A coumarin-based fluorescent chemosensor for Zn2+ in aqueous ethanol media.

A coumarin-based fluorescent chemosensor 1 for Zn(2+) was designed and synthesized. Compound 1 exhibits lower background fluorescence due to intramolecular photoinduced electron transfer. However, upon mixing with Zn(2+) in 30% (v/v) aqueous ethanol, a "turn-on" fluorescence emission is observed. The fluorescence emission increases linearly with Zn(2+) concentration in the range 0.5-10 micromol L(-1) with a detection limit of 0.29 micromol L(-1). No remarkable emission enhancement was, however, observed for other metal ions. The proposed chemosensor was applied to the determination of Zn(2+) in water samples with satisfactory results.