Detecting Pesticide Dodine by Displacement of Fluorescent Acridine from Cucurbit[10]uril Macrocycle

According to a simple guest-replacement fluorescence turn-on mechanism, we constructed a fluorescent probe system based on cucurbit[10]uril (Q[10]) and protonated acridine (AD) to detect the pesticide dodine (DD). Formation of a homoternary inclusion complex AD₂@Q[10] in both aqueous solution and solid state was studied by means of ¹H NMR spectroscopy and X-ray crystallography. Although AD can emit strong fluorescence in aqueous solution, the homoternary inclusion complex AD₂@Q[10] does not exhibit any fluorescence. Upon the addition of the pesticide DD into the aqueous solution of AD₂@Q[10], the AD molecules in the Q[10] cavity are displaced by the pesticide DD, and strong fluorescence recovers. The fluorescent probe system based on Q[10] and AD provided a wide determination of DD from 0 to 4.0 × 10^-5 mol·L^-1 with a low limit of detection of 1.827 × 10^-6 mol·L^-1. The guest-replacement fluorescence turn-on mechanism is also confirmed by ¹H NMR spectroscopy. Further, the fluorescent probe can directly detect DD residues in real agricultural products, and obvious fluorescence signal was observed under UV irradiation.