Engineering the pore size of interpenetrated metal–organic frameworks for molecular sieving separation of C2H2/C2H4†

Selective removal of acetylene (C₂H₂) from ethylene (C₂H₄) presents considerable challenges due to their extremely close molecular size and physical properties. Herein, we successfully prepared two novel isomorphous interpenetrated adsorbents, i.e. Zn-SDBA-dpe and Zn-SDBA-bpy (SDBA = 4,4′-sulfonyldibenzoic acid, dpe = 4,4′-vinylenedipyridine, bpy = 4,4′-bipyridyl), for molecular sieving of C₂H₂ from C₂H₄. The uniform interpenetration of Zn-SDBA-bpy possessing contracted and suitable cavities only allows the diffusion of C₂H₂, while excluding C₂H₄ molecules. As a result, Zn-SDBA-bpy exhibits an exceptional C₂H₂/C₂H₄ uptake ratio of 11.93, and remarkable selectivities of 936.7 and 229.9 for the 50/50 and 1/99 C₂H₂/C₂H₄ mixtures, respectively. Dynamic breakthrough experiments further corroborate its superior feasibility for C₂H₂/C₂H₄ separation. Moreover, computational simulations reveal the multiple host–guest interactions for C₂H₂ and the underlying mechanism of molecular sieving within Zn-SDBA-bpy.