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

Published

July 14, 2020

Author(s)

Dominik P. Halter, Ryan Klein, Michael A. Boreen, Benjamin Trump, Craig Brown, Jeffrey R. Long

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 (δV = −7.8%), triggered by D₂ adsorption at low pressures. This deformation creates two optimized binding pockets for hydrogen (Q_st = −8.6 kJ/mol) per pore, in agreement with H₂ adsorption data. Analogous experiments with CD₄ (Qst = −24.8 kJ/mol) 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.

Citation

Chemical Science

Volume

11

Issue

26

Pub Type

Journals

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Keywords

MOF, adsorption

Citation

Halter, D. , Klein, R. , Boreen, M. , Trump, B. , Brown, C. and Long, J. (2020), Self-Adjusting Binding Pockets Enhance H₂ and CH₄ Adsorption in a Uranium-Based-Metal–Organic Framework, Chemical Science, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=930233 (Accessed April 26, 2024)