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Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study

[Image: see text] The design of molecular water oxidation catalysts (WOCs) requires a rational approach that considers the intermediate steps of the catalytic cycle, including water binding, deprotonation, storage of oxidizing equivalents, O–O bond formation, and O(2) release. We investigated severa...

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Autores principales: Boniolo, Manuel, Hossain, Md Kamal, Chernev, Petko, Suremann, Nina F., Heizmann, Philipp A., Lyvik, Amanda S.L., Beyer, Paul, Haumann, Michael, Huang, Ping, Salhi, Nessima, Cheah, Mun Hon, Shylin, Sergii I., Lundberg, Marcus, Thapper, Anders, Messinger, Johannes
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2022
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9214691/
https://www.ncbi.nlm.nih.gov/pubmed/35658429
http://dx.doi.org/10.1021/acs.inorgchem.2c00631
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author Boniolo, Manuel
Hossain, Md Kamal
Chernev, Petko
Suremann, Nina F.
Heizmann, Philipp A.
Lyvik, Amanda S.L.
Beyer, Paul
Haumann, Michael
Huang, Ping
Salhi, Nessima
Cheah, Mun Hon
Shylin, Sergii I.
Lundberg, Marcus
Thapper, Anders
Messinger, Johannes
author_facet Boniolo, Manuel
Hossain, Md Kamal
Chernev, Petko
Suremann, Nina F.
Heizmann, Philipp A.
Lyvik, Amanda S.L.
Beyer, Paul
Haumann, Michael
Huang, Ping
Salhi, Nessima
Cheah, Mun Hon
Shylin, Sergii I.
Lundberg, Marcus
Thapper, Anders
Messinger, Johannes
author_sort Boniolo, Manuel
collection PubMed
description [Image: see text] The design of molecular water oxidation catalysts (WOCs) requires a rational approach that considers the intermediate steps of the catalytic cycle, including water binding, deprotonation, storage of oxidizing equivalents, O–O bond formation, and O(2) release. We investigated several of these properties for a series of base metal complexes (M = Mn, Fe, Co, Ni) bearing two variants of a pentapyridyl ligand framework, of which some were reported previously to be active WOCs. We found that only [Fe(Py5OMe)Cl](+) (Py5OMe = pyridine-2,6-diylbis[di-(pyridin-2-yl)methoxymethane]) showed an appreciable catalytic activity with a turnover number (TON) = 130 in light-driven experiments using the [Ru(bpy)(3)](2+)/S(2)O(8)(2–) system at pH 8.0, but that activity is demonstrated to arise from the rapid degradation in the buffered solution leading to the formation of catalytically active amorphous iron oxide/hydroxide (FeOOH), which subsequently lost the catalytic activity by forming more extensive and structured FeOOH species. The detailed analysis of the redox and water-binding properties employing electrochemistry, X-ray absorption spectroscopy (XAS), UV–vis spectroscopy, and density-functional theory (DFT) showed that all complexes were able to undergo the M(III)/M(II) oxidation, but none was able to yield a detectable amount of a M(IV) state in our potential window (up to +2 V vs SHE). This inability was traced to (i) the preference for binding Cl(–) or acetonitrile instead of water-derived species in the apical position, which excludes redox leveling via proton coupled electron transfer, and (ii) the lack of sigma donor ligands that would stabilize oxidation states beyond M(III). On that basis, design features for next-generation molecular WOCs are suggested.
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spelling pubmed-92146912022-06-23 Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study Boniolo, Manuel Hossain, Md Kamal Chernev, Petko Suremann, Nina F. Heizmann, Philipp A. Lyvik, Amanda S.L. Beyer, Paul Haumann, Michael Huang, Ping Salhi, Nessima Cheah, Mun Hon Shylin, Sergii I. Lundberg, Marcus Thapper, Anders Messinger, Johannes Inorg Chem [Image: see text] The design of molecular water oxidation catalysts (WOCs) requires a rational approach that considers the intermediate steps of the catalytic cycle, including water binding, deprotonation, storage of oxidizing equivalents, O–O bond formation, and O(2) release. We investigated several of these properties for a series of base metal complexes (M = Mn, Fe, Co, Ni) bearing two variants of a pentapyridyl ligand framework, of which some were reported previously to be active WOCs. We found that only [Fe(Py5OMe)Cl](+) (Py5OMe = pyridine-2,6-diylbis[di-(pyridin-2-yl)methoxymethane]) showed an appreciable catalytic activity with a turnover number (TON) = 130 in light-driven experiments using the [Ru(bpy)(3)](2+)/S(2)O(8)(2–) system at pH 8.0, but that activity is demonstrated to arise from the rapid degradation in the buffered solution leading to the formation of catalytically active amorphous iron oxide/hydroxide (FeOOH), which subsequently lost the catalytic activity by forming more extensive and structured FeOOH species. The detailed analysis of the redox and water-binding properties employing electrochemistry, X-ray absorption spectroscopy (XAS), UV–vis spectroscopy, and density-functional theory (DFT) showed that all complexes were able to undergo the M(III)/M(II) oxidation, but none was able to yield a detectable amount of a M(IV) state in our potential window (up to +2 V vs SHE). This inability was traced to (i) the preference for binding Cl(–) or acetonitrile instead of water-derived species in the apical position, which excludes redox leveling via proton coupled electron transfer, and (ii) the lack of sigma donor ligands that would stabilize oxidation states beyond M(III). On that basis, design features for next-generation molecular WOCs are suggested. American Chemical Society 2022-06-06 2022-06-20 /pmc/articles/PMC9214691/ /pubmed/35658429 http://dx.doi.org/10.1021/acs.inorgchem.2c00631 Text en © 2022 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Boniolo, Manuel
Hossain, Md Kamal
Chernev, Petko
Suremann, Nina F.
Heizmann, Philipp A.
Lyvik, Amanda S.L.
Beyer, Paul
Haumann, Michael
Huang, Ping
Salhi, Nessima
Cheah, Mun Hon
Shylin, Sergii I.
Lundberg, Marcus
Thapper, Anders
Messinger, Johannes
Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study
title Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study
title_full Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study
title_fullStr Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study
title_full_unstemmed Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study
title_short Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study
title_sort water oxidation by pentapyridyl base metal complexes? a case study
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9214691/
https://www.ncbi.nlm.nih.gov/pubmed/35658429
http://dx.doi.org/10.1021/acs.inorgchem.2c00631
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