Synthesis, structure and biological properties of benzimidazole-based Cu(II)/Zn(II) complexes

Three new complexes formulated as [Cu(mbmb)(2)Cl-2] (1), [Cu(mbmb)(2)(NO3)(2)] (2), and [Zn(mbmb)(2)Cl-2] (3) (mbmb = 1-[(2-methyl-1H-benzoimidazol-1-yl)methyl]-1H-benzotriazole) have been synthesized and characterized. Complexes 1-3 showed mononuclear structures and the central metal ions of complexes 1-3 exhibited a four-coordinated environment. We evaluated the antioxidant activity against DPPH and antidiabetic activity against alpha-amylase of complexes 1-3 and ligand (mbmb) in vitro. The results of DPPH free radical scavenging assay showed that complexes 1 and 2 exhibited higher antioxidant activity among the synthesized compounds and their IC50 values were 43.72 mu g/mL and 43.76 mu g/mL, respectively. The IC50 values in vitro antidiabetic studies of complex 1 (0.74 mg/mL) and complex 2 (1.00 mg/mL) were much smaller than those of standard acarbose (2.34 mg/mL) and the ligand mbmb (39.87 mg/mL), which showed effective inhibition on alpha-amylase. Additionally, the solid-state fluorescent properties of these three complexes and ligand mbmb were investigated at room temperature.