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Modeling Near-Edge Fine Structure X-ray Spectra of the Manganese Catalytic Site for Water Oxidation in Photosystem II
KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.ORCID iD: 0000-0002-1763-9383
2012 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 41, 17157-17167 p.Article in journal (Refereed) Published
Abstract [en]

The Mn Is near-edge absorption fine structure (NEXAFS) has been computed by means of transition-state gradient-corrected density functional theory (DFT) on four Mn4Ca clusters modeling the successive S-0 to S-3 steps of the oxygen-evolving complex (OEC) in photosystem II (PSII). The model clusters were obtained from a previous theoretical study where they were determined by energy minimization. They are composed of Mn(III) and Mn(IV) atoms, progressing from Mn(III)(3)Mn(IV) for S-0 to Mn(III)(2)Mn(IV)(2) for S-1 to Mn(III)Mn(IV)(3) for S-2 to Mn(IV)(4) for S-3, implying an Mn-centered oxidation during each step of the photosynthetic oxygen evolution. The DFT simulations of the Mn Is absorption edge reproduce the experimentally measured curves quite well. By the half-height method, the theoretical IPEs are shifted by 0.93 eV for the S-0 -> S-1 transition, by 1.43 eV for the S-1 -> S-2 transition, and by 0.63 eV for the S-2 -> S-3 transition. The inflection point energy (IPE) shifts depend strongly on the method used to determine them, and the most interesting result is that the present clusters reproduce the shift in the S-2 -> S-3 transition obtained by both the half-height and second-derivative methods, thus giving strong support to the previously suggested structures and assignments.

Place, publisher, year, edition, pages
2012. Vol. 134, no 41, 17157-17167 p.
Keyword [en]
Oxygen-Evolving Complex, Photoelectron Binding-Energies, Time-Dependent Dft, Absorption-Spectroscopy, Electronic-Structure, Amino-Acids, Centered Oxidation, Building-Blocks, Chemical-Shifts, Transition
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-106135DOI: 10.1021/ja306794pISI: 000309854700042ScopusID: 2-s2.0-84867548419OAI: diva2:573832
Swedish Research CouncilEU, FP7, Seventh Framework ProgrammeSwedish e‐Science Research Center

QC 20121203

Available from: 2012-12-03 Created: 2012-11-29 Last updated: 2013-04-08Bibliographically approved

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