Intermolecular Proton-Coupled Electron Transfer Reactivity from a Persistent Charge-Transfer State for Reductive Photoelectrocatalysis
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1.
California Institute of Technology
Abstract
Interest in applying proton-coupled electron transfer (PCET) reagents in reductive electro- and photocatalysis requires strategies that mitigate the competing hydrogen evolution reaction. Photoexcitation of a PCET donor to a charge-separated state (CSS) can produce a powerful H-atom donor capable of being electrochemically recycled at a comparatively anodic potential corresponding to its ground state. However, the challenge is designing a mediator with a sufficiently long-lived excited state for bimolecular reactivity. Here, we describe a powerful ferrocene-derived photoelectrochemical PCET mediator exhibiting an unusually long-lived CSS (τ ∼ 0.9 μs). In addition to detailed photophysical studies, proof-of-concept stoichiometric and catalytic proton-coupled reductive transformations are presented, which illustrate the promise of this approach.
Copyright and License
© 2024 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0.
Acknowledgement
We thank the NIH (R01 GM-070757 (J.C.P.) and 1S10OD032151-01 (J.R.W.)) for support of this work. We also thank the Dow Next Generation Educator Funds and Instrumentation Grants for their support of the NMR facility at Caltech, and the Resnick Water and Environment Laboratory at Caltech for the use of their instrumentation. The authors are grateful to the American Chemical Society Petroleum Research Fund for support. We are thankful to Dr. David Vander Velde for technical NMR guidance and the laboratory of Professor Ryan Hadt for assistance with spectroelectrochemical studies. P.G.B. thanks the Ramón Areces Foundation for a postdoctoral fellowship. C.G.R. acknowledges the support of the NSF for a graduate fellowship (GRFP). J.C.P. is grateful to the Resnick Sustainability Institute for generous support of enabling facilities on the Caltech campus. Finally, we acknowledge use of the Beckman Institute Laser Resource Center, which is supported by the Arnold and Mabel Beckman Foundation.
Funding
National Institutes of Health General Medical Sciences. R01 GM-075757 (JCP) National Institutes of Health grant 1S10OD032151-01 (JRW)
Contributions
P.G.-B. and C.G.R. contributed equally. The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.
Data Availability
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Experimental methods; synthetic details; electrochemical data; UV-vis data; pKa calculation; data from stoichiometric and catalysis experiments; fluorescence data; transient absorption data; reaction quantum yield determination; spectroelectrochemistry of {Fc–N–an}; isotope scrambling experiment; H2 quantification for CPE; and DFT calculations (PDF)
Conflict of Interest
The authors declare no competing financial interest.
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Additional details
Identifiers
- ISSN
- 1520-5126
- PMCID
- PMC11082884
- DOI
- 10.1021/jacs.4c02610
Funding
- National Institutes of Health
- R01 GM-075757
- National Institutes of Health
- 1S10OD032151-01
- Dow Chemical (United States)
- Dow Next Generation Educator Fund
- American Chemical Society
- Petroleum Research Fund
- Fundación Ramón Areces
- National Science Foundation
- NSF Graduate Research Fellowship
- Resnick Sustainability Institute
- Arnold and Mabel Beckman Foundation