Salicylideneanilines-Based\nCovalent Organic Frameworks\nas Chemoselective Molecular Sieves

Abstract

Porous materials such as covalent\norganic frameworks (COFs) are\ngood candidates for molecular sieves due to the chemical diversity\nof their building blocks, which allows fine-tuning of their chemical\nand physical properties by design. Tailored synthesis of inherently\nfunctional building blocks can generate framework materials with chemoresponsivity,\nleading to controllable functionalities such as switchable sorption\nand separation. Herein, we demonstrate a chemoselective, salicylideneanilines-based\nCOF (SA-COF), which undergoes solvent-triggered tautomeric switching.\nThis is unique compared to solid-state salicylideneanilines’\ncounterpart, which typically requires high energy input such as photo\nor thermal activation to trigger the enol–keto tautomerisim\nand <i>cis</i>–<i>trans</i> isomerization.\nAccompanying the tautomerization, the ionic properties of the COF\ncan be tuned reversibly, thus forming the basis of size-exclusion,\nselective ionic binding or chemoseparation in SA-COF demonstrated\nin this work.