A Novel Dimesogen with a Cholesteric Phase of Wide Temperature Range: Synthesis and Characterisation

Dimesogenic compounds consisting of two non-identical mesogenic units connected through a polymethylene spacer are now of interest in the area of liquid crystal research. Previous studies have shown that dimesogens made up of a cholesteryl ester unit and a Schiff's base unit connected through a central alkyl spacer give rich mesomorphism. We have taken up investigations to study the effects of replacing the Schiff's base moiety with a tolan unit. As an example, the dimesogen; cholesteryl 6-[4-(4-n-butyloxyphenylethynyl)phenoxy]hexanoate was synthesized and studied for its liquid crystalline properties. Although this compound shows only one mesophase, viz., the cholesteric phase, the temperature range of the mesophase is very wide, perhaps one of the largest ranges reported to date.