1. Structural Studies of Oxomanganese Complexes for Water Oxidation Catalysis

  1. Antoni Llobet
  1. Ivan Rivalta,
  2. Gary W. Brudvig and
  3. Victor S. Batista

Published Online: 18 APR 2014

DOI: 10.1002/9781118698648.ch1

Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes

Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes

How to Cite

Rivalta, I., Brudvig, G. W. and 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 (ed A. Llobet), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9781118698648.ch1

Editor Information

  1. Institute of Chemical Research of Catalonia, Tarragona, Spain

Author Information

  1. Department of Chemistry, Yale University, New Haven, CT, USA

Publication History

  1. Published Online: 18 APR 2014
  2. Published Print: 16 MAY 2014

ISBN Information

Print ISBN: 9781118413371

Online ISBN: 9781118698648

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Keywords:

  • Water oxidation;
  • photosystem II;
  • oxomanganese complex;
  • artificial photosynthesis;
  • DFT;
  • QM/MM

Summary

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.