Design and Synthesis of Dual Fluorophore for Detection of Fe3+ and Hg2+ in Aqueous Solution Through Fluorescence "Turn-Off".

Here, we report the design and synthesis of a new bicyclic compound 6, annulated with benzene and the 8-hydroxyquinoline fluorophore. The probe exhibits a moderate aggregation-induced emission (AIE) behavior upon the addition of water up to 17%. Furthermore, the probe exhibits a highly selective fluorescence turn-off response toward Fe3+ and Hg2+ ions in a DMSO/H2O (83:17, v/v) solution over a range of other competitive metal ions. The probe displayed low detection limits of 3.69 μM for Fe3+ and 6.08 μM Hg2+. Probe 6 shows a fast recognition time of ions and can monitor Fe3+ and Hg2+ ions in real time. The sensing mechanism is thoroughly investigated by time-dependent 1H NMR studies, which indicate coordination interactions between the quinoline framework and the metal ions. The probe demonstrates high sensitivity and dual-selectivity toward metal ion sensing, making it a valuable tool for monitoring the environment.