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I.A. Khotina L.S. Lepnev N.S. Burenkova P.M. Valetsky A.G. Vitukhnovsky 《Journal of luminescence》2004,110(4):232-238
New materials based on low-generation polyphenylene dendrimers with the light emission in the blue spectrum range were synthesized and examined for an efficient organic light emitting diodes (OLED) application. It has been shown that the ratio of p-phenylene groups with high fluorescence parameters to 1,3,5-triphenylbenzene groups with low fluorescent parameters may be the possible reason for the experimental variations of relative quantum yield of photoluminescence in the compounds explored. The quantum yield value is increased with a number of dendrimer generations up to 50–70%. The role of bromine atoms as the luminescence quenchers have been demonstrated, which is important for synthesis route choice. 相似文献
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S. V. Lindeman Yu. T. Struchkov I. A. Khotina V. N. Mikhailov A. L. Rusanov 《Russian Chemical Bulletin》1994,43(11):1873-1879
The crystal structure of 1,3,5-tris[4-(phenylethynyl)phenyl]benzene (1) has been investigated. Compound1 represents a model of the repeating unit of the most typical polyphenylene, which contains 1,3,5-trisubstituted benzene rings (chain centers) and acetylenic groups (complex-forming and cross-linking centers) in the main chain. The acetylene groups of neighboring molecules have a tendency to close mutual arrangement, which is favorable for their topochemical interaction. However, the relative conformational rigidity of molecules1 restricts not only the possibility of the optimal adjustment of the reactive sites of neighboring molecules to one another, but also hampers the close packing of molecules in the crystal, which contains channels filled by the solvent molecules (chloroform).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1986–1992, November, 1994.The work was carried out with the financial support of the International Science Foundation and the American Crystallographic Association. 相似文献
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Shtykova EV Svergun DI Chernyshov DM Khotina IA Valetsky PM Spontak RJ Bronstein LM 《The journal of physical chemistry. B》2004,108(20):6175-6185
Functionality-enhanced nanostructured matrices generated by intercalating polyoctadecylsiloxane (PODS) with octadecene (ODC) or octadecylamine (ODA) are employed as reaction media in which to grow Pt nanoparticles. Small-angle X-ray scattering (SAXS) signatures confirm that the amphiphilic PODS matrix orders into lamellae with a periodicity (d) of 5.24 nm, which corresponds to the siloxy bilayer and a double layer of alkyl tails. The regular packing of the hydrophobic tails becomes distorted upon introduction of ODC or ODA. Incorporation of K[(C2H4)PtCl3].H2O (a Zeise salt) into the PODS/ODC matrix, followed by reduction of the Pt ions by NaBH4 or H2, results in the localization of Pt compounds and nanoparticles along the siloxy bilayers, which remain dimensionally unchanged. Electron density profiles deduced from PODS/ODA, however, provide evidence for considerable structural reorganization upon metalation with H2PtCl6.6H2O. In this case, the siloxy bilayers broaden due to the presence of PtCl62- ions, and the hydrophobic layers become distorted due to the formation of (PtCl62-)(ODAH+)2 complexes. Subsequent reduction by NaBH4 restores the inherent PODS organization, while H2 reduction partially preserves the distorted matrix, indicating that some Pt nanoparticles form in close proximity to the siloxy bilayer. Transmission electron microscopy reveals that relatively monodisperse Pt nanoparticles measuring approximately 1 nm in diameter are located along the siloxy bilayers, whereas anomalous SAXS further indicates that nanoparticles form aggregates of comparable size to d within the PODS double layers. 相似文献
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I. A. Khotina A. I. Kovalev N. S. Kushakova M. A. Babushkina Yu. V. Vasil’ev A. S. Peregudov 《Russian Chemical Bulletin》2013,62(10):2234-2244
A series of model cyclotrimers was studied by NMR spectroscopy using 2D COSY, HSQC, and HMBC correlations to establish the structures of branched oligophenylenes, whose branching center is the 1,3,5-triphenyl-substituted benzene ring. 相似文献
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D. A. Rud’ L. Zh. Nikoshvili T. P. Loginova A. V. Naumkin Yu. L. Slovokhotov V. G. Matveeva M. G. Sul’man I. A. Khotina 《Polymer Science Series B》2010,52(1-2):49-56
Structured polyphenylenes that are used as matrices for immobilization of palladium nanoparticles are synthesized through the cyclocondensation of acetylaromatic compounds followed by structuring at different temperatures and, as a result, different crosslink densities. The relationship between the structure and structuring temperature of the polymers is investigated. It is shown that the sizes of palladium nanoparticles immobilized in polyphenylene matrices depend on the conditions of polymer structuring. The resulting catalytic systems are examined for the selective hydrogenation of triple bonds in acetylene alcohols. 相似文献
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R. N. Nurmukhametov A. V. Shapovalov A. M. Sergeev N. S. Kushakova I. A. Khotina 《Journal of Applied Spectroscopy》2011,78(1):31-37
A branched oligophenylene has been synthesized based on 1,3,5-tri(4′-bromophenyl)benzene. Absorption and fluorescence spectra
were studied and fluorescence quantum yields and lifetimes were measured for the compound in solution. It is demonstrated
that the absorption spectrum is a superposition of p-quaterphenyl, p-terphenyl, and biphenyl chromophore absorption bands
in a 1:2:1 ratio. The oligomer fluorescence spectrum is found to depend on the excitation wavelength. It is shown that the
oligomer fluorescence is determined by two fluorochromic groups, namely fragments with branched p-terphenyl and p-quaterphenyl
units. The main fluorescence maxima for these fluorochromic groups coincide with each other and lie in the vicinity of λ =
360 nm. A very weak fluorescence band found in the region 380–440 nm is excited by light with a wavelength lying beyond the
oligomer self-absorption region. The reasons for a decrease in fluorescence quantum yields of branched models and the studied
oligophenylene as compared with those of linear p-polyphenylene chromophores are discussed. 相似文献
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R. N. Nurmukhametov A. V. Shapovalov A. M. Sergeev A. I. Kovalev N. S. Kushakova I. A. Khotina 《Journal of Applied Spectroscopy》2011,78(3):344-351
Absorption spectra and fluorescence parameters (spectra, quantum yields, and lifetimes) were obtained for a number of branched
oligophenylenes (OPh) with long-wavelength chromophores such as p-quaterphenyl (OPh4-2), p-pentaphenyl (OPh5), and p-hexaphenyl (OPh6) and for oligofluorenylphenylenes (OFl) in solutions and films. It is demonstrated that the absorption spectrum
of OPh4-2 is a superposition of p-quaterphenyl, p-terphenyl, and diphenyl absorption bands taken in a ∼3:2:2 ratio. The obtained OPh5 and OPh6 absorption and fluorescence
spectra are shown to be determined mainly by the longest-wavelength chromophores, p-pentaphenyl and p-hexaphenyl, respectively. It is demonstrated that the obtained compounds contain traces of impurities with fluorescence at
longer wavelengths than that of the base material. The branched oligomers exhibit high fluorescence quantum yields in solutions,
those for OPh5 and OPh6 reaching 1. Transparent fluorescent films were produced from all of the synthesized oligomers. 相似文献
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Russian Chemical Bulletin - Homocondensation of 1,3-di(5-acenaphthenyl)but-2-en-1-one obtained by dimerization of 5-acetylacenaphthene leads to 1,3,5-tri(5-acenaphthenyl)benzene. No alternative... 相似文献