Synthesis and Crystal Structure of a Dinuclear Cu(Ⅱ) Complex Based on a Carboxyl-substituted 1H-1,2,3-Triazole and Its DNA Cleavage Activity

The novel dinuclear copper complex [Cu2(H2O)2(DMF)2(L)2](1, H2 L = 5-phenyl-2H-1,2,3-triazole-4-carboxylic acid, DMF = N,N-dimethyl-formamide) has been synthesized and characterized by X-ray single-crystal diffraction. The compound crystallizes in triclinic system, space group P1 with a = 9.591, b = 10.508, c = 15.515 ?, β = 75.11°, V = 1446.2 ?3, Z = 2, Mr = 683.62, Dc = 1.570 g/cm3, μ = 1.531 mm-1, F(000) = 700, the final R = 0.0404 and w R = 0.1130 for 5327 observed reflections with I > 2σ(I). In each unit of the complex, two Cu2+ ions coordinated with two triazole ligands to form a dimeric [5,6,5] tricyclic structure. The central Cu atom is five-coordinated, and each copper atom shows a square pyramidal geometry. The crystal structure is stabilized by the inversion-related O–H···O hydrogen bond and C–H···O hydrogen bonding interactions to form a layer structure. Fluorescent spectra show an obvious quenching of fluorescence compared with free 1,2,3-triazole ligand. The results of agarose gel electrophoresis indicate that this complex can cleave the plasmid supercoiled DNA within shorter time in the 50-folds excess of ascorbate under physiological conditions, providing a new example in the research for artificial metal nucleic acid enzyme.