8 Hydroxyquinoline Benzoate

8-Hydroxyquinoline benzoates were developed as a new set of 8-HQ derivatives for highly sensitive fluorescent chemosensors for transition metal ions. A prominent fluorescence enhancement was found in the presence of transition metal ions such as Hg²⁺ and Cu²⁺, and this was suggested to result from the suppression of radiationless transitions from the nπ* state in the chemosensors.

Applications : Distinct color change was found for azo 8-hydroxyquinoline benzoate upon addition of Hg²⁺ or Cu²⁺ in CH₃CN, which allows for detection of Hg²⁺ or Cu²⁺ from other metal ions by the ‘naked eye’.