A New Coumarin-Based Fluorescent Chemosensor for Selection Detection of Zinc Ions in Aqueous Ethanol

In this study, a coumarin-based Schiff base (1) was designed and synthesized as a Zn²⁺-selective fluorescent chemosensor based on the PET mechanism. The structure of compound 1 was characterized by ¹H NMR and ¹³C NMR. The fluorescence properties of this chemosensor toward various metal ions were explored by fluorescence and UV–vis spectra. The results indicated that the chemosensor had high selectivity toward Zn²⁺ over other coexisting metal ions. The binding stoichiometry of 1 toward Zn²⁺ was determined to be 1:1 by Job's plot. Furthermore, the chemosensor was reversible for Zn²⁺ in an ethanol/H₂O (7:3, V/V) solution by the addition of Na₂ EDTA. The above experimental results demonstrate that 1 can be used as a fluorescent chemosensor for the real-time detection of Zn²⁺ in biological species and environmental systems.