A novel colorimetric and ratiometric fluorescent probe for visualizing SO₂ derivatives in environment and living...

Monitoring sulfur dioxide (SO₂) derivatives in environment is of great significance due to their harmful effects to the environment and human health. In this study, a fluorescent probe (CZBT) for SO₂ derivatives was prepared from 9-ethyl-9H-carbazole-3,6-dicarboxaldehyde and 2-methyl-benzothiazolium, which displayed a noticeable color change from yellow to colorless along with a remarkable fluorescence change from yellow to blue in response to HSO₃^-. The probe could quantitatively determine the concentration of HSO₃^- with excellent selectivity, high sensitivity and low limit of detection. ¹H NMR and HR-MS spectra demonstrated that a selective 1, 4-nucleophilic addition occurred on the bridge double bond in CZBT. The probe was successfully used to determine the SO₂ derivatives in several real water samples with good recovery. Furthermore, the probe was employed for monitoring the level of intracellular HSO₃^- in HeLa (human cervical cancer) cells by fluorescence imaging. These results indicated that CZBT has a good capability for monitoring SO₂ derivatives in environment and living cells.