Synthesis, spectroscopic, thermal properties, Calf thymus DNA binding and quantum chemical studies of M(II) complexes

A new series of transition metal complexes of Cu(II), Co(II), Ni(II), Mn(II) and Cd(II) were prepared from the ligand of 5-(4-benzenesulfonic acid azo)-2-thioxo-4-thiazolidinone (H2L). The M(II) complexes were structurally elucidated by elemental analysis, infrared spectra, spectral studies, thermal analysis, magnetic measurements and X-ray diffraction analysis. Elemental analysis and IR result suggested the ligand was bonded to the metal ions in monobasic/neutral bidentate through the nitrogen atom of the hydrazone group and oxygen atom of carbonyl group. The bond length, bond angle, HOMO, LUMO and quantum chemical parameters were calculated to confirm the geometry of the ligand and the M(II) complexes. In vitro antimicrobial behavior of ligand (H2L) and its M(II) complexes (1-5) was screened with targeted bacterial and fungal strains. Spectroscopic (UV-vis) technique was employed in order to study the binding mode and binding strength of the ligand (H2L) and its M(II) complexes to Calf thymus DNA (CT-DNA). Intercalation is the most possible mode of interaction of the ligand (H2L) and its M(II) complexes with CT-DNA and the determined binding constants. Molecular docking was used to predict the binding between the starts (4-aminobenzenesulfonic acid (start 1) and 2-thioxo-4-thiazolidinone (start 2)) and tautomers (A-C) of ligand (H2L) with the receptors of prostate cancer mutant (PDB code: 2Q7K) and breast cancer mutant (PDB code: 3HB5).