Recent progress in Michael addition-based fluorescent probes for sulfur dioxide and its derivatives

Sulfur dioxide (SO2) is a harmful environmental pollutant. Inhaled SO2 can be rapidly hydrated into its derivatives, bisulfite (HSO3−) and sulfite (SO32−). SO2 derivatives are well known as preservatives and antioxidants, which are used in food and beverages to prevent oxidation and bacterial growth. Although SO2 can be endogenously generated in mammals and exhibits unique bioactivities in regulating cardiovascular function, excessive SO2 and its derivatives have toxic effects on humans and animals for triggering adverse reactions and diseases. A large number of fluorescent probes for SO2 and its derivatives have been designed and reported due to their high sensitivity and selectivity, high temporal and spatial resolution, non-invasive and non-destructive detection as well as real-time visualization in situ. In this review, we have summarized the recent progress of Michael addition-based fluorescent probes for SO2 and its derivatives. These probes are categorized and concluded according to the different α,β-unsaturated compounds (i.e., Michael acceptors). The design strategies, sensing performances, detection mechanisms and applications of these probes are discussed in detailed. Finally, a general overview about the design of probes for SO2 and its derivatives is provided, which will facilitate the development of ideal probes for SO2 and its derivatives.