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The impact of defects and crystal size on negative gas adsorption in DUT-49 analyzed by in situ 129Xe NMR spectroscopy.

preprint
submitted on 10.03.2020 and posted on 11.03.2020 by Simon Krause, Florian Reuter, Sebastian Ehrling, Volodymyr Bon, Irena Senkovska, Stefan Kaskel, Eike Brunner
The origin of crystal size-dependent adsorption behavior of flexible metal-organic frameworks is increasingly studied. In this contribution, we probe the solid-fluid interactions of DUT-49 crystals of different size by in situ 129Xe NMR spectroscopy at 200 K. With decreasing size of the crystals, the average solid-fluid interactions are found to decrease reflected by a decrease in chemical shift of adsorbed xenon from 230 to 200 ppm explaining the lack of adsorption-induced transitions for smaller crystals. However, recent studies propose that these results can also originate from the presence of lattice defects. To investigate the influence of defects on the adsorption behavior of DUT-49 we synthesized a series of samples with tailored defect concentrations and characterized them by in situ 129Xe NMR. In comparison to the results obtained for crystals with different size we find pronounced changes of the adsorption behavior and influence of the chemical shift only for very high concentrations of defects, which further emphasizes the important role of particle size phenomena.

Funding

European Union’s Horizon 2020 research and innovation programme (grant agreement No. 742743).

Deutsche Forschungsgemeinschaft (Research Unit FOR 2433 “MOF-Switches”)

History

Email Address of Submitting Author

simon.krause@rug.nl

Institution

University of Groningen

Country

The Netherlands

ORCID For Submitting Author

https://orcid.org/0000-0001-9504-8514

Declaration of Conflict of Interest

no conflict of interest

Version Notes

Initial submission

Exports