Formation of banana phases in bent-shaped molecules with unusual bent angles as low as 60°

Abstract

We prepared a homologous series of bent-shaped molecules with a low bent angle of about 60° using a 1,7-naphthalene central core, a long side wing in which one phenyl ring is attached to the classical wing via an ester linkage and alkoxy tail groups with numbers of carbons of 4 to 14. All the compounds form well-defined mesophases. Two calamitic nematic (N) and SmA phases, and two banana SmAPA and B4 phases were identified with a sequence of N–SmA–SmAPA–B4 upon decreasing temperature. In all these phases, molecules behave as bent molecules irrespective of the low bent angle of approximately 60°, and are packed with the bent direction perpendicular to the n-director. SmAPA is different from SmA only by having biaxiality, and exhibits antiferroelectric switching characteristic of banana smectic phases.