Coumarin-based ‘turn-off’ fluorescent chemosensor with high selectivity for Cu2+ in aqueous solution

• Chemosensor 1 exhibits high selectivity and sensitivity to Cu2+ ions.
• The 1:1 stoichiometry for the 1-Cu2+ complex is formed.
• Chemosensor 1 has a linear response to Cu2+ ranging from 1.0 to 7.0 μM.
• The detection limit is determined to be 1.81 nM.

Coumarin-based “turn-off” fluorescent chemosensor, 3-acetoacetyl-7-diethylaminocoumarin (1), has been synthesized and structurally characterized by IR, 1H NMR and X-ray crystal structure analysis. The fluorescence behaviors in the presence of various metal ions were investigated in aqueous media. 1 Exhibits highly selective and sensitive absorbance and fluorescence sensing ability for Cu2+ over other metal ions. Addition of Cu2+ to the aqueous solution of 1 gave rise to obvious absorbance change and fluorescence quenching. Other competing ions, such as Mg2+, Ba2+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, Pb2+, Cd2+, Hg2+, induced negligible absorbance and fluorescence changes under the same conditions. The job’s plot showed that the stoichiometry between 1 and Cu2+ was estimated to be 1:1. The fluorescence intensity varied almost linearly vs. the concentration of Cu2+ (1.0–7.0 μM), and the detection limit of Cu2+ was estimated to be 1.81 nM, indicating that 1 can be used as “turn-off” fluorescent chemosensor to selectively detect Cu2+ in aqueous solution.

Chemosensor 1 was synthesized and exhibited highly selective and sensitive fluorescence sensing ability for Cu2+ over other metal ions in aqueous media. The fluorescence quenching response of 1 for Cu2+ indicated that 1 can be used as “turn-off” fluorescent chemosensor to selectively detect Cu2+.Figure optionsDownload as PowerPoint slide