Synthesis, characterization, DFT calculations, protein binding and molecular docking studies of mononuclear dioxomolybdenum(VI) complexes with ONS donor ligand

Abstract Several new dioxomolybdenum(VI) complexes containing tridentate ONS donor ligand (H2L) derived from pyridoxal and S-benzyldithiocarbazate have been synthesized by refluxing MoO2(acac)2 with Schiff base ligand and Lewis base (B) (where, B = pyridine, γ-picoline, 1-methylimidazole, tetrahydrofuran) in 1:1:1.5 molar proportions in methanol. The complexes having general formula MoO2LB (1–4) are thoroughly characterized by elemental analyses and various spectroscopic techniques (IR, 1H NMR, UV–Vis and mass spectra). The structures of the complexes have been optimized by Density Functional Theory (DFT) calculations. The hexa coordinated metal center possesses a distorted octahedral geometry in all the complexes. The redox behavior of the complexes is studied by cyclic voltammetry. The oxo-transfer reactivity of the MoO2LB complexes with PPh3 has also been examined. The interactions of the complexes with Bovine Serum Albumin (BSA) protein are investigated spectroscopically by absorption, fluorescence titration and fluorescence life time measurements. The values of the Stern-Volmer constant (KSV), binding constant (Kb) and number of binding sites (n) are determined which indicates significant binding with BSA protein. Fluorescence spectral change also indicates efficient FRET from the protein to ligand and complexes. Molecular docking studies have also been carried out to understand the binding modes and interaction patterns of the dioxomolybdenum(VI) complexes with BSA.