Influence of the Optical Purity on the Smectic Layer Thickness and the Transition Order in Enantiomeric Mixtures of an Antiferroelectric Liquid Crystal

Abstract

The transition behavior in the (R)- and (S)-mixtures of 4-(1-trifluoromethylheptyloxycarbonyl)phenyl 4-(5-dodecyl-oxypyrimidin-2-yl)benzoate (TFMHPDOPB) has been studied by X-ray diffraction. Two important findings were made. In all the mixtures, the transition is of the first order irrespective of the spontaneous polarization and the transition sequences; SmA-SmC^* _A (pure enantiomers), SmA-SmC^* (R:S=3:1) and SmA-SmC (racemate). The layer thickness depends on the optical purity even in the SmA phase, although the overall profiles of the temperature dependence are almost the same in all the mixtures.