Synthesis Of Carbazole-Based Fluorescent Porous Polymers For Pesticide Detection

Pesticide residues in crops,soil,and water continue to be a major source of concern due to potential threats to human health and food safety.In light of this issue,there is an urgent need to develop dependable,sensitive,and portable detection tools for monitoring and early warning of potential pesticide residues in food,soil,and water.Pesticide detection methods such as gas chromatography-mass spectrometry and high performance liquid chromatography are widely used,but the detection process is time-consuming and labor-intensive,requiring professional technicians to operate expensive instruments and sending samples to the laboratory for analysis.Existing pesticide detection methods have numerous flaws.We synthesized two fluorescent porous polyacetals,JY1 and JY2,with fluorescent pendant groups in order to develop high-sensitivity sensing materials and portable detection devices.Four pesticides were chosen for fluorescence sensing experiments.The polymer JY1 has an ultra-fast response time（2 s）,an ultra-low detection limit（30 ppb）for the pesticide imidacloprid,and the Stern-Volmer constant reaches 50063 M^-1,which is 23-51 times greater than the previously reported porous organic polymer(980-2173 M^-1)and demonstrated excellent anti-interference to apple peel,field soil extracts,and various ions.Density functional theory（DFT）,polymer pore structure,pesticide ultraviolet absorption,and polymer excitation spectroscopy were used to investigate the sensing factors between pesticides and polymers.According to research,the fluorescence sensing between pesticides and polymers is caused by the interaction of electron transfer,polymer pore structure,and the inner filter effect.Furthermore,we successfully prepared the polymer JY1 fluorescent silica gel detection plate,which overcomes the shortcomings of the previously reported fluorescent coating on paper,which is unstable and easily comes off during use.Naked eye experiments show that the polymer JY1 detection device exhibits rapid fluorescence quenching in an aqueous solution of imidacloprid at a concentration of 29μM.Furthermore,after washing with ethanol,the fluorescence intensity can be completely recovered,the detection plate can be reused,and the detection plate’s fluorescence intensity will not decrease.The fluorescent porous polyacetal JYs and their detection device have the advantages of sensitive fluorescence response,portability,and good reusability,and have broad application prospects in pesticide residue monitoring and early warning.