Preparation And Properties Of Porous Lanthanide Metalorganic Framework Materials

Metal organic framework materials(MOFs)are a kind of periodic polymeric materials rising in recent 20 years.Each repeating unit is combined into a porous structure by organic ligands and metal ions or clusters in the form of coordination bonds.Ln-MOFs have been widely used as fluorescent sensors to detect and identify metal cations,anions,volatile organic compounds,explosives,temperature and p H.Rare earth metal ions are widely used in the preparation of Ln-MOFs because of their unique 4f electronic layer structure and various coordination forms.Ln-MOFs combine the unique fluorescence emission of lanthanide elements into MOFs materials,which are the integrators of two advantageous materials.According to the performance requirements of fluorescence detection,the matching lanthanide elements and ligands can be selected to design and synthesize targeted sensing materials.The application of rare earth ln MOFs in fluorescence sensors has developed rapidly in recent years.In this work,Eu and Tb are selected to synthesize a series of fluorescent sensing materials with different organic ligands and explore their properties:(1)Eu-NDC was synthesized with Eu³⁺as the central ion and 2,6-naphthalene dicarboxylic acid as the ligand in the solvent of N,N-dimethylformamide.It was found that it can be used as a fluorescent sensor to specifically identify crystal violet and uric acid in aqueous solution.The detection effect of crystal violet is excellent,and the detection limit is 0.0992?M?The UV-Vis spectra of crystal violet and uric acid were detected.It was found that they overlapped with the UV-Vis and fluorescence spectra of Eu-NDC.The energy competition and transfer may lead to the quenching phenomenon,which makes the detection materials more scientific.The material has good stability and can be reused.(2)Eu-BDC was also synthesized by solvothermal method.The material has the strongest characteristic emission peak at 618 nm,which is consistent with the special emission of Eu³⁺.The detection experiment of trilyl benzene blue in aqueous solution was carried out,and the detection limit was calculated to be 1.05?M.It can specifically recognize triphenyl blue under the interference of metal cations and anions.(3)The material Tb-BTC with Tb³⁺as the central ion was synthesized by solvothermal method.Compared with the other two synthetic materials,the biggest advantage of the complex is that it has good water stability,can be prepared into aqueous suspension,and the selected solvent is more environmentally friendly.Its aqueous suspension has stable green luminescence.In the fluorescence recognition detection of tetracycline,it is found that it can highly selectively recognize tetracycline from mixed ions in aqueous solution through luminescence quenching,and the detection limit is 1.007?M.The material has good stability and recoverability.The whole research work shows that rare earth Ln-MOFs can be used as a fluorescent sensor to detect macromolecular pollutants,and is ready for the subsequent application of lanthanide Ln-MOFs as a fluorescent sensor to detect and identify macromolecular pollutants in solution phase.