Effect of the Position of Fluorine Substituent Introduced into the Benzene Ring System on the Electro-Optical Properties of Phenylbiphenyl Carboxylate Series of AFLCS

Abstract

We have prepared two phenyl biphenyl carboxylate series of antiferroelectric liquid crystal compounds having the fluorine substituent in the core structure, using the optically active alcohols (R)-1,1,1-trifluoro-2-decanol and (R)-1,1,1-trifluoro-7-ethoxy-2-heptanol. The physical and electro-optical properties in a homogeneously aligned AFLC cells (1.5 w m) have been measured as functions of temperature/applied field. The magnitude of the spontaneous polarization and optical tilt angle of the 3F-substituted (outer fluoro system) compounds was found to be larger than that obtained 2F-substituted (inner fluoro system) compounds. (R)-TFMEOHPNBC exhibited V-shaped switching between SmA* and SmC A * phase. However, (R)-TFMN2FPNBC and (R)-TFM3FPNBC exhibited U-shaped switching with threshold voltage between SmA* and SmC A * phase. (R)-TFMNPNBC and (R)-TFMEOH3FPNBC having small pre-transitional effect were shown to have the uniform alignment state in the dark state.