Sulphur ligated siamese twin mesogens

Abstract

The synthesis of 3,3′-sulphinyl-bis-[alkyl 4-(4-substituted benzoyloxy)-benzoates] and 3,3′-sulphonyl-bis-[alkyl 4-(4-substituent-benzoyloxy)-benzoates] is described. These new nematic compounds are of the ligated siamese twin type. By microscopy and DSC calorimetry the thermal behaviour was investigated. Many of the new compounds transform on quenching to the glassy nematic state with glass temperatures above room temperature. Above the glass temperature the substances behave like highly viscous but ordinary nematics. The substances may be used for the construction of new thermo-electrooptic displays. By means of dielectric and X-ray investigations we were able to show that the two halves of the twin molecules are in an antiparallel orientation in the nematic state. In mixtures of the new compounds with rod-like nematics reentrant nematic behaviour was observed.