The Systhesis,Structure,and Property Of Metal-organic Framwork Based On Aromatic Carboxylate And Nitrogen Heterocycle Ligands

The metal-organic frameworks（MOFs）have attracted extensive attention because of their unique physical and chemical properties.MOFs can be prepared into various forms by controlling the reaction conditions,including nanoparticles,nanorods,nanotubes,nanosheets,etc.However,designing and synthesizing MOFs with specific applications is still a big challenge.Compared with the single ligand,using mixed ligands to prepare MOFs can introduce multiple functional groups,which can not only enrich the structure but also introduce multiple functions into one material.Therefore,we selected aromatic carboxylate ligands and nitrogen heterocyclic ligands to successfully prepare 5compounds,respectively.Based on the structural characteristics,we discussed their potential applications in iodine adsorption,electrocatalysis and fluorescence sensing.The main contents are as follows:（1）Usingthecarboxylicacidligand tetrakis[（4-carboxyphenyl）oxamethyl]methane（H₄L）and Co（NO₃）₂·6H₂O,a three-dimensional organic framework[Co₂（H₃L）（CON（CH₃）₂）₃]·3H₂O·2DMF（1）with a pore size of 10×10?² was prepared under solvothermal condition.Based on the synthesis of compound 1,through a mixed ligand strategy,the nitrogen heterocyclic ligand 4-amino-3,5-bis（4-pyridyl）-1,2,4-triazole（L₁）was added to react with zinc nitrate.The three-dimensional pillar compound[Zn₂（L）₂（L₁）_1/2]·2DMA（2）was successfully synthesized by optimizing the reaction conditions.Compound 1 can be used as electrocatalyst for OER.The overpotential of compound 1 is only 0.28 V(current density=10 m A cm^-2),showing better electrocatalytic performance than commercial ruthenium oxide.Compound 2 shows strong fluorescence emission and can selectively detect Fe³⁺through fluorescence quenching effect.（2）On the basis of system（1）,[Ni₂（L）（L₂）]·4H₂O·2DMF（3）and[Co₂（HL）（L₂）_3/2（CH₃NCH₃）]·2H₂O（4）were successfully synthesized under solvothermal condition by using the nitrogen heterocyclic ligand1,4-bis（1-imidazolyl）benzene（L₂）instead of L₁.Compound 3 shows 3D structure with two different channels.While compound 4 has 3D five-fold interpenetrating structure.Therefore,compound 4 exhibits better thermal and chemical stability than compound 3.Replacing carboxylic acid ligand H₄L with trimellitic acid（H₃BTC）,three-dimensional compound[Ni₂（HBTC）（L₂）₂（HCOO）₂（H₂O）]n（5）with double pillars structure was obtained.Compound 5 can keep the structural integrity under different organic solvents and p H conditions.The iodine sorption/release capability of complex 4 has been studied in solution.The results demonstrate it has reversible iodine loading and rapid removal ability.