Molecular sieving can lead to ultrahigh selectivity and low regeneration energy because it completely excludes all larger molecules via a size restriction mechanism. However, it allows adsorption of all molecules smaller than the pore aperture and so separations of complicated mixtures can be hindered. Here, we report an intermediate-sized molecular sieving (iSMS) effect in a metal–organic framework (MAF-41) designed with restricted flexibility, which also exhibits superhydrophobicity and ultrahigh thermal/chemical stabilities. Single-component isotherms and computational simulations show adsorption of styrene but complete exclusion of the larger analogue ethylbenzene (because it exceeds the maximal aperture size) and smaller toluene/benzene molecules that have insufficient adsorption energy to open the cavity. Mixture adsorption experiments show a high styrene selectivity of 1,250 for an ethylbenzene/styrene mixture and 3,300 for an ethylbenzene/styrene/toluene/benzene mixture (orders of magnitude higher than previous reports). This produces styrene with a purity of 99.9%+ in a single adsorption–desorption cycle. Controlling/restricting flexibility is the key for iSMS and can be a promising strategy for discovering other exceptional properties.
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The data that support the plots within this paper and other finding of this study are available from the corresponding authors upon reasonable request. CCDC 1581460−1581461 entries contain supplementary single-crystal X-ray diffraction data for 1·pX and structural details of 1′. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
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This work was supported by the NSFC (21731007, 21821003, 91622109 and 21701191), Guangdong Pearl River Talents Program (2017BT01C161) and Guangdong Province Key Area R&D Program (2019B010940001).
The authors declare no competing interests.
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Zhou, DD., Chen, P., Wang, C. et al. Intermediate-sized molecular sieving of styrene from larger and smaller analogues. Nat. Mater. 18, 994–998 (2019). https://doi.org/10.1038/s41563-019-0427-z
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