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Title: Controlling Proton Delivery through Catalyst Structural Dynamics

Authors:
 [1];  [2];  [2];  [2];  [2];  [2];  [2];  [2];  [2]
  1. Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57 Richland WA 99352 USA; 221 Science Center, State University of New York at Fredonia, Fredonia NY 14063 USA
  2. Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57 Richland WA 99352 USA
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Molecular Electrocatalysis (CME)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1388790
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Angewandte Chemie (International Edition); Journal Volume: 55; Journal Issue: 43; Related Information: CME partners with Pacific Northwest National Laboratory (lead); University of Illinois, Urbana-Champaign; Pennsylvania State University; University of Washington; University of Wyoming
Country of Publication:
United States
Language:
English
Subject:
catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), bio-inspired, energy storage (including batteries and capacitors), hydrogen and fuel cells, charge transport, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Cardenas, Allan Jay P., Ginovska, Bojana, Kumar, Neeraj, Hou, Jianbo, Raugei, Simone, Helm, Monte L., Appel, Aaron M., Bullock, R. Morris, and O'Hagan, Molly. Controlling Proton Delivery through Catalyst Structural Dynamics. United States: N. p., 2016. Web. doi:10.1002/anie.201607460.
Cardenas, Allan Jay P., Ginovska, Bojana, Kumar, Neeraj, Hou, Jianbo, Raugei, Simone, Helm, Monte L., Appel, Aaron M., Bullock, R. Morris, & O'Hagan, Molly. Controlling Proton Delivery through Catalyst Structural Dynamics. United States. doi:10.1002/anie.201607460.
Cardenas, Allan Jay P., Ginovska, Bojana, Kumar, Neeraj, Hou, Jianbo, Raugei, Simone, Helm, Monte L., Appel, Aaron M., Bullock, R. Morris, and O'Hagan, Molly. 2016. "Controlling Proton Delivery through Catalyst Structural Dynamics". United States. doi:10.1002/anie.201607460.
@article{osti_1388790,
title = {Controlling Proton Delivery through Catalyst Structural Dynamics},
author = {Cardenas, Allan Jay P. and Ginovska, Bojana and Kumar, Neeraj and Hou, Jianbo and Raugei, Simone and Helm, Monte L. and Appel, Aaron M. and Bullock, R. Morris and O'Hagan, Molly},
abstractNote = {},
doi = {10.1002/anie.201607460},
journal = {Angewandte Chemie (International Edition)},
number = 43,
volume = 55,
place = {United States},
year = 2016,
month = 9
}
  • The fastest synthetic molecular catalysts for production and oxidation of H2 emulate components of the active site of natural hydrogenases. The role of controlled structural dynamics is recognized as a critical component in the catalytic performance of many enzymes, including hydrogenases, but is largely neglected in the design of synthetic molecular cata-lysts. In this work, the impact of controlling structural dynamics on the rate of production of H2 was studied for a series of [Ni(PPh2NC6H4-R2)2]2+ catalysts including R = n-hexyl, n-decyl, n-tetradecyl, n-octadecyl, phenyl, or cyclohexyl. A strong correlation was observed between the ligand structural dynamics and the rates ofmore » electrocatalytic hydrogen production in acetonitrile, acetonitrile-water, and protic ionic liquid-water mixtures. Specifically, the turnover frequencies correlate inversely with the rates of ring inversion of the amine-containing ligand, as this dynamic process dictates the positioning of the proton relay in the second coordination sphere and therefore governs protonation at either catalytically productive or non-productive sites. This study demonstrates that the dynamic processes involved in proton delivery can be controlled through modifications of the outer coordination sphere of the catalyst, similar to the role of the protein architecture in many enzymes. The present work provides new mechanistic insight into the large rate enhancements observed in aqueous protic ionic liquid media for the [Ni(PPh2NR2)]2+ family of catalysts. The incorporation of controlled structural dynamics as a design parameter to modulate proton delivery in molecular catalysts has enabled H2 production rates that are up to three orders of magnitude faster than the [Ni(PPh2NPh2)]2+complex. The observed turnover frequencies are up to 106 s-1 in acetonitrile-water, and over 107 s-1 in protic ionic liquid-water mixtures, with a minimal increase in overpotential. This material is based upon work supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, and was performed in part using the Molecular Science Computing Facility (MSCF) in the William R. Wiley Environmental Molecular Sciences Laboratory, a DOE national scientific user facility located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for DOE.« less
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