Synthesis, crystal structure and interaction with DNA and HSA of (N,N'-dibenzylethane-1,2-diamine) transition metal complexes

A new ligand, N,N'-dibenzylethane-1,2-diamine (L) and its four transition metal(II) complexes, ML2(OAc)(2) center dot 2H(2)O (M=Cu, Ni, Zn, Co), have been synthesized and characterized by elemental analysis, mass spectra, molar conductivity, NMR and IR. Moreover, the crystals structure of Cu(II) and Ni(II) complexes characterized by single crystal X-ray diffraction showed that the complexes have a similar molecular structure. Ni(II) has an regular octahedral coordination environment complexes, but typical Jahn Teller effect influenced Cu(II) in an elongated octahedral environment. The interaction between complexes and calf thymus DNA were studied by UV and fluorescence spectra measure, which showed that the binding mode of complexes with DNA is intercalation. Under physiological pH condition, the effects of Cu(OAc)(2)L-2 center dot 2H(2)O and Ni(OAc)(2)L-2 center dot 2H(2)O on human serum albumin were examined by fluorescence. The results of spectroscopic measurements suggested that the hydrophobic interaction is the predominant intermolecular force. The enthalpy change Delta H-0 and the entropy change Delta S-0 of Cu(OAc)(2)L-2 center dot 2H(2)O and Ni(OAc)(2)L-2 2H(2)O were calculated to be -11.533 kJ mol(-1) and 46.339J mol(-1) K-1, -11.026 kJ mol(-1) and 46.396J mol(-1) K-1, respectively, according to the Scatchard's equation. The quenching mechanism and the number of binding site (n approximate to 1) were also obtained from fluorescence titration data. (C) 2008 Elsevier Inc. All rights reserved.