New DNA-binding ruthenium(II) complexes as photo-reagents for mononucleotides and DNA

✍ Scribed by Cécile Moucheron; Andrée Kirsch-De Mesmaeker

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 162 KB
• Volume: 11
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199808/09)11:8/9<577::aid-poc53>3.0.co;2-x

✦ Synopsis

The spectroscopic properties of two photoprobes for DNA, Ru(phen) 2 (PHEHAT) 2 and Ru(TAP) 2 (PHEHAT) 2 (phen = 1,10-phenanthroline, TAP = 1,4,5,8-tetraazaphenanthrene, PHEHAT = 1,10phenanthrolino[5,6-b]-1,4,5,8,9,12-hexaazatriphenylene), were examined and compared with those of complexes containing either an extended planar ligand (DPPZ) or p-acceptor ligands. The orbitals involved in the absorption and emission processes for Ru(phen) 2 (PHEHAT) 2 imply the PHEHAT ligand, whereas the chromophore and luminophore for Ru(TAP) 2 (PHEHAT) 2 are associated with the Ru(II) → TAP MLCT transition. The two complexes exhibit completely different behaviour in the presence of DNA. Whereas Ru(phen) 2 (PHEHAT) 2 , which does not emit in water, luminesces upon intercalation between the DNA base pairs, the luminescence of Ru(TAP) 2 (PHEHAT) 2 is quenched by binding to DNA. Emission quenching is also observed in the presence of GMP, with a quenching rate constant of 1.25 Â 10 9 l mol À1 s À1 . This strongly suggests the presence of a photoinduced electron transfer from the guanine residues of GMP or DNA to the excited complex and leads to the conclusion that this complex is a good DNA photoreagent.