Examination of the structural features necessary for mesophase formation with aroylhydrazinato-nickel(II) and -copper(II) complexes

Abstract

N-Methylidene complexes and a series of N-alkylidene- and N-arylalkylidene-aroylhydrazinato-nickel(II) and -copper(II) complexes were synthesized in high yield and their mesomorphic nature studied. Only the N-methylidene complexes gave mesomorphic compounds as the larger N-alkylidene or N-aralkylidene groups probably prevented mesophase formation due to increased molecular broadening effects. The nickel(II) complexes were found to be highly stable even in the isotropic phase and generally gave wide liquid-crystalline temperature ranges. This contrasted with the very narrow temperature ranges of the copper(II) complexes, which rapidly decomposed in or just before attaining the isotropic phase.