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611.
Oksana M. Kamoshenkova 《Journal of fluorine chemistry》2010,131(2):248-253
The reactions of 1,3,5-tris(fluorosulfonyl)benzene 1 with nucleophilic agents were investigated. It was found that morpholine, β,β,β-trifluoroethanol in the presence of triethylamine and sodium azide formed corresponding 1,3,5-trisulfonyl derivatives. In contrast, nucleophiles such as aniline, thiourea, and potassium thiocyanate do not react with compound 1 even in excess and under moderate heating. The conditions for the selective fluorine atom substitution in one SO2F group with morpholine, DMAP and aniline in the presence of triethylamine as well as in two SO2F groups with DMAP were found. Anionic σ-complex of compound 1 with nitromethane was isolated as individual compound. 相似文献
612.
S. K. Klimenko T. I. Tyrina N. N. Sorokin V. G. Kharchenko 《Chemistry of Heterocyclic Compounds》1986,22(2):155-161
The reaction of 1-phenyl-3-(3,4-dimethoxyphenyl)-3-(2-oxocyclohexyl)-1-propanone with hydrogen sulfide and acids gives an intramolecular rearrangement product, 2-phenyl-2,4-ortho-(14,15-dimethoxybenzo)-cis-1-thiadecalin in addition to the usual products of disproportionation of intermediate 2-phenyl-4-(3,4-dimethoxyphenyl)-5,6-tetramethylene-4H-thiopyran, namely, 5,6-tetramethylenethiopyrilium salts and 2-phenyl-4-(3,4-dimethoxyphenyl)-cis-1-thiadecalin. The configurational and conformational assignments for the sulfides, their sulfoxides, and sulfones were made by 13C NMR spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 199–205, February, 1986. 相似文献
613.
Lyudmyla V. Karabanova Raymond L. D. Whitby Vladimir A. Bershtein Alina V. Korobeinyk Pavel N. Yakushev Oksana M. Bondaruk Andrew W. Lloyd Sergey V. Mikhalovsky 《Colloid and polymer science》2013,291(3):573-583
Acid-oxidized multiwalled carbon nanotubes (MWCNTs) were introduced into a polyurethane (PU) matrix at low filler levels (0.01–0.25 wt%) through either van der Waals or covalent interactions, and their glass transition dynamics using dynamic mechanical analysis and laser-interferometric creep rate spectroscopy was investigated. The nanocomposites reveal substantial impact on the PU glass transition dynamics, which depends on the nanotube content and type of interfacial interactions. The pronounced dynamic heterogeneity within the glass transition covering 200 °C range and the displacement of main PU relaxation maxima from around 0 to 80–140 °C were registered. The results are treated in the framework of chemical inhomogeneity, constrained dynamics effects, and different motional cooperativities. The peculiariaties of the glass transition dynamics in the composites are reflected in their dynamic and static mechanical properties, in particular a two- to threefold increase in modulus and tensile strength for the covalent interfacial interaction of MWCNTs with PU. 相似文献
614.
Dr. Oksana Kel Dr. Alexandre Fürstenberg Dr. Nathalie Mehanna Dr. Cyril Nicolas Dr. Benoît Laleu Martin Hammarson Prof. Bo Albinsson Prof. Jerôme Lacour Prof. Eric Vauthey 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(22):7173-7180
The interaction of a series of chiral cationic [4]helicene derivatives, which differ by their substituents, with double‐stranded DNA has been investigated by using a combination of spectroscopic techniques, including time‐resolved fluorescence, fluorescence anisotropy, and linear dichroism. Addition of DNA to helicene solutions results to a hypochromic shift of the visible absorption bands, an increase of fluorescence quantum yield and lifetime, a slowing down of fluorescence anisotropy decay, and a linear dichroism in flow‐oriented DNA, which unambiguously points to the binding of these dyes to DNA. Both helicene monomers and dimeric aggregates, which form at higher concentration, bind to DNA, the former most probably upon intercalation and the latter upon groove binding. The binding constant depends substantially on the dye substituents and is, in all cases, larger with the M than the P enantiomer, by factors ranging from 1.2 to 2.3, depending on the dye. 相似文献
615.
Adjoint functors and projectivization in representation theory of partially ordered sets are used to generalize the algorithms of differentiation by a maximal and by a minimal point. Conceptual explanations are given for the combinatorial construction of the derived set and for the differentiation functor. 相似文献
616.
617.
618.
The shape of the light absorption band by a local tetragonal center at the transition 1 5(x, y) is investigated in a semiclassical approximation. In addition to interaction with fully-symmetric (1), Jahn-Teller (3, 4) vibrations, inter-action is also taken into account with vibrations 5, which admix an electron level 4(z) to the electronic state 5, which is separated from 5 by the energetic gap . An analytic computation of the band shape is performed in the first order of the expansion of the form function in –1. An asymmetric two-hump band is obtained, where the long-wave maximum always has higher intensity than the shortwave maximum.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 62–67, December, 1987. 相似文献
619.
The breakdown of the aligned states of Néel ferrimagnets in an applied magnetic field is considered. The behaviour of isotropic two-and three-sublattice ferrimagnets is treated in the framework of the mean-field approximation. A phenomenological method also limited by the mean-field approximation is used to analyse the behaviour of the anisotropic ferrimagnet. Particular emphasis is placed on the vicinity of the compensation temperature. Approximate analytical expressions which are valid near the compensation temperature are given for the phase-boundary positions, typical magnetic fields, and temperature ranges of the phase diagrams. 相似文献
620.
Małgorzat Kozbia Marek Pietraszkiewicz Oksana Pietraszkiewicz 《Journal of inclusion phenomena and macrocyclic chemistry》1998,30(1):69-77
A chiral crown ether incorporating a methyl -d-mannopyranoside unit displayed pronounced enantioselection of amino acids in partition liquid chromatography experiments involving solvent systems of limited miscibility: water–ethanol–2,2,4-trimethylpentane. The same system has been used for amino acid transport across a liquid membrane containing the crown ether, and in liquid–liquid extraction experiments. Remarkable enantioselection has been noted for amino acids in all the processes studied. 相似文献