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

Abstract

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.