Chiral liquid crystalline compounds with a re-entrant SmA* phase

Abstract

Unusual mesomorphic behaviour has been found in a series of rod-like liquid crystalline (LC) compounds with two chiral centres in the molecular chain. A re-entrant paraelectric SmA* (SmA*_RE) phase has been discovered below the ferroelectric SmC* phase on cooling for one homologue. So far this compound is the only one exhibiting the re-entrancy of the smectic A phase in chiral LC system with structural parameters so close to the upper SmA* phase. X-Ray studies, as well as dielectric spectroscopy, spontaneous polarization and tilt angle measurements have been carried out to characterize studied compounds. We compare various homologues and look for tendencies in physical properties behaviour.