Modelling of infrared spectra and structural aspects of polymorphism of mesogens with hydrogen bond
| Autor: | G. A. Puchkovskaya, E. S. Vedyaeva, A.A. Yakubov, Lev M. Babkov, Sergey I. Tatarinov |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
chemistry.chemical_classification
Chemistry Hydrogen bond Organic Chemistry Mesophase Infrared spectroscopy Photochemistry Analytical Chemistry Inorganic Chemistry Homologous series chemistry.chemical_compound Crystallography Polymorphism (materials science) Liquid crystal Conformational isomerism Spectroscopy Alkyl |
| Zdroj: | Journal of Molecular Structure. :457-461 |
| ISSN: | 0022-2860 |
| DOI: | 10.1016/s0022-2860(98)00881-3 |
| Popis: | The results of investigations of polymorphism and mesomorphic states in the homologous series of alkylcyclohexanecarboxylic-, alkyl- and alkoxybenzoic acids, some of their fluorinated derivatives, as well as in a five component mixture of alkyl- and alkoxyderivatives of cyanobiphenyl with hydroxy substituents in biphenyl fragments were discussed. The usual methods of modelling in vibrational spectroscopy were used. The samples were investigated in the 100–500 K temperature range. The spectra were recorded in the 33–4000 cm −1 spectral region. The frequencies of normal modes and intensities in the IR spectra were calculated for conformers of H-bonded complexes with various orientations of alkyl (AR) or fluorinated alkyl radicals (FAR) with respect to the residue of the molecular complex. The polymorphism of these compounds was shown to have conformational character. The solid crystal (SC) ↔ liquid crystal (LC) ↔ isotropic liquid (I) transitions and dissolution of these materials in CCl 4 were accompanied with rearrangement of the system of H-bonded dimers which includes the formation of open dimers, chain associates and monomers. |
| Databáze: | OpenAIRE |
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