A novel “off-on” type fluorescent chemosensor for detection of Zn2+ and its zinc complex for “on-off” fluorescent sensing of sulfide in aqueous solution, in vitro and in vivo.

We reported a new quinoline-based fluorescent probe 1 for Zn 2+ and S 2− . 1 showed a highly selective fluorescence enhancement toward Zn 2+ over other metal ions including Cd 2+ , and the resulting 1 -Zn 2+ complex could detect only S 2− among the various anions. The detection limits (0.09 μM and 0.88 μM) for Zn 2+ and S 2− were much lower than recommended values (76 μM for Zn 2+ and 14.8 μM for S 2− ) by WHO. Their recognition mechanisms were explained by Job plots, UV–vis titrations, 1 H NMR titrations, ESI-mass, and theoretical calculations. Moreover, compound 1 with the great photostability and low biotoxicity showed sequentially off-on-off fluorescent bio-imaging of Zn 2+ and S 2− in both HeLa cells and live zebrafish larvae. [ABSTRACT FROM AUTHOR]