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Photophysics of an Intramolecular Hydrogen-Evolving Ru-Pd Photocatalyst

Tschierlei, Stefanie; Presselt, Martin; Kuhnt, Christian; Yartsev, Arkady LU ; Pascher, Torbjörn LU ; Sundström, Villy LU ; Karnahl, Michael; Schwalbe, Matthias; Schaefer, Bernhard and Rau, Sven, et al. (2009) In Chemistry: A European Journal 15(31). p.7678-7688
Abstract
Photoinduced electron-transfer processes within a precatalyst for intramolecular hydrogen evolution [(tbbpy)(2)Ru(tpphz)PdCl2](2+) (RuPd; tbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine, tpphz = tetrapyrido[3,2-a:2',3'c:3 '',2 '',-h:2"',3'''-j]phenazine) have been studied by resonance Raman and ultrafast time-resolved absorption spectroscopy. By comparing the photophysics of the [(tbbpy)(2)Ru(tpphz)](2+) subunit Ru with that of the supramolecular catalyst RuPd, the individual electron-transfer steps are assigned to kinetic components, and their dependence on solvent is discussed. The resonance Raman data reveal that the initial excitation of the molecular ensemble is spread over the terminal tbbpy and the tpphz ligands. The subsequent... (More)
Photoinduced electron-transfer processes within a precatalyst for intramolecular hydrogen evolution [(tbbpy)(2)Ru(tpphz)PdCl2](2+) (RuPd; tbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine, tpphz = tetrapyrido[3,2-a:2',3'c:3 '',2 '',-h:2"',3'''-j]phenazine) have been studied by resonance Raman and ultrafast time-resolved absorption spectroscopy. By comparing the photophysics of the [(tbbpy)(2)Ru(tpphz)](2+) subunit Ru with that of the supramolecular catalyst RuPd, the individual electron-transfer steps are assigned to kinetic components, and their dependence on solvent is discussed. The resonance Raman data reveal that the initial excitation of the molecular ensemble is spread over the terminal tbbpy and the tpphz ligands. The subsequent excited-state relaxation of both Ru and RuPd on the picosecond timescale involves formation of the phenazine-centered intraligand charge-transfer state, which in RuPd precedes formation of the Pd-reduced state. The photoreaction in the heterodinuclear supramolecular complex is completed on a subnanosecond timescale. Taken together, the data indicate that mechanistic investigations must focus on potential rate-determining steps other than electron transfer between the photoactive center and the Pd unit. Furthermore, structural variations should be directed towards increasing the directionality of electron transfer and the stability of the charge-separated states. (Less)
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organization
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publication status
published
subject
keywords
spectroscopy, time-resolved, ruthenium, photophysics, electron transfer, palladium
in
Chemistry: A European Journal
volume
15
issue
31
pages
7678 - 7688
publisher
John Wiley & Sons
external identifiers
  • wos:000268845000021
  • scopus:67949106339
ISSN
1521-3765
DOI
10.1002/chem.200900457
language
English
LU publication?
yes
id
71197ade-4f13-44fa-863c-cd3856f4ec5d (old id 1478348)
date added to LUP
2009-09-29 10:14:37
date last changed
2017-12-10 04:18:45
@article{71197ade-4f13-44fa-863c-cd3856f4ec5d,
  abstract     = {Photoinduced electron-transfer processes within a precatalyst for intramolecular hydrogen evolution [(tbbpy)(2)Ru(tpphz)PdCl2](2+) (RuPd; tbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine, tpphz = tetrapyrido[3,2-a:2',3'c:3 '',2 '',-h:2"',3'''-j]phenazine) have been studied by resonance Raman and ultrafast time-resolved absorption spectroscopy. By comparing the photophysics of the [(tbbpy)(2)Ru(tpphz)](2+) subunit Ru with that of the supramolecular catalyst RuPd, the individual electron-transfer steps are assigned to kinetic components, and their dependence on solvent is discussed. The resonance Raman data reveal that the initial excitation of the molecular ensemble is spread over the terminal tbbpy and the tpphz ligands. The subsequent excited-state relaxation of both Ru and RuPd on the picosecond timescale involves formation of the phenazine-centered intraligand charge-transfer state, which in RuPd precedes formation of the Pd-reduced state. The photoreaction in the heterodinuclear supramolecular complex is completed on a subnanosecond timescale. Taken together, the data indicate that mechanistic investigations must focus on potential rate-determining steps other than electron transfer between the photoactive center and the Pd unit. Furthermore, structural variations should be directed towards increasing the directionality of electron transfer and the stability of the charge-separated states.},
  author       = {Tschierlei, Stefanie and Presselt, Martin and Kuhnt, Christian and Yartsev, Arkady and Pascher, Torbjörn and Sundström, Villy and Karnahl, Michael and Schwalbe, Matthias and Schaefer, Bernhard and Rau, Sven and Schmitt, Michael and Dietzek, Benjamin and Popp, Juergen},
  issn         = {1521-3765},
  keyword      = {spectroscopy,time-resolved,ruthenium,photophysics,electron transfer,palladium},
  language     = {eng},
  number       = {31},
  pages        = {7678--7688},
  publisher    = {John Wiley & Sons},
  series       = {Chemistry: A European Journal},
  title        = {Photophysics of an Intramolecular Hydrogen-Evolving Ru-Pd Photocatalyst},
  url          = {http://dx.doi.org/10.1002/chem.200900457},
  volume       = {15},
  year         = {2009},
}