High Pressure In Situ Single-Crystal X-Ray Diffraction Reveals Turnstile Linker Rotation Upon Room-Temperature Stepped Uptake of Alkanes

Dewald P van Heerden; Vincent J Smith; Himanshu Aggarwal; Leonard J Barbour

doi:10.1002/anie.202102327

High Pressure In Situ Single-Crystal X-Ray Diffraction Reveals Turnstile Linker Rotation Upon Room-Temperature Stepped Uptake of Alkanes

Angew Chem Int Ed Engl. 2021 Jun 7;60(24):13430-13435. doi: 10.1002/anie.202102327. Epub 2021 Apr 28.

Authors

Dewald P van Heerden¹, Vincent J Smith², Himanshu Aggarwal³, Leonard J Barbour¹

Affiliations

¹ Department of Chemistry and Polymer Science, Stellenbosch University, Matieland, 7602, South Africa.
² Department of Chemistry, Rhodes University, Makhanda, 6140, South Africa.
³ Department of Chemistry, Birla Institute of Technology and Science, Hyderabad, 500078, India.

PMID: 33780117
DOI: 10.1002/anie.202102327

Abstract

The rare availability of suitable single-crystal X-ray diffraction (SCXRD) structural data allows for the direct interpretation of the response of a framework to gas sorption and may lead to the development of improved functional porous materials. We report an in situ SCXRD structural investigation of a flexible MOF subjected to methane, ethane, propane, and butane gas pressures. Supporting theoretical investigations indicate weak host-guest interactions for the crystallographically modelled gaseous guests and, in addition, reveal that a turnstile mechanism facilitates the transport of alkanes through the seemingly nonporous system. Inflections present in the adsorption isotherms are furthermore rationalized as due to gate-opening, but without the expected creation of new accessible space.

Keywords: alkane adsorption; flexible MOF; gated uptake; linker rotation; stepped isotherm.

Grants and funding

47121/National Research Foundation