Direct Observation of Temperature-Dependent Excited-State Equilibrium in Dinuclear Ruthenium Terpyridine Complexes Bearing Electron-Poor Bridging Ligands

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• 作者：Ronald Siebert ; Christoph Hunger ; Julien Guthmuller ; Florian Schlu虉tter ; Andreas Winter ; Ulrich S. Schubert ; Leticia Gonza虂lez ; Benjamin Dietzek ; Ju虉rgen Popp
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：June 30, 2011
• 年：2011
• 卷：115
• 期：25
• 页码：12677-12688
• 全文大小：1170K
• 年卷期：v.115,no.25(June 30, 2011)
• ISSN：1932-7455

文摘

Dinuclear ruthenium鈥搕erpyridine complexes, bearing highly conjugated bridging ligands, have been investigated by time- and temperature-dependent emission spectroscopy, femtosecond time-resolved transient-absorption spectroscopy, and time-dependent density functional theory calculations. These terpyridine compounds show room-temperature emission around 640 nm and lifetimes between 140 and 230 ns. Reduction of the temperature results in an overall increase of emission lifetime. However, the specific temperature dependence of the luminescence lifetime depends on the particular bridging ligand. This ligand-specific behavior is found to correlate with the electronic structure of the ligand, which indicates an excited-state equilibrium between a highly delocalized ³MLCT and a ligand-centered ³蟺蟺* excited-state. Due to this equilibrium a prolonged room-temperature lifetime is observed.