A new copper(II) complex with mixed-ligands of a Schiff base derived from L-phenylalanine and o-vanillin and 1,10-phenanthroline, [Cu(o-van-phe)phen]•CH₃OH, has been synthesized and characterized by elemental analyses and IR spectra. Single crystal X-ray diffraction results suggest that the complex structure belongs to monoclinic crystal system, C₂ space group with the cell dimensions: a＝1.15637(17) nm, b＝1.8562(2) nm, c＝1.34249(18) nm, β＝98.385(2)°, V＝2.8509(7) nm³, D_c＝1.335 g/cm³, Z＝4, F(000)＝1188, the final R₁＝0.0574, and wR₂＝0.1540 [I＞2σ(I)]. The copper(II) ion is five-coordinated and displays CuN₃O₂ distorted square-pyramid coordination geometry. The dimeric structure is formed by hydrogen bonds of two adjacent molecules. The interaction of the complex with CT-DNA has been investigated by UV, fluorescence and circular dichroism (CD) spectra. Results show that this copper(II) complex binds to calf thymus DNA (CT-DNA) in an intercalative mode and its intrinsic binding constant K_b is 9.697×10³ L•mol^－1. Furthermore, the DNA cleavage activity of this copper complex has also been studied by submarine gel electrophoresis, and it was found that this complex can cleave circular plasmid pBR322 DNA to both nicked and linear forms.

Key words: copper(II) complex, L-phenylalanine, Schiff base, crystal structure, DNA