Selective gas uptake and rotational dynamics in a (3,24)-connected metal–organic framework material

DOI: 10.1021/jacs.0c11202

Authors: William J. F. Trenholme (University of Manchester) , Daniil I. Kolokolov (Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences) , Michelle Bound (University of Nottingham) , Stephen P. Argent (University of Nottingham) , Jamie A. Gould (University of Nottingham; Newcastle University) , Jiangnan Li (University of Manchester) , Sarah A. Barnett (Diamond Light Source) , Alexander J. Blake (University of Nottingham) , Alexander G. Stepanov (Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences; Novosibirsk State University) , Elena Besley (University of Nottingham) , Timothy L. Easun (University of Nottingham; Cardiff University) , Sihai Yang (University of Nottingham) , Martin Schroeder (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society , VOL 71

State: Published (Approved)
Published: February 2021

Abstract: The desolvated (3,24)-connected metal–organic framework (MOF) material, MFM-160a, [Cu3(L)(H2O)3] [H6L = 1,3,5-triazine-2,4,6-tris(aminophenyl-4-isophthalic acid)], exhibits excellent high-pressure uptake of CO2 (110 wt% at 20 bar, 298 K) and highly selective separation of C2 hydrocarbons from CH4 at 1 bar pressure. Henry’s law selectivities of 79:1 for C2H2:CH4 and 70:1 for C2H4:CH4 at 298 K are observed, consistent with ideal adsorption solution theory (IAST) predictions. Significantly, MFM-160a shows a selectivity of 16:1 for C2H2:CO2. Solid-state 2H NMR spectroscopic studies on partially deuterated MFM-160-d12 confirm an ultra-low barrier (∼2 kJ mol–1) to rotation of the phenyl group in the activated MOF and a rotation rate 5 orders of magnitude slower than usually observed for solid-state materials (1.4 × 106 Hz cf. 1011–1013 Hz). Upon introduction of CO2 or C2H2 into desolvated MFM-160a, this rate of rotation was found to increase with increasing gas pressure, a phenomenon attributed to the weakening of an intramolecular hydrogen bond in the triazine-containing linker upon gas binding. DFT calculations of binding energies and interactions of CO2 and C2H2 around the triazine core are entirely consistent with the 2H NMR spectroscopic observations.

Journal Keywords: Hydrocarbons; Phenyls; Nuclear magnetic resonance spectroscopy; Selectivity; Materials

Diamond Keywords: Carbon Capture and Storage (CCS); Gas Separation

Subject Areas: Chemistry, Materials


Instruments: I19-Small Molecule Single Crystal Diffraction

Added On: 01/03/2021 09:25

Discipline Tags:

Earth Sciences & Environment Climate Change Chemistry Materials Science Metal-Organic Frameworks Metallurgy Organometallic Chemistry

Technical Tags:

Diffraction Single Crystal X-ray Diffraction (SXRD)