Synthesis, characterization, DNA-binding and DNA-photocleavage studies of [Ru(bpy)2(pmip)]2+ and [Ru(phen)2(pmip)]2+ (pmip = 2-(2′-pyrimidyl)imidazo[4,5-f][1,10]phenanthroline

Two new Ru(II) complexes, [Ru(bpy)2(pmip)]2+ (1) and [Ru(phen)2(pmip)]2+ (2), have been synthesized and characterized by elemental analysis, ESI-MS and 1H NMR spectra. Their DNA-binding properties were studied by means of UV–VIS, emission and CD spectra, thermal denaturation and viscosity measurements as well as their DNA-photocleavage properties. The experimental results show that both 1 and 2 can bind to DNA in an intercalative mode; the DNA-binding affinity of 2 is greater than that of 1, which suggests that the ancillary ligands have a significant effect on the spectroscopic properties and DNA-binding behavior of the Ru(II) complexes. Under irradiation with UV light, the Ru(II) complexes show excellent efficiency of cleaving DNA. This research may provide valuable insight into the interactions of metal complexes with DNA, knowledge that is an excellent backdrop for the rational design of promising drugs.

The melting curves of CT-DNA in the absence and presence of the complexes are presented. On addition of 1 or 2, the Tm of DNA increases to 66.5 and 68.8 °C, respectively, at a concentration ratio [DNA]/[Ru] of 10:1, which indicates that both 1 and 2 can bind to DNA in an intercalative mode and the DNA-binding affinity of 2 is greater than that of 1.Figure optionsDownload as PowerPoint slide