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Seif-Eddine M, Cobb SJ, Dang Y, Abdiaziz K, Bajada MA, Reisner E, Roessler MM. Operando film-electrochemical EPR spectroscopy tracks radical intermediates in surface-immobilized catalysts. Nat Chem 2024; 16:1015-1023. [PMID: 38355827 DOI: 10.1038/s41557-024-01450-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Accepted: 01/12/2024] [Indexed: 02/16/2024]
Abstract
The development of surface-immobilized molecular redox catalysts is an emerging research field with promising applications in sustainable chemistry. In electrocatalysis, paramagnetic species are often key intermediates in the mechanistic cycle but are inherently difficult to detect and follow by conventional in situ techniques. We report a new method, operando film-electrochemical electron paramagnetic resonance spectroscopy (FE-EPR), which enables mechanistic studies of surface-immobilized electrocatalysts. This technique enables radicals formed during redox reactions to be followed in real time under flow conditions, at room temperature and in aqueous solution. Detailed insight into surface-immobilized catalysts, as exemplified here through alcohol oxidation catalysis by a surface-immobilized nitroxide, is possible by detecting active-site paramagnetic species sensitively and quantitatively operando, thereby enabling resolution of the reaction kinetics. Our finding that the surface electron-transfer rate, which is of the same order of magnitude as the rate of catalysis (accessible from operando FE-EPR), limits catalytic efficiency has implications for the future design of better surface-immobilized catalysts.
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Affiliation(s)
- Maryam Seif-Eddine
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, UK
| | - Samuel J Cobb
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Yunfei Dang
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, UK
| | - Kaltum Abdiaziz
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, UK
- Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr, Germany
| | - Mark A Bajada
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Maxie M Roessler
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, UK.
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2
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Sharma S, Shaheeda S, Shaw K, Bisai A, Paul A. Two-Electron- and One-Electron-Transfer Pathways for TEMPO-Catalyzed Greener Electrochemical Dimerization of 3-Substituted-2-Oxindoles. ACS Catal 2023. [DOI: 10.1021/acscatal.2c06361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Sulekha Sharma
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
| | - Saina Shaheeda
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
| | - Kundan Shaw
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
| | - Alakesh Bisai
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, Nadia, West Bengal 741 246, India
| | - Amit Paul
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462 066, India
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3
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Engineering synergistic effects of immobilized cooperative catalysts. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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4
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Tocqueville D, Crisanti F, Guerrero J, Nubret E, Robert M, Milstein D, von Wolff N. Electrification of a Milstein-type catalyst for alcohol reformation. Chem Sci 2022; 13:13220-13224. [PMID: 36425491 PMCID: PMC9667915 DOI: 10.1039/d2sc04533h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 10/14/2022] [Indexed: 12/02/2023] Open
Abstract
Novel energy and atom efficiency processes will be keys to develop the sustainable chemical industry of the future. Electrification could play an important role, by allowing to fine-tune energy input and using the ideal redox agent: the electron. Here we demonstrate that a commercially available Milstein ruthenium catalyst (1) can be used to promote the electrochemical oxidation of ethanol to ethyl acetate and acetate, thus demonstrating the four electron oxidation under preparative conditions. Cyclic voltammetry and DFT-calculations are used to devise a possible catalytic cycle based on a thermal chemical step generating the key hydride intermediate. Successful electrification of Milstein-type catalysts opens a pathway to use alcohols as a renewable feedstock for the generation of esters and other key building blocks in organic chemistry, thus contributing to increase energy efficiency in organic redox chemistry.
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Affiliation(s)
- Damien Tocqueville
- Laboratoire d'Electrochimie MoléculaireUniversité Paris Cité, CNRS Paris F-75006 France
| | - Francesco Crisanti
- Laboratoire d'Electrochimie MoléculaireUniversité Paris Cité, CNRS Paris F-75006 France
| | - Julian Guerrero
- Laboratoire d'Electrochimie MoléculaireUniversité Paris Cité, CNRS Paris F-75006 France
| | - Esther Nubret
- Laboratoire d'Electrochimie MoléculaireUniversité Paris Cité, CNRS Paris F-75006 France
| | - Marc Robert
- Laboratoire d'Electrochimie MoléculaireUniversité Paris Cité, CNRS Paris F-75006 France
- Institut Universitaire de France (IUF) Paris F-75005 France
| | - David Milstein
- Department of Molecular Chemistry and Materials Science, The Weizmann Institute of Science Rehovot 7610001 Israel
| | - Niklas von Wolff
- Laboratoire d'Electrochimie MoléculaireUniversité Paris Cité, CNRS Paris F-75006 France
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5
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Tay NES, Lehnherr D, Rovis T. Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis. Chem Rev 2022; 122:2487-2649. [PMID: 34751568 PMCID: PMC10021920 DOI: 10.1021/acs.chemrev.1c00384] [Citation(s) in RCA: 131] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do electrochemistry and photoredox catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) that enable bond formations not constrained by the rules of ionic or 2 electron (e) mechanisms. Instead, they enable 1e mechanisms capable of bypassing electronic or steric limitations and protecting group requirements, thus enabling synthetic chemists to disconnect molecules in new and different ways. However, while providing access to similar intermediates, electrochemistry and photoredox catalysis differ in several physical chemistry principles. Understanding those differences can be key to designing new transformations and forging new bond disconnections. This review aims to highlight these differences and similarities between electrochemistry and photoredox catalysis by comparing their underlying physical chemistry principles and describing their impact on electrochemical and photochemical methods.
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Affiliation(s)
- Nicholas E S Tay
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Dan Lehnherr
- Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Tomislav Rovis
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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6
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Bruggeman DF, Mathew S, Detz RJ, Reek JNH. Comparison of homogeneous and heterogeneous catalysts in dye-sensitised photoelectrochemical cells for alcohol oxidation coupled to dihydrogen formation. SUSTAINABLE ENERGY & FUELS 2021; 5:5707-5716. [PMID: 34912969 PMCID: PMC8577521 DOI: 10.1039/d1se01275d] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 09/30/2021] [Indexed: 05/14/2023]
Abstract
This study examines two strategies-homo- and heterogeneous approaches for the light-driven oxidation of benzyl alcohol in dye-sensitised photoelectrochemical cells (DSPECs). The DSPEC consists of a mesoporous anatase TiO2 film on FTO (fluorine-doped tin oxide), sensitised with the thienopyrroledione-based dye AP11 as the photoanode and an FTO-Pt cathode combined with a redox-mediating catalyst. The homogeneous catalyst approach entails the addition of the soluble 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to the DSPEC anolyte, while the heterogeneous strategy employs immobilisation of a TEMPO analogue with a silatrane anchor (S-TEMPO) onto the photoanode. Irradiation of the photoanode oxidises the TEMPO-moiety to TEMPO+, both in the homogeneous and the heterogeneous system, which is a chemical oxidant for benzyl alcohol oxidation. Photoanodes containing the heterogeneous S-TEMPO+ demonstrate decreased photocurrent, attributed to introducing alternative pathways for electron recombination. Moreover, the immobilised S-TEMPO demonstrates an insufficient ability to mediate electron transfer from the organic substrate to the photooxidised dye, resulting in device instability. In contrast, the homogeneous approach with TEMPO as a redox-mediating catalyst in the anolyte is efficient in the light-driven oxidation of benzyl alcohol to benzaldehyde over 32 hours, promoted by the efficient electron mediation of TEMPO between AP11 and the organic substrate. Our work demonstrates that operational limitations in DSPECs can be solved by rational device design using diffusion-mediated electron transfer steps.
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Affiliation(s)
- D F Bruggeman
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van 't Hoff Institute for Molecular Sciences, University of Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands
| | - S Mathew
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van 't Hoff Institute for Molecular Sciences, University of Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands
| | - R J Detz
- Netherlands Organisation for Applied Scientific Research (TNO) - Energy Transition Studies Radarweg 60 Amsterdam The Netherlands
| | - J N H Reek
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van 't Hoff Institute for Molecular Sciences, University of Amsterdam Science Park 904 1098 XH Amsterdam The Netherlands
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7
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Li S, Bartlett BM. Selective Chloride-Mediated Neat Ethanol Oxidation to 1,1-Diethoxyethane via an Electrochemically Generated Ethyl Hypochlorite Intermediate. J Am Chem Soc 2021; 143:15907-15911. [PMID: 34553910 DOI: 10.1021/jacs.1c05976] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Selective primary alcohol oxidation to form aldehydes products without overoxidation to carboxylic acids remains a key chemistry challenge. Using simple alkylammonium chloride as the electrolyte with a glassy carbon working electrode in neat ethanol solvent, 1,1-diethoxyethane (DEE) was prepared with >95% faradaic efficiency (FE). DEE serves as a storage platform protecting acetaldehyde from overoxidation and volatilization. UV-vis spectroscopy shows that the reaction proceeds through an ethyl hypochlorite intermediate as the sole chloride oxidation product, and that this intermediate decomposes unimolecularly (rate constant k = (6.896 ± 0.516) × 10-4 s-1) to form HCl catalyst and acetaldehyde, which undergoes rapid nucleophilic attack by ethanol solvent to form the DEE product. This indirect oxidation mechanism enables ethanol oxidation at much less positive potentials due to the fast kinetics for chloride anion oxidation.
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Affiliation(s)
- Siqi Li
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Bart M Bartlett
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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8
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Wolff N, Rivada‐Wheelaghan O, Tocqueville D. Molecular Electrocatalytic Hydrogenation of Carbonyls and Dehydrogenation of Alcohols. ChemElectroChem 2021. [DOI: 10.1002/celc.202100617] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Niklas Wolff
- Laboratoire d'Électrochimie Moléculaire Université de Paris, CNRS F-75006 Paris France
| | | | - Damien Tocqueville
- Laboratoire d'Électrochimie Moléculaire Université de Paris, CNRS F-75006 Paris France
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9
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Pan N, Xinen Lee M, Bunel L, Grimaud L, Vitale MR. Electrochemical TEMPO-Catalyzed Oxidative Ugi-Type Reaction. ACS ORGANIC & INORGANIC AU 2021; 1:18-22. [PMID: 36855635 PMCID: PMC9954374 DOI: 10.1021/acsorginorgau.1c00003] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Oxidative isocyanide-based multicomponent reactions (oxidative IMCRs) are very useful tools for the rapid construction of molecular diversity starting from readily available and stable substrates. Despite all their benefits, such multicomponent reactions are underdeveloped and strictly limited to 3-component processes. Indeed, in the presence of several reaction partners, the oxidation event needs to be rigorously chemoselective, which becomes incredibly more intricate as the number of reactive components increases. Nonetheless, we could overcome this significant pitfall and reach the first oxidative Ugi-type 4-IMCR by capitalizing on a very mild and green TEMPO-catalyzed electro-oxidation process. Employing alcohols as aldehyde surrogates and in the notable absence of any supporting electrolyte, this transformation proved to be extremely chemoselective in the presence of an amine and was compatible with a wide range of alcohols, amines, isocyanides, and carboxylic acids.
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Affiliation(s)
- Na Pan
- Laboratoire des
biomolécules, LBM, Département de chimie, École
Normale Supérieure, PSL University,
Sorbonne Université, CNRS, 75005 Paris, France,Shanghai Engineering Research Center of Molecular Therapeutics and
New Drug Development, SCME, East China Normal
University, 3663 Zhongshanbei Road, Shanghai 200062, China
| | - Maegan Xinen Lee
- Laboratoire des
biomolécules, LBM, Département de chimie, École
Normale Supérieure, PSL University,
Sorbonne Université, CNRS, 75005 Paris, France
| | - Louis Bunel
- Laboratoire des
biomolécules, LBM, Département de chimie, École
Normale Supérieure, PSL University,
Sorbonne Université, CNRS, 75005 Paris, France
| | - Laurence Grimaud
- Laboratoire des
biomolécules, LBM, Département de chimie, École
Normale Supérieure, PSL University,
Sorbonne Université, CNRS, 75005 Paris, France,
| | - Maxime R. Vitale
- Laboratoire des
biomolécules, LBM, Département de chimie, École
Normale Supérieure, PSL University,
Sorbonne Université, CNRS, 75005 Paris, France,
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10
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Goes SL, Mayer MN, Nutting JE, Hoober-Burkhardt LE, Stahl SS, Rafiee M. Deriving the Turnover Frequency of Aminoxyl-Catalyzed Alcohol Oxidation by Chronoamperometry: An Introduction to Organic Electrocatalysis. JOURNAL OF CHEMICAL EDUCATION 2021; 98:600-606. [PMID: 34366442 PMCID: PMC8345316 DOI: 10.1021/acs.jchemed.0c01244] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Organic electrosynthesis is an increasingly popular tool for driving and probing redox reactions. Recent advances in this field often employ an electrocatalyst to enhance the selectivity and efficiency of electrochemical reactions. A laboratory experiment was developed to introduce students to relevant mechanistic techniques in electrochemistry for analysis of electrocatalytic reactions using aminoxyl-catalyzed alcohol oxidation as a case study. This lab activity employs cyclic voltammetry for qualitative assessment of catalytic turnover prior to introducing students to chronoamperometry, an underutilized technique that facilitates quantitative determination of the rate of catalysis. Students identify and rationalize the important features of reversible electron transfer and a catalytic reaction in a cyclic voltammogram, probe the origin of scan rate effects on these traces, and calculate turnover frequency using a series of chronoamperograms. The method employs safe and readily available reagents: basic aqueous buffer solution, alcohol substrate, and an inexpensive organic aminoxyl catalyst. Student data presented herein were obtained from a course attended by undergraduate students, graduate students, and pharmaceutical chemists.
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Affiliation(s)
- Shannon L. Goes
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Mikayla N. Mayer
- Department of Chemistry, University of Missouri–Kansas City, 5009 Rockhill Rd., Kansas City, MO 64110, United States
| | - Jordan E. Nutting
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Lena E. Hoober-Burkhardt
- Department of Chemistry, University of Missouri–Kansas City, 5009 Rockhill Rd., Kansas City, MO 64110, United States
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Mohammad Rafiee
- Department of Chemistry, University of Missouri–Kansas City, 5009 Rockhill Rd., Kansas City, MO 64110, United States
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11
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Bruggeman DF, Bakker TMA, Mathew S, Reek JNH. Redox-Mediated Alcohol Oxidation Coupled to Hydrogen Gas Formation in a Dye-Sensitized Photosynthesis Cell. Chemistry 2020; 27:218-221. [PMID: 32902899 PMCID: PMC7839774 DOI: 10.1002/chem.202003306] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/31/2020] [Indexed: 11/06/2022]
Abstract
This work reports a dye-sensitized photoelectrochemical cell (DSPEC) that couples redox-mediated light-driven oxidative organic transformations to reductive hydrogen (H2 ) formation. The DSPEC photoanode consists of a mesoporous anatase TiO2 film on FTO (fluorine-doped tin oxide), sensitized with the thienopyrroledione-based dye AP11, while H2 was formed at a FTO-Pt cathode. Irradiation of the dye-sensitized photoanode transforms 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) to the oxidized TEMPO (TEMPO+ ), which acts as a chemical oxidant for the conversion of benzyl alcohol. The TEMPO0/+ couple, previously used as redox mediator in DSSC, mediates efficient electron transfer from the organic substrate to the photo-oxidized dye. A DSPEC photoreactor was designed that allows in situ monitoring the reaction progress by infrared spectroscopy and gas chromatography. Sustained light-driven oxidation of benzyl alcohol to benzaldehyde within the DSPEC photoreactor, using of TEMPO as mediator, demonstrated the efficiency of the device, with a photocurrent of 0.4 mA cm-2 , approaching quantitative Faradaic efficiency and exhibiting excellent device stability.
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Affiliation(s)
- Didjay F Bruggeman
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098, XH, Amsterdam, The Netherlands
| | - Tijmen M A Bakker
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098, XH, Amsterdam, The Netherlands
| | - Simon Mathew
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098, XH, Amsterdam, The Netherlands
| | - Joost N H Reek
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098, XH, Amsterdam, The Netherlands
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12
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Terry BD, DiMeglio JL, Cousineau JP, Bartlett BM. Nitrate Radical Facilitates Indirect Benzyl Alcohol Oxidation on Bismuth(III) Vanadate Photoelectrodes. ChemElectroChem 2020. [DOI: 10.1002/celc.202000911] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Bradley D. Terry
- Department of Chemistry University of Michigan 930 N. University Ave. Ann Arbor MI 48109-1055 USA
| | - John L. DiMeglio
- Department of Chemistry University of Michigan 930 N. University Ave. Ann Arbor MI 48109-1055 USA
| | - John P. Cousineau
- Department of Chemistry University of Michigan 930 N. University Ave. Ann Arbor MI 48109-1055 USA
| | - Bart M. Bartlett
- Department of Chemistry University of Michigan 930 N. University Ave. Ann Arbor MI 48109-1055 USA
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