Design,Synthesis And Catalytic Properties Of Novel Three-dimensional Covalent Organic Frameworks

Covalent organic frameworks(COFs),as an emerging class of porous crystalline polymers,feature ordered channel structure,high surface areas and easy functionalization,and could be effectively applied in many fields including catalysis,sensing,separation and photoelectrics.Therefore,it has been widely concerned by chemists.However,three-dimensional(3D)COFs materials are far less explored.The main difficulties lie in the crystallization and structural characterization.Because 3D COFs can display open active sites and effective confinement effects,which have potential applications in many research fields.Therefore,it is of great significance to design and synthesize 3D COFs materials with novel topological structure and function.In this thesis,we report the design and synthesis of novel functional 3D COFs and explore the catalytic performance of COFs.The thesis is divided into five chapters:In Chapter 1,the research background of COFs were introduced,including the design and synthesis of COFs and the performance studies.In particular,the research progress of 3D COFs is described in detail.Then,the research background of the topic of the thesis is expounded,and the progress of the work is introduced.In Chapter 2,two novel 3D COFs with a twofold-interpenetrated ffc topology are synthesized via imine condensations between two square and trigonal building units.COFs were used as photocatalysts in the visible-light-driven cross dehydrogenation coupling(CDC)reactions and exhibited good photocatalytic activity.In addition,they were applied in asymmetric ?-alkylation of aldehydes integrating with the chiral organic catalyst under visible light irradiation.The targeted products are produced in satisfactory yields with up to 94% enantiomeric excess.In Chapter 3,based on the principle of reticular chemistry,two tbo-COFs isostructural to the HKUST-1 were firstly synthesized by using square and triangle building units.The resulting COFs both crystallize in the cubic Pm3? space group and adopt a non-interpenetrated open framework.The COFs can be efficient heterogeneous photocatalysts for the hydroxylation of arylboronic acids and the defluoroalkylation of1,3-bis(trifluoromethyl)-benzene,which achieved well results with the yields of 99%and 85%,respectively and exhibited good photocatalytic performance.In Chapter 4,a series of chiral diene monomers were synthesized and reacted with porphyrin derivatives to obtain chiral COFs via imine condensations.The structure of COFs was preliminarily simulated,and the performance of chiral COFs was explored in asymmetric catalysis.In Chapter 5,a briefly conclusion and outlook were given.