Design And Synthesis Of Fluorescent Metal Organic Frameworks To Application In The Detection Of Pesticide Residues

The effective use of pesticides and antibiotics is the fundamental guarantee for the normal development of agricultural production such as plantation,forestry,animal husbandry and fishery.As the society’s demand for agricultural products increases,the abuse of pesticides and antibiotics has also worsened,and the accumulation of pesticide residues in the environment is increasing day by day.Some pesticide residues can seriously damage the ecological balance,and can cause serious health risks to humans and other organisms through the enrichment of the food chain.Therefore,it is of great significance and value to develop a method that can sensitively and specifically detect these pesticide residues.Compared with traditional methods,fluorescence detection has the advantages of high sensitivity,strong portability and low cost.Fluorescence detection based on metal organic framework materials（MOFs）has the advantages of good stability,strong specificity,and recyclability.In recent years,it has gradually become a research hotspot in the field of detection.Based on this,this study successfully constructed four new MOFs using functional ligands and trivalent metal ions,and investigated the sensitivity,specificity,competitiveness,and recyclability of two of them for the detection of pesticide residues.Their detection potential of pesticide residues in actual samples,the results are as follows:（1）Synthesis using a mixed metal strategy,the nitrogen-rich triazine ligand{2,4,6-tris[（p-carboxyphenyl）amino]-1,3,5-triazine}（H₃TATAB）is combined with In³⁺and Tb³⁺in solvothermal a case of 3D mixed-metal MOF with a diameter of about 2.8 nm was synthesized under the conditions,[In₃Tb₃O₃（TATAB）₄（H₂O）₆]?12DMF?12H₂O（1）,1 has a high density of Lewis acidic metal ions and Lewis basic-NH-sites that decorate the pore walls.Fluorescence sensing studies have shown that 1 can specifically detect nitenpyram,it can still maintain good stability and sensitivity after 7 cycles of nitenpyram,and the detection limit for nitenpyram is as low as 0.17μg/m L,and the recovery rate in environmental water samples is 98.86-108.82%.Therefore,the use of ligands with good luminescence metal centers and multiple active sites to construct a MOF will be beneficial to the detection and application of target pesticide residues.（2）This experiment is designed to synthesize a photoactive viologen-derived functional ligand bromide 1-（3,5-isophthalic acid）-4,4’-bipyridine.The viologen-derived ligands have enriched their photoactive functions due to the existence of viologen radicals.We used it as the ligand and the high oxidation state Y³⁺as the metal center,and constructed two cases of two-dimensional ions under solvothermal conditions MOFs:[Y（ipbp）₂（H₂O）₃]NO₃·1.5H₂O（2）and[Y₃（ipbp）₄（COO）₄（H₂O）₂]NO₃（3）,and compound 2 can grow into a new 0D MOF{[Y（ipbp）₂·6H₂O]H₂ipbp·3H₂O·NO₃^-}（4）by adding water as a solvent after grinding.Compared with 2,3 with tri-nuclear cluster unit has higher stability.3 has a sensitive photochromic phenomenon and can change from yellow to green within 5 s at a wavelength of 635 nm.In addition,3 showed specific fluorescence quenching to the banned antibiotic nitrofurazone.The degree of quenching was different in the presence of different concentrations of nitrofurazone.It showed a more sensitive detection ability and the detection limit was as low as 0.77μg/m L.The recovery rate in sample detection is 94.70-109.85%.The use of ionic viologen ligands to construct a 2D ionic framework can not only increase the force between the host and the guest,but also increase the area of action,which can provide a certain reference for the subsequent design and application of MOFs.