Investigation of conformational mobility of 4-pentyl-4'-cyanobiphenyl by IR spectroscopy methods

Abstract

The conformational mobility and structure of 4-pentyl-4'-cyanobiphenyl (5CB) in liquid and liquid crystal states have been investigated by methods of IR spectroscopy. IR absorption spectra are measured in the temperature range of 297-425 K in 400-4000 cm-1 spectral region. The IR spectra are modeled for the conformers of 5CB which differ in the orientaiton of the alkyl radical wiht respect to the biphenyl fragment and of the benzene rings with respect to one another. It is found that the temperature changes of IR spectra are determined by the molecule conformational mobility of 5CB. From the analysis of the spectra, we determined the most probable configurations of the molecules which were realized in the sample within the studied temperature interval.