The effect of a lateral substituent on the mesomorphic properties of 4-cyanophenyl 4-(4-alkyloxybenzoyloxy)benzoates

Abstract The thermal properties of 4-cyanophenyl 4-(4-alkyloxybenzoyloxy)benzoates having a lateral substituent have been examined. Commencing with the nonyloxy homologue the hydrogen derivative shows a smectic A phase having a partially bilayered arrangement (SAAd). When the substituents are introduced at position X, the SAd phase commences from the octyloxy homologue, and the chlorine and bromine derivatives show an additional SAd phase in the low temperature region. When the substituents are introduced at position Y, the SAd phase commences either from the undecyloxy or the dodecyloxy homologue, and the nitro derivative shows two tilted phases in the low temperature region. Compounds having a methoxy group at position Z have difficulty in forming the SAd phase. The effect of the substituent on the thermal properties of the smectic phases has been discussed in terms of the electrostatic and structural properties of the substituents. A driving force for the formation of the partially bilayered arrangement is also discussed.