Iodine Adsorption via Porous Molecular Solids Based on Coordination Containers Derived from Naphthalene-1,8-dicarboxylate

Efficient methods to sequester the radioactive iodine element are urgently needed in the nuclear and environmental industries. Nanoporous solid adsorbents based on container molecules are particularly suited for achieving iodine sequestration due to their uniquely tunable intrinsic and extrinsic porous structure. In the present work, we describe the design and synthesis of two new coordination containers based on a sulfonylcalixarene precursor and naphthalene-1,8-dicarboxylate linker and demonstrate their promising application for iodine adsorption and release. We show that, in addition to the more common C–H···π hydrogen bonding and hydrophobic interactions, another less appreciated type of noncovalent interaction, namely, a dual Br···π binding motif, can be introduced through the modification of the dicarboxylate linker with a bromine substituent to strengthen the crystal packing and maintain the solid-state porosity of the molecular containers. These synthetic coordination containers not only exhibit an excellent adsorption capacity for iodine vapor at a solid–gas interface but also show an effective iodine capture ability from a hexane solution through a solid–liquid interface. Importantly, the adsorption of iodine by these porous molecular solids displays remarkable reversibility and recyclability, indicating their promising practical utility for iodine capture and release.