Host-guest-mediated phosphate salt pillar[6]arene supramolecular fluorescent probe for rapid detection of paraquat

A water-soluble Phosphate salt pillar[6]arene (PP6A) was used as the host, and (E)-4-[2-(6-hydroxy-2-naphthalenyl)ethenyl]-1-methylpyridinium iodide (HMI) served as the guest to prepare a water-soluble supramolecular inclusion complex HMI/PP6A through a saturated aqueous solution method. The formation of the inclusion complex was confirmed by UV-Vis, ¹H NMR, 2D NMR, FT-IR, and XRD. The host-guest complexation behavior of PP6A and HMI was investigated using fluorescence and UV-Vis spectroscopy, revealing that the two components form a stable 1:1 inclusion complex. HMI forms an inclusion complex with PP6A, electron transfer occurs, leading to a significant quenching of its fluorescence. The HMI/PP6A inclusion complex was employed as a supramolecular fluorescence probe for the high-selectivity and high-sensitivity detection of paraquat (PQ). When PQ was added to the HMI/PP6A complex, the system exhibited a significant fluorescence enhancement effect, with a detection limit as low as 2.76 × 10^-7 M. Spiked recovery experiments in real samples (apple, tomato) demonstrated the accuracy of PQ detection using the HMI/PP6A complex. This fluorescence probe offers excellent selectivity, a wide pH-response range, and strong anti-interference properties, providing a novel and feasible approach for the precise detection of pesticide residues in food.