Regenerable and Highly Stable Two-Dimensional Imine-Based Covalent Organic Framework for Simultaneous Rapid Detection and Adsorption of Cu²⁺ Ions

The development of efficient fluorescent probes and adsorbents for detecting and removing Cu²⁺, which pose potential environmental and health risks, is a highly active area of research. However, achieving simultaneously improved fluorescence detection efficiency and enhanced adsorption capacity in a single porous probe remains a significant challenge. In this study, we successfully synthesized a two-dimensional imine-based TAP-COF using 2,4,6-triformylphloroglucinol and tri(4-aminophenyl)amine as raw materials. TAP-COF exhibited excellent properties, including a large specific surface area of 685.65 m²·g^–1, exceptional thermal stability (>440 °C), chemical stability, temporal stability, and recyclability. Fluorescence testing revealed that TAP-COF exhibited remarkable specificity and high sensitivity for detecting Cu²⁺. The fluorescence mechanism, in which the excited state intramolecular proton transfer was impeded by the interaction of Cu²⁺ with CO and C–N bonds on TAP-COF upon the addition of Cu²⁺, was further elucidated through experimental and theoretical methods. Furthermore, the adsorption capacity of TAP-COF toward Cu²⁺ was investigated, confirming the excellence of TAP-COF as a fluorescent probe and adsorbent for the specific detection and removal of Cu²⁺. This work holds significant implications for improving environmental and human health concerns associated with Cu²⁺ contamination.