Nonplanar Monomer Strategy for Soluble Covalent Organic Frameworks with Reversible Thermal Behavior

The inherent insolubility and poor processability of conventional covalent organic frameworks (COFs) represent a formidable obstacle to their practical deployment. Herein, we present a molecular design paradigm that circumvents this limitation by using a nonplanar monomer featuring a sterically congested, double‑layer conjugated benzene ring to construct a soluble heat-triggered solubility COF (HTS-COF). This structure substantially enlarges the interlayer spacing and attenuates π-π stacking interactions, thereby conferring reversible heat‑triggered solubility without compromising crystallinity or structural integrity. The resultant HTS‑COF readily undergoes solution processing into uniform membranes and aerogels. Notably, under dynamic filtration, the HTS‑COF membrane achieves expeditious and highly efficient iodine sequestration from both aqueous and organic media, exhibiting outstanding rejection efficiency and cycling stability.