Guest‐mediated dynamic sieving in a metal–organic framework for separation of C 2 H 6 from C 2 hydrocarbons

Chemical separations are essential to modern industry, yet account for a substantial fraction of global energy consumption due to thermally driven distillation processes. Molecular sieving using porous materials offers an energy‐efficient alternative; however, conventional designs rely on static pore apertures that fundamentally limit selectivity. Herein, we report a guest‐mediated dynamic sieving strategy using a Ni‐based helical channel framework ( Ni‐HCF ) to achieve C 2 H 6 exclusion from C 2 hydrocarbons. Thermally activated motions of residual confined guest species (DMF and DMA + ) dynamically regulate transport pathways, overcoming static crystallographic aperture dimensions. Synergized by selective favorable interactions with unsaturated hydrocarbons at open nickel sites, Ni‐HCF enables precise discrimination between unsaturated (C 2 H 2 , C 2 H 4 ) and saturated (C 2 H 6 ) gases. Consequently, Ni‐HCF achieves exceptional Ideal Adsorbed Solution Theory (IAST) selectivities at 273 K of 344 for C 2 H 2 /C 2 H 6 and 21 for C 2 H 4 /C 2 H 6 . This work demonstrates guest‐enabled dynamic gating as a general design paradigm for high‐performance molecular separations in energy‐efficient industrial processes.