Molecular Motions of 4-n-alkyl-4′-cyanobiphenyls in Liquid Crystal Phases

On the basis of a model which takes into account the couplings of the conformational transitions in the alkyl chain with the orientational diffusion of the molecule, the outcome of various experiments performed in the liquid crystal phases of n-alkyl-cyanobiphenyl (nCB) systems can be analyzed and interpreted. The relaxation rates for the various positions in the flexible chain and in the biphenyl core, derived from 3H and 13C NMR experiments, and the frequency dependence of the complex dielectric permittivity, obtained from dielectric relaxation data, have been considered in detail.