Sorting of C4 Olefins with Interpenetrated Hybrid Ultramicroporous Materials by Combining Molecular Recognition and Size-Sieving

C-4 olefin separations present one of the great challenges in hydrocarbon purifications owing to their similar structures, thus a single separation mechanism often met with limited success. Herein we report a series of anion-pillared interpenetrated copper coordination for which the cavity and functional site disposition can be varied in 0.2 angstrom scale increments by altering the anion pillars and organic linkers (GeFSIX-2-Cu-i (ZU-32), NbFSIX-2-Cu-i (ZU-52), GeFSIX-14-Cu-i (ZU-33)), which enable selective recognition of different C-4 olefins. In these materials the rotation of the organic linkers is controlled to create a contracted flexible pore window that enables the size-exclusion of specific C-4 olefins, while still adsorbing significant amounts of 1,3-butadiene (C4H6) or 1-butene (n-C4H8). Combining the molecular recognition and size-sieving effect, these materials unexpectedly realized the sieving of C4H6/n-C4H8, C4H6/iso-C4H8, and n-C4H8/iso-C4H8 with high capacity.