Towards an artificial model for Photosystem II: A manganese(II,II) dimer covalently linked to ruthenium(II) tris-bipyridine via a tyrosine derivative

Licheng Sun, Mary Katherine Raymond, Ann Magnuson, Denis Legourriérec, Markus Tamm, Malin Abrahamsson, Ping Huang Kenéz, Jerker Mårtensson, Gunnar Stenhagen, Leif Hammarström, Stenbjörn Styring, Björn Åkermark

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Abstract

In order to model the individual electron transfer steps from the manganese cluster to the photooxidized sensitizer P680+ in Photosystem II (PS II) in green plants, the supramolecular complex 4 has been synthesized. In this complex, a ruthenium(II) tris-bipyridine type photosensitizer has been linked to a manganese(II) dimer via a substituted L-tyrosine, which bridges the manganese ions. The trinuclear complex 4 was characterized by electron paramagnetic resonance (EPR) and electrospray ionization mass spectrometry (ESI-MS). The excited state lifetime of the the ruthenium tris-bipyridine moiety in 4 was found to be about 110 ns in acetonitrile. Using flash photolysis in the presence of an electron acceptor (methylviologen), it was demonstrated that in the supramolecular complex 4 an electron was transferred from the excited state of the ruthenium tris-bipyridine moiety to methylviologen, forming a methylviologen radical and a ruthenium(III) tris-bipyridine moiety. Next, the Ru(III) species retrieved the electron from the manganese(II/II) dimer in an intramolecular electron transfer reaction with a rate constant k(ET)>1.0x107 s-1, generating a manganese(II/III) oxidation state and regenerating the ruthenium(II) photosensitizer. This is the first example of intramolecular electron transfer in a supramolecular complex, in which a manganese dimer is covalently linked to a photosensitizer via a tyrosine unit, in a process which mimics the electron transfer on the donor side of PS II. Copyright (C) 1999 Elsevier Science Inc.

Original languageEnglish
Pages (from-to)15-22
Number of pages8
JournalJournal of Inorganic Biochemistry
Volume78
Issue number1
DOIs
Publication statusPublished - Jan 15 2000

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Keywords

  • Artificial photosynthesis
  • Electron transfer
  • Manganese dimer complexes
  • Photosystem II
  • Ruthenium complexes

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry

Cite this

Sun, L., Raymond, M. K., Magnuson, A., Legourriérec, D., Tamm, M., Abrahamsson, M., Huang Kenéz, P., Mårtensson, J., Stenhagen, G., Hammarström, L., Styring, S., & Åkermark, B. (2000). Towards an artificial model for Photosystem II: A manganese(II,II) dimer covalently linked to ruthenium(II) tris-bipyridine via a tyrosine derivative. Journal of Inorganic Biochemistry, 78(1), 15-22. https://doi.org/10.1016/S0162-0134(99)00200-7