Binuclear Fe(II) and Cu(II) complexes with 2-(pyridin-2-yl)-1H-benzimidazole and 4,4′-bipyridine: Synthesis, characterization, DFT insights, broad-spectrum bioactivity and docking study

This study presents the synthesis, structural characterization, theoretical analysis, and biological assessment of two novel binuclear complexes: FeBBNZBIPY and CuBBNZBIPY. These complexes were synthesized from 2-(pyridin-2-yl)-1H-benzimidazole (BBNZ) and 4,4′-bipyridine (BIPY). FT-IR analysis confirmed the bidentate coordination mode of BBNZ and BIPY, while molar conductivity measurements indicated the non-electrolytic nature of both complexes. Structural determination identified FeBBNZBIPY as [Fe₂ (BBNZ)₂(BIPY)(Cl)₆] and CuBBNZBIPY as [Cu₂(BBNZ)₂(BIPY)(Cl)₄(H₂O)₂], both displaying octahedral geometries as verified by spectroscopic analysis. Density functional theory (DFT) calculations provided insights into their electronic properties. Biological assays revealed enhanced anti-inflammatory, antifungal, antibacterial, and antioxidant activities, with CuBBNZBIPY demonstrating superior anti-inflammatory and antioxidant efficacy, showing IC₅₀ values of 90.13 and 72.61 µM, respectively. Molecular docking studies further highlighted specific protein interactions, with CuBBNZBIPY exhibiting high binding energies of −8.71, −8.79, −8.92, and −8.92 kcal/mol against targets 5iq9, 6CLV, 5IJT, and 5IKT, respectively, underscoring the therapeutic potential of these complexes across various biomedical applications.