Synthesis, Characterization, and Anisotropic Properties of 5-Alkoxy-2-((4-(Phenyldiazenyl)Phenylimino)Methyl)phenol and Their Copper(II) Complexes

A new homologous series of bidentate Schiff bases 5-alkoxy-2-((4-(phenyldiazenyl) phenylimino)methyl) phenol and their Cu(II) complexes have been synthesized and characterized by spectroscopic techniques along with studies on the mesomorphic properties. Phase transitions of all the Schiff bases and Cu(II) complexes in this series are enantiotropic. The ligands with n-octyloxy and n-decyloxy flexible chains exhibit the nematic (N) and smectic A (SmA) phases, the latter of which is characterized by focal conic fan-shaped texture. In contrast, the Cu(II) complexes show exclusively the SmA phase, which is ascribed to the presence of Cu-O and Cu-N coordination modes. For the same reason, the thermal stabilities of the complexes have also been improved.