Enhancement of Gas Sorption and Separation Performance via Ligand Functionalization within Highly Stable Zirconium-Based Metal–Organic Frameworks

Abstract

By using a modulated synthetic strategy, three isostructural Zr-based metal organic frameworks [Zr6O4(OH)4(EDDC)6] (JLU-Liu34), [Zr6O4(OH)4(EDDC-NO2)6] (JLU-Liu35), and [Zr6O4(OH)4(EDDC-NH2)6] (JLU-Liu36) (H2EDDC = (E)-4,4′-(ethene-1,2-diyl)dibenzoic acid, H2EDDC-NO2 = (E)-2,2′-dinitro-4,4′-(ethene-1,2-diyl)dibenzoic acid, H2EDDC-NH2 = (E)-2,2′-diamino-4,4′-(ethene-1,2-diyl)dibenzoic acid) which possess different substituent groups have been successfully synthesized. Significantly, the framework and crystallinity of the functionalized Zr-metal–organic frameworks (Zr-MOFs) are well-retained even though the nature of the functional group is different (NO2 is electron-withdrawing, whereas NH2 is electron-releasing). All of the three analogues display 12-connected fcu topology, and the classical Zr6 clusters in the porous crystal make the whole framework approach high chemical and thermal stability. As a result of the functionalization effect, the three analogues show different sorption and separation abiliti...