Synthesis Of Fluorescent Probes Based On Tetrastyrene Derivatives And Application In The Detection Of Paraquat And Atrazine

In the rapid development of agriculture,pesticides play a vital role in the growth and protection of crops and the storage and transportation of agricultural products.However,pesticide residues in soil,water and agricultural products will pollute the environment and affect human health.Therefore,a fast and effective chemical method is needed to detect pesticide residues in the environment.At present,the traditional methods for detecting pesticide residues mainly include gas chromatography,mass spectrometry,high performance liquid chromatography,and gas chromatography tandem mass spectrometry.Although these methods have high sensitivity and accuracy,they have disadvantages such as complex sampling technology,cumbersome process,expensive detection costs,require of technical professionals and inconvenient on-site detection.Therefore,a sensitive,effective,simple,fast,and easy-to-operate method is needed to quantitatively detect pesticide residues in the environment.Fluorescence analysis method has the advantages of obvious phenomenon,high sensitivity,simple and fast detecting process,easy operation and so on.Aggregation induced emmision（AIE）is a new type of photoluminescence phenomenon,and molecules with AIE effect are widely used in detection.AIE molecules such as tetrastyrene（TPE）show extremely weak fluorescence in dilute solution,but show strong fluorescence in the aggregated state.The strong fluorescence is caused by restriction of the intramolecular motions of AIE molecules in the clustered state,whose fluorescence phenomenon is contrary to the aggregation caused quenching of traditional fluorescent materials.In this project,we designed and synthesized two TPE derivatives as fluorescent probes with AIE effect to explore their recognition and detection for pesticides paraquat and atrazine respectively,and explore their detection limits and selectivity.The main research contents in this paper are as follows:1.Based on the column[5]aromatic hydrocarbon as the recognition group of the pesticide paraquat,an AIE fluorescent probe linked between the column[5]aromatic hydrocarbon and TPE was designed and synthesized.In the presence of paraquat,the host-guest complex between the column[5]aromatic hydrocarbon of the probe and paraquat restricts the intramolecular motions,resulting in enhanced fluorescence.The¹H NMR spectrum of the probe and paraquat showed the effective combination of them.TPE-1 can be used as a fluorescence-enhanced probe for detecting paraquat.The phenomenon is obvious.The limit of detection this method is 1.84?M and the detection process of paraquat by TPE-1 is completed within 30 minutes.The probe also showed good selectivity and sensitivity to paraquat under the interference of other pesticides.At the same time,the probe also shows the potential to detect paraquat in real sample running water.2.According to the structure of the pesticide atrazine containing two secondary amines,a fluorescent probe TPE-2 rich in amino groups was designed and synthesized,and the aniline group was introduced on the basis of the parent tetrastyrene.The amino group in the probe TPE-2 can be protonated under acidic conditions to generate NH₃⁺and form hydrogen bonds,showing good AIE properties.When the volume ratio of water（p H=5）to tetrahydrofuran is8:2,it emits strong fluorescence.With the addition of atrazine,the secondary amine in atrazine neutralizes the hydrogen ions in the system,destroys the hydrogen bond structure between probe molecules and causes fluorescence quenching.The limit of detection of this method is 2.25?M.The fluorescence quenching process of TPE-2 by atrazine is completed within 3 minutes,which can achieve the purpose of quick detection of atrazine.Under the interference of common pesticides,TPE-2 can detect atrazine sensitively and selectively within limits.In addition,this method also shows the potential to detect atrazine in real sample soil.