Overcoming the selectivity-stability trade-off: A hydrophobic pillar[6]arene derivative-based electroanalytical strategy for diquat detection

Electrochemical detection of diquat (DQ) herbicide residue faces challenges in achieving the trade-off among selectivity, sensitivity, and stability in complex matrices. To overcome this, we reported a supramolecular electrochemical sensor (P6-TATR/AB/GCE) based on a newly synthesized electron-rich, hydrophobic pillar[6]arene-triazatruxene derivative (P6-TATR) integrated with acetylene black (AB). The sensor leverages the high conductivity and electrocatalytic activity of AB, while P6-TATR enables selective DQ recognition through synergistic electrostatic interaction, host-guest complexation, and competitive adsorption. This synergistic combination facilitates rapid DQ reduction at the electrode interface, enabling high-performance DQ monitoring. The proposed sensor demonstrated a low detection limit (0.784 nM), wide linear range (0.001–16.0 μM), and exceptional specificity against 100-fold interfering pesticides and ions. The sensor exhibited excellent reproducibility, with relative standard deviations (RSD) of 2.43% (intra-day), 2.94% (inter-day), and 3.08% (batch-to-batch). It also demonstrated robust long-term stability, retaining 90.4% of its initial signal after 150 days. Practical application in food and environmental samples yielded satisfactory recoveries (80.0%–116.0%) with RSD ≤ 7.4% ( n  = 3), which were corroborated by High Performance Liquid Chromatography (HPLC) validation. The fabricated electrode outperforms existing DQ sensors in selectivity and stability, offering a new strategy for utilizing hydrophobic macrocycles in electrochemical analysis.