X-ray Emission Spectroscopy of Mn Coordination Complexes Toward Interpreting the Electronic Structure of the Oxygen-Evolving Complex of Photosystem II

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• 作者：Katherine M. Davis ; Mark C. Palenik ; Lifen Yan ; Paul F. Smith ; Gerald T. Seidler ; G. Charles Dismukes ; Yulia N. Pushkar
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：February 18, 2016
• 年：2016
• 卷：120
• 期：6
• 页码：3326-3333
• 全文大小：371K
• ISSN：1932-7455

文摘

X-ray emission (XES) spectroscopy is an attractive technique for analysis of the electronic structure of molecules, materials, and metalloproteins. However, a better understanding of XES results is required. Using a combination of experiment and ground-state density functional theory analysis, we rationalize differences in the X-ray emission spectra of multinuclear Mn complexes. Model compounds, including dinuclear [Mn₂O₂L′₄](ClO₄)₃ (L′= 2,2′-bipyridyl, [1]) and two examples from the Mn₄O₄L₆ “cubane” family of model compounds (L = (p-R-C₆H₄)PO₂⁻, R = OCH₃ [2], CH₃ [3] ), were compared with the Oxygen Evolving Complex of Photosystem II. Our analysis shows that changes in the structure of the Mn complexes, resulting in changes to the spin polarization, can introduce significant spectral shifts in compounds of the same formal redox state. The implications of changes in spin polarization for understanding photosynthetic water-splitting catalysis is discussed.