Mesomorphic properties of low molecular compounds containing α-cyanostilbene as a mesogenic group

Abstract

In order to clarify the effect of the sequence linkage between liquid group and flexible alkyl chain on the mesomorphic structure of the low molecular liquid crystal (LC)s, we synthesized the twin and core type low molecular LCs with different sequence of the linkage group. Thermal properties of the twin and core type I Cs were investigated by polarized optical microscopy, different scanning calorimetry and X-ray diffraction measurements. Core type LCs with phenyl-oco- linkage group exhibited nematic and smectic phases depending upon the flexible alkyl chain length. An odd-even effect on the clearing point for the core type LCs were observed, however an odd-even effect on the entropy changes for clearing points was not shown. Twin type LCs with phenyl-oco- linkage group exhibited a nematic phase. Λ remarkable odd-even effect on both phase transition temperatures and entropy changes was displayed for the twin type LCs.