Exploring the versatility of sulfur-containing heterocyclic metal complexes: Application in medical and prospects of visible-light-driven photocatalysis

Abstract

Numerous heterocyclic moieties serve as the foundational structure for clinically employed drugs, underscoring the significance of heterocycles in the innovation of pharmacologically active compounds. In the present investigation, a heterocyclic skeleton of thiophene-clubbed benzimidazole (tmb) was developed and utilized to synthesize seven novel series of metal (M(II) = Co, Ni, Cu, and Zn) complexes to explore diverse applications including pharmacological and photocatalytic performance. A sharp singlet peak appeared at 5.72 ppm (tmb) and 5.94 ppm for the Zn(II)-tmb complex corresponding to -CH₂ protons, as evidenced by ¹H NMR results, confirming the formation of targeted compounds. Antimicrobial assay and docking studies confirmed that the mixed metal complex; [Cu(tmb)₂(1,10-phen)Cl₂] possesses the highest activity and displayed significant biofilm inhibition, achieving 86.35 and 89.8% at concentrations of 1 and 0.020 mg/mL, respectively against E. coli. Furthermore, the photocatalytic activity was monitored by the degradation of methylene blue dye under direct sunlight and [Cu(tmb)₂Cl₂] exhibited a maximum degradation efficiency of 96.15% in 45 min. These findings could serve as inspiration for the development of benzimidazole-based metal complexes as effective anti-biofilm and photocatalytic agents.