A water soluble hydrazone probe for subsequent fluorescent detection of Zn2+ and S2− in neat aqueous solution and imaging in mitochondria of living cells

A simple water soluble hydrazone sensor (1·Cl) has been developed to selectively chelate with Zn2+ via an O2N donor set, leading to specific fluorescence enhancements. The highly emissive 1-Zn2+ complex can serve as a reversible on-off sensor for S2−. The detection limits of 1·Cl for Zn2+ and S2− are 66.0 and 32.6 nM, respectively. The recognition mechanism was carefully investigated through FL, UV-vis, 1H NMR, ESI-MS, time-resolved fluorescence, and density functional theory (DFT) calculations. Owing to the mitochondria-targeting ability of the terminal quaternary ammonium moiety, 1·Cl was successfully applied to image mitochondrial Zn2+ and S2−.