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, 1H 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.