The design of stable adsorbents capable of selectively capturing dioxygen with a high reversible capacity is a crucial goal in functional materials development. Drawing inspiration from biological O2 carriers, we demonstrate that coupling metal-based electron transfer with secondary coordination sphere effects in the metal–organic framework Co2(OH)2(bbta) (H2bbta = 1H,5H-benzo(1,2-d:4,5-d′)bistriazole) leads to strong and reversible adsorption of O2. In particular, moderate-strength hydrogen bonding stabilizes a cobalt(III)-superoxo species formed upon O2 adsorption. Notably, O2-binding in this material weakens as a function of loading, as a result of negative cooperativity arising from electronic effects within the extended framework lattice. This unprecedented behavior extends the tunable properties that can be used to design metal–organic frameworks for adsorption-based applications.
Bibliographical noteFunding Information:
Experimental work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-SC0019992, while computational efforts were supported by the Nanoporous Materials Genome Center, which is funded by the U.S. DoE, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under award DE-FG02−17ER16362. X-ray powder diffraction data were collected on Beamline 17-BM-B at the Advanced Photon Source, a U.S. DoE Office of Science User Facility operated by Argonne National Laboratory. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. DoE, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Additionally, X-ray powder diffraction data was collected at Beamline 12.2.2 at the Advanced Light Source (ALS), which is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U. S. DoE under Contract No. DE-AC02-05CH11231. Computational resources were provided in part by the Minnesota Supercomputing Institute (MSI) at the University of Minnesota. We are grateful to the National Science Foundation for graduate research fellowship support of J.O., D.A.R., and L.E.D. We further thank Prof. Peidong Yang for use of a scanning electron microscope; Dr. Matthew Koc, Dr. Benjamin Snyder, Dr. Tianpin Wu, Dr. Andrey Yakovenko, Dr. Wenqian Xu, Dr. Jacob Tarver, and Maria Paley for experimental assistance; Dr. Rebecca L. Siegelman, Dr. Miguel I. Gonzalez, Dr. Jeffrey D. Martell, Ari B. Turkiewicz, and Dr. Andy I. Nguyen for helpful discussions; and Dr. Katie R. Meihaus for editorial assistance.
© 2020, The Author(s).