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L. M. Babkov O. V. Gorshkova G. A. Puchkovskaya I. N. Khakimov 《Journal of Structural Chemistry》1998,39(1):44-48
The polymorphism, conformation mobility and structure of 4-cyano-4′-pentalkoxybiphenyl (5OCB) in different physical states
are studied by IR spectroscopy. The spectra were measured in the frequency range 400–4000 cm−1 at temperatures from 300 to 350 K. The IR spectra of 5OCB are modeled using the concept of conformational mobility of these
molecules. An analysis of the experimental and theoretical spectra reveals absorption bands whose spectroscopic parameters
are sensitive to variations of temperature (experiment) and conformation (theory); a relationship between these changes is
established. It is concluded that the polymorphism of 5OCB is of conformation type. In the solid crystalline state, 5OCB molecules
have conformations with a planar biphenyl fragment; the angle of orientation of the plane of the carbon framework of the alkyl
radical relative to the biphenyl fragment decreases as the temperature increases from 35° in the solid crystalline state to
10° in the liquid crystalline and isotropic liquid states. In both of these states the biphenyl fragment becomes nonplanar.
The angle between the phenyl rings is up to 30°.
Saratov State University. Institute of Physics, Ukrainian Academy of Sciences. Samarkand State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 1, pp. 55–60, January–February, 1998.
This work was supported by RFFR grant No. 97-03-32175a. 相似文献
3.
L. M. Babkov E. S. Vedyaeva G. A. Puchkovskaya 《Journal of Structural Chemistry》2002,43(6):1027-1032
IR spectra were simulated for a series of alkyl and fluoroalkyl cyclohexanecarboxylic acids, whose experimental spectra have been previously recorded in the temperature range 77–500 K. The simulation was performed taking into account the conformational mobility of the molecules and a decrease in the hydrogenbond energy of Hcomplexes during heating. It has been shown that temperatureinduced changes in the spectra are caused by conformational transitions accompanied by rotation of alkyl/fluoroalkyl and or carboxyl groups and a decrease in hydrogebond energy during heating. 相似文献
4.
L. M. Babkov E. S. Vedyaeva G. A. Puchkovskaya A. A. Yakubov 《Journal of Structural Chemistry》1998,39(3):426-431
Structural aspects of polymorphism are studied for homologous series of alkylbenzoic acids with a completely or partially
fluorinated alkyl radical. IR absorption spectra were measured in the range 60-4000 cm−1 at 100–500 K. The spectra were interpreted by computer simulation on a PC with LEV-100 software realizing the fragmentary
approach to solving the mechanical and optoelectronic problems by the method of M. V. Volkenshtein, M. A. El’yashevich, L.
A. Gribov, and B. I. Stepanov. The previous assumptions that the samples possess conformational mobility and are conformationally
nonhomogeneous are confirmed by comparing the spectra of the title compounds measured at different temperatures with those
calculated for conformer models with different degrees of twisting of fluoroalkyl radicals and their different orientations
relative to the other part of the complex.
N. G. Chernyshevskii Saratov State University. Institute of Physics, Ukrainian Academy of Sciences (Kiev). Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 522–528, May–June, 1998.
This work was supported by RFFR grant No. 97-03-32175a. 相似文献
5.
The electronic absorption spectrum of pyridine N-oxide vapor in the region of the third electronic transition (43,000-46,000
cm-1) was recorded. The frequencies and intensities of vibronic bands, including the 0–0 band at 43,896 cm-1, were measured An assignment of the frequencies of fundamental vibrations in the third electronically excited state is suggested
The matrices of rotation and shift of normal coordinates due to electronic excitation are calculated, and the vibronic spectrum
of pyridine N-oxide is interpreted on the basis of these matrices.
Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 2, pp. 357–362, March–April, 1997. 相似文献
6.
Problems on the normal vibrations of pyrimidine in the ground and excited states are solved. The matrices of rotation and shift of normal coordinates due to electronic excitation and Franck-Condon integrals are calculated. The vibronic spectra of pyrimidine are interpreted. Based on this interpretation, bond lengths and bond angles in the electronically excited first singlet state of the molecule are calculated: C1C2 1.388 å, C2N3 1.366 å, N3C4 1.352 å, C-H 1.099 å; C6C1C2 105.5?, N3C4N5 127.8?, H2C2N3 110.1?. 相似文献
7.
L. M. Babkov J. Baran N. A. Davydova J. I. Kukielskii S. V. Trukhachev 《Journal of Structural Chemistry》2004,45(4):591-598
The vibrational spectra of a solid crystalline sample of 2-biphenylmethanol have been measured at room temperature. The IR absorption spectra were recorded in the range 400 cm–1–3600 cm–1; Raman spectra were measured in the range 10 cm–1–1640 cm–1. The direct mechanical and optoelectronic problems were solved using the fragment method realized as Lev-100 software; the intensity distribution in the IR spectrum of 2-biphenylmethanol was obtained by the same method. The experimental Raman and IR absorption spectra were interpreted by analyzing the calculated data on the frequencies and forms of normal vibrations and their intensities in the IR spectra. IR absorption spectra were simulated for several models of 2-biphenylmethanol conformers that differ in the mutual orientation of fragments. Based on the results of simulation and comparison of the calculated and experimental spectra of conformers we suggested a model for the conformer realized in the solid phase under normal conditions.Original Russian Text Copyright © 2004 by L. M. Babkov, J. Baran, N. A. Davydova, J. I. Kukielskii, and S. V. TrukhachevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 624–631, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
8.
L. M. Babkov I. I. Gnatyuk G. A. Puchkovskaya S. V. Trukhachev 《Journal of Structural Chemistry》2004,45(3):374-381
The conformational lability of 4-ethyl-4-cyanobiphenyl molecules in solid crystal (SC) and isotropic liquid (IL) states was investigated by IR spectroscopic techniques (experiment and theory). IR absorption spectra were measured at 28°C–95°C in the frequency range 400 cm–1–4000 cm–1. Spectrum simulation was performed using the fragment method with allowance for the conformational fluctuations of molecules. The experimental and calculated spectra were compared and analyzed, and it was shown that in the IL, the samples are mixtures of conformers. The temperature changes in the spectra in the stated range are caused by the conformational lability of molecules.Original Russian Text Copyright © 2004 by L. M. Babkov, I. I. Gnatyuk, G. A. Puchkovskaya, and S. V. TrukhachevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 398–405, May–June, 2004. 相似文献
9.
IR spectra,conformational lability,and intermolecular interactions in long-chain aliphatic compounds
Investigations of the conformational lability and intermolecular interactions in long-chain aliphatic compounds (LACs), namely, in carboxylic acid derivatives (alkyl- and alkoxybenzoic acids; alkylcyclohexanecarboxylic acids and their completely or partially fluoroalkyl-substituted derivatives), 4-cyano-4-p-alkoxybiphenyls, 4-cyano-4-p-alkylbiphenyls, and cholesterol p-n-butyloxybenzoate are reviewed. Major attention is paid to experimental and theoretical IR spectroscopy data. Differential thermal analysis, polarization microscopy, and X-ray diffraction data are also taken into account. A more detailed treatment is presented on IR spectrum simulation based on data about the conformational lability of molecules and their specific (H-bonding) intermolecular interactions. The first mechanism is responsible for the conformational type of polymorphism in LACs and for the structure of the latter in solid crystal (SC) and liquid crystal (LC) states and in isotropic liquids (ILs). The second mechanism complements the structure-forming aspect of polymorphism in carboxylates, which is due to a rearrangement of hydrogen bond systems in H-complexes during polymorphic transitions to the LC and IL states. Both mechanisms are reflected in IR absorption spectra. A more adequate interpretation is possible in order to explain the many spectral features associated with the structure of LAC polymorphs and their H-complexes if these mechanisms are taken into account.Original Russian Text Copyright © 2004 by L.M. BabkovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 389–397, May–June, 2004. 相似文献
10.
A. O. Rasskazov A. G. Bondar' A. V. Babkov Yu. V. Ishchenko 《International Applied Mechanics》1992,28(2):100-107
Kiev Automobile-Transportation Institute. Translated from Prikladnaya Mekhanika, Vol. 28, No. 2, pp. 38–46, February, 1992. 相似文献