A benzothiazole-based fluorescent probe for distinguishing and bioimaging of Hg2+ and Cu2+

- A benzothiazole-based probe for multiple metal ions has been firstly developed.
- The differential sensing mechanisms of Hg2+ and Cu2+ relied on different reaction.
- The probe could be used to monitor Hg2+ and Cu2+in vitro and in vivo with distinct fluorescence changes.

A new benzothiazole-based fluorescent probe 2-(benzo[d]thiazol-2-yl)-4-(1,3- dithian-2-yl)phenol (BT) with two different reaction sites, a thioacetal group (site 1 for Hg2+), and O and N atoms of the benzothiazole dye (site 2 for Cu2+), was designed and synthesized. The probe BT showed ratiometric fluorescent response to Hg2+ and fluorescence quenching behavior to Cu2+, which induces naked-eye fluorescent color changes from green to blue and colorless, respectively. Moreover, it displayed highly sensitivity and selectivity toward Hg2+ and Cu2+ without interference from other metal ions. The sensing mechanisms were also confirmed by 1H NMR titration, mass spectrum and Job's plot analyses. Finally, probe BT was successfully used for fluorescent imaging of Hg2+ and Cu2+ in living cells, demonstrating its potential applications in biological science.

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