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Intramolecular Electron Transfer from Manganese(II) Coordinatively Linked to a Photogenerated Ru(III)-Polypyridine Complex: A Kinetic Analysis

Berglund-Baudin, Helena; Sun, Licheng; Davidov, Roman; Sundahl, Mikael; Styring, Stenbjörn LU ; Åkermark, Björn; Almgren, Mats and Hammarström, Lef (1998) In The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory 102(15). p.2512-2518
Abstract
For further investigations in the field of artificial photosynthesis, a model compound, 1, has been developed to mimic the electron-transfer steps from the manganese cluster to P680+ in photosystem II. In this model compound the photosensitizer ruthenium(II)-trisbipyridyl was linked to a manganese(II) ion through a bridging ligand. Photoexcitation of 1 in the presence of the electron acceptor methyl viologen (MV2+) lead to electron transfer from the Ru moiety to MV2+. Laser flash photolysis experiments at different concentrations of 1 were performed in order to follow the subsequent reduction of the photooxidized Ru(III) species. A kinetic model, taking different parallel reactions into account, could explain the experimental data. It was... (More)
For further investigations in the field of artificial photosynthesis, a model compound, 1, has been developed to mimic the electron-transfer steps from the manganese cluster to P680+ in photosystem II. In this model compound the photosensitizer ruthenium(II)-trisbipyridyl was linked to a manganese(II) ion through a bridging ligand. Photoexcitation of 1 in the presence of the electron acceptor methyl viologen (MV2+) lead to electron transfer from the Ru moiety to MV2+. Laser flash photolysis experiments at different concentrations of 1 were performed in order to follow the subsequent reduction of the photooxidized Ru(III) species. A kinetic model, taking different parallel reactions into account, could explain the experimental data. It was shown that the major part of the photooxidized Ru(III) created was reduced again by intramolecular electron transfer from the attached Mn(II), with a rate constant of 1.8 × 105 s-1. However, Mn(II) was partially dissociated from 1, giving a fraction of Ru(III) without Mn(II) attached. In these complexes electron transfer could occur only after a rate-limiting reassociation of Mn(II), with a rate constant 2.9 × 109 M-1 s-1. In the analysis of the data, the fraction of dissociated Mn(II) could be determined independently at each concentration of 1, utilizing the fact that bound Mn(II) quenched the excited state, probably by energy transfer. (Less)
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author
organization
publishing date
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Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
volume
102
issue
15
pages
2512 - 2518
publisher
The American Chemical Society
external identifiers
  • scopus:0001085111
ISSN
1520-5215
DOI
10.1021/jp9731866
language
English
LU publication?
yes
id
4272ca44-69cb-42e9-847a-485fa9d41639 (old id 125468)
date added to LUP
2007-07-04 12:02:02
date last changed
2017-08-06 04:23:00
@article{4272ca44-69cb-42e9-847a-485fa9d41639,
  abstract     = {For further investigations in the field of artificial photosynthesis, a model compound, 1, has been developed to mimic the electron-transfer steps from the manganese cluster to P680+ in photosystem II. In this model compound the photosensitizer ruthenium(II)-trisbipyridyl was linked to a manganese(II) ion through a bridging ligand. Photoexcitation of 1 in the presence of the electron acceptor methyl viologen (MV2+) lead to electron transfer from the Ru moiety to MV2+. Laser flash photolysis experiments at different concentrations of 1 were performed in order to follow the subsequent reduction of the photooxidized Ru(III) species. A kinetic model, taking different parallel reactions into account, could explain the experimental data. It was shown that the major part of the photooxidized Ru(III) created was reduced again by intramolecular electron transfer from the attached Mn(II), with a rate constant of 1.8 × 105 s-1. However, Mn(II) was partially dissociated from 1, giving a fraction of Ru(III) without Mn(II) attached. In these complexes electron transfer could occur only after a rate-limiting reassociation of Mn(II), with a rate constant 2.9 × 109 M-1 s-1. In the analysis of the data, the fraction of dissociated Mn(II) could be determined independently at each concentration of 1, utilizing the fact that bound Mn(II) quenched the excited state, probably by energy transfer.},
  author       = {Berglund-Baudin, Helena and Sun, Licheng and Davidov, Roman and Sundahl, Mikael and Styring, Stenbjörn and Åkermark, Björn and Almgren, Mats and Hammarström, Lef},
  issn         = {1520-5215},
  language     = {eng},
  number       = {15},
  pages        = {2512--2518},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory},
  title        = {Intramolecular Electron Transfer from Manganese(II) Coordinatively Linked to a Photogenerated Ru(III)-Polypyridine Complex: A Kinetic Analysis},
  url          = {http://dx.doi.org/10.1021/jp9731866},
  volume       = {102},
  year         = {1998},
}