Xiao-Feng Yang

A fluorescein-based fluorogenic and chromogenic chemodosimeter for the sensitive detection of sulfide anion in aqueous solution

A highly sensitive chromo- and fluorogenic chemodosimeter for sulfide anion was developed based on its nucleophilicity. 2,4-Dinitrobenzenesulfonyl-fluorescein (I) is a weakly fluorescent compound. Upon mixing with sulfide anion in aqueous acetone solution, the 2,4-dinitrobenzenesulfonyl group of I was efficiently removed and highly fluorescent fluorescein was released, hence leading to the dramatic increases in both fluorescence and absorbance of the reaction solution. The fluorescence increment is linear with sulfide anion concentration in the range 50-1000 nmol L(-1) with a detection limit of 4.3 nmol L(-1) (3sigma). The proposed chemodosimeter showed excellent selectivity toward sulfide anion and was successfully applied to the determination of sulfide anion in synthetic wastewater samples.

A ratiometric fluorescent probe for bisulphite anion, employing intramolecular charge transfer

4-(1H-benzimidazol-2-yl)benzaldehyde (1) has been developed as a new ratiometric fluorescent probe for bisulphite, based on the modulation of intramolecular charge transfer (ICT). Upon mixing with bisulphite in aqueous ethanol, an aldehyde-bisulphite adduct was formed and the ICT of the probe was switched off, which resulted in a ratiometric fluorescence response with an enhancement of the ratios of emission intensities at 368 and 498 nm. The detection range of the probe for bisulphite is in the 2.0-200 µmol/L concentration range and the detection limit is 0.4 µmol/L. Probe 1 produces a ratiometric fluorescent response to bisulphite with a marked emission wavelength shift (130 nm) and displays high selectivity for bisulphite over other anions.

A highly sensitive fluorescent probe for tiopronin based on the cleavage of 2, 4-dinitrobenzenesulfonate.

A highly sensitive fluorogenic probe for tiopronin was proposed. 2,4-Dinitrobenzenesulfonyl-fluorescein (I) is an almost nonfluorescent compound. Upon mixing with tiopronin in aqueous solution, the 2,4-dinitrobenzenesulfonyl group of I was efficiently removed and its parent dye fluorescein was released, hence leading to dramatic increases in both fluorescence and absorbance of the reaction mixture. Under optimal conditions, the fluorescence increase is linear with tiopronin concentration in the range 5.0-600 ng mL(-1), with a detection limit of 1.5 ng mL(-1) (3sigma). The proposed method has been successfully applied to tiopronin determination in pharmaceutical preparations and in spiked human urine samples.