Columnar metallomesogens based on vanadyl(VI) and cobalt(II) complexes of N,N '-bis[3-(3,4-dialkoxyphenyl)3-oxopropenyl]ethylenediamines

The preparation, characterization and mesomorphic properties of vanadyl(VI) and cobalt( II) complexes derived from N, N'-bis[3-(3,4-dialkoxyphenyl)-3- oxopropenyl]ethylenediamines are described. These half-disk-shaped molecule s exhibited columnar mesophases over a wide range of temperature, as charac terized by DSC analysis and polarizing optical microscopy. The structure of the mesophases was also confirmed as columnar hexagonal (Co1(ho)) by powde r XRD. The vanadyl complexes were found to have substantially higher cleari ng temperatures and wider mesophase temperatures than the analogous cobalt complexes. The influence of the metal centres on the mesomorphic temperatur es may be attributed to better intermolecular dative association in the van adyl complexes than in the cobalt complexes.