Abstract

ESTIMATION OF THE STABILITY CONSTANTS OF COMPLEXES DERIVED FROM AZO DYES AND A NUMBER OF TRANSITION METAL IONS, THERMODYNAMIC STUDY

Emad A. S. Al-Hyali* and Amal Esmaiel

ABSTRACT

This study included the synthesis of two azo dyes from the reaction of the heterocyclic compound, 2- amino thiazole, with beta naphthol, and resorcinol via diazonium ion. The prepared dyes were identified using spectral methods such as FT-IR spectra, U.V visible spectroscopy and C-13 NMR techniques. Also, these dyes were distinguished by a number of their physical properties such as melting points, colors, highest absorption band (λmax), molar absorption coefficient (Ԑmax), and the molecular weight. The work also included calculating the stability constants of the complexes prepared from the reaction of these dyes with cobalt, nickel and copper ions after determining the nature of the complexes using the method of continuous variation (Job method), which showed the best combination ratios between the ligand and the metal ion was (1:1 dye: metal) ratio. Optimization conditions are carried out by studying the effect of concentration, effect of time, influence of the acidity function (pH) and effect of temperature. Thermodynamic functions were estimated depending on the influence of temperature on the values of the stability constants. The practical part was supported by a theoretical calculation based on quantum mechanical method. The connection sites between the metal and the ligand were clarified and these variables were correlated with the stability constants of the resulting complexes.

Keywords: Stability constant, Thiazole, azo dyes, Metal ion- Ligand Complex.