A cucurbit[8]uril-based fluorescent probe for the selective detection of pymetrozine

Herein, we report a simple fluorescence-enhanced system for the selective recognition and determination of the insecticide pymetrozine. 1H NMR spectroscopic data indicate that 1,2-bis(4-pyridyl)ethylene (BPE) is partially encapsulated in the cavity of the cucurbit[8]uril (Q[8]) in aqueous solution, forming a stable 1:2 host-guest inclusion complex. Good evidence is also provided by other characterization techniques including single crystal X-ray diffraction, UV-Vis and fluorescence spectroscopies. This host-guest inclusion complex shows weak fluorescence in aqueous solution. Interestingly, the addition of pymetrozine greatly enhanced the fluorescence of the host-guest inclusion complex. In contrast, no significant fluorescence enhancement was observed on addition of 10 other pesticides. The concentration of pymetrozine in aqueous solution was easily detected based on the linear relationship between fluorescence intensity and pymetrozine concentration. Therefore, this paper reports a new method to identify and determine pymetrozine by fluorescence enhancement.