Synthesis, Structure, Cytotoxic Activities and DNA-Binding Properties of a 1D Copper(II) Complex Bridged both by Oxamidate and Terephthalato Groups

A new one-dimensional copper(II) polymer with formula of [Cu-2(heae)(tpa)](n)center dot nH(2)O, where heae(2-) and tpa(2-) stand for the dianions of N,N'-bis(N-hydroxyethylaminoethyl)oxamide and terephthalic acid, respectively, has been synthesized and characterized by elemental analysis, conductivity measurement, IR and electronic spectral studies, and single-crystal X-ray diffraction. The crystal structure consists of a one-dimensional copper(II) coordination polymeric chain constructed by the [Cu-2(heae)](2+) cations as the inorganic second building units (SBUs) and the tpa(2-) anions as linkers. The Cu center dot center dot center dot Cu separations through the bridges of heae(2-) and tpa(2-) are 5.2472(6) and 10.9677(8) , respectively. Both the copper(II) ions have square pyramidal coordination geometries. A three-dimensional hydrogen bonding network is observed in the crystal. The measured molar conductivity suggests that the polymer may stay intact in solution as the 1D polymer in the crystal. The cytotoxicities of the polymeric copper(II) complex were tested by Sulforhodamine B (SRB) assays against human hepatocellular carcinoma cell SMMC-7721 and human lung adenocarcinoma cell A549. The polymer exhibits potent cytotoxic effects against the two cell lines. The binding properties of the copper(II) polymer with herring sperm DNA (HS-DNA) have been investigated by using UV absorption and fluorescence spectra and electrochemical techniques and viscosity. The results show that the copper(II) polymer interacts with HS-DNA in the mode of intercalation with the intrinsic binding constant of 1.07 x 10(4) M-1.