Aryl-modified ruthenium bis(terpyridine) complexes:: Quantum yield of 1O2 generation and photocleavage on DNA

Six Ru(II)bis(tpy) (tpy = 2,2':6.2-terpyridine) complexes, functionalized with one or two 2-naphthyl, 1-pyrenyl, or 9-anthracenyl at 4'-position of terpyridine respectively, were investigated with emphasis on their O-1(2) generation quantum yields and photocleavage capabilities on DNA. For naphthyl and pyrenyl modified complexes, the lowest energy excited state is (MLCT)-M-3, and therefore they behave very similarly to the parent complex, [Ru(tPY)(2)](2+). having very low O-1(2) generation quantum yields. In contrast, for anthracenyl modified complexes, the lowest energy excited state is anthracene-localized (3)pi pi(*) state, as a result, they exhibit extremely high O-1(2) generation quantum yields (0.96 and 0.71 for bis- and mono-substituted complexes, respectively) and potent photodamage abilities on calf thymus DNA, suggesting their promising applications in O-1(2)-involved processes, such as DNA photocleavage. (c) 2005 Elsevier B.V. All rights reserved.