Abstract: | Polymorphism and the structure of mesomorphous states of long-chain aliphatic compounds (LAC) have been studied by vibrational
spectroscopy (theory, experiment) using calorimetry, polarizing microscopy (PM), and X-ray diffraction (XRD) analysis as auxiliary
methods. LAC are represented by homologous series of alkyl- and alkoxybenzoic acids, alkylcyclohexanecarboxylic acids, their
completely or partially fluoroalkyl-substituted analogs, and 4-cyano-4′-(n-alkoxy)biphenyls. The studies were performed at
77–500 K. IR absorption and Raman spectra were measured at 30–4000 cm−1. The compounds are characterized by conformational polymorphism. The molecules and their H-complexes undergo structural rearrangements
during phase and conformational transitions. In the course of the rearrangements, alkyl and fluoroalkyl radicals (AR and FAR)
are twisted, and carboxyl groups are disordered. The rearrangements dictate the structure of mesophases, which are mostly
formed of H-complexes consisting of dimers, monomers, and open associates.
N. G. Chernyshevskii Saratov State University. Institute of Physics, Ukrainian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 338–344, March–April, 1995.
Translated by L. Smolina |