Study On Triazole Carboxylate MOFs As Fluorescent Probes

Metal organic framework materials（MOFs）are a new type of porous materials,which are widely used in catalysis,hydrogen storage,drug loading,sensing and other fields.Its use in fluorescence sensing has the advantages of high sensitivity,low cost and short response time,so it has certain application value in the detection of organic matter and small molecule recognition.Based on this,this thesis selected triazole carboxylic acid ligands with abundant N-and O-donors,5-（1,2,4-triazol-1-yl）isophthalic acid（H₂tyia）,The high energy conjugated triazole group in the body and the rich coordination mode of carboxylic acid provide a guarantee for the design and regulation of fluorescent probe materials with the expected structure and function.In this paper,seven novel fluorescence MOFs were synthesized by solvothermal method based on H₂tyia and rare earth metals Eu（III）,Tb（III）,Dy（III）,Sm（III）,Gd（III）,Nd（III）and transition metal Zn（II）.The structures were analyzed by X-single crystal diffraction and characterized by elemental analysis,PXRD,TGA,solid fluorescence analysis,etc.,and its application as fluorescent probes were studied,as follows:Seven new compounds:[Eu₂（tyia）₃·（H₂O）₃]_n（1）,{[Tb₂（tyia）₃·（H₂O）₃]·3H₂O}_n（2）,{[Dy₂（tyia）₃·（H₂O）₃]·3H₂O}_n（3）,{[Sm₂（tyia）₃·（H₂O）₃]·3H₂O}_n（4）,{[Gd₂（tyia）₃·（H₂O）₃]·3H₂O}_n（5）,{[Nd₂（tyia）₃·（H₂O）₃]·3H₂O}_n（6）,{[Zn₂（tyia）₂·（H₂O）₂]·H₂O}_n（7）,were hydrothermally synthesized.The structural analysis of the compounds 1-7 found that the compounds 1-6 are all crystalline in the triclinic system,P-1 space group,and their asymmetric unit structure has two independent metal ions（Ln1 and Ln2）,both of which have metal atoms.The metal atoms are all nine-coordinated,and the coordination configurations are all distorted tetrahedrons.The compounds form a one-dimensional（1D）,two-dimensional（2D）and three-dimensional（3D）structure diagram through the Ln-O and Ln-N bonds;Compound 7 crystallizes in the orthorhombic Pbcn space group.Compound 7 center metal ion is pentacoordinated,distorted octahedral configuration.1D zigzag line（[Zn-H₂tyia]_n）formed by the tyia^2-ligands and Zn（II）without considering carboxyl coordination.Furthermore,the neighboring 1D chains are connected by tyia^2-ligands to form 3D framework.The compounds containing Tb（III）,Sm（III）,Gd（III）and Nd（III）were used as fluorescent probes to mark 1-naphthol（1-N）,thiodiacetic acid（TDGA）,uric acid（UA）and hippuric acid（HA）in urine.Tb-MOFs have a strong fluorescence quenching effect on the biomarker 1-N,and the lowest recognition concentration is as low as 5.5×10^-6 M.Sm-MOFs,Gd-MOFs,and Nd-MOFs have fluorescence enhancement effects on biomarkers TDGA,UA,and HA,respectively.The minimum recognition concentrations are 1.7×10^-6 M,4.9×10^-7 M and 4.6×10^-6 M.The fluorescence characteristics of the interaction of compound 7 with small organic molecules were investigated.The results show that the compound can react quickly to low concentrations of styrene,with a minimum recognition concentration of 1.06×10^-6 M,and has the potential to act as a sensitive chemical detector.The completion of the above paper work provides a scientific basis and experimental basis for the development of new medical materials and fluorescent probes as disease prevention and diagnosis.