Mimicking the electron donor side of Photosystem II in artificial photosynthesis.
This review focuses on our recent efforts in synthetic ruthenium-tyrosine-manganese chemistry mimicking the donor side reactions of Photosystem II. Tyrosine and tryptophan residues were linked to ruthenium photosensitizers, which resulted in model complexes for proton-coupled electron transfer from amino acids. A new mechanistic model was proposed and used to design complexes in which the mechanism could be switched between concerted and step-wise proton-coupled electron transfer. Moreover, a manganese dimer linked to a ruthenium complex could be oxidized in three successive steps, from Mn (2) (II,II) to Mn (2) (III,IV) by the photo-oxidized ruthenium sensitizer. This was possible thanks to a charge compensating ligand exchange in the manganese complex. Detailed studies of the ligand exchange suggested that at high water concentrations, each oxidation step is coupled to a proton-release of water-derived ligands, analogous to the oxidation steps of the manganese cluster of Photosystem II.
Lomoth
Reiner
R
Department of Physical Chemistry, Uppsala University, Box 579, 751 23 Uppsala, Sweden.
Magnuson
Ann
A
Sjödin
Martin
M
Huang
Ping
P
Styring
Stenbjörn
S
Hammarström
Leif
L
D032701:Biomimetics; D004583:Electrons; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism*; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism
D045332:Photosystem II Protein Complex; D014443:Tyrosine; D014364:Tryptophan