Photoinduced Energy Transfer in a Conformationally Flexible Re(I)/Ru(II) Dyad Probed by Time-Resolved Infrared Spectroscopy: Effects of Conformation and Spatial Localization of Excited States
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- 作者：Timothy L. Easun ; Wassim Z. Alsindi ; Michael Towrie ; Kate L. Ronayne ; Xue-Zhong Sun ; Michael D. Ward ; Michael W. George
- 刊名：Inorganic Chemistry
- 出版年：2008
- 出版时间：June 16, 2008
- 年：2008
- 卷：47
- 期：12
- 页码：5071 - 5078
- 全文大小：1591K
- 年卷期：v.47,no.12(June 16, 2008)
- ISSN：1520-510X
文摘
The dyad RuLRe contains {Re(bpy)(CO)3Cl} and {Ru(bpy)(bpyam)2}2+ termini (bpy = 2,2′-bipyridine; bpyam = 4,4′-diethylamido-2,2′-bipyridine) separated by a flexible ethylene spacer. Luminescence studies reveal the expected Re → Ru photoinduced energy transfer, with partial quenching of ReI-based triplet metal-to-ligand charge-transfer (3MLCT) luminescence and consequent sensitization of the RuII-based 3MLCT luminescence, which has a component with a grow-in lifetime of 0.76 (
lusmn.gif">0.2) ns. The presence of IR-active spectroscopic handles on both termini [CO ligands directly attached to ReI and amide carbonyl substituents on the bpy ligands coordinated to RuII] allowed the excited-state dynamics to be studied by time-resolved IR (TRIR) spectroscopy in much more detail than allowed by luminescence methods. A combination of picosecond- and nanosecond-time-scale TRIR studies revealed the presence of at least three distinct Re → Ru energy-transfer processes, with lifetimes of ca. 20 ps and 1 and 13 ns. This complex behavior occurs because of a combination of two different Ru-based 3MLCT states (Ru → L and Ru → bpyam), which are sensitized by energy transfer from the ReI donor at different rates; and the presence of at least two conformers of the flexible molecule RuLRe, which have different Re···Ru separations.
lusmn.gif">0.2) ns. The presence of IR-active spectroscopic handles on both termini [CO ligands directly attached to ReI and amide carbonyl substituents on the bpy ligands coordinated to RuII] allowed the excited-state dynamics to be studied by time-resolved IR (TRIR) spectroscopy in much more detail than allowed by luminescence methods. A combination of picosecond- and nanosecond-time-scale TRIR studies revealed the presence of at least three distinct Re → Ru energy-transfer processes, with lifetimes of ca. 20 ps and 1 and 13 ns. This complex behavior occurs because of a combination of two different Ru-based 3MLCT states (Ru → L and Ru → bpyam), which are sensitized by energy transfer from the ReI donor at different rates; and the presence of at least two conformers of the flexible molecule RuLRe, which have different Re···Ru separations.