Synthesis, structural elucidation, and DNA binding behavior of a ternary copper(II) complex featuring substituted bipyridyl and dicarboxylate ligands

The present research study is centered around the synthesis, characterization, and biological application of a ternary mixed-ligand based binuclear Cu(II) complex [Cu₂(trans-1,4-chdc)(4,4′-Me₂-2,2′-bpy)₂(5,5′-Me₂-2,2′-bpy)₂]·2(cis-H₂1,4-chdc)·2(BF₄¯) (1) by meticulous incorporation of 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me₂-2,2′-bpy), 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me₂-2,2′-bpy) and cis- and trans- mixture of 1,4-cyclohexanedicarboxylic acid (H₂1,4-chdc). Hirshfeld analysis is employed to validate non-bonded interactions, demonstrating the existence of widespread π···π stacking interactions between adjacent 4,4′-Me₂-2,2′-bpy ligands at a distance of 3.757 Å, forming a one-dimensional (1D) supramolecular polymer chain. The biological activity of complex 1 is explored via docking study, driven by the inherent biological inclination of the Cu(II) complexes. Agreeably, the coordination complex 1 displays a favorable binding to DNA, specifically binds to the major groove of DNA and the aromatic pyridine ring of the ligand partially intercalates into the base pairs with a binding constant (K_b) of 1.98 × 10⁵ M⁻¹.