Study On The Construction Of Molecularly Imprinted Fluorescent Sensor And Its Application In Detection Of Ambient Aromatic Nitro Compounds

An important chemical intermediate,aromatic nitro compounds are widely used in the synthesis of dyes,pesticides,pharmaceutical products,explosives and rubber.They will be released into the environment in the form of industrial waste during the process of industrial production.They can easily penetrate and accumulate in soil or groundwater due to their good solubility in water.They are highly toxic to aquatic organisms and can even endanger human health and cause breathing to stop.Therefore,environmental protection agencies in many countries regard it as a priority to control pollutants.Molecular imprinting technology is a technology that specifically recognizes target analytes.The combination of fluorescence analysis and molecular imprinting technology can be used in the field of analysis and detection with the advantages of strong selectivity,high sensitivity and good stability.This project intends to synthesize alkenyl fluorescent ionic liquids with multiple recognition sites,and use them as fluorescent signal carriers to construct a molecularly imprinted fluorescent sensor for the analysis and detection of aromatic nitro compounds.1.Coumarin alkenyl ionic liquids with strong fluorescent properties were synthesized from 4-bromomethyl-7-methoxycoumarin and1-vinylimidazole.And a new molecularly imprinted fluorescent sensor for the detection of 4-nitroaniline was prepared by polymerization using coumarin alkenyl ionic liquid as a fluorescent functional monomer,4-nitroaniline as a template molecule,ethylene glycol dimethacrylate(EGDMA)as a crosslinking agent and azodiisobutyronitrile(AIBN)as an initiator.The prepared fluorescent molecularly imprinted polyionic liquid was characterized by NMR,FTIR,SEM,nitrogen adsorption-desorption,and specific surface area calculation.The experimental results show that 4-nitroaniline can rapidly quench the fluorescence of the sensor in 30 s,and has a good linear relationship with the fluorescence quenching intensity in the concentration range of 2.67-10000 n M(4-nitroaniline).The correlation coefficient is 0.992,and the detection limit is 0.8 n M(S/N=3).The sensor has good selectivity to4-nitroaniline and has been successfully applied to the determination of4-nitroaniline in actual samples,and the recovery rate is 97.7%-103.2%.The developed method was compared with that of liquid chromatography.2.Alkenyl ionic liquids with strong fluorescence were synthesized from1-(bromomethyl)naphthalene and 1-vinylimidazole.A new molecularly imprinted fluorescent sensor for the determination of 4-nitrophenol was prepared by polymerization using alkenyl ionic liquid as a fluorescent functional monomer,4-nitrophenol as a template molecule,N,N-methylenebisacrylamide(MBA)as a crosslinking agent and azodiisobutyronitrile as an initiator.The prepared molecularly imprinted polyionic liquid was characterized by NMR,FTIR,SEM,and BET.The experimental results show that 4-nitrophenol can rapidly quench the fluorescence of the sensor in 60 s,and has a good linear relationship with the fluorescence quenching intensity in the concentration range of 10–10000 n M(4-nitrophenol).The correlation coefficient is 0.9977,and the detection limit is 3 n M(S/N=3).The sensor has a good response to 4-nitrophenol,and has been successfully applied to the rapid determination of 4-nitrophenol in environmental water samples of Jiaxing City with a recovery rate of98.5%-109%,and its effectiveness and practicability were verified.3.Fe₃O₄ magnetic nanoparticles were synthesized by hydrothermal method,and then alkenyl Fe₃O₄@Si O₂was obtained by coating and modifying the surface of Fe₃O₄magnetic nanoparticles.Next,a dialkenyl ionic liquid was synthesized through a two-step reaction by using4,4'-(9-Fluorenylidene)diphenol,1,2-dibromoethane and 1-vinylimidazole as raw materials.A new Fe₃O₄@Si O₂@MIPIL sensor for the detection of imidacloprid was prepared by polymerization using alkenyl Fe₃O₄@Si O₂as a carrier,dialkenyl ionic liquid as a dienyl fluorescent functional monomer,imidacloprid as a template molecular,AIBN as an initiator and MBA as a crosslinking agent.The prepared Fe₃O₄@Si O₂@MIPIL sensor was characterized by FTIR,TGA,TEM,nitrogen adsorption-desorption.The results show that imidacloprid can rapidly quench the fluorescence of the sensor in 1 min,and has a good linear relationship with the fluorescence quenching intensity in the concentration range of 1-1000 n M(imidacloprid).The correlation coefficient is 0.995,and the detection limit is 0.3 n M(S/N=3).Fe₃O₄@Si O₂@MIPIL sensor has good selectivity for imidacloprid,and has been successfully applied to the determination of imidacloprid in actual samples with a recovery rate of 94.80%-109.40%,and a satisfactory result has been obtained.