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

Timothy L. Easun, Wassim Z. Alsindi, Michael Towrie, Kate L. Ronayne, Xue Zhong Sun, Michael D. Ward, Michael W. George

Research output: Journal PublicationArticlepeer-review

33 Citations (Scopus)

Abstract

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 (±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.

Original languageEnglish
Pages (from-to)5071-5078
Number of pages8
JournalInorganic Chemistry
Volume47
Issue number12
DOIs
Publication statusPublished - 16 Jun 2008
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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