A zinc(II) metal–organic complex based on 2-(2-aminophenyl)-1H-benzimidazole ligand: Exhibiting high adsorption capacity for aromatic hazardous dyes and catecholase mimicking activity

Abstract

A dual functional metal–organic complex (MOC) {[Zn(L1)(Cl)2]·DMF} (1), ( L1 = 2-(2-aminophenylbenzimidazole) was synthesized by a solvothermal method and characterized by various analytical techniques. Crystals of 1 were harvested by a solvent evaporation method, and single-crystal X-ray diffraction (SCXRD) analysis revealed that 1 adopted a distorted tetrahedral geometry around the central metal ion. The topological simplification of 1 ascertained the simple hcb net. The bulk-phase purity of as-synthesized 1 was confirmed by the decent match of powder X-ray diffraction (PXRD) patterns with the simulated patterns. The band gap and chemical reactivity potential of 1 were confirmed by HOMO-LUMO analysis. Complex 1 showed the efficient adsorption of cationic methylene blue (MB) and anionic methyl orange (MO) dyes from wastewater with good uptake. At room temperature and at neutral pH, complex 1 exhibited the highest removal efficiencies (90% and 80%) and adsorption capacities (qe = 116.22 mg/g and 102.62 mg/g) for MB and MO dyes, respectively. The plausible mechanism of cationic and anionic dyes removal is based on insight from structural information and existance of array of non-covalent interactions in complex 1. Additionally, complex 1 was also evaluated for catecholase-like activity in ethanol for the oxidation of 3,5-DTBC to 3,5-DTBQ. Complex 1 showed good catecholase-like activity with potential catechol conversion results, kcat = 0.98⨯102 h−1, KM = 0.0506 M, and Vmax = 0.0485⨯10-3 M min−1.