Abstract
5-Chloro-3-hydroxy-4-(phenylediazenyl)pyridine-2(1H)-one and its derivatives (HLn) were synthesized and characterized using different spectroscopic techniques. The geometrical structures of the ligands are carried out by HF method with 3-21G basis set. The proton-ligand dissociation constant of the ligands (HLn) and their metal-ligand stability constants with (Mn2+, Co2+, Ni2+ and Cd2+) have been determined potentiometrically. The potentiometric studies were carried out in 0.1 M (KCl) and 10% (by volume) DMF-water mixture. The effect of temperature was studied at (298,308 and 318 K) and the corresponding thermodynamic parameters (Delta G, Delta H and Delta S) were derived and discussed. The dissociation process is non-spontaneous, endothermic and entropically unfavorable. The formation of the metal complexes has been found to be spontaneous, endothermic and entropically favorable. (C) 2014 Elsevier B.V. All rights reserved.