Interaction of two cis dioxo-Mo(VI) complexes with DNA and BSA: Synthesis, structural elucidation, Hirshfield surface analysis and electrochemical evaluation

Abstract

Two novel cis-dioxo Mo(VI) complexes ([MoO2(L)(py)] and [MoO2(L)(DMSO)]), containing a tridentate hydrazine Schiff base ligand (HL), were synthesized and fully characterized. Single crystal X-ray diffraction analysis of both complexes revealed that these compounds had an octahedral geometry around the Mo(VI) central ion coordinated by the donor atoms of the deprotonated ligand, two oxido groups and oxygen or nitrogen atom of DMSO and pyridine molecules. Fluorescence quenching technique, UV–Vis absorption titration, and cyclic voltammetry were applied to determine the binding parameters and mechanism of the interaction of each complex with DNA. The obtained results demonstrated that both complexes had a relatively strong affinity to bind to the DNA via its grooves with partially insertion of their aromatic groups into the DNA duplex. The corresponding binding constants were calculated to be 6.02 × 105 M−1 and 1.12 × 106 M−1 for [MoO2(L)(py)] and [MoO2(L)(DMSO)], respectively. Investigation of the interaction of the cis dioxo-Mo(VI) complexes with bovine serum albumin (BSA) using UV–Vis absorption titration represented the change of the polarity of the environment surrounded the aromatic amino acid residues of the protein. Fluorescence quenching studies at different temperatures showed that the interaction of the Mo complexes with BSA was mainly enthalpy-driven process and was performed mainly via van der Waals contacts or hydrogen bonding. The values of binding constants were in the range of 5.84 × 105 to 3.52 × 108 M−1, which indicated an optimal interaction between BSA and the synthesized complexes making the protein suitable for transportation of the complexes.