Porous halogen-bonded frameworks assembled through hetero-polytopic ion pair templation

Halogen-bonding (XB) interactions have been extensively studied in the preparation of crystalline frameworks, yet porous 3D framework materials built on XBs remain elusive. The donor-acceptor interactions are strengthened by use of anionic XB acceptors; however, the requisite charge-balancing cations typically disrupt the framework and occupy potential void space. In this work, we prepare a tetratopic XB donor bearing a crown ether moiety for sodium cation sequestration. We show that when this ion pair receptor is crystallised with NaCl it gives a 3D framework that is porous to solvent and vapour, and undergoes single-crystal-to-single-crystal reactions.