A novel colorimetric and fluorescence anion sensor with a urea group as binding site and a coumarin group as signal unit

A novel colorimetric and fluorescent anion sensor based on urea substituted with a coumarin moiety and a pendant phenylazo unit was synthesized and evaluated according to the binding site-signalling subunit approach. The azo group was exploited as the chromogene, the urea moiety providing the anion binding site and the coumarin system was responsible for fluorescence. As such, the dye enabled visual detection of acetate ion in DMSO (color change light yellow to red) without resorting to spectroscopic instrumentation. More importantly, the sensor displayed significant fluorescence enhancement response to anions such as acetate, because of complex formation.