Towards polynuclear metal complexes with enhanced bioactivities: Synthesis, crystal structures and DNA cleaving activities of Cu-II, Ni-II, Zn-II, Co-II and Mn-II complexes derived from 4-carboxy-1-(4-carboxybenzyl) pyridinium bromide

作者：Chen Ming; Chen Ming Zhen; Zhou Chun Qiong; Lin Wei Er; Chen Jin Xiang^*; Chen Wen Hua; Jiang Zhi Hong

来源：Inorganica Chimica Acta, 2013, 405: 461-469.

DOI：10.1016/j.ica.2013.02.008

• Dicarboxylic ligand
• Transition metal complexes
• Crystal structures
• DNA cleavage

Six transition metal complexes, that is, {[Cu(Ccbp)(2)]center dot 4H(2)O}(n) (1), [Ni(H2O)6](Ccbp)(2)center dot 4H(2)O (2), [M(Ccbp)(2)-(H2O)(4)]center dot 2H(2)O-2MeOH (M = Zn-II (3), Co-II (4), Mn-II (5)), and [Cu(Cbp)(2)(H2O)(2)](NO3)(2)center dot 4H(2)O (6) were synthesized from the reaction of 4-carboxy-1-(4-carboxybenzyl)pyridinium bromide (H(2)CcbpBr) and N-(4-carboxybenzyl)pyridinium bromide (HCbpBr) with the corresponding metal salts in the presence of NaOH, respectively. All these metal complexes were characterized by IR, elemental analyses and single crystal X-ray crystallography. In complex 1, every two Ccbp(-) ions bridge two Cu2+ ions through four terminal carboxylate ions in a monodentate coordination mode, thus forming a one-dimensional polymer structure. Complex 2 is an ionic metal complex consisting of isolated [M(H2O)(6)](2+) dications and Ccbp(-) anions. Complexes 3-5 have similar structures, in which the central metal atom in [M(Ccbp)(2)(H2O)(4)] unit adopts a slightly distorted octahedral geometry. In complex 6, the central Cu atom adopts a distorted tetrahedral coordination geometry that is formed from two unidentate Cbp ligands and two H2O molecules. Agarose gel electrophoresis studies on the cleavage of plasmid pBR322 DNA by complexes 1-6 indicated that only complex 1 was capable of efficiently cleaving DNA, most probably via an oxidative mechanism. Kinetic assay of complex 1 afforded the maximal catalytic rate constant k(max) of 0.50 h(-1) and Michaelis constant K-M of 0.60 mM, respectively. Ethidium bromide displacement experiments indicated that complex 1 had a binding affinity of (3.10 +/- 0.90) x 10(5) M-1 toward calf-thymus DNA, 10- to 55-fold higher than those shown by H(2)CcbpBr and complexes 2-5. The high cleaving efficacy of complex 1 is thought to be due to its polynuclear structure.

• 单位
  南方医科大学