Design and synthesis of fluorescent reagents for selective detection of dopamine

I report the development of (E)-2,2′-(5-(2-(4-(dicyanomethylene)-6-methyl-4H-pyran-2-yl)vinyl)-2-hydroxy benzylazanediyl)diacetic acid Fe(II) complex (1-Fe2+), a fluorescent reagent that can be used to detect dopamine. 1-Fe2+ was constructed using the cyanopyranyl group as the fluorophore and an Fe2+ complex both as the ligand exchange site and fluorescence quenching moiety. In contrast to the weak fluorescence emission of 1-Fe2+ in the absence of dopamine, a much stronger fluorescence emission was observed following the addition of dopamine owing to the release of Fe2+ from compound 1, which indicates significant fluorescence enhancement and the binding of Fe2+ to dopamine. The fluorescence intensities of the reagent were plotted as a function of the dopamine concentration and a good linear relationship was observed. The reaction of 1-Fe2+ with dopamine was not affected by the presence of foreign substances, thereby allowing for the highly selective detection of dopamine. The experimental results clearly showed that 1-Fe2+ is a good dopamine indicator, and it can be widely employed in dopamine detection protocols.