Singlet and triplet energy transfer processes in ruthenium(II) bipyridine complexes containing covalently bound

Singlet and tripler energy transfer processes in [Ru(bipy)(2)(4-methyl-4'-(2-arylethyl)-2,2'-bipyridine)](2+) have been investigated, where aryl = 2-naphthyl (Ru-Naph), 9-anthryl (Ru-Anth) and 1-pyrenyl (Ru-Pyrene). In each case fluorescence from the aromatic chromophore is quenched by intramolecular energy transfer to Ru(bipy)(3)(2+) whereas emission from the Ru(bipy)(3)(2+) moiety is controlled by the relative energy of its (3)MLCT state and the pendant arene tripler states, Consequently (3)MLCT emission is observed for Ru-Naph whereas it is fully quenched for Ru-Anth. When the two states are isoenergetic (e.g. Ru-Pyrene) a long-lived (3)MLCT emission is observed which decays with the same lifetime as the pyrene tripler state (5.23 mu s).