Inverse Hydrocarbon Recognition via Nitro Group–Programmed Soft Porous Crystal for One-Step C<sub>3</sub>H<sub>6</sub> Purification
Jingmeng Wan, Jia‐Jia Zheng, Ling Huang, Junfeng Bai, Susumu Kitagawa, Jingui Duan
Abstract
The energy-intensive separation of propylene (C 3 H 6 ) from propane (C 3 H 8 ) is a major industrial challenge. To address this, we introduce a concept of molecular recognition based on hydrogen atom content (H δ + ) using cooperative host–guest interactions in soft porous crystals. Guided by this principle, we designed a flexible porous crystal, NTU-99-NO 2, incorporating electronegative nitro group receptors into a dynamic framework. This material exhibits unprecedented inverse selectivity: a 2-fold higher uptake of C 3 H 8 over C 3 H 6 at 298 K, 1 bar. Crystallographic, theoretical, and in situ studies reveal that only C 3 H 8 triggers pore expansion and secondary adsorption, enabled by nitro group-mediated recognition. Comparative studies with hydroxyl- and methyl-functionalized analogs confirm the crucial role of receptor electronegativity. NTU-99-NO 2 enables the direct, one-step production of polymer-grade C 3 H 6, combining breakthrough selectivity, structural adaptability, and scalable synthesis. This work establishes a generalizable design strategy for adaptive, receptor-guided separations in porous materials.