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 (Zn 2+ , Cd 2+ and Hg 2+ ) 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 Zn 2+ -sensing ability with red-to-green fluorescence change, selective Cd 2+ -sensing ability with red-to-yellow fluorescence change and selective Hg 2+ -sensing ability with fluorescence enhancement, respectively. Moreover, it could detect simultaneously Zn 2+ , Cd 2+ and Hg 2+ 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 8.22×10 -8 M, 2.36×10 -7 M and 3.43×10 -8 M for Zn 2+ , Cd 2+ and Hg 2+ , respectively. These sensing abilities were applied as test strips for detecting Zn 2+ , Cd 2+ and Hg 2+ , and were used for living cell imaging, implying a high efficient and simple method for analyzing trace IIB elements (Zn 2+ , Cd 2+ and Hg 2+ ) simultaneously in complex environments and living bodies.