New DNA-Interactive Manganese(II) Complex of Amidooxime: Crystal Structure, DFT Calculation, Biophysical and Molecular Docking Studies

A manganese(II) complex [Mn-II(HL1)(2)(Cl)-(CH3COO)] (1) based on the amidooxime ligand was synthesized and characterized by single-crystal X-ray diffraction studies, elemental analysis, UV-vis, and IR spectroscopy. The structural and spectral parameters were further supported using DFT/B3LYP. The complex (1) is mononuclear, having an octahedral geometry. The interaction of 1 with calf thymus DNA was investigated by spectroscopic and calorimetric techniques. The complex was found to interact with DNA through the groove-binding mode. From the isothermal titration calorimetry experiment, the binding constant between 1 and DNA was estimated to be (4.39 +/- 0.01) x 10(5) M-1. The negative standard molar Gibbs energy change (Delta G(0)) and positive entropy (T Delta S-0) values obtained from the calorimetry study confirmed the spontaneity of 1-DNA complexation. Thermodynamic parameters also suggested that the process of interaction of 1 with DNA was entropy-driven. The molecular docking study revealed that 1 binds at G30, C29, T31, A14, and G13 base pairs of the DNA chain in the minor groove.