Fast, through-bond mediated energy transfer from Ir(III) to Ru(II) in di- and tetranuclear heterometallic assemblies: elucidation of a two-step Ir - Ir - Ru energy transfer process (Articolo in rivista)

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  • Fast, through-bond mediated energy transfer from Ir(III) to Ru(II) in di- and tetranuclear heterometallic assemblies: elucidation of a two-step Ir - Ir - Ru energy transfer process (Articolo in rivista) (literal)
Anno
  • 2007-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1039/b608227k (literal)
Alternative label
  • C. Sabatini; A. Barbieri; F. Barigelletti; K. J. Arm; J. A. G. Williams (2007)
    Fast, through-bond mediated energy transfer from Ir(III) to Ru(II) in di- and tetranuclear heterometallic assemblies: elucidation of a two-step Ir - Ir - Ru energy transfer process
    in Photochemical & photobiological sciences (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • C. Sabatini; A. Barbieri; F. Barigelletti; K. J. Arm; J. A. G. Williams (literal)
Pagina inizio
  • 397 (literal)
Pagina fine
  • 405 (literal)
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  • 6 (literal)
Rivista
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  • In: Photochemical & Photobiological Sciences, vol. 6 pp. 397 - 405. RSC- The Royal Society of Chemistry and Owner Societies, 2007. (literal)
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  • 4 (literal)
Note
  • ISI Web of Science (WOS) (literal)
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  • 1. CNR, ISOF, I-40129 Bologna, Italy 2. Univ Durham, Dept Chem, Durham DH1 3LE, England (literal)
Titolo
  • Fast, through-bond mediated energy transfer from Ir(III) to Ru(II) in di- and tetranuclear heterometallic assemblies: elucidation of a two-step Ir - Ir - Ru energy transfer process (literal)
Abstract
  • Energy transfer processes triggered by light excitation (exc = 278 nm) have been investigated in a heterometallic complex, Ir-Ru, and in a tetranuclear assembly, (IrF4)2-Ir-Ru, containing iridium(III) and ruthenium(II) centres {Ir represents the unit [(ppy)2Ir(bpy)]+, Ru is [Ru(bpy)3]2+ and IrF4 is [Ir(F2ppy)2(4-bpy-C6H4-)]+ (ppy = 2-phenylpyridyl, bpy = 2,2-bipyridyl)}. In the dinuclear species, the two metallic components are linked by a biphenylene bridge connected between the 4-positions of the bpy of Ir and one of the three bpy's of Ru. The tetrametallic species comprises the dimeric unit appended with IrF4 units at the 4-positions of the ppy ligands. For both the dinuclear and tetranuclear complexes, the metal centers are held at fixed distances by the interposed phenylene bridges. We have obtained the optical (absorption and emission) properties for the mononuclear species IrF4, Ir and Ru and for the polymetallic species Ir-Ru and (IrF4)2-Ir-Ru. For Ir-Ru, the Ir Ru energy transfer step is exothermic by ca. 0.22 eV, based on the emission energies of the respective mononuclear components at 77 K. In turn, within (IrF4)2-Ir-Ru, the excited state energy of IrF4 is ca. 0.26 eV higher than Ir. By using exc = 278 nm, it is possible to predominantly excite the iridium-based units of both Ir-Ru and (IrF4)2-Ir-Ru. For both cases, energy transfer is found to be fast and efficient with ken 2 × 108 s-1, leading to detectable emission only from the Ru component both at room temperature and at 77 K. In particular, for (IrF4)2-Ir-Ru, based on the evaluated intermetallic distances (e.g. 28.5 Å for the shortest IrF4-Ru distance) and the overlap integrals of donor and acceptor units, the observed energy transfer is too fast to be accounted for by through-space Förster transfer. In this species, energy transfer probably occurs in a two-step process, IrF4IrRu, both steps involving a through-bond Dexter mechanism. (literal)
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