Most studies of steroid liquid crystals have been limited to cholesterol moiety. In the search for the better cholesteric liquid crystals, attempts were made to synthesize new steroid liquid crystals which have flat segment of aromatic cholesterol A-ring and strong dipole on the molecular axis such as cyano or alkoxy group. Also, to study the conformational effect of new systems, several phenol-type steroids which have double bond along the molecular axis were synthesized.
Among the prepared derivatives, only 1-methyl-19-norcholesta-1,3,5,6-tetraen-3-ol p-cyanobenzoic acid ester was found to exhibit cholesteric liquid crystal characteristics. Others had smectic liquid crystal character. Having the chiral centers in the steroid main body, it was expected that the new systems had cholesteric meso-phases. But the steroid derivatives exhibited the different liquid crystalline characters depending on the substituents such as cyano and alkoxy groups, and also on whether the main body had double bond along the molecular axis or not. Particularly, the derivatives of 4-methyl-19-norcholesta-1,3,5-trien-1-ol did not exhibit any liquid crystalline property.
