Geometrical structure, molecular docking and potentiometric studies of Schiff base ligand

Abstract

Schiff base ligand of 4-(((2-hydroxynaphthalen-1-yl)methylene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (HL) was synthesized and characterized by IR spectroscopy. The molecular structure of the ligand is optimized theoretically and the quantum chemical parameters are calculated. Molecular docking was used to predict the binding of the ligand with the receptor of prostate cancer 2q7k-hormone and 3hb5-oxidoreductase receptor of breast cancer. The proton–ligand dissociation constant of HL and its metal stability constants with Mn2+, Co2+, Ni2+ and Cu2+ have been determined potentiometrically. The potentiometric studies were carried out in 0.1M KCl and 20% (by volume) DMF–water mixture. At constant temperature the stability constants of the formed complexes increase in the order of Cu2+>Ni2+>Co2+>Mn2+. The effect of temperature was studied at 298, 308 and 318K and the corresponding thermodynamic parameters (ΔG, ΔH and ΔS) 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.