Synthesis, Characterization, DNA-binding Properties and DNA Cleavage of a New Ternary Copper(II) Complex with Mixed-ligands of Tridentate Schiff Base and 1,10-Phenanthroline

A new copper(II) complex, [Cu(naph‐leu)phen]CH3OH·0.5H2O, in which naph‐leu is the tridentate Schiff base ligand derived from the condensation of 2‐hydroxy‐1‐naphthaldehyde and L‐leucine, phen is phenanthroline, has been synthesized and characterized by elemental analyses, IR spectra and single crystal X‐ray diffraction. The DNA‐binding properties of this complex have been investigated by absorption spectra, fluorescence spectra and circular dichroism (CD) spectra, as well as viscosity measurement. Results show that this copper(II) complex binds to calf thymus DNA (CT‐DNA) in an intercalative mode and its intrinsic binding constant Kb is 4.87×103 L·mol−1. Furthermore, the DNA cleavage activity of this copper(II) complex has also been investigated by submarine gel electrophoresis. Interestingly, it was found that this complex can cleave the supercoiled plasmid pBR322 DNA to both nicked and linear forms. A new copper(II) complex, [Cu(naphleu)phen]CH3OH·0.5H2O, has been synthesized and characterized. The DNA‐binding properties of this complex have been investigated by UV, fluorescence and CD spectra, as well as viscosity measurement. Furthermore, the DNA cleavage activity of this complex has also been investigated by submarine gel electrophoresis.