Title: Mimicking the Electron Transport Chain and Active Site of [FeFe] Hydrogenases in One Metal–Organic Framework: Factors That Influence Charge Transport

Abstract

[FeFe] hydrogenase (H2ase) enzymes are effective proton reduction catalysts capable of forming molecular dihydrogen with a high turnover frequency at low overpotential. The active sites of these enzymes are buried within the protein structures, and substrates required for hydrogen evolution (both protons and electrons) are shuttled to the active sites through channels from the protein surface. Metal–organic frameworks (MOFs) provide a unique platform for mimicking such enzymes due to their inherent porosity which permits substrate diffusion and their structural tunability which allows for the incorporation of multiple functional linkers. Furthermore, we describe the preparation and characterization of a redox-active PCN-700-based MOF (PCN = porous coordination network) that features both a biomimetic model of the [FeFe] H₂ase active site as well as a redox-active linker that acts as an electron mediator, thereby mimicking the function of [4Fe4S] clusters in the enzyme. Rigorous studies on the dual-functionalized MOF by cyclic voltammetry (CV) reveal similarities to the natural system but also important limitations in the MOF-enzyme analogy. Most importantly, and in contrast to the enzyme, restrictions apply to the total concentration of reduced linkers and charge-balancing counter cations that can be accommodated within the MOF. Successive charging of the MOF results in nonidealmore » interactions between linkers and restricted mobility of charge-compensating redox-inactive counterions. Consequently, apparent diffusion coefficients are no longer constant, and expected redox features in the CVs of the materials are absent. Such nonlinear effects may play an important role in MOFs for (electro)catalytic applications.« less

Authors:

Castner, Ashleigh T.  ^[1];

• Search DOE PAGES for author "Castner, Ashleigh T."
• Search DOE PAGES for ORCID "0000-0002-8732-6470"

Johnson, Ben A.  ^[1];

• Search DOE PAGES for author "Johnson, Ben A."
• Search DOE PAGES for ORCID "0000-0002-6570-6392"

Cohen, Seth M.  ^[2];

• Search DOE PAGES for author "Cohen, Seth M."
• Search DOE PAGES for ORCID "0000-0002-5233-2280"

Ott, Sascha  ^[1]

• Search DOE PAGES for author "Ott, Sascha"
• Search DOE PAGES for ORCID "0000-0002-1691-729X"

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+ Show Author Affiliations

1. Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, 75120 Uppsala, Sweden
2. Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92023-0358, United States

Publication Date:

Mon May 24 00:00:00 EDT 2021

Research Org.:

Uppsala Univ. (Sweden); Univ. of California, San Diego, La Jolla, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division

OSTI Identifier:

1784459

Alternate Identifier(s):

OSTI ID: 1785624; OSTI ID: 1871938

Grant/Contract Number:  

FG02-08ER46519

Resource Type:

Published Article

Journal Name:

Journal of the American Chemical Society

Additional Journal Information:

Journal Name: Journal of the American Chemical Society Journal Volume: 143 Journal Issue: 21; Journal ID: ISSN 0002-7863

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Redox reactions; Peptides and proteins; Metal organic frameworks; Charge transport; Cluster chemistry; MOFs, catalysis, hydrogenases