Synthesis, crystal structure, and DNA interaction and cleavage studies of a novel dinuclear Cu(II) complex with 3-indolylacetic acid

A novel dinuclear Cu(II) complex [Cu 2 (C 10 H 8 NO 2 ) 4 (CH 3 OH) 2 ] · 2CH 3 OH ( I ), where C 10 H 8 NO 2 is anion of 3-indolylacetic acid, was synthesized and characterized by elemental analysis, IR spectroscopy, 1 H NMR and single crystal X-ray diffraction. X-ray crystallography shows that Cu 2+ ion is six-coordinated, embedded in a distorted octahedral center. Each Cu 2+ ion is coordinated with four carboxylic oxygen atoms from four ligands, one oxygen atom from methanol and the other Cu 2+ ion. Each ligand links two Cu 2+ ions through carboxylic oxygen atoms, forming a dinuclear Cu(II) complex. The complex forms a two-dimensional layer structure through N-H…O i intermolecular hydrogen bonds. The interaction of complex I with calf-thymus DNA (CT-DNA) has been explored by electronic absorption spectroscopy, EB (ethidium bromide) displacement experiments, salt effect, and viscosity measurements. All the results indicate that the complex binds to DNA in a partial intercalative mode. Moreover, agarose gel electrophoresis assay demonstrates that the complex possesses the ability to cleave pBR322 plasmid DNA.