A copper(II) complex with 2-(2'-pyridyl)benzimidazole and L-arginine: synthesis, structure, antibacterial activities, and DNA interaction

摘要

A Cu(II) complex with 2-(2'-pyridyl)benzimidazole and L-arginine has been synthesized and investigated by elemental analysis, molar conductivity, IR, UV/vis, and X-ray diffraction. The complex crystallizes in the triclinic space group P1 with six molecules in a unit cell of dimensions a=10.6397(5) A, b= 19.2178(8)A, c=20.0387(9)A, α = 75.3670(10)°, β=79.4670(10)°, γ = 87.4470(10)°, V= 3897.6(3) A~3, R_1 =0.0408, and wR_2 = 0.0502. The complex contains six crystallo-graphically independent complexes, Cu1, Cu2, Cu3, Cu4, Cu5, and Cu6, which have a distorted square-pyramidal geometry. The complex was screened for its in vitro antibacterial activities against two Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Salmonella) micro-organisms. The complex exhibited good antibacterial activities against the micro-organisms compared with HPB and Cu(ClO_4)_2. Interaction of the complex with DNA was studied by electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroic spectroscopy, viscosity measurements, and agarose gel electrophoresis. Results suggest that the complex could bind to CT-DNA via partial intercalation, and cleave the plasmid DNA with involvement of hydroxyl radicals, and probably singlet oxygen-like copper-oxo species in the presence of ascorbate.