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Electronic Coupling and Electrocatalysis in Redox Active Fused Iron Corroles
[Image: see text] Conjugated arrays composed of corrole macrocycles are increasingly more common, but their chemistry still lags behind that of their porphyrin counterparts. Here, we report on the insertion of iron(III) into a β,β-fused corrole dimer and on the electronic effects that this redox act...
Autores principales: | , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2022
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9799712/ https://www.ncbi.nlm.nih.gov/pubmed/36512733 http://dx.doi.org/10.1021/acs.inorgchem.2c01389 |
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author | Mizrahi, Amir Bhowmik, Susovan Manna, Arun K. Sinha, Woormileela Kumar, Amit Saphier, Magal Mahammed, Atif Patra, Moumita Fridman, Natalia Zilbermann, Israel Kronik, Leeor Gross, Zeev |
author_facet | Mizrahi, Amir Bhowmik, Susovan Manna, Arun K. Sinha, Woormileela Kumar, Amit Saphier, Magal Mahammed, Atif Patra, Moumita Fridman, Natalia Zilbermann, Israel Kronik, Leeor Gross, Zeev |
author_sort | Mizrahi, Amir |
collection | PubMed |
description | [Image: see text] Conjugated arrays composed of corrole macrocycles are increasingly more common, but their chemistry still lags behind that of their porphyrin counterparts. Here, we report on the insertion of iron(III) into a β,β-fused corrole dimer and on the electronic effects that this redox active metal center has on the already rich coordination chemistry of [H(3)tpfc] COT, where COT = cyclo-octatetraene and tpfc = tris(pentafluorophenyl)corrole. Synthetic manipulations were performed for the isolation and full characterization of both the 5-coordinate [Fe(III)tpfc(py)](2)COT and 6-coordinate [Fe(III)tpfc(py)(2)](2)COT, with one and two axial pyridine ligands per metal, respectively. X-Ray crystallography reveals a dome-shaped structure for [Fe(III)tpfc(py)](2)COT and a perfectly planar geometry which (surprisingly at first) is also characterized by shorter Fe–N (corrole) and Fe–N (pyridine) distances. Computational investigations clarify that the structural phenomena are due to a change in the iron(III) spin state from intermediate (S = 3/2) to low (S = 1/2), and that both the 5- and 6-coordinated complexes are enthalpically favored. Yet, in contrast to iron(III) porphyrins, the formation enthalpy for the coordination of the first pyridine to Fe(III) corrole is more negative than that of the second pyridine coordination. Possible interactions between the two corrole subunits and the chelated iron ions were examined by UV–Vis spectroscopy, electrochemical techniques, and density functional theory (DFT). The large differences in the electronic spectra of the dimer relative to the monomer are concluded to be due to a reduced electronic gap, owing to the extensive electron delocalization through the fusing bridge. A cathodic sweep for the dimer discloses two redox processes, separated by 230 mV. The DFT self-consistent charge density for the neutral and cationic states (1- and 2-electron oxidized) reveals that the holes are localized on the macrocycle. A different picture emerges from the reduction process, where both the electrochemistry and the calculated charge density point toward two consecutive electron transfers with similar energetics, indicative of very weak electron communication between the two redox active iron(III) sites. The binuclear complex was determined to be a much better catalyst for the electrochemical hydrogen evolution reaction (HER) than the analogous mononuclear corrole. |
format | Online Article Text |
id | pubmed-9799712 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | American Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-97997122022-12-30 Electronic Coupling and Electrocatalysis in Redox Active Fused Iron Corroles Mizrahi, Amir Bhowmik, Susovan Manna, Arun K. Sinha, Woormileela Kumar, Amit Saphier, Magal Mahammed, Atif Patra, Moumita Fridman, Natalia Zilbermann, Israel Kronik, Leeor Gross, Zeev Inorg Chem [Image: see text] Conjugated arrays composed of corrole macrocycles are increasingly more common, but their chemistry still lags behind that of their porphyrin counterparts. Here, we report on the insertion of iron(III) into a β,β-fused corrole dimer and on the electronic effects that this redox active metal center has on the already rich coordination chemistry of [H(3)tpfc] COT, where COT = cyclo-octatetraene and tpfc = tris(pentafluorophenyl)corrole. Synthetic manipulations were performed for the isolation and full characterization of both the 5-coordinate [Fe(III)tpfc(py)](2)COT and 6-coordinate [Fe(III)tpfc(py)(2)](2)COT, with one and two axial pyridine ligands per metal, respectively. X-Ray crystallography reveals a dome-shaped structure for [Fe(III)tpfc(py)](2)COT and a perfectly planar geometry which (surprisingly at first) is also characterized by shorter Fe–N (corrole) and Fe–N (pyridine) distances. Computational investigations clarify that the structural phenomena are due to a change in the iron(III) spin state from intermediate (S = 3/2) to low (S = 1/2), and that both the 5- and 6-coordinated complexes are enthalpically favored. Yet, in contrast to iron(III) porphyrins, the formation enthalpy for the coordination of the first pyridine to Fe(III) corrole is more negative than that of the second pyridine coordination. Possible interactions between the two corrole subunits and the chelated iron ions were examined by UV–Vis spectroscopy, electrochemical techniques, and density functional theory (DFT). The large differences in the electronic spectra of the dimer relative to the monomer are concluded to be due to a reduced electronic gap, owing to the extensive electron delocalization through the fusing bridge. A cathodic sweep for the dimer discloses two redox processes, separated by 230 mV. The DFT self-consistent charge density for the neutral and cationic states (1- and 2-electron oxidized) reveals that the holes are localized on the macrocycle. A different picture emerges from the reduction process, where both the electrochemistry and the calculated charge density point toward two consecutive electron transfers with similar energetics, indicative of very weak electron communication between the two redox active iron(III) sites. The binuclear complex was determined to be a much better catalyst for the electrochemical hydrogen evolution reaction (HER) than the analogous mononuclear corrole. American Chemical Society 2022-12-13 2022-12-26 /pmc/articles/PMC9799712/ /pubmed/36512733 http://dx.doi.org/10.1021/acs.inorgchem.2c01389 Text en © 2022 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 | Mizrahi, Amir Bhowmik, Susovan Manna, Arun K. Sinha, Woormileela Kumar, Amit Saphier, Magal Mahammed, Atif Patra, Moumita Fridman, Natalia Zilbermann, Israel Kronik, Leeor Gross, Zeev Electronic Coupling and Electrocatalysis in Redox Active Fused Iron Corroles |
title | Electronic Coupling and Electrocatalysis in Redox
Active Fused Iron Corroles |
title_full | Electronic Coupling and Electrocatalysis in Redox
Active Fused Iron Corroles |
title_fullStr | Electronic Coupling and Electrocatalysis in Redox
Active Fused Iron Corroles |
title_full_unstemmed | Electronic Coupling and Electrocatalysis in Redox
Active Fused Iron Corroles |
title_short | Electronic Coupling and Electrocatalysis in Redox
Active Fused Iron Corroles |
title_sort | electronic coupling and electrocatalysis in redox
active fused iron corroles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9799712/ https://www.ncbi.nlm.nih.gov/pubmed/36512733 http://dx.doi.org/10.1021/acs.inorgchem.2c01389 |
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