Novel U-shaped liquid crystals for electro-optic devices

摘要

We would like to report here novel molecular design for electro-optic liquid crystal devices, i.e. catechol derivatives for reduction in threshold voltage and binaphthyl derivatives for blue phases with a wide temperature range. A threshold voltage of a nematic mixture consisting of a host liquid crystal and 10wt% of a catechol derivative, 1-{6-(3,4-difluorophenyloxy)hexyloxy}-2-{6-[4-(4-fluorophenyl)phenyloxy]hexyloxy}benzene, was markedly lower than that of the host LC. The U-shaped compound was found to induce larger dielectric anisotropy in the nematic phase of the mixture than the corresponding monomeric compound. Then, we prepared a homologous series of novel chiral dimeric compounds, (R)-2,2′-bis{6-[4-(2-(2-fluoro-4-butyloxyphenyl)pyrimidine-5-yl)phenyloxy]alkyloxy}-1,1′-binaphthyl. The binaphthyl derivatives with an even number of atoms in the spacers showed a chiral nematic phase, however, those with an odd number of atoms showed a blue phase in a relatively wide temperature range between the isotropic and smectic A phases. We discuss structure-property relationships in the U-shaped system.