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

We prepared a homologous series of bent-shaped molecules with a low bent angle of about 60 degrees 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 SmAP(A) and B4 phases were identified with a sequence of N-SmA-SmAP(A)-B4 upon decreasing temperature. In all these phases, molecules behave as bent molecules irrespective of the low bent angle of approximately 60 degrees, and are packed with the bent direction perpendicular to the n-director. SmAP(A) is different from SmA only by having biaxiality, and exhibits antiferroelectric switching characteristic of banana smectic phases.