Electro-optical investigations and effect of asymmetry in bent-core liquid crystals

We report the synthesis and mesomorphic properties of a homologous series (10a–10g) of bent-core molecules constructed through covalent linkage of structurally non-symmetrical rod-like mesogens connected with a 1, 3-phenylene unit. The study of homologous series underlines the importance of length and nature of terminal chains. The homologues of shorter chains show a typical non-switchable rectangular columnar B₁ phase, while the switchable lamellar (B₂) phase is induced on moving to higher homologues. X-ray diffraction patterns indicate the presence of B₁ and B₂ mesophases. Polarised optical microscopy investigations under electric field in the B₂ phases revealed the existence of anticlinic antiferroelectric texture. The measured spontaneous polarisation value in one of the compounds is 936 nC cm^?2, a high polarisation value in bent-core liquid crystals.