Variable-temperature FTIR investigation of a laterally substituted ferroelectric liquid-crystalline benzoate

Abstract

The temperature dependence of the frequency shifts of the CO str. bands for ester and keto groups has been measured for 4-(2-methyloctanoyl)-4′-biphenyl 4-octyloxybenzoate and 4-(2-methyloctanoyl)biphenyl-4′-yl 3-chloro-4-octyloxybenzoate. Different behaviour for the frequency shifts has been observed between the ester and keto CO groups. Introduction of the lateral chloro substituent was found to have a stronger effect on the frequency shift for the keto CO str. band in the smectic phases than in the isotropic phase. A possible existence of the intermolecular interaction between the chloro substituent and the keto CO group has been proposed. The frequency shift behaviour obtained in the dilution studies also supports this hypothesis.