A supramolecular fluorescent substance constructed by cucurbit [8]uril and triphenylamine derivate: AIE properties and application for the detection of 4-nitroaniline in aqueous system.

Supramolecular substances with aggregation-induced emission (AIE) characteristics have been attracting increased attention. In this work, a supramolecular AIE fluorescent sensor was successfully constructed using a triphenylamine (TPA) derivative, 4,4',4''-(nitrilotris(benzene-4,1-diyl))tris(1-methylpyridin-1-ium) (TPA-PM), as the guest molecule, and Cucurbit[8]uril (Q[8]) as the host one. Physical characterizations, including UV-vis absorption, photoluminescence, 1H NMR, and Mass spectrometry (MS), proved the formation of a [2 + 3] supramolecular complex, TPA-PM2@Q[8]3. Compared with TPA-PM, the as-constructed TPA-PM2@Q[8]3 exhibited greatly enhanced fluorescence emission in aqueous solution, displaying significant AIE effect. Intriguingly, since 4-nitroaniline (4-NA) in aqueous solution could cause the dissociation of the host-guest complex, the strong fluorescence of TPA-PM2@Q[8]3 could be rapidly and highly selectively quenched by 4-NA in aqueous solution without interferences of other nitro-aromatic compounds and common ions. Additionally, the sensing capacity of TPA-PM2@Q[8]3 for 4-NA remained well in actual water samples, indicating its potential practical application.