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A new 3-hydroxyphthalimide-based turn-on fluorescent probe is designed and synthesized. This probe can be used to determine the presence of Hg2+ ions by fluorescence spectroscope with high selectivity over other metal ions in aqueous solution. The analytical detection limit for Hg2+ is as low as 6.5 × 10−7 M. The recognition mechanism is attributed to Hg2+-promoted carbonothioate group cleavage and a subsequent excited-state intramolecular proton transfer mechanisms.

A carbazole-based fluorescent probe, 2-(9-ethyl-9H-carbazol-3-yl) isoindoline-1,3-dione, with a low detection limit (2.673 × 10−6 M) for the detection of hydrazine is designed and synthesized based on Gabriel reaction. The probe responds selectively to hydrazine over other amino compounds with marked fluorescence enhancement. Moreover, test paper experiments indicated its great potential in the environment monitoring of hydrazine in aqueous solution.

A new fluorescent chemodosimeter 1 comprising coumarin as a fluorophore and a carbonothioate group as recognition unit was designed and synthesized. Its structure was confirmed by single crystal X-ray crystallography. The compound 1 shows almost no fluorescence in HEPES buffer (10 mM, pH 7.0), while displays obvious fluorescence enhancement after addition of Hg2+ over other metal ions. The recognition mechanism is attributed to the Hg2+-promoted hydrolysis reaction. In addition, 1 could be successfully applied to detect the concentrations of Hg2+ in real water samples by fluorescence turn-on response.

New colorimetric and fluorometric fluoride ion probe, anthra[1,9-cd]pyrazol- 6(2H)-one (1), was synthesized by one-step condensation. The probe 1 shows F−-selective color change from colorless to pink and appearance of red fluorescence. The fluorescence quantum yield of free probe 1 in DMSO was calculated to be 0.03. After addition of 15 equiv. of F−, its fluorescence quantum yield can be increased to 0.37. The analytical detection limit for F− was 2.8 × 10− 7 M. 1H NMR analysis and DFT calculation show that the F−-induced colorimetric and fluorometric responses of 1 are driven by deprotonation process.

A novel turn-on colorimetric and fluorescent sensor 1 based on rhodamine B was developed as a colorimetric and fluorescent chemosensor for Fe3+. Upon addition of Fe3+ in aqueous ethanol, the 1 displayed a distinct color change from colorless to pink and a significant fluorescence enhancement, which can be directly detected by the naked eye. The stoichiometry of 1 to Fe3+ complex was found to be 1:1 and the detection limit was determined as low as 7.68 × 10−7 M. The results suggest that the sensor 1 may provide a conveniently method for visual detection of Fe3+ with high sensitivity. Furthermore the sensor has been utilized for fluorescence imaging of Fe3+ in living cells.

A new fluorescent chemosensor based upon 2,5-diphenylfuran and di(2-picolyl)amine (DPA) was designed and synthesized. Its structure was confirmed by single crystal X-ray diffraction and its photophysical properties were studied by absorption and fluorescence spectra. This compound can be used to determine Cu2+ ion with high selectivity among a series of cations in aqueous DMSO. This sensor forms a 1:1 complex with Cu2+ and displays fluorescent quenching.

A new fluorescent molecule clip derived from diethoxycarbonyl glycoluril with two 2,5-diphenyl-furan sidewalls was designed and synthesized. Its structure and conformation was confirmed by single-crystal X-ray diffraction. Its binding properties, investigated by fluorescence spectroscopey, showed that it can selectively bind Fe3+ with fluorescence quenching.Key words: diethoxycarbonyl glycoluril, molecular clip, fluorescence, Fe(III).

A pair of novel fluorescent molecular clips was synthesized from diethoxycarbonal glycoluril cyclic ether and 1,2-dihydro-indazol-3-one. Their structures and conformations were confirmed by single crystal X-ray diffraction and chemosensory properties were studied by fluorescent spectroscope. Both of them exhibited selective recognition toward Fe 3+ over other metal ions examined in DMF/CH 3 OH (50:1, v/v).