Bent-core mesogens with thiophene units

Abstract

Bent-core mesogens with thiophene and 2,2′-bithiophene units at the periphery of the aromatic core were synthesized and investigated by polarizing microscopy, XRD and electrooptical methods. Resorcinol, 2,7-naphthalenediol and 3,4′-biphenyldiol were used as bent units, phenyl thiophene-2-carboxylates form the rod-like wings and n-alkyl chains as well as olefin- and silylated-terminated alkyl chains were attached as flexible end-groups. A broad variety of different mesophase structures, incorporating ferroelectric and antiferroelectric switching smectic as well as modulated smectic phases, was obtained. Compared with the corresponding benzoates, these thiophene derived compounds form nearly identical LC phase structures, but have significantly reduced transition temperatures, which make them advantageous for applications.