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201.
Zhuo Wang Feng‐Ying Bai Yong‐Heng Xing Prof. Dr. Yan Xie Mao‐Fa Ge Shu‐Yun Niu 《无机化学与普通化学杂志》2010,636(8):1570-1575
Two new lanthanide complexes [Sm2(ad)2.5(BSA)(H2O)2]n ( 1 ) and [Nd2(ad)2.5(BSA)(H2O)2]n ( 2 ) (H2ad = adipic acid, HBSA = benzenesulfonic acid) were synthesized hydrothermally from the reaction of the lanthanide ions (Ln3+) with flexible aliphatic dicarboxylate and the rigid benzene sulfonic acid and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. They crystallize monoclinic in space group P21/ c. Structural analyses revealed that the two complexes have intricate 3D net structures constructed by the bridging adipic ligand and benzenesulfonic acid. The thermogravimetric analysis of 1 and 2 , as well as photoluminescent properties of 1 are discussed in detail. 相似文献
202.
Dr. Gilles Alcaraz Dr. Sylviane Sabo‐Etienne 《Angewandte Chemie (International ed. in English)》2010,49(40):7170-7179
There have been a number of approaches developed for the catalyzed dehydrogenation of amine–boranes as potential dihydrogen sources for hydrogen storage applications in recent years. Key advances in this area have been recently made thanks to catalytic and stoichiometric studies. In this Minireview, the fate of amine–boranes upon coordination to a metal center is discussed with a particular emphasis on B? H activation pathways. We focus on the few cases in which coordination of the resulting dehydrogenated product could be achieved, which includes the coordination of aminoborane, the simplest unit resulting from dihydrogen release of ammonia–borane. 相似文献
203.
Sharma SK Roudaut G Fabing I Duplâtre G 《Physical chemistry chemical physics : PCCP》2010,12(42):14278-14284
The triplet state of positronium, o-Ps, is used as a probe to characterize a starch-20% w/w sucrose matrix as a function of temperature (T). A two-step decomposition (of sucrose, and then starch) starts at 440 K as shown by a decrease in the o-Ps intensity (I(3)) and lifetime (τ(3)), the latter also disclosing the occurrence of a glass transition. Upon sucrose decomposition, the matrix acquires properties (reduced size and density of nanoholes) that are different from those of pure starch. A model is successfully established, describing the variations of both I(3) and τ(3) with T and yields a glass transition temperature, T(g) = (446 ± 2) K, in spite of the concomitant sucrose decomposition. Unexpectedly, the starch volume fraction (as probed through thermal gravimetry) decreases with T at a higher rate than the free volume fraction (as probed through PALS). 相似文献
204.
Ruohong Sui Suya Liu Gilles A. Lajoie Paul A. Charpentier 《Journal of separation science》2010,33(11):1604-1609
The search for a method to fabricate monolithic inorganic columns has attracted significant recent attention due to their unique ability in separation applications of various biomolecules. Silica and polymer based monolithic columns have been prepared, but titania and other metal oxide monoliths have been elusive, primarily due to their fragility. This article describes a new approach for preparing nanostructured titania based columns, which offer better performance over conventional particle packed columns for separating a wide variety of biomolecules including phosphopeptides. TiO2 monolithic aerogels were synthesized in separation columns using in situ sol‐gel reactions in supercritical carbon dioxide (scCO2) followed by calcination, and compared to those prepared in heptanes. The characterization results show that scCO2 is a better solvent for the sol‐gel reactions, providing lower shrinkage with the anatase TiO2 monolith composed of nanofibers with very high surface areas. The monolithic columns show the ability to isolate phosphopeptides with little flow resistance compared to conventional titania particle based microcolumns. 相似文献
205.
David Semrouni O. Petru Balaj Florent Calvo Catarina F. Correia Carine Clavaguéra Gilles Ohanessian 《Journal of the American Society for Mass Spectrometry》2010,21(5):728-738
The structure of the sodiated peptide GGGGGGGG-Na+ or G8-Na+ was investigated by infrared multiple photon dissociation (IRMPD) spectroscopy and a combination of theoretical methods.
IRMPD was carried out in both the fingerprint and N—H/O—H stretching regions. Modeling used the polarizable force field AMOEBA
in conjunction with the replica-exchange molecular dynamics (REMD) method, allowing an efficient exploration of the potential
energy surface. Geometries and energetics were further refined at B3LYP-D and MP2 quantum chemical levels. The IRMPD spectra
indicate that there is no free C-terminus OH and that several N—Hs are free of hydrogen bonding, while several others are
bound, however not very strongly. The structure must then be either of the charge solvation (CS) type with a hydrogen-bound
acidic OH, or a salt bridge (SB). Extensive REMD searches generated several low-energy structures of both types. The most
stable structures of each type are computed to be very close in energy. The computed energy barrier separating these structures
is small enough that G8-Na+ is likely fluxional with easy proton transfer between the two peptide termini. There is, however, good agreement between
experiment and computations in the entire spectral range for the CS isomer only, which thus appears to be the most likely
structure of G8-Na+ at room temperature. 相似文献
206.
Density Functional Theory and post‐Hartree Fock calculations reveal an unusual energy profile for Zn? S and Zn? N bond dissociation reactions in several [Zn(SR)4]2? and [Zn(Im)(SR)3]? complexes. The Zn? S bond dissociation in tetrathiolate dianions, which is highly exothermic in the gas phase, proceeds through a late transition state which can be rationalized on the basis of an avoided crossing resulting from Coulomb repulsion between the anionic fragments and ligand‐to‐metal charge‐transfer in the [Zn(SR)4]2? complexes. When solvation models for water, DMSO, or acetonitrile are included, some complexes become stable while others are metastable, so this constitutes the first theoretical model which is in full agreement with the experimental data for various [Zn(SR)4]2?, [Zn(SR)3]?, and [Zn(Im)(SR)3]? complexes. The analysis given here indicates that the Zn(Cys)4 and Zn(His)(Cys)3 cores of numerous proteins are metastable with respect to Zn? S and Zn? N bond dissociation, respectively. This is consistent with the kinetic lability at the zinc‐centers and illustrates that in nature, thermodynamic stability is imparted upon the zinc cores by the protein environment. 相似文献
207.
Krzysztof Ejsmont Joel Boeglin Claude Didierjean Gilles Guichard Christian Jelsch 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(6):o292-o294
The crystal structure of the title compound, C16H23N3O4·CH3CN, was refined using a multipolar atom model transferred from an experimental electron‐density database. The refinement showed some improvement in crystallographic statistical indices compared with the independent atom model. The triazepane ring adopts a twist‐boat conformation. In the crystal structure, the molecule forms intermolecular contacts with 14 different neighbours. There are two N—H...O and one C—H...O intermolecular hydrogen bond. 相似文献
208.
Gilles Gasser Jonathan D. Carr Stephen J. Green Sean M. Cafferkey James H.R. Tucker 《Journal of organometallic chemistry》2010,695(2):249-3763
Two new ligand derivatives of ferrocene, namely N-4-[3,5-di-(2-pyridyl)-1,2,4-triazoyl]ferrocene carbimine (L1) and N-4-[3,5-di-(2-pyridyl)-1,2,4-triazoyl]ferrocene carbamide (L2), were synthesised in good yields by reacting the known compound 3,5-di-pyridine-2-yl-[1,2,4]triazol-4-ylamine (1) with ferrocenecarbaldehyde and chlorocarbonyl ferrocene, respectively. The structures of L1 and L2 were determined by X-ray crystallography. The complexation of L1 and L2 with CuI, AgI, ZnII and CdII was studied by NMR and UV-vis spectroscopies, as well as by electrochemistry, with titrations used to determine metal:ligand stoichiometries. The cyclic voltammograms of L1 and L2 and their respective complexes indicated reversible one-electron transfers corresponding to the Fc0/+ redox couple (Fc = ferrocene), with formal electrode potentials shifting to more positive values upon metal complexation. 相似文献
209.
Alban A. Letailleur Sergey Yu Grachev Elin Søndergård Christophe Couteau Gilles Lérondel Emmanuelle Peter 《Journal of luminescence》2011,131(12):2646-2651
The application of alumina-doped ZnO (AZO) films as luminescent material for large area lighting sources has been evaluated. Thin films were grown on quartz using magnetron sputtering and subsequently annealed under argon atmosphere in a rapid thermal annealing experiment. Below 550 °C, red-shift of the optical band gap and increase of the visible emission are observed in agreement with Al diffusion and formation of interstitial oxygen atoms. At temperatures higher than 800 °C, diffusion is activated and Ostwald ripening leads to the formation of larger grains and an increase of the crystalline phase. The photoluminescence (PL) intensity is enhanced, specifically in the UV range. As a result the emission spectrum of AZO thin films can be adjusted by the annealing conditions, with equal contributions from the UV and orange parts of the PL spectrum resulting in an efficient white emission as quantified using the color space map of the Commission Internationale de l'Éclairage. 相似文献
210.
We provide a resolution of one of the long-standing puzzles in the theory of disordered systems. By reformulating the functional renormalization group for the critical behavior of the random field Ising model in a superfield formalism, we are able to follow the associated supersymmetry and its spontaneous breaking along the functional renormalization group flow. Breaking is shown to occur below a critical dimension d(DR) ? 5.1 and leads to a breakdown of the "dimensional reduction" property. We compute the critical exponents as a function of dimension and give evidence that scaling is described by three independent exponents. 相似文献