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11.
Oleg Ya Borbulevych Ronald D ClarkAngela Romero Li TanMikhail Yu Antipin Vladimir N NesterovBeatriz H Cardelino Craig E MooreMohan Sanghadasa Tatiana V Timofeeva 《Journal of Molecular Structure》2002,604(1):73-86
Molecular and crystal structure of a series of derivatives of N,N-dimethyl-4-nitroaniline has been studied by both X-ray diffraction method and high-level ab initio calculations. According to these data, the dimethylamino groups were found to have a trigonal-pyramidal configuration and are considerably turned with respect to the ring plane in all molecules having a substituent in the ortho-position; on the contrary, this group is planar in the meta-substituted molecules. Topological analysis of the electron density function for all molecules studied within the framework of Bader's ‘atoms in molecules’ (AIM) theory revealed that introduction of a substituent into the ortho- or meta-position of the ring results in increasing of the contribution of the resonance forms different from the quinoid one. Contribution of the latter form is predominant for the structure of N,N-dimethyl-4-nitroaniline (1). Topological analysis of the electron density distribution was used to explain a decreasing of the molecular hyperpolarisabilites of the ortho- and meta-substituted compounds as compared with those for 1. 相似文献
12.
Jones SC Coropceanu V Barlow S Kinnibrugh T Timofeeva T Brédas JL Marder SR 《Journal of the American Chemical Society》2004,126(38):11782-11783
A complex featuring two triarylamine redox centers bridged by Pt, trans-bis(triethylphosphine)-bis{4-[bis(4-methoxyphenyl)amino]phenylethynyl} platinum(II), has been synthesized as a model system for pi-conjugated Pt-containing polymers. Analysis of the intervalence charge-transfer band displayed by its mixed-valence monocation affords a quantitative assessment of electronic delocalization through the Pt bridge; this is found to be only slightly smaller than that determined for a benzene-bridged analogue. These results are supported by density functional theory calculations, which show that the active orbitals involved in the electron-transfer process in both cases have similar delocalization through the bridging unit. 相似文献
13.
Khankhasaeva S. Ts. Badmaeva S. V. Dashinamzhilova E. Ts. Timofeeva M. N. Burgina E. B. Budneva A. A. Paukshtis E. A. 《Kinetics and Catalysis》2004,45(5):708-713
The effect of modification on the structural, acidic, and catalytic properties of a natural layered aluminosilicate containing 90% montmorillonite was studied. With the use of low-temperature nitrogen adsorption and XRD analysis, it was found that the addition of hydroxo complexes of aluminum prevents the silicate layers of the layered aluminosilicate from closing upon heating and results both in the formation of stable micropores and in a considerable increase in the specific surface area. The acidic properties of the H, Na, and Al forms of the layered aluminosilicate were studied by IR spectroscopy of adsorbed CO molecules and by the indicator method. After modification with hydroxo complexes of aluminum, the number of Lewis acid sites and the accessibility of acidic OH groups to CO adsorption increased. The total number and strength of acid sites increased as the calcination temperature of the layered aluminosilicate was increased. A correlation between catalytic activity in the reaction of acetone dimerization and the number of acid sites in different forms of the layered aluminosilicate was obtained. 相似文献
14.
Larisa Timofeeva Andrey Lyashchenko Irina Balakaeva Alexandr Lileev Yulia Simonova 《International Journal of Polymer Analysis and Characterization》2020,25(6):409-420
Abstract The high-frequency dielectric relaxation of aqueous solutions of protonated diallylammonium polyelectrolyte, namely poly(diallylmethylammonium trifluoroacetate) has been studied at the maximum water dispersion frequencies, 7.5–25?GHz, and temperatures of 288, 298, and 308?K. Dielectric relaxation parameters have been calculated and compared with similar characteristics of aqueous solutions of monomer, diallylmethylammonium trifluoroacetate, and pyrrolidinium trifluoroacetate salt simulated structure of pyrrolidinium polymer link. It has been concluded that although the monomer features hydrophobic hydration, its polymer exhibits hydrophilic hydration properties. This change is related to conformation of hydrophilic-hydrophobic polycations in aqueous solutions and the change in the structure of polymer links. 相似文献
15.
1H NMR was applied to study the interaction of chloral hydrate in deuterionitrobenzene solution with tetrabutylammonium salts of the heteropoly acids (HPA) belonging to five structural types: Keggin (H3PW12O40, H3PMo12O40, H4SiW12O40), Dawson (-H6P2W18O62, -H6P2Mo18O62, -H4S2Mo18O62), H6P2W21O71(H2O)3, H6As2W21O69(H2O), and H21B3W39O132. The surface of the HPA anions is nonuniform in acid-base properties. A general rule for all HPA was found, namely, that the HPA acidity increases with a decrease in the specific anion charge (per W or Mo atom). 相似文献
16.
17.
G. I. Timofeeva A. A. Tepanov V. A. Lopanov V. S. Romanova 《Russian Chemical Bulletin》2012,61(8):1635-1637
Association of methyl esters of peptide-containing maleimidofullerenes in aqueous solutions was studied by the diffusion method. It was found that dissolution of these compounds follows a mechanism differing from that for the corresponding salts and that the degree of association of fullerene derivatives is affected most strongly by the structure of the molecule as a whole rather than by the peptide nature. 相似文献
18.
Timofeeva Е. Е. Panchenko E. Yu. Surikov N. Yu. Tagiltsev A. I. Pichkaleva M. V. Larchenkova N. G. Chumlyakov Yu. I. Andreev V. A. 《Russian Physics Journal》2019,61(12):2231-2235
Russian Physics Journal - Stress-induced and thermal-induced martensitic transformations (MTs) in compression were investigated in [001]-oriented Ti–50.6 at.% Ni single crystals aged at 573 K... 相似文献
19.
V. P. Andreev P. S. Sobolev D. O. Zaitsev S. M. Timofeeva 《Russian Journal of General Chemistry》2018,88(10):2108-2113
The coordination of zinc(II) tetraphenylporphine with pyridines was studied by electronic spectroscopy. Linear correlations were found between the thermodynamic and kinetic parameters of coordination in different solvents. The effect of the solvent on the stability constants of the complexes and the thermodynamics of complex formation are discussed. 相似文献
20.