoved in a vacuum oven at 90 ℃ for 24 h.This portion of the sample was cut and used as blank matrix for preparation of calibration curve and definita amounts of standard solutions of the 10 VOC′s wer added to it and treated in the same way as the sample.A similar portion of the sample was cut and transferred into the headspace bottle,closed the bottle immediately and equilibrized at 100 ℃ for 30 min.HP-INNOWAX chromatographic column was used for separation at programed temperature elevation from 20 ℃ to 220 ℃.FID was adopted for determination.Detection limits(3S/N) found for the 10 VOC′s were ranged from 0.2 to 2.0 μg·dm-2.Values of recovery and RSD′s(n=6) were in the ranges of 82.5%-97.6% and 1.0%-14.0% respectively.%采用顶空-气相色谱法测定了食品用软质塑料包装材料中具有代表的10种挥发性有机物(VOC′s),包括甲苯、乙酸乙酯、2,4-戊二酮、2-乙基-1-己醇、1-壬醛、癸烷醛、十二烷醛、癸烷、正辛烷及十二烷,并用基体匹配法抵消了样品本身的基体干扰。从待分析样品(包装膜)裁取约100cm2大小片样置于真空烘箱中,于90℃烘24h,此片试样即可作为空白基质,再加入一定量的上述VOC标准溶液制备校准曲线。另取同一样品一片,剪碎后移入顶空瓶中,立即盖紧,在100℃平衡30min。方法中用HP-INNOWAX色谱柱在20℃~220℃温度区间程序升温,对各VOC进行分离,采用火焰离子化检测器检测。测得10种VOC′s的检出限(3S/N)在0.2~2.0μg.dm-2之间。另测

  10. Surface modified carbon nanoparticle papers and applications on polymer composites

    Science.gov (United States)

    Ouyang, Xilian

    a tensile strength of 360 MPa and an electrical conductivity of 4.45x104 S/m, much better than any similar materials reported in the literature. However, they didn't show good gas barrier properties. Since the GO paper presented zero gas permeability for both CO2 and H2, a hybrid paper fabrication approach was proposed to combine the advantages of individual GP and GO papers. This was done by filtering GP and GO layer by layer with GO sandwiched in between two layers of GP. The resulting hybrid papers showed high mechanical tensile strength and EMI shielding effectiveness that are close to GP nanopapers, and excellent gas barrier properties that comparable to GO nanopapers. The GP, GO and GP-Go-GP hybrid nanopapers have been successfully coated onto the thermoplastic surface by thermal lamination and injection molding. In the third part, the effect of PANI-CNF nanopapers and a chelating agent, 2, 4- Pentanedione (2, 4-P) on kinetics of an in-mold coating (IMC) resin was investigated. The results showed that the presence of amine functionalized carbon nanoparticles tended to retard the resin reaction, while 2, 4-P was capable of promoting the redox based free radical polymerization by forming a complex with the cobalt promoter in the initiation step. In order to understand the chemical and physical changes during the resin curing process, kinetics study on two major resin components, i.e. hexanediol diacrylate (HDDA) and styrene (St), were carried out using an integrated analysis design: differential scanning calorimetry (DSC) for overall reaction, Fourier transform infrared spectroscopy (FTIR) for individual component reactions, and rheometry for liquid-solid transition during the reaction. The gel point of this radical polymerization resin system was found to be <2% which implied that most curing was conducted in the solid phase. The results showed that the double bonds in acrylates and St followed an azeotropic polymerization pattern.

  11. 钒掺杂二氧化钛薄膜制备与材料特性分析%Preparation and characterization of V-doped titanium oxide thin films

    Institute of Scientific and Technical Information of China (English)

    刘欢; 龚树萍; 刘剑桥; 万久晓; 周东祥

    2011-01-01

    V-doped TiO2 films were prepared by sol-gel method starting from tetrabutyl titanate and vanadium(Ⅲ) 2,4-pentanedionate.Their properties were characterized by XRD,UV-Vis absorption spectra,FT-IR,and XPS with the undoped film samples as the control.Both the V-doped and undoped TiO2 films are anatase and the band gap decreases from 3.28 to 3.15eV,with a red shift in the absorption of V-doped TiO2 film compared to the undoped samples.The V-doped films consist of vanadium atoms in the V4+ and V5+ oxidation states,generating deep defect levels and the valence bandedge might extend into the forbidden band gap,inducing the band gap narrowing effect and enhancing the bandedge absorption.At the grain boundaries of TiO2,those impurity defects located deep inside the gap become closer to the top of the valence band and hence tend to trap the photo-generated holes,which would contribute to inhibit the recombination of photogenerated carriers and become highly attractive for application in photocatalytic materials.%以钛酸四丁酯和乙酰丙酮钒(Ⅲ)为主要原料,采用溶胶-凝胶法制备了钒掺杂二氧化钛薄膜,利用XRD、紫外-可见吸收光谱、FT-IR及XPS等表征手段,将其与未掺杂二氧化钛薄膜进行了材料特性对比研究。结果表明两种薄膜均为锐钛矿结构,引入钒后二氧化钛的禁带宽度由3.28eV减小至3.15eV,吸收带边红移至可见光范围;XPS分析证实制备的钒掺杂二氧化钛薄膜中钒以四价和五价两种氧化价态存在,可能在二氧化钛禁带中引入较深的杂质能级而引起价带顶向禁带拓展,从而产生引起禁带宽度变窄效应,扩展了二氧化钛带边光吸收。理论分析还表明,钒掺杂引起的深能级杂质在二氧化钛晶界处易于形成有效的陷阱俘获光生空穴,从而抑制光生载流子的复合,尤其适于用作光催化材料。