The synthesis and transition temperatures of some ferroelectric host materials based on 4- and 4′-(trans-4-alkylcyclohexylmethoxy)-2,3-difluorobiphenyls

Abstract

A range of 2,3-difluoro-substituted biphenyls incorporating a cyclohexylmethoxy unit as one terminal chain has been prepared and these materials are compared to the analogous compounds already reported with a dimethylene linking group. Related, directly-linked cyclohexylbiphenyls and some open-chain analogues have also been prepared which add to the diversity of the compounds reported. These were prepared as host materials of low birefringence for ferroelectric (S∗_c) mixtures and in general, the compounds have quite high S_c phase stability. Metallation procedures have been used to prepare arylboronic acids which were employed in palladium-catalysed cross-coupling reactions to provide good yields of liquid crystal materials. The synthesis and transition temperatures of these compounds are discussed and compared with each other and with other selected ortho-difluoro-substituted systems.