Benzothiazole-Pyimidine-Based BF2 Complex for Selective Detection of Cysteine.

Due to the similar structure and reactivity of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), the simultaneous discrimination of Cys over Hcy and GSH by a single fluorescent sensor is still a great challenge. In this work, a benzothiazole-pyimidine-based boron difluoride complex (BPB) was developed as a new fluorescent sensor for Cys. The sensor exhibits a highly selective "turn-on" response to cysteine over Hcy, GSH and other amino acids in aqueous solution at physiological pH. The observed pseudo-first-order rate constant for the reaction of BPB with Cys was calculated to be about 0.062 min(-1) . The detection limit of this sensor for Cys was determined to be 332 nm, and bioimaging of exogenous Cys by this sensor was successfully applied in living cells, thus indicating that this sensor holds great potential for biological applications.