uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Towards an artificial model for Photosystem II: A manganese(II,II) dimer covalently linked to ruthenium(II) tris-bipyridine via a tyrosine derivative
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
Show others and affiliations
2000 (English)In: Journal of Inorganic Biochemistry, ISSN 0162-0134, E-ISSN 1873-3344, Vol. 78, no 1, 15-22 p.Article in journal (Refereed) Published
Abstract [en]

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 kET > 1.0 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.

Place, publisher, year, edition, pages
2000. Vol. 78, no 1, 15-22 p.
Keyword [en]
ruthenium complexes, manganese dimer complexes, artificial photosynthesis, electron transfer, photosystem II, ELECTRON-TRANSFER, MNIIMNIII COMPLEXES, PHOTOSYNTHESIS, PROTEINS, CATALASE, SPECTRA, ENZYMES, SYSTEMS, REDOX
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-89494DOI: 10.1016/S0162-0134(99)00200-7PubMedID: 10714701OAI: oai:DiVA.org:uu-89494DiVA: diva2:161008
Available from: 2001-10-19 Created: 2001-10-19 Last updated: 2016-01-07
In thesis
1. Electron Transfer in Ruthenium-Manganese Complexes for Artificial Photosynthesis: Studies in Solution and on Electrode Surfaces
Open this publication in new window or tab >>Electron Transfer in Ruthenium-Manganese Complexes for Artificial Photosynthesis: Studies in Solution and on Electrode Surfaces
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In today’s society there is an increasing need for energy, an increase which for the most part is supplied by the use of fossil fuels. Fossil fuel resources are limited and their use has harmful effects on the environment, therefore the development of technologies that produce clean energy sources is very appealing. Natural photosynthesis is capable of converting solar energy into chemical energy through a series of efficient energy and electron transfer reactions with water as the only electron source. Thus, constructing an artificial system that uses the same principles to convert sunlight into electricity or storable fuels like hydrogen is one of the major forces driving artificial photosynthesis research.

This thesis describes supramolecular complexes with the intention of mimicking the electron transfer reactions of the donor side in Photosystem II, where a manganese cluster together with a tyrosine catalyses the oxidation of water. All complexes are based on Ru(II)-trisbipyridine as a photosensitizer that is covalently linked to electron donors like tyrosine or manganese. Photochemical reactions are studied with time-resolved transient absorption and emission measurements. Electrochemical techniques are used to study the electrochemical behavior, and different photoelectrochemical techniques are used to investigate the complexes adsorbed onto titanium dioxide surfaces. In all complexes, intramolecular electron transfer occurs from the linked donor to photo-oxidized Ru(III). It is also observed that coordinated Mn(II) quenches the excited state of Ru(II), a reaction that is found to be distance dependent. However, by modifying one of the complexes, its excited state properties can be tuned in a way that decreases the quenching and keeps the electron transfer properties. The obtained results are of significance for the development of multinuclear Ru-Mn complexes that are capable of multi-electron transfer.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2001. 69 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 669
Physics, Artificial photosynthesis, electron transfer, energy transfer, ruthenium, manganese, titanium dioxide, Fysik
National Category
Physical Sciences
Research subject
Physical Chemistry
urn:nbn:se:uu:diva-1468 (URN)91-554-5154-3 (ISBN)
Public defence
2001-11-09, The Svedberg Lecture Hall, Institute of Chemistry, Uppsala University, Uppsala, 10:15
Available from: 2001-10-19 Created: 2001-10-19Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Magnuson, AnnHammarström, LeifStyring, Stenbjörn
By organisation
Department of Physical ChemistryMolecular Biomimetics
In the same journal
Journal of Inorganic Biochemistry
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 415 hits
ReferencesLink to record
Permanent link

Direct link