New fluorescent receptor composed of two imidazoliums, two pyrenes and a boronic acid for the recognition of DOPAC

A new fluorescent receptor composed of two imidazoliums, two pyrenes and a boronic acid has been synthesized and studied for the recognition of 3,4-dihydroxyphenylacetic acid (DOPAC), which is the metabolite of dopamine. Dopamine, l-DOPA and catechol also induced fluorescence quenching effects, however, 1 displayed a largest association constant with DOPAC. In addition, d-fructose, d-glucose and l-phenylalanine did not show any significant fluorescence change. These fluorescence changes were observed at pH 7.4 in HEPES(0.02 M, pH 7.4)–CH3CN (95:5, v/v). As far as we are aware of, our receptor 1 is the first example of fluorescent chemosensor which shows selectivity for DOPAC. The unique intermolecular excimer formation and fluorescence quenching effects with DOPAC and catechol are carefully explained based on the theoretical calculations.