Polar columnar and lamellar mesophases in homologous bent-core compounds derived from methyl 3,5-dihydroxybenzoate

Abstract

The synthesis and mesomorphic properties of the first three homologous series of symmetrical seven-ring bent-core compounds derived from methyl 3,5-dihydroxybenzoate have been described. In all the three series the lower homologues show an intercalated smectic (B6) phase. The middle homologues exhibit a polar columnar phase that shows antiferroelectric characteristics, while the higher homologues exhibit a switchable smectic phase with chiral conglomerates (SmCPAF). More interestingly, in one of the homologues, coexistence of a switchable columnar phase and a switchable lamellar phase has been observed. The mesophases were characterised using classical techniques of polarised light optical microscopy, differential scanning calorimetry, X-ray diffraction and electro-optical studies.