Rapid Turn-On Fluorescence Detection of Copper(II): Aromatic Substituent Effects on the Response Rate

Oxidative cyclization of o-phenylazo aniline was utilized as a turn-on fluorescent probe of the copper(II) ion. The number and the position of electron donating groups on the probes were systematically varied to investigate the effect of aryl substituent on reactivity toward copper ion. Among the series of analogous probes, the 2,4,6-trimethoxy substituted probe exhibits not only a faster (40-times faster) reaction but also a lower detection limit (20 times lower) than previously reported probes under identical conditions. The comparative kinetic studies reveal that both the number and the position of substitution have a significant impact on the reactivity toward copper, which will be discussed in the manuscript.