Halogen Bonding Stabilizes Permanent Porosity

Halogen bonding has emerged as an intuitive and programmable handle for constructing ordered molecular solids. However, its ability to support permanent porosity has remained unresolved. Here, we report a self-complementary strategy that surpasses this long-standing limitation, delivering the first rigorously characterized permanently porous halogen-bonded organic framework (XOF). A threefoldsymmetric 2-iodooxazole terminated tecton spontaneously assembles into a low-density, crystalline network that remains intact upon complete solvent removal. Permanent porosity is confirmed by gas adsorption-desorption measurements using N2 at 77 K, and the porous topology was monitored via X-ray diffraction. This framework is sustained by π-stacked tectons linked through one-dimensional helical chains of C-I•••N halogen bonding, yielding full three-dimensional connectivity. Subtle torsional disorder within these chains can be resolved crystallographically, providing rare insight into molecular-level disorder in highly ordered porous frameworks. This work defines a new upper bound for halogen bonding in materials design, establishing XOFs as a distinct permanently porous materials platform.