Molecular Ordering and Even-Odd Effect in a Homologous Series of Nematic Liquid Crystals

Abstract

Order parameters have been measured in a homologous series of nematic liquid crystals, $p$-alkoxyazoxybenzenes, by ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ NMR. The ordering exhibits an even-odd alternation along the series, and a comparison of our data at the isotropic-nematic transition temperatures is made for the first time with a recent theory of Marčelja which explicitly accounts for end-chain interactions between the molecules. Some conclusions are drawn concerning molecular conformational motion and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ spin relaxation in the nematic phase.