Synthesis, crystal structure and DNA-binding properties of a new copper(II) complex with l-valine Schiff base and 1,10-phenanthroline

A new copper(II) complex, [Cu(sal-l-val)phen] (sal-l-val = a Schiff base derived from salicylaldehyde and l-valine, phen = 1,10-phenanthroline), has been synthesized and characterized by elemental analysis, IR spectra and X-ray single crystal diffraction. Results show that this crystal structure of the copper(II) complex belongs to triclinic crystal system, P1 space group with crystallographic data: a = 10.3710(16) Å, b = 13.9350(19) Å, c = 16.670(2) Å, α = 79.970(2)°, β = 75.623(2)°, γ = 84.160(3)° and Z = 4. The copper(II) complex has four independent structures in the crystallographic asymmetric unit, three of them show distorted square-pyramidal and the fourth displays distorted trigonal bipyramid CuN3O2 coordination geometry. In the crystal, π–π stacking and the intermolecular hydrogen bonds form two-dimensional network. The interactions between the copper(II) complex and calf thymus DNA(CT-DNA) have been studied by using UV, fluorescence and CD spectra, as well as viscosity and thermal denaturation measurements. Experiment results confirm that the copper(II) complex binds to CT-DNA in an intercalative mode.