Synthesis and physical properties of novel liquid crystal trimers containing resorcinol as a linking unit

Abstract

A homologous series of novel liquid crystal trimers in which cyanobiphenyl and phenylpyrimidine moieties are connected via resorcinol was prepared and their physical properties investigated. 3‐{6‐[4‐(4‐Cyanophenyl)phenyl]hexyloxy}‐1‐{6‐[4‐(5‐octylpyrimidine‐2‐yl)phenyl]hexyloxy}benzene, compound I‐(6,6), was found to show monotropic nematic, smectic A and anticlinic smectic C (SmCanti) phases. We investigated the effects of the spacer length and the linking group on the phase transition behaviour. In addition, trimers with identical mesogenic units were prepared and their physical properties compared with those containing two different mesogens. Only the meta‐substituted trimers showed the SmCanti phase despite its reduced tendency to exhibit liquid crystallinity than the ortho‐ and para‐substituted trimers.