Synthesis and Mesomorphic Properties of 4-Substituted Phenyl-4'-(4”-n-Alkoxy Benzoyloxy) Cinnamates

The transition temperatures and the melting enthalpies were measured for 4-substituted phenyl cinnamates. The effects of groups (CN, NO2, Br) on the persistence of the nematic phase was found to increase with increasing polarity of the group. The lateral substitution of a methoxy group was found to decrease the nematic—isotropic transition temperatures and to inhibit the formation of the smectic phase which was present in the bromine substituted compound. The smectic phase was investigated by X-ray scattering and optical observation and is probably a smectic A phase.