Molecular docking, potentiometric and thermodynamic studies of some azo quinoline compounds

The ligands of 5-(4-derivative phenyl azo)-8-hydroxyquinoline and its derivatives (HL_n) were synthesized from the coupling of the quinoline with diazonium salt derived from aniline and its p-derivatives and characterized by different spectroscopic techniques. Molecular docking was used to predict the binding between azo compounds with the receptor of breast cancer mutant 3hb5-oxidoreductase. The X-ray diffraction, XRD, pattern of the ligand (HL₃) is polycrystalline nature. The proton-ligand dissociation constant of the azo compounds (HL_n) and metal–ligand stability constants of their complexes with metal ions (Mn^2 +, Co^2 +, Ni^2 + and Cu^2 +) have been determined by potentiometric technique in 0.1 M KCl and 50% (by volume) DMF–water mixture. For the same ligand at constant temperature, the stability constants of the formed complexes increase in the order Mn^2 +, Co^2 +, Ni^2 + and Cu^2 +. The effect of temperature was studied at 298, 308 and 318 K and the corresponding thermodynamic parameters (∆ G, ∆ H and ∆ 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.