关键词: 席夫碱, Cu(II)配合物, 晶体结构, 儿茶酚氧化酶活性

Abstract: Four complexes, [Cu(L1)Cl2] (1), [Cu(SCN) 2] (2), [Cu(L1)bpy](ClO4)2·CH3OH (3), and [Cu(L2)bpy](ClO4)2 (4) were synthesized by reacting the NNN tridentate Schiff base ligands, 2-((1H-benzimidazol-2-yl-ethylimino)-methyl) pyridine (L1) or 2-((1H-benzimidazol-2-yl-propylimino)-methyl) pyridine (L2) with Cu(II) salts in methanol (where bpy = 2, 2’-bipyridine). The structures of the complexes were characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction, single-crystal X-ray diffraction and thermal gravimetric analysis. In the solid state, complexes 1-4 are mononuclear Cu(II) complexes and the Cu(II) ions exhibit distorted square pyramidal coordination geometry, with τ values ranging from 0.088 to 0.34. Catecholase activity of the complexes has been studied using 3, 5-di-tert butyl catechol (3, 5-DTBC) as model substrate, and kinetic parameters (Vmax, Kcat, KM) were calculated using the Michaelis-Menten model and Lineweaver-Burk plot. The results demonstrate that all complexes exhibit catecholase activity, with the catechol oxidation rates following the order of 2>3≈4>1. The oxidation rates depend on the distortion of the Cu(II) coordination environment and the bond lengths of the leaving group of Cu(II) ions.

Key words: Schiff base, Cu(II) complexes, Crystal structure, Catecholase activity