Discotic liquid-crystal behaviour of some multinuclear phthalocyanine derivatives

Abstract

The liquid-crystal properties are reported for a series of multinuclear phthalocyanines containing either two or three macrocyclic ring units. All but one of the compounds, the ‘dimer’ with the shortest spacer group between the two rings, exhibit discotic columnar mesophase behaviour. On cooling from the isotropic liquid the liquid-crystalline dimers show two distinct mesophases and the trimers one. Phase-transition temperatures are dependent upon the length of the linkages and whether or not copper is inserted into the macrocycle. The materials become very viscous, if not glass-like, when cooled to room temperature but retain the mesophase features defined by X-ray diffraction measurements.