Cyclotriphosphazene as a Dendritic Core for the Preparation of Columnar Supermolecular Liquid Crystals

A series of supermolecular liquid crystals has been synthesized by combining a cyclotriphosphazene unit as a dendritic core and polycatenar mesogenic units. Microsegregation of the alkyl chains and the aromatic central cores together with space-filling properties make these cyclophosphazenes adopt a discotic conformation and are assembled in a columnar mesophase. Furthermore, IR spectra taken over a range of temperatures provide evidence that the discotic structure and columnar assembly are highly stabilized by H-bonding. The columnar mesophase can be maintained or vitrified at room temperature depending on the length of the terminal alkyl chains. Structural characterization of these assemblies has been carried out by X-ray diffraction. Helical ordering has been detected in oriented samples of these materials.