Biothiol detection by “ON-OFF-ON” fluorescence probe based on anthracene derivative

Two thiols fluorescent probes of copper complex based on anthracene derivative was designed. Two compounds (1 and 2) were obtained by the reaction of 9-furaldehyde with benzenesulfonamide and p-nitrobenzenesulfonamide. Then, these compounds were combined with copper ion and two copper complexes (compound 1-Cu2+ and compound 2-Cu2+) formed. Due to the paramagnetic effect of copper caused fluorescence quenching, two compounds showed strong fluorescence while compound-Cu2+ almost had no fluorescence. With the additions of cysteine (Cys) and glutathione (GSH), the fluorescence intensities recovered again. While the additions of other amino acids almost did not induce any change. UV–Vis, fluorescence spectra and Circular Dichroism suggested that two copper complexes showed better selectivity and sensitivity to small molecule biothiols among amino acids tested. In addition, cytotoxicity experiments showed that two fluorescence probes have potential application value for biological thiols detection in live cells.