Studies On Two Lanthanide Complexes Synthesized Based On Nitroxylic Acid Ligands As Fluorescent Probes

At present,the development of industry and agriculture has brought all kinds of benefits to human beings,meanwhile,accompanied by a variety of pollutants,which has caused a great threat to human life safety,and become major problems plaguing human beings.Industrial pollution includes excessive metal ions,nitro compounds and organic solvents;Agricultural pollution includes antibiotics and pesticides used in stock farming and agriculture.Therefore,it is an urgent need to find a detection method for the above pollutants for human health,and fluorescence sensing is a detection method developed rapidly in recent years.Lanthanide metal complexes（Ln-MOFs）have unique advantages in fluorescence sensing due to their excellent luminescence properties.Rare earth metal complexes with multiple emission peaks can be used as ratio fluorescence sensors to eliminate environmental interference.Therefore,two complexes with Dy and Sm as center atoms and 2,5-2（1-1,2,4-triazole-1-yl）terephthalic acid as ligands were synthesized by hydrothermal reaction.The crystal structure and properties of two complexes were analyzed and characterized,and the fluorescence sensing experiments of them were carried out.The main research contents include:1.[Dy（L）（NO₃）（DMF）₃]_nand[Sm（L）（NO₃）（DMF）₃]_nwere prepared by hydrothermal synthesis method,and their structural,purity and stability were analyzed.2.The ability of Dy complex to detect antibiotics and nitro compounds was studied.As the results showed that Dy complex could identify ornidazole,metronidazole and dimethylimidazole,with detection limits of 0.0398,0.0512 and 0.0550μM,respectively.In nitro compounds,p-nitrophenol can be recognized with the detection limit of 0.0676μM.The fluorescence quenching mechanism was also analyzed and explained.3.The detection ability of Sm complex on metal ion,organic solvent and pesticide was studied.As the results showed that Sm complex could effectively recognize Al³⁺in metal ions,and the detection limit was 0.082μM.In organic solvent,DMSO can be effectively detected with the detection limit of 0.112μM.Among pesticides,niacsulfuron can be effectively identified and the detection limit is 7.28 n M.The mechanism of fluorescence enhancement was analyzed and explained.