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Title: X-ray emission spectroscopy of biomimetic Mn coordination complexes

Journal Article · · Journal of Physical Chemistry Letters

Understanding the function of Mn ions in biological and chemical redox catalysis requires precise knowledge of their electronic structure. X-ray emission spectroscopy (XES) is an emerging technique with a growing application to biological and biomimetic systems. Here, we report an improved, cost-effective spectrometer used to analyze two biomimetic coordination compounds, [MnIV(OH)2(Me2EBC)]2+ and [MnIV(O)(OH)(Me2EBC)]+, the second of which contains a key MnIV=O structural fragment. Despite having the same formal oxidation state (MnIV) and tetradentate ligands, XES spectra from these two compounds demonstrate different electronic structures. Experimental measurements and DFT calculations yield different localized spin densities for the two complexes resulting from MnIV–OH conversion to MnIV=O. The relevance of the observed spectroscopic changes is discussed for applications in analyzing complex biological systems such as photosystem II. In conclusion, a model of the S3 intermediate state of photosystem II containing a MnIV=O fragment is compared to recent time-resolved X-ray diffraction data of the same state.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Grant/Contract Number:
AC02-06CH11357
OSTI ID:
1364024
Journal Information:
Journal of Physical Chemistry Letters, Vol. 8, Issue 12; ISSN 1948-7185
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 28 works
Citation information provided by
Web of Science

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Cited By (10)

Theory of chemical bonds in metalloenzymes XXI. Possible mechanisms of water oxidation in oxygen evolving complex of photosystem II journal December 2017
Theory of chemical bonds in metalloenzymes XXII: a concerted bond-switching mechanism for the oxygen–oxygen bond formation coupled with one electron transfer for water oxidation in the oxygen-evolving complex of photosystem II journal December 2018
What Mn K β spectroscopy reveals concerning the oxidation states of the Mn cluster in photosystem II journal January 2017
Theoretical and computational investigations of geometrical, electronic and spin structures of the CaMn 4 O X (X = 5, 6) cluster in the Kok cycle S i (i = 0–3) of oxygen evolving complex of photosystem II journal March 2019
DIY XES-development of an inexpensive, versatile, and easy to fabricate XES analyzer and sample delivery system journal February 2019
Explaining the Different Geometries of the Water Oxidising Complex in the Nominal S 3 State Crystal Structures of Photosystem II at 2.25 Å and 2.35 Å journal October 2018
Theory of chemical bonds in metalloenzymes XXII: a concerted bond-switching mechanism for the oxygen–oxygen bond formation coupled with one electron transfer for water oxidation in the oxygen-evolving complex of photosystem II text January 2018
Theory of chemical bonds in metalloenzymes XXI. Possible mechanisms of water oxidation in oxygen evolving complex of photosystem II text January 2018
Theory of chemical bonds in metalloenzymes XXII: a concerted bond-switching mechanism for the oxygen–oxygen bond formation coupled with one electron transfer for water oxidation in the oxygen-evolving complex of photosystem II text January 2018
Theory of chemical bonds in metalloenzymes XXI. Possible mechanisms of water oxidation in oxygen evolving complex of photosystem II text January 2018