Molecular Sieving of C₂‐C₃ Alkene from Alkyne with Tuned Threshold Pressure in Robust Layered Metal–Organic Frameworks

Abstract

Abstract C 2 ‐C 3 alkyne/alkene separation is of great importance; however, designing materials for an efficient molecular sieving of alkenes from alkynes remains challenging. Now, two hydrolytically stable layered MOFs, [Cu(dps) 2 (GeF 6 )] (GeFSIX‐dps‐Cu, dps=4,4′‐dipyridylsulfide) and [Zn(dps) 2 (GeF 6 )] (GeFSIX‐dps‐Zn), can achieve almost complete exclusion of both C 3 H 6 and C 2 H 4 from their alkyne analogues. GeFSIX‐dps‐Cu displays a notable advanced threshold pressure for alkynes adsorption and thus substantial uptakes at lower pressures, providing record C 3 H 4 /C 3 H 6 uptake ratios and capacity‐enhanced C 2 H 2 /C 2 H 4 sieving for a wide composition range. Metal substitution (Zn to Cu) affords fine tuning of linker rotation and layer stacking, creating slightly expanded pore aperture and interlayer space coupled with multiple hydrogen‐bonding sites, allowing easier entrance of alkyne while excluding alkene. Breakthrough experiments confirmed tunable sieving by these MOFs for C 3 H 4 /C 3 H 6 and C 2 H 2 /C 2 H 4 mixtures.