Liquid crystalline compounds with 2,2-disubstituted cyclopropane end groups in their side chains

Novel liquid crystalline compounds with racemic and enantiomerically pure 2 ,2-difluoro-, 2,2-dichloro-, 2,2-dibromo-, and 2,2-bis(trifluoromethyl)-cyc lopropane-1-carboxylate end groups have been synthesized. The Ps values, ti lt angles, and response times of SmC* mixtures containing 10 wt% of the nov el optically active liquid crystalline compounds in a SmC base mixture were measured. and the potential of the novel compounds as chiral dopants for f erroelectric liquid crystal mixtures was estimated. The novel liquid crysta lline compounds with racemic bis(trifluoromethyl)cyclopropane have a remark ably strong tendency to form smectic phases SmB and SmA. The bistrifluorome thyl derivatives exhibited only SmB and SmA phases although the correspondi ng compounds with 2,2-difluoro-, 2,2-dichloro-, and 2,2-dibromocyclopropane rings showed nematic or chiral nematic phases. In some cases, almost perfe ct substitutions of the nematic phases by the smectic phases upon changing the substituents from halogen to trifluoromethyl were observed.