Synthesis and characterization of a novel series of unsymmetric dimesogenic compounds containing cholesteryl ester and nitroazobenzene moieties

The synthesis and mesomorphic properties of a novel series of dimesogenic compounds containing cholesteryl ester and 4'-nitroazobenzene moieties were reported. The two mesogenic units of these compounds were linked through dicarboxylic ester bonds, and the alkylene spacers' lengths were 2, 4, 6 and 8 methylenes. Their chemical structure and liquid crystalline properties were characterized by FT-IR, H-1 NMR, hot-stage coupled polarizing optical microscopy and DSC. The results showed that these dimesogenic compounds were cholesteric liquid crystals over a wide range both in heating and cooling processes. They exhibit iridescent colors in the liquid crystalline states. These compounds are potential candidates for applications in liquid crystalline exhibition and optical-electric functional devices. (c) 2006 Elsevier B.V. All rights reserved.