Abstract / Summary
Abstract Two novel Ni(II) and Cu(II) mixed-ligand complexes, NiMBIM and CuMBIM, were successfully synthesized using 1-isopropyl-1H-benzimidazole-2-carbaldehyde (MB) and 2-(4,5-diphenyl-1H-imidazol-2-yl)phenol (IM). Their structures were characterized via CHN elemental analysis, UV–Vis and FT-IR spectroscopy, mass spectrometry, molar conductivity, magnetic susceptibility, and thermal analysis. NiMBIM adopts a tetrahedral geometry, while CuMBIM forms a distorted octahedral structure with coordinated chloride and water. Conductivity measurements indicated that NiMBIM behaves as a 1:1 electrolyte in ethanol (43.15 μS cm 2 mol −1 ), whereas CuMBIM is non-electrolytic (9.06 μS cm 2 ol −1 ). Thermogravimetric analysis confirmed the presence of one coordinated water molecule in CuMBIM and none in NiMBIM. Density Functional Theory (DFT) calculations revealed that CuMBIM possesses the smallest HOMO–LUMO gap (1.61 eV), highest softness (σ = 0.62), and electrophilicity (ω = 9.58), indicating superior reactivity. TD-DFT simulations of the electronic spectra showed good agreement with experimental UV–Vis data, supporting the proposed structures and transition assignments. Biological evaluations demonstrated promising in vitro antimicrobial activity for both complexes, with CuMBIM exhibiting the highest inhibition against Klebsiella pneumoniae (26.00 ± 0.14 mm) and Candida albicans (24.30 ± 0.15 mm). Anti-inflammatory assays confirmed effective inhibition, with IC50 values of 30.25 µg/µL for CuMBIM and 32.88 µg/µL for NiMBIM. Molecular docking studies targeting FabH-CoA (PDB: 1HNJ) and COX-2 (PDB: 1CX2) corroborated these results, showing CuMBIM achieves the strongest binding affinities (− 8.80 and − 10.90 kcal/mol) through key hydrogen bonding and electrostatic interactions, consistent with its enhanced in vitro biological activity.