THE ORIGIN OF THE HELICAL TWIST INVERSION IN SINGLE-COMPONENT CHOLESTERIC LIQUID-CRYSTALS

The cholesteric twist inversion by temperature variation of a single c omponent thermotropic liquid crystalline system was experimentally inv estigated and is explained by the partial twisting power model, evalua ting the temperature dependent pitch of five different configurations of a benzoic acid biphenyl ester with two chiral centers. The temperat ure dependence of the twisting power and the cholesteric pitch for sev eral stereoisomeric compounds can in first approximation be predicted by the partial twisting powers of the individual chiral centers determ ined from the partially racemic configurations.