Preparation of PIE‐Active Poly(2,4‐thiazolidinediones) by Oxidative Polymerization and Simultaneous Specific Detection of Cu ²⁺ /Co ²⁺ Ions

In this study, poly(2, 4-thiazolidinedione) (PTD) is prepared by oxidative polymerization using 2,4-thiazolidinedione (TD) as monomer. PTD exhibits significant polymerization-induced emission (PIE) at 540 nm, resulting from the intramolecular aggregation of thiazole heterocycles and the formation of electron-space conjugation. The PIE-active PTD demonstrates simultaneously specific detection of Cu²⁺/Co²⁺ with detection limits as low as 0.47 µM and 68.9 nM, respectively, even in the presence of 14 common metal ions and 11 anions. Fluorescence quenching experiments reveal that Cu²⁺/Co²⁺ coordinates with PTD to form a 1:2 non-fluorescent complex through a static quenching mode. Most importantly, the efficient differentiation between Cu²⁺ and Co²⁺ is achieved using dynamic color recognition technology based on smartphone APP and UV-vis absorption spectroscopy. This approach innovatively combines solution color gradient change with smartphone RGB to establish a semi-quantitative and convenient detection method. The lower detection limits of Cu²⁺/Co²⁺ reached 36.2 and 37.8 nMm with naked eye recognition, which provides a technological solution for the rapid detection of Cu²⁺/Co²⁺ ions without the aid of large-scale instruments. In brief, the successful preparation and detection application of PIE-active PTD open up a straightforward and feasible path for molecular design of fluorescent non-conjugated polymers from non-fluorescent monomers.