Discotic liquid crystals of transition-metal complexes. Part 18.—Discotic liquid crystalline behaviour in phthalocyanine compounds substituted by steric hindrance groups at the core

Abstract

Phthalocyanine compounds substituted with steric hindrance groups have been synthesized: octakis(2-ethyl-hexyl)phthalocyanine (1b) and bis[octakis(4-octadecyloxyphenyl)phthalocyaninato]lutetium(III) complex (2d). These compounds exhibit a wide temperature range of discotic liquid-crystalline properties. Each of these compounds shows a discotic tetragonal disordered columnar mesophase (D_tet.d) or a discotic plain rectangular disordered columnar mesophase [D_rd(p2m)] with a lattice very close to tetragonal. This D_rd(p2m) phase is a novel discotic mesophase that has not been reported to date. It was found that the introduction of the steric hindrance groups, 2-ethylhexyl (b) and 4-octadecyloxyphenyl (d), tend to induce the appearance of the D_tet.d phase.