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Porous molecular sorbents have excellent selectivity towards hydrocarbon separation with energy saving techniques. However, to realize commercialization, molecular sieving processes should be faster and more efficient compared to extended frameworks. In this work, we show that utilizing fluorine to improve the hydrophobic profile of leaning pillararenes affords a substantial kinetic selective adsorption of benzene over cyclohexane (20 : 1 for benzene). The crystal structure shows a porous macrocycle that acts as a perfect match for benzene in both the intrinsic and extrinsic cavities with strong interactions in the solid state. The fluorinated leaning pillararene surpasses all reported organic molecular sieves and is comparable to the extended metal–organic frameworks that were previously employed for this separation such as UIO‐66. Most importantly, this sieving system outperformed the well‐known zeolitic imidazolate frameworks under low pressure, which opens the door to new generations of molecular sieves that can compete with extended frameworks for more sustainable hydrocarbon separation. [ABSTRACT FROM AUTHOR]

Developing the competence of molecular sorbents for energy‐saving applications, such as C8 separations, requires efficient, stable, scalable, and easily recyclable materials that can readily transition to commercial implementation. Herein, we report an azobenzene‐based cage for the selective separation of p‐xylene isomer across a range of C8 isomers in both vapor and liquid states with selectivity that is higher than the reported all‐organic sorbents. The crystal structure shows non‐porous cages that are separated by p‐xylene molecules through selective CH–π interactions between the azo bonds and the methyl hydrogen atoms of the xylene molecules. This cage is stable in solution and can be regenerated directly under vacuum to be used in multiple cycles. We envisage that this work will promote the investigation of the azo bond as well as guest‐induced crystal‐to‐crystal phase transition in non‐porous organic solids for energy‐intensive separations. [ABSTRACT FROM AUTHOR]

Keywords: azobenzene; C8 separations; host-guest interactions; intrinsically porous materials; organic cages EN azobenzene C8 separations host-guest interactions intrinsically porous materials organic cages 21433 21433 1 11/18/20 20201123 NES 201123 B Ein stabiler und rezyklierbarer b nichtporöser Azobenzol-basierter organischer Käfig (AZO-Cage), der selektiv für I p i -Xylol (pX) gegenüber allen C SB 8 sb -Isomeren ist, wird von N. M. Khashab und Mitarbeitern in der Zuschrift auf S. 21551 vorgestellt. AZO-Cage geht einen Kristall-zu-Kristall-Phasenübergang selektiv in Gegenwart von pX in der Flüssig- und Dampfphase ein, was es zu einer idealen Plattform für die Stofftrennung von Benzolderivaten macht. AZO-Cage geht einen Kristall-zu-Kristall-Phasenübergang selektiv in Gegenwart von pX in der Flüssig- und Dampfphase ein, was es zu einer idealen Plattform für die Stofftrennung von Benzolderivaten macht. [Extracted from the article]