LIQUID-CRYSTALS DERIVED FROM MONO-SUBSTITUTED ALICYCLIC AND HETEROALICYCLIC RINGS

Twenty two liquid crystalline mono-substituted cyclopentanes and cyclohexanes including their oxygen analogues were prepard and studied. Smectic phases with clearing temperatures less-than-or-equal-to 80-degrees-C were observed, and these do not differ considerably between the esters of the more flexible five-membered ring derivatives and those of the conformationally more rigid six-membered rings. In case of the latter, decreasing clearing points ar observed with increasing ratios of the axial conformation (static conformational effect). Altogether rather low clearing points are observed, which may be interpreted by a dynamic conformational effect owing to which fast ring inversion causes the compounds to appear in a bulkier shape, and this results in a disadvantageous packing in the mesophase.