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Title: Concerted One-Electron Two-Proton Transfer Processes in Models Inspired by the Tyr-His Couple of Photosystem II

Nature employs a TyrZ-His pair as a redox relay that couples proton transfer to the redox process between P680 and the water oxidizing catalyst in photosystem II. Artificial redox relays composed of different benzimidazole–phenol dyads (benzimidazole models His and phenol models Tyr) with substituents designed to simulate the hydrogen bond network surrounding the TyrZ-His pair have been prepared. Furthermore, when the benzimidazole substituents are strong proton acceptors such as primary or tertiary amines, theory predicts that a concerted two proton transfer process associated with the electrochemical oxidation of the phenol will take place. Furthermore, theory predicts a decrease in the redox potential of the phenol by ~300 mV and a small kinetic isotope effect (KIE). Indeed, electrochemical, spectroelectrochemical, and KIE experimental data are consistent with these predictions. Our results were obtained by using theory to guide the rational design of artificial systems and have implications for managing proton activity to optimize efficiency at energy conversion sites involving water oxidation and reduction.
Authors:
ORCiD logo [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [4] ; ORCiD logo [5] ;  [2] ;  [2] ; ORCiD logo [1] ;  [2]
  1. Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Chemistry
  2. Arizona State Univ., Tempe, AZ (United States). School of Molecular Sciences
  3. Univ. of Paris-Sud, Orsay (France). Lab. of Physical Chemistry
  4. Univ. of Virginia, Charlottesville, VA (United States). Dept. of Chemistry
  5. Univ. of California, San Diego, CA (United States). Dept. of Chemistry and Biochemistry
Publication Date:
Report Number(s):
PNNL-SA-125688
Journal ID: ISSN 2374-7943
Grant/Contract Number:
FG02-03ER15393; AC05-76RL01830
Type:
Published Article
Journal Name:
ACS Central Science
Additional Journal Information:
Journal Volume: 3; Journal Issue: 5; Journal ID: ISSN 2374-7943
Publisher:
American Chemical Society (ACS)
Research Org:
Univ. of Illinois, Urbana-Champaign, IL (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1355945
Alternate Identifier(s):
OSTI ID: 1361539; OSTI ID: 1361968