Chiral nematic octasilsesquioxanes

The octasilsesquioxane cage has been successfully derivatised by platinum-catalysed hydrosilylation reaction of the alkene functionality of appropriate laterally substituted, chiral mesogenic moieties to yield monodisperse multipodal octamers. The liquid-crystalline silsesquioxanes were characterised by multinuclear MR, SEC, TGA, POM and X-ray diffractometry. The giant supermolecular materials display remarkably wide temperature range enantiotropic chiral nematic phases and glass transitions near to room temperature. One of the materials is iridescent and has properties similar to a low molar mass material even though it has a size approaching that of a small globular protein. Thus these observations raise questions as to whether the materials act as singular molecular entities or as spherical side chain polymers.