A Coumarin-Based Fluorescent Chemosensor for Zn2+ in Aqueous Ethanol Media

A coumarin-based fluorescent chemosensor 1 for Zn2+ was designed and synthesized. Compound 1 exhibits lower background fluorescence due to intramolecular photoinduced electron transfer. However, upon mixing with Zn2+ in 30% (v/v) aqueous ethanol, a “turn-on” fluorescence emission is observed. The fluorescence emission increases linearly with Zn2+ concentration in the range 0.5–10 μmol L−1 with a detection limit of 0.29 μmol L−1. No remarkable emission enhancement was, however, observed for other metal ions. The proposed chemosensor was applied to the determination of Zn2+ in water samples with satisfactory results.