title: Sequential Proton Coupled Electron Transfer (PCET): Dynamics Observed over 8 Orders of Magnitude in Time.
abstract: Charge transfer mechanisms lay at the heart of chemistry and biochemistry. Proton coupled electron transfers (PCET) are central in biological processes such as photosynthesis and in the respiratory chain, where they mediate long-range charge transfers. These mechanisms are normally difficult to harness experimentally due to the intrinsic complexity of the associated biological systems. Metal-peptide cations experience both electron and proton transfers upon photoexcitation, proving an amenable model system to study PCET. We report on a time-resolved experiment designed to follow this dual charge transfer kinetics in [HG3W+Ag](+) (H = histidine, G = glycine, W = tryptophan) on time scales ranging from femtoseconds to milliseconds. While electron transfer completes in less than 4 ps, it triggers a proton transfer lasting over hundreds of microseconds. Molecular dynamics simulations show that conformational dynamic plays an important role in slowing down this reaction. This combined experimental and computational approach provides a view of PCET as a single phenomenon despite its very wide time-domain span.
authors.affiliation: Institut Lumière Matière, UMR5306 Université Claude Bernard Lyon1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
authors.forename: Luke
authors.initials: L
authors.lastname: MacAleese
authors.affiliation: Group of Applied Physics (GAP) Biophotonics, Université de Genève , Chemin de Pinchat 22, CH-1211 Geneva, Switzerland.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Hermelin
authors.affiliation: Department of Chemistry, University of Basel , Klingelbergstr 80, CH-4056 Basel, Switzerland.
authors.forename: Krystel El
authors.initials: KE
authors.lastname: Hage
authors.affiliation: Institut Lumière Matière, UMR5306 Université Claude Bernard Lyon1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Chouzenoux
authors.affiliation: Institut Lumière Matière, UMR5306 Université Claude Bernard Lyon1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kulesza
authors.affiliation: Institut Lumière Matière, UMR5306 Université Claude Bernard Lyon1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Antoine
authors.affiliation: Group of Applied Physics (GAP) Biophotonics, Université de Genève , Chemin de Pinchat 22, CH-1211 Geneva, Switzerland.
authors.forename: Luigi
authors.initials: L
authors.lastname: Bonacina
authors.affiliation: Department of Chemistry, University of Basel , Klingelbergstr 80, CH-4056 Basel, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Meuwly
authors.affiliation: Group of Applied Physics (GAP) Biophotonics, Université de Genève , Chemin de Pinchat 22, CH-1211 Geneva, Switzerland.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Wolf
authors.affiliation: Institut Lumière Matière, UMR5306 Université Claude Bernard Lyon1-CNRS, Université de Lyon 69622 Villeurbanne cedex, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd