title: Two new dicopper(II) complexes with oxamido-bridged ligand: synthesis, crystal structures, DNA binding/cleavage and BSA binding activity.
abstract: New oxamido-bridged copper(II) complexes, [Cu(2)(oxbp)(H(2)O)(2)(NCS)(2)] (1) and [Cu(2)(oxbp)(μ-DMSO)(2)(NCS)(2)][Cu(2)(oxbp)(DMSO)(2)(NCS)(2)] (2) (H(2)oxbp=N,N'-bis(2-(diethylamino)ethyl)oxalamide), were synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR, and electronic spectra. X-ray analysis revealed that complex 1 consists of neutral binuclear [Cu(2)(oxbp)(H(2)O)(2)(NCS)(2)] units which forms a two-dimensional network through intermolecular hydrogen bonds and complex 2 is constructed by neutral [Cu(2)(oxbp)(μ-DMSO)(2)(NCS)(2)] (2a) and [Cu(2)(oxbp)(DMSO)(2)(NCS)(2)] (2b) entities which alternately distribute to form a two-dimensional network by means of quasi μ-DMSO bridge and intermolecular hydrogen bonds. In both 1 and 2, bicopper centers are linked by the "trans-form" oxamido bridges with the distances of 5.272 Å for 1 and av. 5.296 Å for 2, respectively. The interaction of Cu(II) complexes with DNA was investigated by UV-visible, fluorescence emission spectrometry and agarose gel electrophoresis. The apparent binding constant (K(app)) values of 3.16×10(5) M(-1) for 1 and 4.9×10(5) M(-1) for 2 suggest moderate intercalative binding modes between the complexes and DNA. Complex 1 displayed efficient oxidative cleavage of supercoiled DNA, which might indicate that the underlying mechanism involves singlet oxygen (((1))O(2)) as reactive oxygen species. Complex 2 is characteristic of the involvement of a singlet oxygen-like entity and hydrogen peroxide in the cleavage process. In addition, our present work showed, by fluorescence spectrometry of BSA with complexes, both 1 and 2 bind to BSA with a medium affinity through a static mode which is tentatively assigned binding to Trp134 in BSA.
authors.affiliation: Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics (Theranostics), School of Pharmacy, Tianjin Medical University, Tianjin 300070, PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Xue
authors.forename: Cheng-Zhi
authors.initials: CZ
authors.lastname: Xie
authors.forename: Yan-Wen
authors.initials: YW
authors.lastname: Zhang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Qiao
authors.forename: Xin
authors.initials: X
authors.lastname: Qiao
authors.forename: Jing-Yuan
authors.initials: JY
authors.lastname: Xu
authors.forename: Shi-Ping
authors.initials: SP
authors.lastname: Yan
mesh_terms: D000818:Animals; D002417:Cattle; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000737:chemistry*
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D012710:Serum Albumin, Bovine; D003300:Copper; D004247:DNA