A simple excited-state intramolecular proton transfer probe based on a new strategy of thiol–azide reaction for the selective sensing of cysteine and glutathione

A simple azido-substituted fluorescent sensor AHBO showing a selective turn-on response to cysteine (Cys) and glutathione (GSH) over homocysteine (Hcy), sulfide and other amino acids has been constructed, which is based on the mechanism of selective nucleophilic substitution–rearrangement reactions.