Two new complexes: [Cu(dppz)(L-val)(H 2 O)]ClO 4 (1) and [Cu(dppz)(L-tyr)(H 2 O)]ClO L-val＝L-valinate, L-tyr＝L-tyrosinate) have been synthesized and investigated by elemental analysis, molar conductivity, UV-Vis and IR spectroscopies. Complex 1 has been structurally characterized by the single-crystal X-ray diffraction method, which crystallizes in the triclinic space group P-1 in a unit cell of a＝0.9095 (2)

The complexes showed good antibacterial activities against the microorganisms. The interaction between the complexes and calf thymus DNA in aqueous solution was investigated adopting electronic absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and cyclic voltammetry. Results suggest that the two complexes can bind to DNA by intercalative mode. In addition, the result of agarose gel electrophoresis suggested that the complexes can cleave the plasmid DNA at physiological pH and room temperature. Mechanistic studies with different inhibiting reagents reveal that hydroxyl radicals, and a singlet oxygen-like copper-oxo species are all involved in the DNA scission process mediated by the complexes.