Negative cooperativity upon hydrogen bond-stabilized O2 adsorption in a redox-active metal–organic framework

• Published in: Nature communications Vol. 11; no. 1; p. 3087
• Main Authors: Oktawiec, Julia, Jiang, Henry Z. H., Vitillo, Jenny G., Reed, Douglas A., Darago, Lucy E., Trump, Benjamin A., Bernales, Varinia, Li, Harriet, Colwell, Kristen A., Furukawa, Hiroyasu, Brown, Craig M., Gagliardi, Laura, Long, Jeffrey R.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.06.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 639/638/263; 639/638/298; 639/638/298/921; Adsorbents; Adsorption; Bonding strength; Carbon dioxide; Catalysis; Cobalt; Cooperativity; Coordination; Electron transfer; Functional materials; Humanities and Social Sciences; Hydrogen bonding; Hydrogen bonds; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Metal-organic frameworks; Metals; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-16897-z

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 O 2 carriers, we demonstrate that coupling metal-based electron transfer with secondary coordination sphere effects in the metal–organic framework Co 2 (OH) 2 (bbta) (H 2 bbta = 1 H ,5 H -benzo(1,2- d: 4,5- d ′)bistriazole) leads to strong and reversible adsorption of O 2 . In particular, moderate-strength hydrogen bonding stabilizes a cobalt(III)-superoxo species formed upon O 2 adsorption. Notably, O 2 -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. Oxygen capture is attractive for catalysis, sensing, and separations, but engineering stable and selective adsorbents is challenging. Here the authors combine metal-based electron transfer with secondary coordination sphere effects in a metal-organic framework, leading to strong and reversible O 2 adsorption that also exhibits negative cooperativity.