A Dual‐Site Fluorescent Probe Designed for Selective Detecting Cys and Fluoride Ions in Distinct Light Regions Through the Regulation of ICT Within the Same Fluorophore

Fluorescent probes have been extensively applied in detection owing to their advantages of high sensitivity, easy operation and rapid response times. However, most of the developed fluorescent probes are capable of monitoring only a single analyte, and studies on dual-site fluorescent probes based on the same fluorophore remain relatively scarce. In this work, we utilized the fluorophore 4-(2-(quinolin-4-yl)vinyl)phenol, which has two modifiable sites (hydroxyl group and the nitrogen atom of the quinoline moiety), to introduce dual recognition groups for Cys and fluoride ions. By modulating the ICT effect to adjust its luminescence properties, we successfully designed and synthesized a novel dual-site fluorescent probe (QP-Cys&F) for the detection of Cys and fluoride ions. This probe could detect Cys and fluoride ions at 665 and 415 nm with detection limits of 0.21 and 2.8 μM, respectively. Leveraging the differential reactivity of its two recognition moieties, the probe enables sequential identification of these two analytes, ultimately generating a new fluorescence signal at 470 nm. This work could offer a new approach for developing multi-target fluorescent probes using a single fluorophore.