Dimesogenic liquid crystal consisting of cholesterol and Schiff base moieties: dependence of LC properties on the spacer length and fluorination of the alkoxy tails

The liquid crystalline properties of two series of non-symmetric liquid crystal dimers consisting of cholesterol and Schiff base moieties interconnected by omega-oxyalkanoyl spacers of varying length are compared: one series (SBOC-n) carry the octyloxy tail on the Schiff base mesogen, and the other (SBOF-n) a perfluoroheptylmethyloxy tail. In general, compounds with the fluorinated alkoxy tail exhibited mesophases over a much wider temperature range than those with the alkoxy tail. The latter series favoured the formation of more diverse mesophases than the former. SBOC-4, -5 and -7, and SBOF-4, -5 and -10 formed the chiral smectic C phase.