Harnessing Halogen Bonds in Porous Molecular Crystals for Efficient SF ₆ /N ₂ Separation

Abstract Halogen bonding offers a directional and tunable noncovalent interaction that remains underexplored in the design of porous molecular materials. Here, we report FPMC‐1‐β , a porous molecular crystal that uniquely integrates permanent porosity, high thermal stability, solution processability, and halogen bonding capability. Upon desolvation, FPMC‐1‐α undergoes a structural transformation into the denser FPMC‐1‐β phase, featuring distorted 1D channels lined with exposed σ‐holes on bromine atoms. This architecture enables selective halogen bond‐mediated interactions with fluorinated gases. FPMC‐1‐β exhibits a sulfur hexafluoride (SF 6 )/N 2 selectivity of 178.6 at 298 K and 1 bar—setting a new record among all reported porous molecular crystals and soluble porous materials. Combined experimental and computational studies reveal that the high selectivity arises from strong F⋯Br halogen bonding with SF 6 , in contrast to the weak, nonspecific interactions observed for N 2 .