Synthesis, mesomorphism, and spectroscopic characterization of new Schiff bases and their Cu(II), Pd(II) complexes

New Schiff bases have been prepared from 1,2-dialkyloxy-4-formyl-5-hydroxybenzene and 4,5-diamino-1,2-didodecyloxybenzene. Pd(II) and Cu(II) complexes are obtained with metal Schiff base ratio of 1:1. The new compounds have been characterized by elemental analyses; IR; and, H-1 NMR, C-13 NMR, and mass spectra. The mesomorphic properties of these complexes were investigated by polarizing microscopy and X-ray diffraction analysis. These complexes form columnar hexagonal (CoIh) mesophases. The influence of the metal centers on the mesomorphic temperatures may be attributed to better intermolecular dative association in the palladium complexes than in the copper complexes.