Two benzothiadiazole-based fluorescent sensors for selective detection of Cu2+ and OH– ions

Two benzothiadiazole-based compounds, namely 4,7-di(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole (1) and 4,7-di(1H-pyrazol-1-yl)benzo-[2,1,3]thiadiazole (2), have been synthesized via Cu-catalyzed cross-coupling reaction, which can be used to detect Cu2+ and OH– by fluorescence quenching with high selectivity and sensitivity, respectively. The detection limits were determined to be 0.11 μM for Cu2+ and 55 μM for OH–. Furthermore, two compounds have cell permeability and 1 could be used for Cu2+ detection in living cells.