[Synthesis and DNA binding spectroscopic studies of Cu(II)-HAsp-Im complexes].

Two novel complexes of [Cu(HAsp)ImH2O]SO4 x 4 H2O and [Cu(Asp)Im(OH)] x 4 H2O (HAsp = Aspartic acid molecule, Asp = Aspartic acid ion, Im = Imidazole) were synthesized and characterized by elemental analysis, IR spectroscopy and TG-DTA. The interactions of the complexes with sperm DNA were studied by electronic absorption and fluorescence spectra. Results showed that the reactions of the two complexes with DNA are obviously different: for [Cu(HAsp)ImH2O]SO4 x 4 H2O, it is intercalation companied by electrostatic effect, while [Cu(Asp)Im(OH)] x 4 H2O mainly cooperates with the nitrogen atom of the DNA base pair, which induces the breakage of DNA double helix. The reasons for these differences in their DNA binding modes were also discussed.