Effect of Core Structure on Spontaneous Polarization in New Ferroelectric Liquid Crystals with a Fluorinated Chiral Part

We have designed a new chiral part, the 2-fluoro-2-methyl alkanoyloxy group and prepared new ferroelectric liquid crystals having this chiral part. The magnitude of spontaneous polarization of 4-(2-fluoro-2-methylhexanoyloxy)phenyl-4'-octyloxybiphenyl-4-carboxylate is about 7 times larger than that of a non fluorinated analogous compound. This remarkable increase of the P s value should be attributable to a fluorine attached together with a methyl group directly to the chiral carbon. Moreover, the effect of the core structure on the spontaneous polarization is also discussed. Introduction of a pyrimidine ring in the core part greatly enhances the spontaneous polarization, over 400 nC/cm2.