Fluorescent liquid crystalline compounds with 1,3,4-oxadiazole and benzo[b]thiophene units

A series of fluorescent liquid crystalline compounds containing 1,3,4-oxadiazole and benzob]thiophene units have been prepared. In CH₂Cl₂ solution, these compounds displayed a fluorescent emission with λ_max at 422–426 nm and quantum yields of 41–48%. Most of them exhibited thermotropic liquid crystalline properties with nematic and/or smectic A phases with excellent thermal stability. This work revealed that longer terminal alkoxy chains would be detrimental to the formation of mesophases for such kind of compounds. The effect of the terminal groups on mesomorphic and spectroscopic property is discussed.