Synthesis, crystal structures and spectral characterization of Cu(II) and Mn(II) complexes of 4-hydroxy-3-methoxybenzaldehyde: antioxidant properties and molecular docking studies

<p>[Cu(L)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>] (<b>1</b>) and [Mn(L)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>] (<b>2</b>) (HL = 4-hydroxy-3-methoxybenzaldehyde) were synthesized and characterized using elemental, spectral (FTIR, ESI-MS, UV–visible, fluorescence and EPR), thermal, cyclic voltammetric, powder, and single crystal X-ray crystallographic studies. Spectral and X-ray data ascertained the structural features, binding modes of ligand and distorted octahedral geometry around the metal ions. Cyclic voltammetric studies confirmed the formation of a quasi reversible redox couple in solution. Crystal structure analysis of <b>1</b> and <b>2</b> reveal the presence of non-covalent interactions, resulting in a 1-D polymeric chain. Antioxidant properties (using DPPH and hydrogen peroxide assay) and molecular docking studies (using 1BNA) are also examined. The binding free energies (calculated from docked models), −270 (<b>1</b>) and −295 kJ mol<sup>−1</sup> (<b>2</b>), suggest that the complexes reasonably bind to DNA, and the DNA-binding affinity of <b>2</b> is stronger than that of <b>1</b>.</p>