Electronic structure of the CaMn4O5 cluster in the PSII system refined to the 1.9 Å X-ray resolution. Possible mechanisms of photosynthetic water splitting

S. Yamanaka, K. Kanda, H. Isobe, K. Nakata, Y. Umena, K. Kawakami, J. R. Shen, N. Kamiya, M. Okumura, T. Takada, H. Nakamura, K. Yamaguchi

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Broken-symmetry (BS) UB3LYP calculations have been performed for the CaMn4O5 cluster (1) in the oxygen-evolving complex (OEC) of the PSII system refined to 1.9 Å resolution by Umena, Kawakami, Kamiya, Shen to elucidate its electronic structure that is crucial for consideration of possible mechanisms of photosynthetic water splitting. Our UB3LYP computations have elucidated the position of protonated oxygen of the CaMn(III)2Mn(IV)2O4(OH) cluster (1a) at the S1 stage of Kok cycle. Starting from the newly elucidated S1 structure of 1a, we have calculated the electronic structure of proton and electron released CaMn(IV)4O5 cluster (1b) that mimics the S4 stage of the cycle. The LUMOs of 1b are depicted for pictorial understanding of electrophilic oxygen sites that are responsible for nucleophilic attack of hydroxide anion (or water) for the O-O bond formation. Implications of present computational results are discussed in relation to possible mechanisms of photosynthetic water splitting.

Original languageEnglish
Title of host publicationAdvanced Topics in Science and Technology in China
PublisherSpringer
Pages250-254
Number of pages5
DOIs
Publication statusPublished - 2013
Externally publishedYes

Publication series

NameAdvanced Topics in Science and Technology in China
ISSN (Print)1995-6819
ISSN (Electronic)1995-6827

Keywords

  • Ab initio DFT calculation
  • Electrophilic mechanism
  • LUMO
  • Protonated structure

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Engineering(all)
  • General

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