Gate-Opening Effect in a Flexible Metal-Organic Framework for Sieving Acetylene.

Adsorptive separation employing porous materials is one of the most promising alternative technologies for CH purification due to its energy-efficient and environmentally friendly advantages. Herein, we present the design and synthesis of a dicopper-paddle-wheel-based metal-organic framework (termed JNU-5-Me) with a carboxylate-azolate organic linker. The use of such a linker results in the axial positions of the dicopper paddle wheels being occupied by azolates, and therefore, a much-improved chemical stability of the framework structure. JNU-5-Me shows negligible adsorption of CH, CH, and CO at 1.0 bar and 298 K, while a gate-opening effect for CH and a large CH adsorption (4.7 mmol g) at 1.0 bar and 298 K. Dynamic breakthrough studies on JNU-5-Me demonstrate its excellent CH separation performance from CH/CO (50/50, v/v) and CH/CO/CH/CH (70/10/10/10, v/v/v/v) mixtures. Additionally, infrared spectroscopy and Grand canonical Monte Carlo (GCMC) simulation reveal that the carboxylate oxygens and methyl groups on the framework are involved in the strong binding of CH, which may be attributed to the gate-opening effect of JNU-5-Me.