o,o-Difluorination of aromatic azide yields a fast-response fluorescent probe for HS detection and for improved bioorthogonal reactions.

The development of efficient bioorthogonal reactions for sensing of endogenous biomolecules and for bioconjugation should be of paramount importance in the field of chemical biology. In this work, the o,o'-difluorinated aromatic azide was firstly employed to develop a new fast-response fluorescent probe 1 for HS detection and for bioorthogonal reactions. Compared with non- and mono-fluorinated probes, 1 showed faster reaction toward HS, the third gasotransmitter, in buffer (pH 7.4), implying that the reaction rate could be enhanced by the dual-fluorine groups. Furthermore, such enhanced reaction rates of 1 were also observed in the Staudinger reaction and strain-promoted azide-alkyne cycloaddition (SPAAC) based on the comparison studies of the non-fluorinated probe. Our results firstly highlight that the o,o'-difluorinated aromatic azide group should be useful for fast bioorthogonal reactions and HS detection.