Ferroelectric liquid crystals containing a chiral β-lactam unit

Abstract

Syntheses, phase transition temperatures and spontaneous polarizations of ferroelectric liquid crystals containing a chiral β-lactam unit are presented. A 3-octyl-substituted β-lactam derivative containing two aromatic rings exhibits a high spontaneous polarization (416 nC cm^–2). Three examples containing an additional benzene ring in the mesogenic core exhibit broad S_C* phases (nearly 100 °C). The presence of fluorine in an ortho position to the β-lactam ring causes a shift of the phases to lower temperatures and an increase in the spontaneous polarizations, probably due to a gauche effect. The short pitch in the new materials makes them candidates for displays based on the deformed helical ferroelectric (DHF) effect.