A novel thioketal containing fluorescent dye for mercury(II) detection via Hg2+-triggered ACQ to AIE transformation

A novel thioketal containing fluorescent dye 1OS was elaborately designed for mercury(II) determination, which not only integrated the benefits of the remarkable specificity of Hg2+-promoted deprotection reaction and the robust emission of AIEgen in aggregated state, but also provided a surprising platform for ACQ-to-AIE switching, i.e. Hg2+-triggered ACQ to AIE transformation. Once encountered Hg2+ ions, the deprotection reaction happened immediately within seconds, accompanied with a conversion of 1OS (ACQ) to 1O (AIE). Excitedly, the probe shows remarkable selectivity and specificity towards Hg2+ both in solution, aggregated and solid states with significant fluorescence color change. When added trace Hg2+ ions into 1OS solution, its PL intensity declined completely with emission color changed from bright green to darkness with LOD as 0.36 mu M. Oppositely, a "turn on" signal was achieved in the aggregated state (fw = 98 %), which exhibited a dramatically enhancement of PL intensity along with fluorescent emission altered from darkness to brilliant yellow. Other common metal cations gave no interference to the probe. Meanwhile, the constructed test strip could "turn on" signify Hg2+ in water solution.