| dc.description.abstract | Abstract
Transition metal complexes of Schiff bases derived from salicyladimines are among the best known of complexes that exhibited mesogenic properties in metallo mesogenic structures. A variety of transition metals, such as Fe, Rh, Ir, VO, Ni, Co, Cu, Pt, Pd etc. forms novel mesomorphism with salicyladimine Schiff bases. The overall molecular shapes of these complexes derived from salicyladimines were more likely of rod-like or brick-like shapes with two or four extended flexible sidechains, and these complexes all exhibited nematic or smectic phases predominantly, regardless of the metal center incorporated in such systems. Difference in the mesogenic properties of these Schiff base metal complexes was attributed to the various types of geometric coordination of the metal centers.
In this work the synthesis and mesomorphic properties of a homologous series of N-(2-hydroxy-4-n-alkoxylbenzylidene)-4-n-alkoxyl phenylanilines and their copper(II) complexes are reported. These rod-like copper(II) complexes exhibited smectic and nematic phases, as predicted for rod-like molecules. Their mesomorphic properties were characterized by DSC thermal analysis, optical polarized microscopy and powder XRD diffraction. All salicyladiminato ligands and their copper(II) complexes exhibited enantiotropy phases. The compounds of ligands showed smectic C (SmC) and nematic (N) phase and copper(II) complexes formed SmC and smectic A (SmA) phases. The difference in formation of mesophases was due to the molecular shape variation. In addition, copper complex with two hexadecyloxy (n=C16) group as sidechains have a widest temperature range of the SmC mesophase. The mesomorphic properties of these copper(II) complexes were also compared with other similar metallomesogenic bis(salicyladiminato)- copper(II) complexes in terms of molecular structures. | en_US |