Accelerated Directional Proton-Coupled Electron Transfer Enabled by Intrinsic Dipole Field in Biomimetic α-Helical...

Proton-coupled electron transfer (PCET) is a fundamental mechanism in energy conversion processes such as photosynthesis and cellular respiration, yet its precise regulation through molecular conformation remains challenging. Here, we report a biomimetic strategy to modulate intramolecular PCET using an α-helical peptide scaffold. By grafting rhodamine dyes onto a designed peptide backbone (Pep-Rh), a well-defined α-helical structure is obtained, providing an intrinsic dipole field that is aligned with the proton transfer pathway during PCET. Spectroscopic, electrochemical, and theoretical analyses reveal that the dipole field of the α-helix accelerates PCET, outperforming nonhelical small molecule and polymeric analogues. This work establishes a new mechanistic framework for regulating PCET through structural dipoles and provides a strategy for precise control of energy conversion. The findings establish a well-defined molecular model for understanding structure-field-function relationships in photoinduced PCET systems, highlighting the role of structural dipoles at the molecular level.