Triarylamine-Based Fluorescent Probe for Cu2+ Detection in Aqueous Solutions and Food and Construction of “Fluorescence-Afterglow” Sensor Membranes

As a common heavy metal pollutant, Cu 2+ seriously endangers environmental safety and human health. A novel triphenylamine-based Schiff base fluorescent probe (triphenylamine-diaminopyridine, TPA-DAP) was synthesized with diaminopyridine as the recognition unit. It exhibits high selectivity, rapid response, large stokes shift, low detection limit of 1.04 μM, obvious fluorescence quenching, and visible color changes toward Cu 2+ . Cu 2+ binds with TPA-DAP to form a stable 2:1 complex and quenches fluorescence through electronic and paramagnetic effects, which can be reversed by vitamin C. The sensing mechanism was verified by HRMS, NMR, and DFT calculations. TPA-DAP achieves effective Cu 2+ detection in actual water samples. The prepared TPA-DAP@PVA/SA composite membrane establishes a fluorescence-afterglow dual-mode platform for portable visual on-site Cu 2+ detection.