The highly selective and sensitive fluorescent detection of SO2 based on an emissive quinoline derivative probe

Sulfur dioxide (SO2) is a common global air pollutant that can cause serious air pollution and lead to a variety of severe diseases. In this study, a tripodal quinoline-based derivative T with two reversible conformations is synthesized. T demonstrates highly selective, sensitive fluorescent SO2 detection in solution. As SO2 is added into a dioxane/water solution, the sensor T purple emission rapidly changes to a green color in a strongly acidic environment. T showed high sensitivity and selectivity toward H2SO4 and SO2 detecting with good detection limits as low as 0.098 μM and 5.438 μM, respectively. The fluorescence sensing process is successfully confirmed via FT-IR, NMR, and ESI-Ms spectrum. Furthermore, DFT calculation reveals the potentially reversible conformation transfer mechanism and selective, sensitive fluorescence sensing behavior driven by host-guest and multiple hydrogen bonding interactions in solution.