Proton transfer dynamics dictate quinone speciation at lipid-modified electrodes

Area of Science:

• Electrochemistry
• Biochemistry
• Membrane Biophysics

Background:

• Proton-coupled electron transfer (PCET) reactions are fundamental in biological energy conversion and alternative energy technologies.
• Quinones play crucial roles in natural enzyme systems for proton transfer and energy processes.
• Controlling PCET mechanisms is key to advancing energy conversion and understanding biological redox reactions.

Purpose of the Study:

• To investigate the influence of proton availability on quinone reaction mechanisms using a bio-inspired membrane system.
• To demonstrate control over PCET pathways by modulating proton flux without altering the redox molecule's structure.
• To establish a novel electrochemical platform for studying PCET reactions.

Main Methods:

• Fabrication of a bio-inspired hybrid bilayer membrane system with a surface-bound quinone.
• Electrochemical control of proton access to the quinone moiety by modifying the membrane environment.
• Incorporation of an alkyl proton carrier within the lipid membrane to modulate proton flux.
• Analysis of reaction pathways (PCET vs. pure electron transfer) under varying proton availability.

Main Results:

• Impeding proton access shifted the quinone reaction from PCET to pure electron transfer.
• Controlled proton flux using a proton carrier enabled a stepwise PCET process.
• The quinone reaction pathway was successfully modulated by controlling proton availability.
• The molecular structure of the quinone remained unchanged throughout the experiments.

Conclusions:

• Modulating proton availability is an effective strategy to control quinone reaction pathways in electrochemical systems.
• The developed hybrid bilayer membrane system provides a versatile platform for studying PCET mechanisms.
• This research offers significant insights into the fundamental principles of PCET reactions and their potential applications.