First organic fluorescent sensor for pesticide paclobutrazol based on tetraphenylimidazole Schiff base

Paclobutrazol is a triazole pesticide used widely in agriculture, but the simple, real-time and in-situ method on detecting paclobutrazol was seldom reported so far. In this work, the first organic fluorescent sensor for detecting paclobutrazol was developed based on a tetraphenylimidazole Schiff base (TPS) with “turn-on” and “color-change” fluorescence response. TPS was synthesized by Schiff-base condensation of amino-tetraphenylimidazole and salicylaldehyde in 79 % yield. The yellow fluorescence of TPS in aqueous media transferred to bright green fluorescence after sensing paclobutrazol. The high sensing selectivity was observed among 23 kinds of herbicides and ions. The detection limitation was 9.3 × 10-8 M. The study on sensing mechanism revealed that 1:1 binding system of TPS with paclobutrazol resulted in strong aggregation effect for better fluorescence emission. The application potential of TPS on sensing paclobutrazol had been explored by the experiments of test paper, real water samples (tap water, mineral water, Minjiang river, lotus pond soil soaking solution) and leaf samples (Ophiopogon japonicus, loquat tree, longan tree, guava tree), indicating the good application prospect of TPS on simple, real-time and in-situ detection of paclobutrazol in real environment. •The first organic fluorescent sensor for herbicide paclobutrazol was reported.•The sensor exhibited the “turn-on” and “color-change” fluorescence on sensing paclobutrazol.•The high sensing selectivity was observed.•The detecting limitation was 9.3 × 10-8 M.•The sensor was applied for detecting paclobutrazol in real samples.