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Title: Electronic Conductivity, Ferrimagnetic Ordering, and Reductive Insertion Mediated by Organic Mixed-Valence in a Ferric Semiquinoid Metal–Organic Framework

Abstract

Here, a three-dimensional network solid composed of Fe III centers and paramagnetic semiquinoid linkers, (NBu 4) 2Fe III 2(dhbq )3 (dhbq2–/3– = 2,5-dioxidobenzoquinone/1,2-dioxido-4,5-semiquinone), is shown to exhibit a conductivity of 0.16 ± 0.01 S/cm at 298 K, one of the highest values yet observed for a metal–organic framework (MOF). The origin of this electronic conductivity is determined to be ligand mixed-valency, which is characterized using a suite of spectroscopic techniques, slow-scan cyclic voltammetry, and variable-temperature conductivity and magnetic susceptibility measurements. Importantly, UV–vis–NIR diffuse reflectance measurements reveal the first observation of Robin–Day Class II/III mixed valency in a MOF. Pursuit of stoichiometric control over the ligand redox states resulted in synthesis of the reduced framework material Na 0.9(NBu 4) 1.8Fe III 2(dhbq) 3. Differences in electronic conductivity and magnetic ordering temperature between the two compounds are investigated and correlated to the relative ratio of the two different ligand redox states. Overall, the transition metal–semiquinoid system is established as a particularly promising scaffold for achieving tunable long-range electronic communication in MOFs.

Authors:
 [1];  [1];  [1];  [1];  [2]
  1. Univ. of California, Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Univ. of Minnesota, Minneapolis, MN (United States). Nanoporous Materials Genome Center
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Org.:
Beamline 17-BM; Beamline 11.3.1
OSTI Identifier:
1488852
Grant/Contract Number:  
FG02-12ER16362; SC0008688
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 137; Journal Issue: 50; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Darago, Lucy E., Aubrey, Michael L., Yu, Chung Jui, Gonzalez, Miguel I., and Long, Jeffrey R.. Electronic Conductivity, Ferrimagnetic Ordering, and Reductive Insertion Mediated by Organic Mixed-Valence in a Ferric Semiquinoid Metal–Organic Framework. United States: N. p., 2015. Web. doi:10.1021/jacs.5b10385.
Darago, Lucy E., Aubrey, Michael L., Yu, Chung Jui, Gonzalez, Miguel I., & Long, Jeffrey R.. Electronic Conductivity, Ferrimagnetic Ordering, and Reductive Insertion Mediated by Organic Mixed-Valence in a Ferric Semiquinoid Metal–Organic Framework. United States. doi:10.1021/jacs.5b10385.
Darago, Lucy E., Aubrey, Michael L., Yu, Chung Jui, Gonzalez, Miguel I., and Long, Jeffrey R.. Tue . "Electronic Conductivity, Ferrimagnetic Ordering, and Reductive Insertion Mediated by Organic Mixed-Valence in a Ferric Semiquinoid Metal–Organic Framework". United States. doi:10.1021/jacs.5b10385. https://www.osti.gov/servlets/purl/1488852.
@article{osti_1488852,
title = {Electronic Conductivity, Ferrimagnetic Ordering, and Reductive Insertion Mediated by Organic Mixed-Valence in a Ferric Semiquinoid Metal–Organic Framework},
author = {Darago, Lucy E. and Aubrey, Michael L. and Yu, Chung Jui and Gonzalez, Miguel I. and Long, Jeffrey R.},
abstractNote = {Here, a three-dimensional network solid composed of FeIII centers and paramagnetic semiquinoid linkers, (NBu4)2FeIII2(dhbq)3 (dhbq2–/3– = 2,5-dioxidobenzoquinone/1,2-dioxido-4,5-semiquinone), is shown to exhibit a conductivity of 0.16 ± 0.01 S/cm at 298 K, one of the highest values yet observed for a metal–organic framework (MOF). The origin of this electronic conductivity is determined to be ligand mixed-valency, which is characterized using a suite of spectroscopic techniques, slow-scan cyclic voltammetry, and variable-temperature conductivity and magnetic susceptibility measurements. Importantly, UV–vis–NIR diffuse reflectance measurements reveal the first observation of Robin–Day Class II/III mixed valency in a MOF. Pursuit of stoichiometric control over the ligand redox states resulted in synthesis of the reduced framework material Na0.9(NBu4)1.8FeIII2(dhbq)3. Differences in electronic conductivity and magnetic ordering temperature between the two compounds are investigated and correlated to the relative ratio of the two different ligand redox states. Overall, the transition metal–semiquinoid system is established as a particularly promising scaffold for achieving tunable long-range electronic communication in MOFs.},
doi = {10.1021/jacs.5b10385},
journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 50,
volume = 137,
place = {United States},
year = {2015},
month = {11}
}

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