Side chain effects on high birefringence liquid crystals

Side chain effects on phase transition temperatures, birefringence and viscosity of four series of isothiocyanato tolane liquid crystals are investigated. In the alkyl and alkoxy isothiocyanato tolane families, short chain helps suppress smectic phase, enhance birefringence and reduce rotational viscosity. In the alkoxy difluoro and,cyclohexane isothiocyanato tolane derivatives, the short chain homologues exhibit an enantiotropic nematic phase. These compounds are particularly attractive for forming eutectic mixtures.