Antiferroelectric Chiral Smectic C Materials Having a 2-Alkyl Alkanoyl Group in the Chiral Part

Abstract

Novel antiferroelectric chiral smectic C (SmC_A ^*) materials are presented. Four homologous compounds having a 2-alkyl alkanoyl group in the chiral part are investigated. Three of them have SmC_A ^* and show very short helical pitch in SmC^*. In contrast, the other one has no SmC_A ^* and exhibits rather long pitch in SmC^*. This result suggests that the length of the pitch relates closely to occurrence of SmC_A ^*. The introduction of an ethyl group into the chiral carbon instead of a methyl group increases the stability of SmC_A ^* in contrast with decreasing that of SmA and SmC^*. All four compounds show the third state even in SmC^* by application of an AC field. Microscope observation indicates that the third state in SmC^* is different from that in SmC_A ^*.