Fluorescence quenching detection of UO2 2+ in aqueous solution based on an organic molecule probe of 6-chloro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide

Abstract A new organic molecule probe has been introduced as a “turn-off” fluorescent sensor to detect trace quantities of UO2 2+ in the presence of several transition metals with promising results. The procedure is based on quenching the fluorescence intensity of 6-chloro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide (L) in the presence of various UO2 2+ concentrations in methanol. The UO2 2+ and L species interact through electrostatic interaction between negatively charged nitrogen atom of the sulfonamide group of L and positively charged UO2 2+, thus facilitating the non-radiative recombination of UO2 2+ and L through the charge transfer or electron transfer processes and leading to the fluorescence quenching of L. The mechanism of quenching was addressed and proved to be static quenching. The impressive quenching of the fluorescence intensity of L by different concentrations of UO2 2+ has been successfully used as a new sensor to measure UO2 2+ in methanol at λ ex = 340 nm, λ em = 380 nm with a linear dynamic range of 0.08–5.0 µM and detection limit and quantification limit of 0.0276 and 0.0837 µM, respectively. The L sensor shows interesting advantages compared to other developed sensors with adequate performance, such as broader linear range and lower detection limit, selectivity, and simplicity, which illustrate its useful practical use. Graphical abstract Fluorescence quenching detection of UO2 2+ in aqueous solution based on an organic molecule probe of 6-chloro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide.