Synthesis, structural characterization, cytotoxic properties and DNA binding of a dinuclear copper(II) complex

In this study a novel dinuclear copper(II) complex with adenine and phenanthroline has been synthesized and its structure determined by single crystal X-ray diffraction. In the dinuclear complex [Cu-2(mu-adenine)(2)(phen)(2)(H2O)2](NO3)(4)center dot 0.5H(2)O (phen = 1,10-phenanthroline) (1) the two Cu(II) centres exhibit a distorted square pyramidal coordination geometry linked by two nitrogen donors from adenine bridges leading to a Cu-Cu distance of 3.242(3) angstrom. Intramolecular and intermolecular pi center dot center dot center dot pi interactions as well as an H-bonding network were observed. The antitumor capacity of the complex has been tested in vitro against human cancer cell lines, cervical carcinoma (HeLa) and colorectal adenocarcinoma (Caco-2), by metabolic tests, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide as reagent. The complex 1 has remarkable low IC50 values of 0.87 +/- 0.06 mu M (HeLa) and 0.44 +/- 0.06 mu M (Caco-2), when compared with values for cisplatin against the same cell lines. The interaction of complex 1 with calf thymus DNA (CT DNA) was further investigated by absorption and fluorescence spectroscopic methods. A binding constant of 5.09 x 10(5) M-1 was obtained from UV-vis absorption studies. (C) 2016 Elsevier Inc. All rights reserved.