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.