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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. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is a kind of gaseous signal molecule in many physiological processes. In order to detect H 2 S, a novel "turn on" fluorescent probe 6,12-dihydroxyperylene-1,7-dione (DPD) was designed and synthesized. The probe DPD is fluorescence silence, while the addition of H 2 S induces an obvious green fluorescence with an obvious color change from dark blue to yellow-green. The probe shows excellent selectivity, fast response (2.5 min) and linear curve (0–90 μM) in wide effective pH range (4–10). Competition experiments are also revealed in corresponding studies and the detection limit is 3.6 μM. The response mechanism is proved to be the reduction of the probe by H 2 S, which is confirmed by 1H NMR. Furthermore, through the fluorescence turn-on signal toward H 2 S in Hela cells, probe DPD was successfully applied to monitor H 2 S in living Hela cells. Unlabelled Image • A "turn-on" probe DPD for hydrogen sulfide was developed. • DPD shows highly selective and sensitive response to hydrogen sulfide. • DPD shows rapid response and high sensitivity toward hydrogen sulfide. • The response mechanism of the probe DPD with H 2 S was confirmed to be reduction of carbonyl groups to hydroxyl groups. • DPD can monitor the exogenous cysteine in solution and living cells. [ABSTRACT FROM AUTHOR]