Role of Intact Hydrogen-Bond Networks in Multiproton-Coupled Electron Transfer

Area of Science:

• Supramolecular Chemistry
• Electrochemistry
• Materials Science

Background:

• Proton translocation is crucial for many biological and chemical processes.
• Designing molecular systems for controlled proton transfer is an active research area.
• Hydrogen-bond networks play a key role in mediating proton transfer pathways.

Purpose of the Study:

• To investigate the role of hydrogen-bond networks in electrochemically driven multiproton transfer.
• To explore the influence of molecular architecture on proton-coupled electron-transfer (PCET) processes.
• To establish design principles for molecular wires facilitating Grotthuss-type proton translocation.

Main Methods:

• Synthesis of pyridylbenzimidazole-phenol model compounds with varying hydrogen-bond network integrity.
• Electrochemical characterization using cyclic voltammetry (CV) at different scan rates.
• Theoretical calculations (electrostatic potentials, electric fields) to understand proton transfer mechanisms.

Main Results:

• An intact hydrogen-bond network facilitates a chemically reversible two-proton-coupled electron-transfer (E2PT) process.
• Disruption of the network leads to a chemically reversible one-proton-coupled electron-transfer (E1PT) at high scan rates.
• At slow scan rates, network disruption results in an irreversible E2PT, involving sequential proton transfer steps.

Conclusions:

• The integrity of the hydrogen-bond network is critical for controlling the reversibility and stoichiometry of PCET reactions.
• Molecular design can tune electrochemical behavior, enabling distinct E1PT and E2PT pathways.
• These findings provide fundamental insights for developing molecular wires for efficient proton transport.