Self-Adjusting Binding Pockets Enhance H2 and CH4 Adsorption in a Uranium-Based Metal-Organic Framework

Dominik Halter, Ryan Klein, Michael Boreen, Benjamin Trump, Craig Brown, Jeffrey Long

Research output: Contribution to journalArticlepeer-review

21 Scopus Citations

Abstract

A new, air-stable, permanently porous uranium(IV) metal–organic framework U(bdc)2 (1, bdc2- = 1,4-benzenedicarboxylate) was synthesized and its H2 and CH4 adsorption properties were investigated. Low temperature adsorption isotherms confirm strong adsorption of both gases in the framework at low pressures. In situ gas-dosed neutron diffraction experiments with different D2 loadings revealed a rare example of cooperative framework contraction (?V = -7.8%), triggered by D2 adsorption at low pressures. This deformation creates two optimized binding pockets for hydrogen (Qst = -8.6 kJ mol-1) per pore, in agreement with H2 adsorption data. Analogous experiments with CD4 (Qst = -24.8 kJ mol-1) and N,N-dimethylformamide as guests revealed that the binding pockets in 1 adjust by selective framework contractions that are unique for each adsorbent, augmenting individual host–guest interactions. Our results suggest that the strategic combination of binding pockets and structural flexibility in metal–organic frameworks holds great potential for the development of new adsorbents with an enhanced substrate affinity.
Original languageAmerican English
Pages (from-to)6709-6716
Number of pages8
JournalChemical Science
Volume11
Issue number26
DOIs
StatePublished - 2020

NREL Publication Number

  • NREL/JA-5900-76743

Keywords

  • CH4 adsorption
  • H2 adsorption
  • metal-organic framework
  • self-adjusting binding pockets
  • uranium

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