Multifunctional covalent organic framework platform unlocked by multi-component strategy for the selective detection and recovery of gold.

Given the urgent need for gold recovery, researchers have been developing covalent organic frameworks (COFs) as gold adsorbents and have achieved significant results. Building on this foundation, the further development of COFs with more comprehensive performance as multifunctional platforms for represents a strategic approach to addressing the evolving demands of practical applications for gold recovery. Fortunately, multi-component strategy offers a wider range of monomer combinations and diverse electronic structures. Compared to post-synthesis modification (PSM), the multi-component strategy provides a more accurate structural composition, making it an ideal approach for achieving precise functional integration. Herein, we synthesized a three-component COF (COF-EB50%, EB stands for ethidium bromide) along with two corresponding two-component COFs as controls. COF-EB50% effectively combines the respective advantages of COF-EB0% and COF-EB100%, exhibiting high adsorption capacity (1807 mg/g) and fast adsorption kinetics (within 10 min). Furthermore, the unique D-A-A' configuration of COF-EB50% optimizes the intramolecular charge transfer (ICT) process, enhancing its fluorescence performance and unlocking visual fluorescence detection of Au3+ (Limit of detection (LOD) is 42 nM). Notably, the fluorochromic response provides a more accurate visual indication. Based on the three-component strategy, this study designed a multi-functional COF platform for highly selective gold detection and adsorption, providing valuable insights into the functional integration of COFs.