Construction Of Bifunctional Chiral MOFs For Catalytic Performance

As a new type of functional materials,the structure,pore size and functionality of the metal-organic frameworks（MOFs）can be easily designed and adjusted by changing metal nodes,ligands and post-synthetic modification methods（PSM）.The combination of the different active sites in MOFs（such as metal nodes,functional organic linkers and guests in pores）makes them become multifunctional materials,which can be used for synergistic catalysis and sequential reaction.In this thesis,two types of MOFs that both contained two spatially isolated active sites were designed and used in heterogeneous asymmetric synergistic catalysis/sequential reaction.This work was carried out from the following aspects:1.N-BOC-L-Proline and PdCl₂（CH₃CN）were used as starting materials to synthesize chiral proline-ligand L₁ and Pd-ligand L₂,then the bifunctional chiral UiO-67-Pro-Pd was prepared via the hydrothermal method.The successful preparation of UiO-67-Pro-Pd was proved by a series of characterization such as powder X-ray diffraction（PXRD）,fourier-infrared（FT-IR）,nuclear magnetic（¹H-NMR）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,thermogravimetric（TG）and N₂ adsorption,etc.Two different active sites were evenly distributed and isolated from each other in the network structure of the MOF.The UiO-67-Pro-Pd was used as an asymmetric sequential reaction catalyst to catalyze the reaction of Suzuki/Asymmetric Aldol,with good yields（87%）and enantiomeric excesses（69.4%）.Meanwhile,the catalyst also showed good substrate suitability and cycle stability.2.Trans-4-hydroxy-BOC-L-proline was used as the starting material to synthesis a proline derivative chiral ligand L₃ via multi-step reaction,and Ru（bpy）₂Cl₂ was used as the raw material to synthesize Ru ligand L₄.The bifunctional chiral UiO-67-Pro-Ru catalyst with isolated catalytic active sites was successfully prepared by hydrothermal method and the structure was characterized by the measurement of fourier-infrared（FT-IR）,ultraviolet-visible（UV-vis）,powder X-ray diffraction（PXRD）,scanning electron microscope（SEM）,transmission electron microscopy（TEM）,thermogravimetry（TG）,N₂ adsorption and so on.Finally,it was used in the photocatalytic asymmetry coupling reaction between a diaryl-substituted-CH₂ unit and aldehyde,and the yield of 32%and the ee value of 92.0%were obtained.The synergistic catalysis of the two active sites in UiO-67-Pro-Ru was also proved.To the best of our knowledge,this is the first heterogeneous photocatalyst to catalyze the asymmetric coupling reaction between diaryl-substituted-CH₂ units and aldehydes.