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Controlling Proton-Coupled Electron Transfer in Bioinspired Artificial Photosynthetic Relays.
Odella, Emmanuel; Mora, S Jimena; Wadsworth, Brian L; Huynh, Mioy T; Goings, Joshua J; Liddell, Paul A; Groy, Thomas L; Gervaldo, Miguel; Sereno, Leónides E; Gust, Devens; Moore, Thomas A; Moore, Gary F; Hammes-Schiffer, Sharon; Moore, Ana L.
Afiliación
  • Odella E; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
  • Mora SJ; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
  • Wadsworth BL; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
  • Huynh MT; Department of Chemistry , Yale University , New Haven , Connecticut 06520-8107 , United States.
  • Goings JJ; Department of Chemistry , Yale University , New Haven , Connecticut 06520-8107 , United States.
  • Liddell PA; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
  • Groy TL; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
  • Gervaldo M; Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales , Universidad Nacional de Río Cuarto , Agencia Postal No. 3, 5800 Río Cuarto , Córdoba , Argentina.
  • Sereno LE; Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales , Universidad Nacional de Río Cuarto , Agencia Postal No. 3, 5800 Río Cuarto , Córdoba , Argentina.
  • Gust D; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
  • Moore TA; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
  • Moore GF; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
  • Hammes-Schiffer S; Department of Chemistry , Yale University , New Haven , Connecticut 06520-8107 , United States.
  • Moore AL; School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287-1604 , United States.
J Am Chem Soc ; 140(45): 15450-15460, 2018 11 14.
Article en En | MEDLINE | ID: mdl-30379075
Bioinspired constructs consisting of benzimidazole-phenol moieties bearing N-phenylimines as proton-accepting substituents have been designed to mimic the H-bond network associated with the TyrZ-His190 redox relay in photosystem II. These compounds provide a platform to theoretically and experimentally explore and expand proton-coupled electron transfer (PCET) processes. The models feature H-bonds between the phenol and the nitrogen at the 3-position of the benzimidazole and between the 1 H-benzimidazole proton and the imine nitrogen. Protonation of the benzimidazole and the imine can be unambiguously detected by infrared spectroelectrochemistry (IRSEC) upon oxidation of the phenol. DFT calculations and IRSEC results demonstrate that with sufficiently strong electron-donating groups at the para-position of the N-phenylimine group (e.g., -OCH3 substitution), proton transfer to the imine is exergonic upon phenol oxidation, leading to a one-electron, two-proton (E2PT) product with the imidazole acting as a proton relay. When transfer of the second proton is not sufficiently exergonic (e.g., -CN substitution), a one-electron, one-proton transfer (EPT) product is dominant. Thus, the extent of proton translocation along the H-bond network, either ∼1.6 Å or ∼6.4 Å, can be controlled through imine substitution. Moreover, the H-bond strength between the benzimidazole NH and the imine nitrogen, which is a function of their relative p Ka values, and the redox potential of the phenoxyl radical/phenol couple are linearly correlated with the Hammett constants of the substituents. In all cases, a high potential (∼1 V vs SCE) is observed for the phenoxyl radical/phenol couple. Designing and tuning redox-coupled proton wires is important for understanding bioenergetics and developing novel artificial photosynthetic systems.

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: J Am Chem Soc Año: 2018 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Estados Unidos

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: J Am Chem Soc Año: 2018 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Estados Unidos