Oligomers and dendrimers based on siloxane and silsesquioxane cores: Does the structure of the central core affect the liquid-crystalline properties?

A series of oligomeric and first generation dendritic materials based on silane-siloxane and silsesquioxane core has been synthesised. The attachment of cyano-biphenyl mesogens separated by spacers to these cores which were varied systematically, resulted in liquid-crystalline materials. The synthesis of the materials is outlined and the liquid-crystalline phase behaviour of the materials, which are of uniform in size and stereochemistry, is described.