Abstract
Photosynthetic water-splitting into O2, protons and electrons is a thermodynamically demanding 4-electron oxidation reaction catalyzed by the oxygen-evolving complex (OEC) of photosystem II (PSII). Recent breakthroughs in X-ray crystallography have resolved the structure of PSII at 1.9 Å resolution, providing fundamental insights on the structure of the OEC, including characterization of the oxomanganese cluster and its ligation scheme by water and proteinaceous side chains. However, simulations of high-resolution extended X-ray absorption fine structure (EXAFS) spectra based on the X-ray model and direct comparisons with EXAFS measurements have suggested reductive damage caused by the high doses of X-ray radiation. Therefore, density functional theory (DFT) and quantum mechanics/molecular mechanics (QM/MM) hybrid methods have been combined to obtain a model OEC in the dark-adapted state most consistent with both high resolution spectroscopy and X-ray diffraction data. DFT studies of biomimetic oxomanganese complexes, including the analysis of O2 evolution catalyzed by the Mn terpy dimer [H2O(terpy)MnIII(μ-O)2MnIV(terpy)OH2]3+ (1, terpy=2,2′:6′,2″-terpyridine), have provided valuable insights on fundamental aspects of the water splitting mechanism. These computational studies suggest that acid/base cofactors present in the buffer environment surrounding the oxomanganese core play a crucial role in the kinetics of O-O bond formation. Similar regulation of catalytic activity is expected to be induced by acid/base cofactors in PSII surrounding the OEC, or by the electrolyte buffer in artificial photosynthetic devices based on biomimetic oxomanganese complexes bound to semiconductor surfaces.
| Original language | English |
|---|---|
| Title of host publication | Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes |
| Publisher | Wiley Blackwell |
| Pages | 1-14 |
| Number of pages | 14 |
| ISBN (Print) | 9781118698648, 9781118413371 |
| DOIs | |
| Publication status | Published - Jun 3 2014 |
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Keywords
- Artificial photosynthesis
- DFT
- Oxomanganese complex
- Photosystem II
- QM/MM
- Water oxidation
ASJC Scopus subject areas
- Engineering(all)
- Materials Science(all)
Cite this
Structural Studies of Oxomanganese Complexes for Water Oxidation Catalysis. / Rivalta, Ivan; Brudvig, Gary W; Batista, Victor S.
Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes. Wiley Blackwell, 2014. p. 1-14.Research output: Chapter in Book/Report/Conference proceeding › Chapter
}
TY - CHAP
T1 - Structural Studies of Oxomanganese Complexes for Water Oxidation Catalysis
AU - Rivalta, Ivan
AU - Brudvig, Gary W
AU - Batista, Victor S.
PY - 2014/6/3
Y1 - 2014/6/3
N2 - Photosynthetic water-splitting into O2, protons and electrons is a thermodynamically demanding 4-electron oxidation reaction catalyzed by the oxygen-evolving complex (OEC) of photosystem II (PSII). Recent breakthroughs in X-ray crystallography have resolved the structure of PSII at 1.9 Å resolution, providing fundamental insights on the structure of the OEC, including characterization of the oxomanganese cluster and its ligation scheme by water and proteinaceous side chains. However, simulations of high-resolution extended X-ray absorption fine structure (EXAFS) spectra based on the X-ray model and direct comparisons with EXAFS measurements have suggested reductive damage caused by the high doses of X-ray radiation. Therefore, density functional theory (DFT) and quantum mechanics/molecular mechanics (QM/MM) hybrid methods have been combined to obtain a model OEC in the dark-adapted state most consistent with both high resolution spectroscopy and X-ray diffraction data. DFT studies of biomimetic oxomanganese complexes, including the analysis of O2 evolution catalyzed by the Mn terpy dimer [H2O(terpy)MnIII(μ-O)2MnIV(terpy)OH2]3+ (1, terpy=2,2′:6′,2″-terpyridine), have provided valuable insights on fundamental aspects of the water splitting mechanism. These computational studies suggest that acid/base cofactors present in the buffer environment surrounding the oxomanganese core play a crucial role in the kinetics of O-O bond formation. Similar regulation of catalytic activity is expected to be induced by acid/base cofactors in PSII surrounding the OEC, or by the electrolyte buffer in artificial photosynthetic devices based on biomimetic oxomanganese complexes bound to semiconductor surfaces.
AB - Photosynthetic water-splitting into O2, protons and electrons is a thermodynamically demanding 4-electron oxidation reaction catalyzed by the oxygen-evolving complex (OEC) of photosystem II (PSII). Recent breakthroughs in X-ray crystallography have resolved the structure of PSII at 1.9 Å resolution, providing fundamental insights on the structure of the OEC, including characterization of the oxomanganese cluster and its ligation scheme by water and proteinaceous side chains. However, simulations of high-resolution extended X-ray absorption fine structure (EXAFS) spectra based on the X-ray model and direct comparisons with EXAFS measurements have suggested reductive damage caused by the high doses of X-ray radiation. Therefore, density functional theory (DFT) and quantum mechanics/molecular mechanics (QM/MM) hybrid methods have been combined to obtain a model OEC in the dark-adapted state most consistent with both high resolution spectroscopy and X-ray diffraction data. DFT studies of biomimetic oxomanganese complexes, including the analysis of O2 evolution catalyzed by the Mn terpy dimer [H2O(terpy)MnIII(μ-O)2MnIV(terpy)OH2]3+ (1, terpy=2,2′:6′,2″-terpyridine), have provided valuable insights on fundamental aspects of the water splitting mechanism. These computational studies suggest that acid/base cofactors present in the buffer environment surrounding the oxomanganese core play a crucial role in the kinetics of O-O bond formation. Similar regulation of catalytic activity is expected to be induced by acid/base cofactors in PSII surrounding the OEC, or by the electrolyte buffer in artificial photosynthetic devices based on biomimetic oxomanganese complexes bound to semiconductor surfaces.
KW - Artificial photosynthesis
KW - DFT
KW - Oxomanganese complex
KW - Photosystem II
KW - QM/MM
KW - Water oxidation
UR - http://www.scopus.com/inward/record.url?scp=84926476408&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84926476408&partnerID=8YFLogxK
U2 - 10.1002/9781118698648.ch1
DO - 10.1002/9781118698648.ch1
M3 - Chapter
SN - 9781118698648
SN - 9781118413371
SP - 1
EP - 14
BT - Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes
PB - Wiley Blackwell
ER -