Coumarin-based thiol chemosensor: synthesis, turn-on mechanism, and its biological application.

A new chemodosimetric probe (1) is reported that selectively detects thiols over other relevant biological species by the turning on of its fluorescence through a Michael type reaction. The fluorogenic process upon its reaction was revealed to be mediated by intramolecular charge transfer, as confirmed by time-dependent density functional theory calculations. The application of probe 1 to cells is also examined by confocal microscopy, and its cysteine preference was observed by an ex vivo LC-MS analysis of the cellular metabolite.