Highly sensitive and selective turn-on fluorescent chemosensors for Hg based on thioacetal modified pyrene.

This work reports a facile strategy for the synthesis of water-soluble fluorescent probes Pyr1 and Pyr2, which have carboxyl and hydroxyl group in the side chain of thioacetal moiety, respectively. Pyr1-2 exhibit exclusively selective turn-on fluorescence response towards Hg over other cations, based on intramolecular charge transfer (ICT) mechanism. Upon addition of Hg, the thioacetal moiety in Pyr1-2 can be converted to aldehyde group, which is confirmed by H NMR titrations. The detection limits for Pyr1-2 are less than 1.80nM in aqueous media, lower than the maximum allowable level of Hg in drinking water by EPA. Moreover, Pyr2 have been successfully used for fluorescence imaging of Hg in living cells, demonstrating potential application in biological science.