Electronic and solvent reorganization in proton-coupled electron transfer captured by ultrafast X-rays
Proton-coupled electron transfer (PCET) is foundational to catalysis, bioenergetics, and energy conversion, yet directly observing the interplay between electronic redistribution, protonation, and solvent reorganization remains challenging. We combine femtosecond optical spectroscopy, ultrafast N K-edge X-ray absorption spectroscopy, and time-resolved X-ray solution scattering to capture the steps of a sequential PCET reaction in water with atomic-site specificity. Using a ruthenium polypyridyl model complex, we resolve the electron redistribution upon photoinduced metal-to-ligand charge transfer and subsequent ( ~ 460 ps) protonation at a ligand nitrogen, as well as the concomitant rearrangement of the first-solvation-shell. Combined with advanced electronic structure and molecular dynamics simulations, our measurements reveal a marked localization of the excited-state electron density at the protonated N site, together with a switch from N···HO to NH···O hydrogen-bonds. These results establish a multimodal X-ray framework for mechanistic insight into PCET and its control in catalysis, artificial photosynthesis, and biological energy flow.
Authors
- Estefanía Sucre‐Rosales (ORCID: https://orcid.org/0000-0002-5486-4264)
- Soumen Ghosh (ORCID: https://orcid.org/0000-0003-0850-4855)
- Matthieu Chollet (ORCID: https://orcid.org/0000-0002-9629-890X)
- R. W. Schoenlein (ORCID: https://orcid.org/0000-0002-6066-7566)
- Giacomo Coslovich (ORCID: https://orcid.org/0000-0002-1601-1287)
- Douglas Garratt (ORCID: https://orcid.org/0000-0002-8637-9984)
- Christina Y. Hampton (ORCID: https://orcid.org/0009-0005-3939-2616)
- Subhradip Kundu (ORCID: https://orcid.org/0000-0002-3610-7008)
- Christopher B. Larsen (ORCID: https://orcid.org/0000-0003-3006-2408)
- Eric Vauthey (ORCID: https://orcid.org/0000-0002-9580-9683)
- Elisa Biasin (ORCID: https://orcid.org/0000-0002-7276-4224)
- Niranjan Govind (ORCID: https://orcid.org/0000-0003-3625-366X)
- Amy A. Cordones (ORCID: https://orcid.org/0000-0001-9897-5380)
- Patrick L. Kramer (ORCID: https://orcid.org/0000-0001-8589-1540)
- David J. Hoffman (ORCID: https://orcid.org/0000-0001-8518-7676)
- Georgi L. Dakovski (ORCID: https://orcid.org/0000-0003-1563-1190)
- Michael Sachs (ORCID: https://orcid.org/0000-0001-9775-9336)
- Benjamin I. Poulter (ORCID: https://orcid.org/0000-0002-2007-0319)
- Abdullah Kahraman (ORCID: https://orcid.org/0000-0003-1611-3061)
- Roberto Alonso‐Mori (ORCID: https://orcid.org/0000-0002-5357-0934)
- Amity Andersen (ORCID: https://orcid.org/0000-0002-6529-0905)
- Kristjan Kunnus (ORCID: https://orcid.org/0000-0002-9777-2685)
- Elizabeth S. Ryland (ORCID: https://orcid.org/0000-0002-9200-1769)
- Sang‐Jun Lee (ORCID: https://orcid.org/0000-0002-8199-3993)
- Tim van Driel
- Sumana L. Raj
- Natalia Powers-Riggs
Institutions
- University of Geneva (CH)
- Pacific Northwest National Laboratory (US)
- University of Auckland (NZ)
- University of Washington (US)
- Indian Institute of Technology Madras (IN)
- Environmental Molecular Sciences Laboratory (US)
- SLAC National Accelerator Laboratory (US)
- Stanford Synchrotron Radiation Lightsource (US)
- Linac Coherent Light Source (US)
Publication Details
- Journal
- Nature Communications
- Published
- 2026-08-26
- DOI
- https://doi.org/10.1038/s41467-026-75943-4
- Primary Topic
- Metal-Catalyzed Oxygenation Mechanisms
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- U.S. Department of Energy
- Office of Science
- Basic Energy Sciences
- Chemical Sciences, Geosciences, and Biosciences Division