Geometrical structures, molecular docking, spectroscopic characterization of mixed ligand and Schiff base metal complexes

Abstract

The mixed ligand mononuclear complexes were synthesized by reaction of MX2·nH2O (M=Cu(II) or Zn(II)) with 4-aminoantipyrine (Lp) and heterocyclic base 1,10-phenanthroline (L). Molecular docking was used to predict the binding between the Schiff base ligands (L1 and L2) and the receptors of prostate cancer mutant 2q7k-hormone and breast cancer mutant 3hb5-oxidoreductase. Also the corresponding Schiff base mixed ligand complexes were prepared by condensation of mixed ligand complex [Zn(Lp)(L)]Cl2 with 1,2-diaminoethane and/or benzaldehyde. All the compounds have been characterized by elemental analysis, conductance measurements, magnetic moments, spectral (UV–vis, IR, 1H &13C NMR and ESR) and thermal studies. The IR showed that the ligand (Lp) act as neutral bidentate through the amino nitrogen atom and carbonyl oxygen moiety. The presence of anion, viz., Cl−, NO2−, SO4−− or NCS− in the coordination sphere is also inferred by the IR spectral data and conductance measurements. The molar conductivities show that all the complexes are non-electrolytes except Zn(II) complexes. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry has been proposed for each complex. The molecular and electronic structures of the Schiff base ligands (L1 and L2) and complexes (1–4) are optimized theoretically and the quantum chemical parameters are calculated. It was found that the ligand (L1) is more stable than the other ligand (L2). The ESR spectral data of copper complexes provided information about their structure on the basis of Hamiltonian parameters and degree of covalency. ESR calculations support the characterization of the structures of the complex geometries.