Boosting Adsorption and Selectivity of Acetylene by Nitro Functionalisation in Copper(II)‐Based Metal–Organic Frameworks

Abstract Purification and storage of acetylene (C 2 H 2 ) are important to many industrial processes. The exploitation of metal–organic framework (MOF) materials to address the balance between selectivity for C 2 H 2 vs carbon dioxide (CO 2 ) against maximising uptake of C 2 H 2 has attracted much interest. Herein, we report that the synergy between unsaturated Cu(II) sites and functional groups, fluoro (−F), methyl (−CH 3 ), nitro (−NO 2 ) in a series of isostructural MOF materials MFM‐190(R) that show exceptional adsorption and selectivity of C 2 H 2 . At 298 K, MFM‐190(NO 2 ) exhibits an C 2 H 2 uptake of 216 cm 3 g −1 (320 cm 3 g −1 at 273 K) at 1.0 bar and a high selectivity for C 2 H 2 /CO 2 (up to ~150 for v/v = 2/1) relevant to that in the industrial cracking stream. Dynamic breakthrough studies validate and confirm the excellent separation of C 2 H 2 /CO 2 by MFM‐190(NO 2 ) under ambient conditions. In situ neutron powder diffraction reveals the cooperative binding, packing and selectivity of C 2 H 2 by unsaturated Cu(II) sites and free −NO 2 groups.