A mononuclear copper(II) complex based on the polypyridyl ligand 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz), [Cu(tptz)2]2+: X-ray crystal structure, DNA binding and in vitro cell cytotoxicity

A water soluble 1,3,5-triazine-based copper(II) complex, [Cu(tptz)2]2+, where tptz is 2,4,6-tris(2-pyridyl)-1,3,5-triazine, has been prepared and characterized by elemental analysis and spectroscopic methods. The solid state structure of the complex as the hexafluorophosphate salt has been determined by single-crystal X-ray crystallography. Its DNA binding propensity and in vitro cytotoxicity have also been studied. The molecular structure shows a compressed octahedral CuN6 coordination geometry as a consequence of strain imposed by the rigid ligands. The interaction of the complex with DNA has been investigated by electronic absorption, competitive fluorescence titration, voltammetric techniques and a gel electrophoresis mobility shift assay. The results reveal that the complex binds to DNA in a moderately strong fashion via intercalation with the partial insertion of a planar polypyridyl ligand between the base stacks of double-stranded DNA. An in vitro cytotoxicity study of the effect of the complex on a human breast adenocarcinoma (MCF-7) cell line by an MTT assay indicates that the complex exhibits a marked cell growth-inhibitory effect with an IC50 value of 1.98 μM, which is significantly better than that observed for cisplatin.

Graphical abstractA water soluble 1,3,5-triazine-based copper(II) complex, [Cu(tptz)2]2+, where tptz is 2,4,6-tris(2-pyridyl)-1,3,5-triazine, has been prepared and characterized by elemental analysis and spectroscopic methods. Its DNA binding propensity and in vitro cytotoxicity have also been studied. The molecular structure shows a compressed octahedral CuN6 coordination geometry as a consequence of strain imposed by the rigid ligands.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis and characterization of a water soluble 1,3,5-triazine-based copper(II) complex, [Cu(tptz)2]2+. ► Single-crystal X-ray crystallography for this complex. ► The molecular structure shows a compressed octahedral CuN6 coordination geometry. ► Investigation of DNA–complex interaction by spectroscopic, electrochemical and gel electrophoresis methods. ► An in vitro cytotoxicity study on a human breast adenocarcinoma with an IC50 better than cisplatin.