Intermolecular Proton-Coupled Electron Transfer Reactivity from a Persistent Charge-Transfer State for Reductive...

Area of Science:

• Photochemistry
• Electrochemistry
• Catalysis

Background:

• Proton-coupled electron transfer (PCET) is crucial for reductive catalysis.
• A major challenge is suppressing the competing hydrogen evolution reaction.
• Developing mediators with long-lived excited states is essential for efficient PCET.

Purpose of the Study:

• To design and characterize a novel photoelectrochemical PCET mediator.
• To investigate strategies for mitigating hydrogen evolution in PCET reactions.
• To demonstrate the utility of the new mediator in reductive transformations.

Main Methods:

• Synthesis of a ferrocene-derived PCET mediator.
• Detailed photophysical studies to determine excited state lifetime.
• Stoichiometric and catalytic proton-coupled reductive transformations.

Main Results:

• The developed mediator exhibits an unusually long-lived charge-separated state (CSS) with a lifetime of approximately 0.9 μs.
• Proof-of-concept stoichiometric and catalytic reductive transformations were successfully demonstrated.
• The mediator effectively facilitates PCET while minimizing hydrogen evolution.

Conclusions:

• Ferrocene-derived mediators with long-lived CSS offer a promising strategy for efficient PCET catalysis.
• This approach can overcome limitations posed by the hydrogen evolution reaction.
• The developed mediator shows significant potential for applications in reductive electro- and photocatalysis.