Discotic liquid crystals of transition metal complexes, Part 30: spontaneous uniform homeotropic alignment of octakis(dialkoxyphenoxy)phthalocyaninatocopper(ii) complexes

Abstract

Six novel octakis(dialkoxyphenoxy)phthalocyaninatocopper(II) complexes (abbreviated as [(CnO)2PhO]8PcCu (n = 9–14)) have been synthesized. It was found that these derivatives exhibit rich mesophases; Colh, Colr1, Colr2, Colr3, Coltet and Cub phases. These mesophases were characterized by microscopic observation, DSC measurements and temperature-dependent X-ray diffraction measurements. Temperature-dependent electronic spectra for the thin films of these complexes revealed that roof-top-shaped dimers in the column gradually change into cofacial dimers as the temperature is increased from rt to their clearing points. Furthermore, the phthalocyanine derivatives for n = 11–14 exhibited spontaneous uniform homeotropic alignment for the Coltet mesophase, which is the first example in discotic liquid crystalline phthalocyanine compounds.