Highly sensitive and selective turn-on fluorescent chemodosimeter for Cu2+ in water via Cu2+-promoted hydrolysis of lactone moiety in coumarin

A nonfluorescent coumarin derivative (1) was synthesized as an efficient turn-on fluorescent chemodosimeter for Cu2+ in water. Mechanism studies suggested that 1 formed a complex with Cu2+ in a 1 : 2 metal-to-ligand ratio, and a 50-fold fluorescence enhancement was observed when the complex simultaneously underwent Cu2+-promoted hydrolysis at ambient temperature.