Therapeutic potential and photocatalytic properties of metal complexes derived from indole-benzimidazole hybrids

Combination of antimicrobial resistance, biofilm formation, and diabetes poses a major challenge in managing infections. The complex web of challenges can be mitigated by addressing these infections by exploring novel therapeutic strategies. As an attempt, a novel series of Co/Ni/Cu/Zn(II) complexes derived from an indole-benzimidazole hybrid ligand was synthesized and characterized using analytical and spectroscopic techniques. The ligand, 2-(1H-indol-3-yl)-1H-benzo[d]imidazole (mib), containing fused indole and benzimidazole moieties, was synthesized from o-phenylenediamine and indole-3-carboxaldehyde. Electronic spectral analysis and magnetic moment measurements suggest a tetrahedral geometry for [Co(mib)2Cl2], [Ni(mib)2Cl2], and [Zn(mib)2Cl2], while [Cu(mib)2Cl2] has a square planar geometry. The incorporation of 1,10-phenanthroline led to octahedral geometry in the mixed-ligand complexes of [Co(mib)2(1,10-phen)Cl2], [Ni(mib)2(1,10-phen)Cl2], and [Cu(mib)2(1,10-phen)Cl2]. The photocatalytic efficiency was evaluated via methylene blue degradation under visible light, where [Co(mib)2Cl2] exhibited highest activity, achieving 77.97% degradation. Biological screening revealed that [Cu(mib)2(1,10-phen)Cl2] has strong antimicrobial and antibiofilm effects against Pseudomonas aeruginosa, with a 74% inhibition rate at 0.067 mg/mL. Molecular docking studies against antidiabetic targets (2PRG, 3L2M, and AF-P38158-F1) confirmed robust binding affinities for [Co(mib)2Cl2], and [Ni(mib)2Cl2]. In vitro test against α-amylase demonstrated exceptional potency of [Co(mib)2Cl2], [Ni(mib)2Cl2], and [Zn(mib)2Cl2], suggesting their promising role as multifunctional agents in both therapeutic and environmental applications.