Preparation of Fluorescent Poly(amide amines) by Modified Three‐Component Ugi Polymerization and Their Specific Detection of Cu²⁺ Ions

ABSTRACT In this study, non‐conjugated fluorescent poly(amide amines) (PAMAs) are synthesized via three‐component Ugi polymerization using monomers containing piperazine structures as feedstock. The synthesized PAMA‐B exhibits strong fluorescence at 430 nm due to intramolecular aggregation of piperazine and amide groups along the macromolecular chain. PAMA‐B selectively detects Cu 2+ ions even among common interfering ions, with a detection limit of 0.51 μM, much lower than the minimum permissible concentration of 30 μM for Cu 2+ ions in drinking water as stipulated by the World Health Organization (WHO). The quenching mechanism involves the static quenching via 1:1 Cu 2+ ions coordination. Recovery tests in tap and river water confirm PAMA‐B's specificity for Cu 2+ ions in the real environments. Furthermore, fluorescent PAMA‐B is fabricated into a convenient test paper for Cu 2+ ions detection in the experiment.