Synthesis, characterization, and DNA binding of the biologically relevant novel cationic molybdenum(VI)–glutathione complex [Mo(GS)(Cl)(H2O)]Cl2

Abstract

The complex [Mo(GS)(Cl)(H2O)]Cl2 (MoG) was synthesized in aqueous medium and its composition has been determined by elemental and thermogravimetric analysis. Binding modes were determined by 1H NMR, 13C NMR, mass, and FT-IR spectrometry. The molecular formula was confirmed by mass spectral analysis. The molecular weight of the complex determined by the Rast camphor method also supports the formulation M r = 525. This molecular formula demands the compound to be a 1:2 electrolyte, which is also supported by the conductance measurement, its value being 210 Ω−1 cm2. The compound is found to be diamagnetic, indicating that the molybdenum is in the +6 oxidation state (d0). The binding of MoG with calf thymus DNA was studied by spectroscopic titration. The interaction ratio was determined by monitoring the DNA 260 nm band as well as the S → Mo LMCT band of the complex observed at 225 nm. The interaction ratio calculated from the above studies was found to be 1:0.70 (DNA:MoG) in both cases, while the binding constant of DNA–MoG was found to be (4.8 ± 0.5) × 105 M−1. The binding constant data indicate that the binding nature is intercalative.