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 <i>o</i>-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 <i>via</i> 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 <i>Pseudomonas aeruginosa,</i> 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]. <i>In vitro</i> 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.