Towards an artificial model for Photosystem II: a manganese(II,II) dimer covalently linked to ruthenium(II) tris-bipyridine via a tyrosine derivative
| Autor: | Jerker Mårtensson, Denis LeGourriérec, Leif Hammarström, Stenbjörn Styring, Markus Tamm, Malin Abrahamsson, Ann Magnuson, Björn Åkermark, Ping Huang Kenéz, Mary Katherine Raymond, Gunnar Stenhagen, Licheng Sun |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
inorganic chemicals
Models Molecular Dimer Photosynthetic Reaction Center Complex Proteins chemistry.chemical_element Electrons Manganese Spectrometry Mass Fast Atom Bombardment Photochemistry Biochemistry Gas Chromatography-Mass Spectrometry Artificial photosynthesis Inorganic Chemistry Bipyridine chemistry.chemical_compound Electron transfer 2 2'-Dipyridyl Coordination Complexes Organometallic Compounds Nuclear Magnetic Resonance Biomolecular chemistry.chemical_classification Photolysis Molecular Structure Electron Spin Resonance Spectroscopy Photosystem II Protein Complex P680 Hydrogen Bonding Electron acceptor Ruthenium chemistry Tyrosine Indicators and Reagents Dimerization |
| Zdroj: | Journal of inorganic biochemistry. 78(1) |
| ISSN: | 0162-0134 |
| Popis: | 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 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 kET1.0 x 10(7) 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. |
| Databáze: | OpenAIRE |
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