Sequential Proton Coupled Electron Transfer (PCET): Dynamics Observed over 8 Orders of Magnitude in Time
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- 作者：Luke MacAleese ; Sylvain Hermelin ; Krystel El Hage ; Pierre Chouzenoux ; Alexander Kulesza ; Rodolphe Antoine ; Luigi Bonacina ; Markus Meuwly ; Jean-Pierre Wolf ; Philippe Dugourd
- 刊名：Journal of the American Chemical Society
- 出版年：2016
- 出版时间：April 6, 2016
- 年：2016
- 卷：138
- 期：13
- 页码：4401-4407
- 全文大小：469K
- ISSN：1520-5126
文摘
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.