Effect of fluorination of molecular rigid core in liquid crystal biphenyl benzoate based homologous series

Liquid crystalline perfluorinated biphenyl benzoates were synthesized and investigated. A highly tilted, neat orthoconic smectic antiferroelectric phase was observed. A homologous series of compounds without and with a single fluorine atom substituted at different positions of a molecular rigid core was investigated by standard methods. Influence of fluorine substitution on physical properties of antiferroelectric smectic phase was discussed as well as influence of fluorination on molecular dipole moment orientation and its value were presented. Decrease in rotational viscosity as a result of fluorine substitution within a molecular rigid core was ascribed to changes of molecular packing.