Synthesis And Photocatalytic Redox Properties Of Novel Metal-organic Framework Compounds

Metal organic framework?MOF?is a new type of hybrid inorganic-organic microporous crystalline material,which is self-assembled directly by metal ions and organic connecting ligands through coordination bonds.The diversity of various building blocks of metal ions and organic linking ligands makes it possible for MOF to have countless different structures,so that the topological structure and porosity in the new MOF can obtain higher benefits.Due to its fascinating structure and extraordinary properties?such as permanent nano-scale porosity,high surface area,good thermal stability and uniform structural cavity?,MOF has great potential in many applications,such as hydrogen storage,Gas separation,catalysis,sensing and biological imaging.In different applications of MOF properties,catalysis research started very early and is becoming one of the fastest growing applications.In this thesis,coordination polymerization with transition metal ions,alkaline earth metal ions,and anthracene dicarboxylic acid ligands was constructed to explore their potential photocatalytic applications.The solvothermal method was used to make the visible light-responsive anthracene dicarboxylic acid ligand coordinate with the transition metal ion and the alkaline earth metal ion to successfully prepare the corresponding metal ion coordination polymer.By using various testing and characterizing methods to study their physicochemical properties,and exploring the visible light photocatalytic organic reactions of two MOFs,the photocatalytic properties and the mechanism of organic reactions were explored.The detailed work is as follows:1.Athree-dimensionalmetal-organicframeworkcompound[Zn₃?OH?₂?ADBEB?₂]·3DEF?1?was synthesized by anthracene dicarboxylic acid ligand and transition metal zinc ion by solvothermal method.Tests on its physico-chemical properties showed that Compound 1 is an ideal photocatalytic material.The prepared MOF is highly efficient for self-coupling of primary amines and oxidative dehydrogenation of secondary amines with green and economical molecular oxygen oxidant assisted selective production of imines.Studies have shown that the reaction mechanism of primary and secondary amine oxides is that the energy transfer and molecular transfer of light-excited MOF to molecular oxygen generate highly reactive superoxide radicals and singlet oxygen,which together constitute high catalytic performance.MOF photogenerated electrons can also be used to reduce nitroaromatics.The results show that in the presence of hydrazine hydrate,reduction of nitroaromatics to produce aniline has a high selectivity.This work demonstrates the tremendous potential of photosensitive MOFs in converting organic substrates into valuable chemicals.2.Synthesis of two-dimensional metal-organic framework[Mg₂·ADBEB₂·6H₂O]·2DMA?2?by solvothermal coordination using anthracene dicarboxylic acid ligand and alkaline earth metal magnesium ions.Through test and characterization,it was verified that compound 2also has ideal visible light absorption properties due to its ligand.In this chapter,compound 2is used to photocatalyze the oxidation of thioethers in a molecular oxygen atmosphere.The experimental results show that the photocatalytic oxidation mechanism for thioethers also utilizes the high catalytic performance of singlet oxygen and superoxide radicals generated by the electron transfer and energy transfer of molecular oxygen by compound 2.Compound 2shows high conversion and selectivity for the photocatalytic oxidation of thioethers.The reduction of nitrobenzene with compound 2 is completed under the action of hydrazine hydrate.The photoelectron generated by compound 2 and the hydrogen source provided by hydrazine hydrate reduce nitrobenzene to aniline.Two experiments on photocatalytic organic reactions show that alkaline earth MOF also has good photocatalytic redox activity in photocatalytic redox reactions.It provides new research ideas for the study of the properties of alkaline earth MOF.