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

C4 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 Å 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 C4 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 C4 olefins, while still adsorbing significant amounts of 1,3-butadiene (C4 H6 ) or 1-butene (n-C4 H8 ). Combining the molecular recognition and size-sieving effect, these materials unexpectedly realized the sieving of C4 H6 /n-C4 H8 , C4 H6 /iso-C4 H8 , and n-C4 H8 /iso-C4 H8 with high capacity.