Pyrene-Based Cationic Fluorophores with High Affinity for BF₄^-, PF₆^-, and ClO₄^- Anions: Detection and Removal

Anions play an indispensable role in the balance and regulation of the ecological environment and human health; however, excess anions can cause serious ecological and environment problems. Therefore, the detection and removal of excess anions in aqueous solution is not only a technological problem but also crucial for environmental protection. Herein, a set of water-soluble pyrene-based cationic fluorophores were synthesized, which exhibit high sensitivity for the detection of the anions BF₄^-, PF₆^-, and ClO₄^- via electrostatic interactions. Such fluorescent probes exhibit "turn-on" emission characteristics even at low concentrations of anions due to anion-π⁺ interactions. Moreover, these fluorescence probes act as efficient precipitating agents for the removal of the BF₄^-, PF₆^-, and ClO₄^- anions from an aqueous environment. This work opens up new avenues for future research on pyrene-based fluorophores as turn-on fluorescence probes for anion detection and as excellent precipitating agents in environmental settings.