Synthesis, Characterization and Thermal Analysis of New Azomethine Metal Complex Pigments

In this research work, the Schiff base (azomethine compound), 1-[N-(5-chloro-2-hydroxyphenyl) imino] methyl}-2-naphthol, has been obtained as an orange solid by reaction of 2-amino-4-chlorophenol and 2-hydroxy-1-naphtaldehyde. Then the new azomethine metal complexes have been synthesized from reaction of the acetate salts of Ni(II), Cu(II), Zn(II) with the above Schiff base ligand. The ynthesized colored complexes have been characterized by IR, UV-Vis and 1H NMR spectroscopy. The thermal behaviors of complexes have been investigated by TGA and DTA. In all complexes the Schiff base acts as a tridentate ligand and coordinates to the metal via two phenolic oxygen and azomethine nitrogen. The Schiff base is insoluble in water and soluble in all common organic solvents. Generally the Schiff bases derived from 2-hydroxynaphtaldehyde show keto-amine and phenol-imine tautomerism and so thermochoromism and photochromism. However all complexes are insoluble in water and in common organic solvents. Both Schiff base and complexes have intense colors and absorption bands in visible spectra according to charge transfer and d-d transitions. They may be having potential applications as azomethine pigments and dyes.

Keywords:

Azomethine , Schiff base , Dye , Complex