Preparation Of Porous Defects MOF-808 And Cu-BTC-Pro And Study On Catalytic Properties

Metal-Organic Frameworks（MOFs）are a new class of porous crystalline materials,which are formed by connecting metal nodes with organic ligands.Their permanent porosity and adaptability for rational design using crystal engineering strategy make them have the characteristics of adsorption,separation and catalysis.Especially,the judicious choice of metal clusters and organic linkers realizes the control of pore size and pore size chemistry,which is conducive to size selective catalysis.Metal-Organic Frameworks（MOFs）are regarded as promising heterogeneous catalysts due to their high specific surface area,highly tunable properties and high density of active sites.However,as the catalytic active sites of MOFs cannot be fully utilized,they are generally used as the carriers of catalysts.while the researches on the catalytic performance of MOFs are rarely reported.In order to further study the application of MOFs,functional study of MOFs itself is a commonly used modification method.The method of forming defective MOFs has been reported and this method has great development.I believe this discovery can provide some reference for other researchers.The stable MOF-808 and Cu-BTC were selected in this work,The defective porous metal-organic framework MOF-808 and Cu-BTC were prepared by mixed cut ligand method.In other words,a second ligand was introduced on the basis of the original experiment.The ligand truncated one or more carboxyl ligands on the basis of the original ligand,and the two ligands were mixed with metal salts to synthesize MOFs.In the synthesis process,ligands compete for coordination,and the second ligand lacks coordination,resulting in pore defects.The summary is as follows:（1）We used a more simple and fast mixed truncation ligand method will Zirconyl chloride,benzene tricarboxylic acid,isophthalic acid,DMF and formic acid were reacted at 130℃,through regulating the second ligands the amount of isophthalic acid,we successfully synthesized a series of MOF-808 with pore defect.The pore defect of MOF-808 were characterized by XRD,TGA,SEM,NMR and physical adsorption.The experimental results show that the mixed truncation ligand strategy is beneficial to the formation of pore defects MOF-808.Then,we tested the probe reaction-Styrene oxide ring opening reaction with the synthesized catalyst pore defect MOF-808.The test results show that the more defects in the synthesized pore defect MOF-808,the better the catalytic activity.The reason is that the pore defect MOF-808 has a higher concentration of coordination unsaturated Zr⁴⁺sites,and the pore defect MOF-808 contains more defects,which makes the reactants easier to contact the active sites,and the larger pores channels are are beneficial to macromolecular reaction and the diffusion of the substrate.（2）With the continuous emergence of chiral drugs,the role of chiral compounds in organisms has been increasingly understood.Therefore,the development of more efficient asymmetric catalytic methods to synthesize chiral compounds has become a research hot topic.The development of chiral catalysts is undoubtedly the key to achieve the high efficiency and high selectivity of asymmetric catalysis.Here,we successfully synthesized a series of Cu-BTC-Pro by mixing the chiral ligand with the original ligand and homobenzene tricarboxylic acid.XRD,NMR,UV and physical adsorption show that the catalyst was synthesized successfully.The amount of chiral ligand in the catalyst is linearly related to the defect concentration of the catalyst Cu-BTC-Pro.We used the synthesized catalyst in the asymmetric aldol condensation of aldehydes to ketones and showed good catalytic activity.Therefore,the mixed truncation ligand strategy can successfully synthesize chiral pore defect MOFs and improve the catalytic activity of asymmetric aldol condensation.