Synthesis,Characterization And Properties Of Carboxylic Acid MOFs

Metal-organic complexes have attracted much attention in many fields,such as proton conduction and fluorescence recognition,because of their rich and diverse structures,adjustable pore size and combination visualization.In the process of MOF self-assembly,the choice of ligand is very important.The selection of carboxylic acid ligands can not only provide a large number of coordination sites and coordination modes,but also provide a large number of proton sources and transmission channels for proton conduction.In addition,introducing rare earth ions with unique luminescence properties into carboxyl complexes is also an important method to construct luminescent materials.The specific research content of this paper is as follows:（1）Three kinds of three-dimensional structural complexes with similar structures are generated by solvothermal self-assembly,respectively:{[Mn_1.5（abtc）_0.4（O₂abtc）_0.6]₂·2（H₃O）·6（H₂O）}_n（1）、{[Mn_1.5（abtc）_0.4（O₂abtc）_0.6]₂·2（H₃O）·6（H₂O）·2Me CN}_n（2）、{Co₃（O₂abtc）·H₂O·IM}_n（3）,and simple structural characterization of these three kinds of crystals was carried out by single crystal X-ray diffraction,elemental analysis,infrared spectrum analysis,thermogravimetric analysis and ultraviolet spectrum analysis.The structure of the three MOFs crystals remained intact at 300℃through thermal stability study.The water stability study showed that the XRD patterns of the three MOFs crystals after water treatment were in good agreement with the single-crystal fitting XRD patterns.Structural analysis shows that there are a large number of water molecules or hydronium ions in pores1-3.The existence of these substances can provide abundant proton sources and convenient proton transmission channels for the proton conduction process.The above results lay a solid foundation for excellent electrical conductivity.The analysis of proton conductivity of 1-3 shows that the maximum conductivity of the three MOFs reaches 2.55×10^-3S·cm^-1,9.02×10^-3S·cm^-1and 4.95×10^-3S·cm^-1at 100℃and 98%humidity,respectively.In addition,the ultraviolet spectrum analysis and the calculation of band gap value show that both 1 and 2have the performance of semiconductor.（2）Eu³⁺was introduced into the pore of UIO-66-（COOH）₂to generate Eu@UIO-66-（COOH）₂by post-modification,using the strong bond and ability between the uncoordinated active carboxyl group in UIO-66-（COOH）₂and the oxygenophilic Eu³⁺.The modified products were characterized by infrared,ultraviolet,thermogravimetric and XRD.The research focused on its proton conductivity and fluorescence recognition ability of antibiotics,and the results showed that its proton conductivity was not outstanding,but through the exploration of fluorescence recognition of nine antibiotics,it has good recognition performance for RND,NFT,DND,MND,OND,NFZ,and can be applied in practice as a fluorescence recognition probe.