Specific and sequential detection of hydrogen sulfide and hypochlorous acid based on a ring-forming reaction and self-assembly

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Some biological small molecules such as hydrogen sulfide (H2S) and hypochlorous acid (HClO), play pivotal roles in numerous biological and pathological processes and are associated with various diseases. The detection and monitoring them is of continued research interest. Here we report a sequential detection mode fluorescence probes that allow for the sensing of HS– and ClO–. The mixture of P and HS– constructs a specific sensing system S for ClO–. The substitution product S is stable in air, which also could be used independently. Mechanism studies demonstrate that HS– substitutes the Cl atom in P. Furthermore, the addition of ClO– facilitates a ring-forming reaction, resulting in the formation of a thiofuran ring within the product (T). Interestingly, P has a highly ordered steric packing and could self-assemble into a rice-spike-like structure. Upon the addition of HS–, the assemblies decompose into free molecules. After interaction with ClO–, these molecules further transform to T with strong assembled capacity, featuring a larger number of nanosheets. This study provides a novel mechanism for sensing HS– and ClO–, cell and living animal imaging further indicating the good application prospects of these probes in biosensing and bioimaging.