An off-on-off fluorescent probe for the sequential detection of Zn2+ and hydrogen sulfide in aqueous solution

A novel selective fluorescent chemosensor (L1) based on 8-aminoquinoline was synthesized and characterized. The sensor exhibited remarkable selectivity for Zn2+ in the presence of other cations in aqueous solution. Density functional theory calculations on L1 and the L1-Zn complex are consistent with the experimental results. Once combined with Zn2+, the complex L1-Zn displayed high specificity for H2S. As HS- is equivalent to H2S in physiological solution, HS- was selected to represent H2S in this work. Among various anions, only HS induced revival of the fluorescence of L1. Signal transduction occurs via reversible formation-separation of complex L1-Zn and ZnS. L1 and the sequential complex L1-Zn have ideal chemical and spectroscopic properties that satisfy the criteria for further Zn2+ and H2S sensing in biological and environmental applications.