共查询到20条相似文献,搜索用时 31 毫秒
1.
Guy Yardeni Israel Zilbermann Eric Maimon Haim Cohen Dan Meyerstein 《Research on Chemical Intermediates》2009,35(4):543-554
A new CeIII complex was synthesized by mixing the ligand “dioxocyclam” with CeIII ions at pH 8.0 and its redox properties were investigated.
相似文献
Dan Meyerstein (Corresponding author)Email: |
2.
Hitoshi Shirase Yurie Miura Yutaka Fukuda 《Monatshefte für Chemie / Chemical Monthly》2009,140(7):807-814
Abstract Mixed-ligand NiII complexes have been synthesized with 1,3-diketonate and bulky tri- or tetra-amine ligands. Their structures were determined
by X-ray crystallography, and solvatochromic behavior was examined by UV–vis–NIR spectroscopy. Steric effects of the bulky
ligands on the coordination distances and spectral properties are discussed.
Graphical Abstract
相似文献
Yutaka FukudaEmail: |
3.
The molecular geometries, relative stabilities, binding energies, and dissociation energies of NaDyBr4 and its molecular ion are discussed. Both the bidentate and tridentate isomers are stable for the neutral species, while
only the bidentate form is stable for NaDyBr4
+.
相似文献
Magdolna Hargittai (Corresponding author)Email: |
4.
The emission spectra of a series of molybdenum(II) chloride clusters containing thiolate ligands, [Mo6(μ3-Cl)8(SR)6]2− (R = Et, Bu, Ph, Bn), have been recorded. These complexes all show a broad emission at ~700 nm after excitation at 337, 400
and 410 nm. Determination of the excited state lifetimes and quantum yields of these complexes in acetonitrile reveals that
(Bu4N)2[Mo6(μ3-Cl)8(SPh)6] displays the longest excited state lifetime of this series (26 μs at 296 K).
相似文献
Lisa F. SzczepuraEmail: |
5.
H. P. Zhang L. C. Yang L. J. Fu Q. Cao D. L. Sun Y. P. Wu R. Holze 《Journal of Solid State Electrochemistry》2009,13(10):1521-1527
Recent progress in studies of several types of core-shell structured electrode materials, including TiO2/C, Si/C, Si/SiO
x
, LiCoO2/C, and LiFePO4/C nanocomposites, including details of their preparation and their electrochemical performance is briefly reviewed. Results
clearly show that the coating shell can effectively prevent the aggregation of the nanosized cores, which are the electrochemically
active materials. In addition, the diffusion coefficients of lithium ions can be increased, and the reversibility of lithium
intercalation and deintercalation is improved. As a result, the cycling behavior is greatly improved. The reviewed results
suggest that core-shell nanocomposites are a good starting point for further development of new promising electrode materials.
相似文献
Y. P. WuEmail: |
R. Holze (Corresponding author)Email: |
6.
E. Santos A. Lundin K. Pötting P. Quaino W. Schmickler 《Journal of Solid State Electrochemistry》2009,13(7):1101-1109
Due to progress in the theory of electrocatalysis and in quantum chemistry, it has become possible to investigate the hydrogen
reaction and perform quantitative calculations for the reaction rate. First, we demonstrate this with model calculations for
the adsorption of hydrogen on Pt(111). In accordance with experimental data, we find hydrogen adsorption at a potential above
the equilibrium potential and with an almost vanishing energy of activation. As a second example, we explain trends in the
catalytic activity of palladium overlayers and clusters on Au(111) electrodes.
Dedicated to J.O’M. Bockris on the occasion of his 85th birthday and in recognition of his contributions to electrochemistry.
相似文献
W. SchmicklerEmail: |
7.
Yan Gao Sabrina Reischmann Johannes Huber Tobias Hanke Rudolf Bratschitsch Alfred Leitenstorfer Stefan Mecking 《Colloid and polymer science》2008,286(11):1329-1334
Single semiconductor quantum dots were embedded into polymer particles with diameters below 0.1 μm by an emulsion polymerization
procedure or via a secondary dispersion approach. The photoluminescence properties of the nanocrystals are retained upon encapsulation,
as demonstrated by fluorescence confocal microscopy.
相似文献
Stefan MeckingEmail: |
8.
Fatemeh Hashemzadeh M. Mehdi Kashani Motlagh Amir Maghsoudipour 《Journal of Sol-Gel Science and Technology》2009,51(2):169-174
In this work, MnO2 nanostructure powders with different crystalline phases have been successfully prepared by hydrothermal and sol–gel methods.
The obtained products were characterized by XRD and SEM techniques and their crystallographic phases and morphological properties
compared. Results showed that α-MnO2, β-MnO2, and δ-MnO2 nanorods were synthesized by hydrothermal method and γ-MnO2 polymorph was obtained by sol–gel method.
相似文献
Amir MaghsoudipourEmail: |
9.
X-ray structures of Diels–Alder adducts of thiophene with N-methylmaleimide and 2,5-dimethylthiophene with N-phenylmaleimide were determined and compared to literature data. In addition, quantum chemical calculations at various levels
of theory were used to study their molecular and electronic structure. A comparison with experimental results showed that
MP2/6-31G*, HF/6-311+G** and PBE1PBE/6-31G* methods give the most accurate structures.
相似文献
Davor MargetićEmail: |
10.
Catherine Marchal-Roch Estelle Ayrault Laurent Lisnard Jérôme Marrot Feng-Xian Liu Francis Sécheresse 《Journal of Cluster Science》2006,17(2):283-290
The trivacant heteropolyanion A-α[PMo9O31(OH2)3]3− spontaneously dimerizes in acetonitrile to form the Dawson complex [P2Mo18O62]6−. A rapid new quantitative preparation of the sodium salt of this Dawson complex is described. In addition, the structure of TBA5[HP2Mo18O62] is given and the featuring data compared with the isomorphous sodium salt (space group C2/c).
相似文献
Catherine Marchal-RochEmail: |
11.
René Dybkaer 《Accreditation and quality assurance》2007,12(12):661-663
Terminology within a small laboratory community can be informal without danger of misunderstanding, but communication with
a wider audience and not least in publications, needs unequivocal terms for defined concepts. As an example, the many meanings
of “concentration” are explored to present a systematic nomenclature, including a concept diagram.
相似文献
René Dybkaer |
12.
I. Berra L. Irusta M. J. Fernández-Berridi Y. R. de Miguel 《Journal of Sol-Gel Science and Technology》2009,49(1):19-28
Novel phenoxy-silica hybrid materials (with 3 wt.% SiO2) have been synthesized using different synthetic procedures. Differential scanning calorimetric (DSC) (Tg), FT-IR and transmission electron microscopy (TEM) results, as well as thermal and mechanical properties, are reported for
these hybrids, which can be classified into three different groups, depending on the number of components synthesized in situ.
Best results in terms of homogeneity (TEM) and mechanical properties have been obtained when the sol–gel process has been
carried out in the presence of a phenoxy resin modified with a pendant alkoxysilane monomer.
相似文献
Y. R. de MiguelEmail: |
13.
The kinetic of the sol–gel hydrolysis and polycondensation reactions of a chiral ORMOSIL precursor was investigated by LCMS
technique as a function of water excess and pH. While the amount of water does not significantly change the kinetics, the
reactions strongly depend on the [H]+ concentration. At pH ≤ 3, the hydrolysis is very fast and the conversion of the precursor is completed within less than 1
h whereas at 80% of the precursor is still present after 50 h at pH = 3.5. This kinetic study allows to define a set of initial
conditions and time ranges required to provide good optical quality dip coated films .
相似文献
L. GuyEmail: |
14.
Vanézia L. Silva Ruy Carvalho Matheus P. Freitas Cláudio F. Tormena Walclée C. Melo 《Structural chemistry》2007,18(5):605-609
Spectrometric and theoretical tools have been employed in this study in order to elucidate the structures of DTPA (diethylenetriaminepentaacetic
acid) complexed to copper and lead. Mass spectrometry allowed determining the 1:1 stoichiometry of metal:ligand, while infrared
spectroscopy demonstrated that both N and O are sites for complexation. 13C NMR analysis showed the existence of free and complexed carboxyl groups, due to a straight singlet at 180.7 ppm (free carboxylic
13C) and to a broad signal at 179.3 ppm (complexed carboxylic 13C, 2
J
Pb…O=C). A distorted NMR signal were observed for the Cu–DTPA carboxyl group, due to the Cu2+ paramagnetism. Based on the spectrometric evidences for the metal–DTPA structures, DFT optimizations were carried out and
an octahedral-like arrangement for the Cu complex and a “shell-like” arrangement for the Pb complex, both hexa-coordinated,
were then proposed for the structures of the titled compounds.
相似文献
Ruy CarvalhoEmail: |
15.
The compounds {[Fe(phen)3]2+(TCNQ–TCNQ)2−) · 2(CH3OH)} (FIWPRD), {[Fe(C5H5)(C5H4CH2NMe3)]+)(TCNQ−) (IKONOL), and {[Cu(1,4,5,12-tetraazacyclo-pentadecane)]2+(TCNQ−)2} (AVOJEA) were reported in the non-centrosymmetric space groups Cc (#9), Pna21 (#33), and P1 (#1). Examination of the several sets of atomic coordinates shows that the space groups are more likely to be C2/c (#15), Pnma (#63), and (#2), respectively. Confirmation of the centrosymmetric models requires access to the diffraction intensities; unfortunately
these are not in the public domain.
相似文献
Frank H. HerbsteinEmail: |
16.
Malcolm H. Chisholm Jason S. D’Acchioli Christopher M. Hadad 《Journal of Cluster Science》2007,18(1):27-49
The electronic structures and the physical properties (vertical excitation energies, vibrational stretching frequencies, and
bond lengths) of a variety of M–M quadruply bonded (M = Mo, W) complexes are investigated using density functional theory
(DFT). By utilizing a variety of pure and hybrid exchange-correlation (XC) functionals and a number basis sets, we are able
to recommend a theoretical methodology for most efficiently probing the electronic structures of homoleptic M2(O2CR)4 and bridged M2(O2C-X-CO2)M2 (R = organic group, typically H; X = conjugated organic group) complexes.
相似文献
Jason S. D’AcchioliEmail: |
17.
Xavier Fuentes-Arderiu 《Accreditation and quality assurance》2006,11(12):640-643
Protometrology is a new term recently proposed to designate the science of observation. As any field of knowledge needs a
terminological system, in this article a system of terms and definitions on protometrology, with examples belonging to clinical
laboratory sciences, is presented. This terminological system starts with the definitions of the two primitive concepts “object”
and “property”.
相似文献
Xavier Fuentes-ArderiuEmail: |
18.
In the present work, results of the interaction between methanol and oxidized platinum surfaces as studied via transients
of open-circuit potentials are presented. The surface oxidation before the exposure to interaction with 0.5 M methanol was
performed at different polarization times at 1.4 V vs reversible hydrogen electrode (RHE). In spite of the small changes in
the initial oxide content, the increase of the pre-polarization time induces a considerable increase of the time needed for
the oxide consumption during its interaction with methanol. The influence of the identity of the chemisorbing anion on the
transients was also investigated in the following media: 0.1 M HClO4, 0.5 M H2SO4, and 0.5 M H2SO4 + 0.1 mM Cl−. It was observed that the transient time increases with the energy of anion chemisorption and, more importantly, without
a change in the shape of the transient, meaning that free platinum sites are available at the topmost layer all over the transient
and not only in the potential region of small oxide ‘coverage’. The impact of the pre-polarization time and the effect of
anion chemisorption on the transients are rationalized in terms of the presence of surface and subsurface oxygen driven by place exchange.
相似文献
Hamilton VarelaEmail: |
19.
S. Vatsadze M. Al-Anber W. R. Thiel H. Lang R. Holze 《Journal of Solid State Electrochemistry》2005,9(11):764-777
Reduction potentials for the first electron transfer to a broad selection of nitrogen containing bi- and polydentate molecules
considered as potential ligands have been determined. Results are compared with data obtained with semiempirical and UV-Vis
spectroscopic data. Close correlations for the investigated molecules are observed. Systematic differences in properties of
molecules with and without the keto moiety can be explained by invoking molecular orbital and surface interaction arguments.
Similar structural arguments can be used to explain the behaviour of 2,4,6-tripyridin-2–yl[1,3,5]triazine. UV-Vis data match
closely those derived from HOMO-LUMO calculations for these molecules.
相似文献
R. HolzeEmail: |
20.
Here, we present a free web-accessible application, developed in the JAVA programming language for the calculation of vicinal
coupling constant (3
J
H,H) of organic molecules with the H–Csp3–Csp3–H fragment. This JAVA applet is oriented to assist chemists in structural and conformational analyses, allowing the user
to calculate the averaged 3
J
H,H values among conformers, according to its Boltzmann populations. Thus, the CAL3JHH program uses the Haasnoot–Leeuw–Altona
equation, and, by reading the molecule geometry from a protein data bank (PDB) file format or from multiple pdb files, automatically
detects all the coupled hydrogens, evaluating the data needed for this equation. Moreover, a “Graphical viewer” menu allows
the display of the results on the 3D molecule structure, as well as the plotting of the Newman projection for the couplings.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
José A. DobadoEmail: |