A novel cucurbit[7]uril-based supramolecular fluorescent probe for the visual and quantitative detection of cyanide

Cyanide is a matter with high toxicity. Cyanide abuse and illegal industrial cyanide-containing waste-water discharge cause huge damage to human health and living environment of human beings. Therefore, it is urgently important to find an accessible and effective method for monitoring and detecting cyanide. Herein, we developed a novel water-soluble supramolecular fluorescent probe, CQU@Q[7], to detect cyanide ion (CN⁻). This probe was constructed by assembly of host-guest interaction between cucurbit[7]uril (Q[7]) and quinoline derivative (CQU). The fluorescence intensity of CQU@Q[7] was almost unchanged in the presence of tested anions, and gradually quenched only upon addition of CN⁻with fluorescence intensity decreasing from 906.16 a.u. to 112.47 a.u.. The limit of detection of CN⁻ is 0.145 µM. Moreover, a stable complex between CQU@Q[7] and CN⁻ was formed in 25 s. The probe's color in solution changes from yellow to brown and finally to burgundy under daylight with increasing amounts of CN⁻. The fluorescent probe reported here was applied to determine CN⁻ in actual water samples with recovery rates of 98.3 %-105.8 % and less than 2 % RSD, and was made into a portal test strips which enable facile detection of CN⁻.