Nucleophilic Ring-Opening of -Benzoylaziridine Combined with Spirolactamization of Rhodol Enables Ratiometric Fluorescence Imaging of Hydropersulfides in .

Hydropersulfides (RSSH) are an important class of reactive sulfur species (RSS) involved in a variety of physiological processes in biological systems. However, selective detection of RSSH is challenging since the persulfide group (-SSH) exhibits reactivity akin to biologically abundant biothiols. To address this issue, we designed as a ratiometric fluorescent probe for RSSH by integrating the nucleophilic ring-opening of an -benzoylaziridine and spirolactamization of a rhodol. The ratiometric sensing of RSSH is realized by modulating Förster resonance energy transfer (FRET) in the coumarin-rhodol dyad. Nucleophilic attack of the -benzoylaziridine moiety in by RSSH affords the corresponding secondary amide ring-opened product, which subsequently undergoes a spontaneous intramolecular spirolactamization to disrupt the π-conjugation structure of the rhodol. The tandem reaction decreases the intramolecular FRET efficiency within the probe and causes a clear dual-emission signal change. Probe possesses outstanding selectivity toward RSSH over biothiols and HS, and is capable of tracking RSSH levels in roots. Moreover, we observed the upregulation of RSSH levels in heavy metal (HM)-induced stress of with probe , and revealed the correlation between -persulfidation and HS levels in living plants.