Experimental and Theoretical Studies on DNA-Binding and Spectral Properties of ‘Light Switch’ Complexes [Ru(L)2(ppn)]2+ (L=2,2′-Bipyridine and 1,10-Phenanthroline; ppn=Pteridino[6,7-f] [1,10]phenanthroline-11,13-diamine)

✍ Scribed by Xue-Wen Liu; Jin-Can Chen; Xia Hu; Hong Li; Kang-Cheng Zheng; Liang-Nian Ji

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: German
• Weight: 425 KB
• Volume: 91
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200890149

✦ Synopsis

Abstract

The ligand pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine (ppn) and its Ru^II^ complexes [Ru(bpy)~2~(ppn)]^2+^ (1; bpy=2,2′‐bipyridine) and [Ru(phen)~2~(ppn)]^2+^ (2; phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis, electrospray MS, ^1^H‐NMR, and cyclic voltammetry. The DNA‐binding behaviors of 1 and 2 were studied by spectroscopic and viscosity measurements. The results indicate that both complexes strongly bind to calf‐thymus DNA in an intercalative mode, with DNA‐binding constants K~b~ of (1.7±0.4)⋅10^6^ M^−1^ and (2.6±0.2)⋅10^6^ M^−1^, respectively. The complexes 1 and 2 exhibit excellent DNA‐‘light switch’ performances, i.e., they do not (or extremely weakly) show luminescence in aqueous solution at room temperature but are strongly luminescent in the presence of DNA. In particular, the experimental results suggest that the ancillary ligands bpy and phen not only have a significant effect on the DNA‐binding affinities of 1 and 2 but also have a certain effect on their spectral properties. [Ru(phen)~2~(ppn)]^2+^(2) might be developed into a very prospective DNA‐‘light switch’ complex. To explain the DNA‐binding and spectral properties of 1 and 2, theoretical calculations were also carried out applying the DFT/TDDFT method.