Localized states in reduced and excited-state ruthenium(II) terpyridyls

Electron transfer triggered sulfoxide isomerization in ruthenium and osmium complexes

“…Naturally, this prompted the determination of the quantum yields of isomerization (Φ S→O ) for these complexes ( Table 1). The work of Ford, McMillin and others suggest that the quantum yield should be similar to those found for photosubstitution, reflecting the presumed role of the LF states in this process [34][35][36][37]47]. For [Ru(tpy)(bpy)(dmso)] 2+ , Φ S→O = 0.024(±0.02) in propylene carbonate.…”

“…In addition, the sharp peak at 550 nm diminishes in intensity and shifts to lower energy. The features in the bleach region correspond to formation of the 3 MLCT state, whereas the absorptions in the red are attributable to * ← * transitions on the reduced ligand and LMCT transitions [34,51,52]. The early time progression affects both of these spectral regions and it seems reasonable to assign this 2.4 ± 0.2 ps time constant to intramolecular vibrational relaxation following the 1 MLCT to 3 MLCT intersystem crossing.…”

“…In the 1980s, the work from a number of laboratories demonstrated that photosubstitution of CH 3 CN on [Ru(tpy)(bpy)(CN 3 CN)] 2+ by pyridine in acetonitrile solution occurred with a quantum yield of 0.0014 (±0.02) [34][35][36][37]. Mechanistic studies suggested a dissociative mechanism involving population of the ligand field (LF) states.…”

Enhanced DNA photocleavage properties of Ru(II) terpyridine complexes upon incorporation of methylphenyl substituted terpyridine and/or the polyazine bridging ligand dpp (2,3-bis(2-pyridyl)pyrazine)

“…The complex, [Ru(tpy) 2 ] 2+ (where tpy = 2,2 0 :6 0 ,2 00 -terpyridine), exhibits less favorable photophysical properties with a very short lifetime of the 3 MLCT (metal to ligand charge transfer) excited state due to the thermal population of the 3 LF (ligand field) excited state [3][4][5][6]. The thermal accessibility of the ligand field state is due to the unfavorable bite angle associated with tpy type ligand for octahedral coordination, lowering the energy of the ligand field state.…”

Effects of substituent on the DNA-binding of ruthenium(II) complexes containing asymmetric tridentate intercalative ligands

“…In contrast, the oxidation potential of complex 1 is more negative than that of complex 2 due to the electron-pushing substituent in complex 1 increasing the electron density on the metal Ru II ion. The first reduction can be assigned to a main ligand (ptmi, pti, and ptni)-centered reduction, and the last two are the characteristic of the ligand tpy [31,32].…”