Unusual photophysical switching in a Ru(II) diimine DNA probe caused by amide functionalisation

Whereas the complex [Ru(phen)(2)Medpq](2+) (phen = 1,10-phenanthroline; Medpq = 2-methyldipyrido[3,2- f:2',3'-h]quinoxaline) is luminescent in both aqueous and nonaqueous solutions, [Ru(phen)(2)dpqa](2+) (2-pentylamidodipyrido[ 3,2-f: 2', 3'-h]-quinoxaline) does not emit in water but does so strongly in organic solvents or when bound to DNA - suggesting its use as a photochemical and photophysical probe for nucleic acids.