A new turn-on fluorescent probe for the detection of copper ion in neat aqueous solution

Abstract A new probe PQ comprising quinoline as a fluorophore and 2-picolinic group as a recognition unit is designed and synthesized with high sensitivity and selectivity toward copper ion. The probe PQ shows almost no fluorescence in HEPES buffer (20 mM, pH 7.0), but displays obvious fluorescence enhancement after the addition of Cu 2+ , this response is considered to be attributed to the Cu 2+ -promoted hydrolysis of PQ to yield a highly fluorescent product, 2-methyl-7-hydroxy-quinoline with fluorescence signal greatly amplified. The probe PQ exhibits remarkable selectivity and sensitivity toward Cu 2+ and the detection limit is as low as 0.15 μM. These results reveal that PQ has the potential to discriminate Cu 2+ over other cations in neat aqueous solution by fluorescence turn-on response. In addition, the cell imaging experiment indicated the probe PQ can be used as a possible sensor to detect Cu 2+ in living cells.