Abstract
The proton-ligand dissociation constant of 5-(4'-alkylphenylazo)-3-phenylamino-2-thioxothiazolidin-4-one (HL (n) ) (n = 1, R = -CH3; n = 2, -H and n = 3, -Cl) and metal-ligand stability constants of its complexes with metal ions (Mn2+, Co2+, Ni2+ and Cu2+) have been determined potentiometrically in 0.1 mol center dot dm(-3) KCl and 40 % (by volume) DMF-water mixture and at 298, 308 and 318 K. The stability constants of the formed complexes increase with the order Mn2+ < Co2+ < Ni2+ < Cu2+. The effect of temperature was studied and the corresponding thermodynamic parameters (a dagger GA degrees, a dagger HA degrees and a dagger SA degrees) were derived and discussed. The dissociation process of the ligands is endothermic and entropically unfavorable. The formation of the metal complexes has been found to be endothermic and entropically favorable. Molecular docking was used to predict the binding mode between azo rhodanine derivatives (HL (n) ) with the 3hb5-oxidoreductase receptor of breast cancer. The values of binding constants (K (i) ) of the azo rhodanine derivatives (HL (n) ) are correlated with Hammett's constant (sigma (R)).