Structural Studies of Oxomanganese Complexes for Water Oxidation Catalysis

Ivan Rivalta, Gary W. Brudvig, Victor S. Batista

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Citation (Scopus)

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 languageEnglish
Title of host publicationMolecular Water Oxidation Catalysis
Subtitle of host publicationA Key Topic for New Sustainable Energy Conversion Schemes
PublisherWiley Blackwell
Pages1-14
Number of pages14
Volume9781118413371
ISBN (Electronic)9781118698648
ISBN (Print)9781118413371
DOIs
Publication statusPublished - 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

Rivalta, I., Brudvig, G. W., & Batista, V. S. (2014). Structural Studies of Oxomanganese Complexes for Water Oxidation Catalysis. In Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes (Vol. 9781118413371, pp. 1-14). Wiley Blackwell. https://doi.org/10.1002/9781118698648.ch1