Paramagnetic rod-like liquid crystals, bis[5-(4-alkoxybenzoyloxy)salicylaldehyde]copper(II)

Abstract

The synthesis and mesogenic behaviour of a homologous series of copper(II) complexes derived from 5-(4-alkoxybenzoyloxy)salicylaldehydes are reported. The complexes exhibit smectic C mesomorphism for alkoxy groups containing eight or more carbon atoms in the terminal chains. These aldehydes therefore favour the formation of metal complexes with liquid-crystalline properties. Electron paramagnetic resonance (EPR) measurements were performed as a function of temperature. The signal can be associated with square-planar Cu²⁺ ions having an |x²y² > ground state. Molecular orientation in the mesophase under a magnetic field is discussed.