Mesomorphic properties and monolayer behaviour of novel liquid crystalline exo-calix[4]arene derivatives

Abstract

Novel calix[4]arene derivatives are synthesized. These are pyrogallol-derived exo-calix[4]arenes with twelve 3-oxaalkanoyloxy chains and exo-calix[4]arenes in which eight or twelve rod-like units (phenylthiadiazole and phenylpyrimidine units) are fixed via spacers with the calix [4] arene central core. The liquid crystalline properties of these compounds are investigated by thermal optical microscopy between crossed polarizers, by differential scanning calorimetry and some of them also by X-ray diffraction. One of the 3-oxaalkanoates forms a hexagonal columnar mesophase, whereas most of the compounds incorporating calamitic units in the lateral chains give liquid crystalline materials with a smectic A-phase. Furthermore the behaviour of selected compounds as thin films at the air–water interface is studied using the Langmuir technique. They form condensed films whereby the molecular areas at the collapse points are determined by the densely packed lateral chains.