Liquid crystalline and dielectric properties of homologous series of substituted 1,3,4-oxadiazoles

Three homologous series of 2-alkylthio-5-phenyl-1,3,4-oxadiazole derivatives were synthesized [1, 2] and their liquid crystalline and dielectric properties investigated. Depending on the chain length, nematic, smectic A and smectic C phases were observed [1]. Dielectric investigations indicate a cross over of epsilon(parallel to o) and epsilon(perpendicular to o) at the N/SmA phase transition. This is explained by a transition from a more statistical into an antiparallel correlation of the dipoles, mainly caused by steric effects.