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Positional effects of second-sphere amide pendants on electrochemical CO(2) reduction catalyzed by iron porphyrins

The development of catalysts for electrochemical reduction of carbon dioxide offers an attractive approach to transforming this greenhouse gas into value-added carbon products with sustainable energy input. Inspired by natural bioinorganic systems that feature precisely positioned hydrogen-bond dono...

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Autores principales: Nichols, Eva M., Derrick, Jeffrey S., Nistanaki, Sepand K., Smith, Peter T., Chang, Christopher J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5915798/
https://www.ncbi.nlm.nih.gov/pubmed/29732079
http://dx.doi.org/10.1039/c7sc04682k
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author Nichols, Eva M.
Derrick, Jeffrey S.
Nistanaki, Sepand K.
Smith, Peter T.
Chang, Christopher J.
author_facet Nichols, Eva M.
Derrick, Jeffrey S.
Nistanaki, Sepand K.
Smith, Peter T.
Chang, Christopher J.
author_sort Nichols, Eva M.
collection PubMed
description The development of catalysts for electrochemical reduction of carbon dioxide offers an attractive approach to transforming this greenhouse gas into value-added carbon products with sustainable energy input. Inspired by natural bioinorganic systems that feature precisely positioned hydrogen-bond donors in the secondary coordination sphere to direct chemical transformations occurring at redox-active metal centers, we now report the design, synthesis, and characterization of a series of iron tetraphenylporphyrin (Fe-TPP) derivatives bearing amide pendants at various positions at the periphery of the metal core. Proper positioning of the amide pendants greatly affects the electrocatalytic activity for carbon dioxide reduction to carbon monoxide. In particular, derivatives bearing proximal and distal amide pendants on the ortho position of the phenyl ring exhibit significantly larger turnover frequencies (TOF) compared to the analogous para-functionalized amide isomers or unfunctionalized Fe-TPP. Analysis of TOF as a function of catalyst standard reduction potential enables first-sphere electronic effects to be disentangled from second-sphere through-space interactions, suggesting that the ortho-functionalized porphyrins can utilize the latter second-sphere property to promote CO(2) reduction. Indeed, the distally-functionalized ortho-amide isomer shows a significantly larger through-space interaction than its proximal ortho-amide analogue. These data establish that proper positioning of secondary coordination sphere groups is an effective design element for breaking electronic scaling relationships that are often observed in electrochemical CO(2) reduction.
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spelling pubmed-59157982018-05-04 Positional effects of second-sphere amide pendants on electrochemical CO(2) reduction catalyzed by iron porphyrins Nichols, Eva M. Derrick, Jeffrey S. Nistanaki, Sepand K. Smith, Peter T. Chang, Christopher J. Chem Sci Chemistry The development of catalysts for electrochemical reduction of carbon dioxide offers an attractive approach to transforming this greenhouse gas into value-added carbon products with sustainable energy input. Inspired by natural bioinorganic systems that feature precisely positioned hydrogen-bond donors in the secondary coordination sphere to direct chemical transformations occurring at redox-active metal centers, we now report the design, synthesis, and characterization of a series of iron tetraphenylporphyrin (Fe-TPP) derivatives bearing amide pendants at various positions at the periphery of the metal core. Proper positioning of the amide pendants greatly affects the electrocatalytic activity for carbon dioxide reduction to carbon monoxide. In particular, derivatives bearing proximal and distal amide pendants on the ortho position of the phenyl ring exhibit significantly larger turnover frequencies (TOF) compared to the analogous para-functionalized amide isomers or unfunctionalized Fe-TPP. Analysis of TOF as a function of catalyst standard reduction potential enables first-sphere electronic effects to be disentangled from second-sphere through-space interactions, suggesting that the ortho-functionalized porphyrins can utilize the latter second-sphere property to promote CO(2) reduction. Indeed, the distally-functionalized ortho-amide isomer shows a significantly larger through-space interaction than its proximal ortho-amide analogue. These data establish that proper positioning of secondary coordination sphere groups is an effective design element for breaking electronic scaling relationships that are often observed in electrochemical CO(2) reduction. Royal Society of Chemistry 2018-02-21 /pmc/articles/PMC5915798/ /pubmed/29732079 http://dx.doi.org/10.1039/c7sc04682k Text en This journal is © The Royal Society of Chemistry 2018 http://creativecommons.org/licenses/by-nc/3.0/ This article is freely available. This article is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported Licence (CC BY-NC 3.0)
spellingShingle Chemistry
Nichols, Eva M.
Derrick, Jeffrey S.
Nistanaki, Sepand K.
Smith, Peter T.
Chang, Christopher J.
Positional effects of second-sphere amide pendants on electrochemical CO(2) reduction catalyzed by iron porphyrins
title Positional effects of second-sphere amide pendants on electrochemical CO(2) reduction catalyzed by iron porphyrins
title_full Positional effects of second-sphere amide pendants on electrochemical CO(2) reduction catalyzed by iron porphyrins
title_fullStr Positional effects of second-sphere amide pendants on electrochemical CO(2) reduction catalyzed by iron porphyrins
title_full_unstemmed Positional effects of second-sphere amide pendants on electrochemical CO(2) reduction catalyzed by iron porphyrins
title_short Positional effects of second-sphere amide pendants on electrochemical CO(2) reduction catalyzed by iron porphyrins
title_sort positional effects of second-sphere amide pendants on electrochemical co(2) reduction catalyzed by iron porphyrins
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5915798/
https://www.ncbi.nlm.nih.gov/pubmed/29732079
http://dx.doi.org/10.1039/c7sc04682k
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