First fluorescence sensor for simultaneously detecting three kinds of IIB elements (Zn2+, Cd2+ and Hg2+ ) based on aggregation-induced emission

This work report the first AIE-based fluorescence sensor that can simultaneously detect three kinds of IIB elements (Zn2+, Cd2+ and Hg2+) in aqueous media. The thiourea-bridging bis-tetraphenylethylene (Bis-TPE) was synthesized by the condensation reaction of formyltetraphenylethylene and bis-thiosemicarbazide derivative in 82 % yield. Due to the AIE effect in the aqueous medium, the long-wavelength fluorescence was observed at 500-526 nm. It displayed high selective Zn2+-sensing ability with red-to-green fluorescence change, selective Cd2+ -sensing ability with red-to-yellow fluorescence change and selective Hg2+ -sensing ability with fluorescence enhancement, respectively. Moreover, it could detect simultaneously Zn2+, Cd2+ and Hg2+ in the mixed solution of these three kinds of cations by the fluorescence change with the assistance of Cl(- )and ATP. The sensing mechanism was confirmed as 1:1 stoichiometric ratio between host and guest. The detection limits were as low as 8.22 x 10(-8) M, 2.36 x 10(-7) M and 3.43 x 10(-8) M for Zn2+, Cd2+ and Hg2+, respectively. These sensing abilities were applied as test strips for detecting Zn2+, Cd2+ and Hg2+, and were used for living cell imaging, implying a high efficient and simple method for analyzing trace IIB elements (Zn2+, Cd2+ and Hg2+ ) simultaneously in complex environments and living bodies.