Catalytic Properties Of Chiral COFs Synthesized Based On Asymmetric Catalytic Strategy

Covalent organic frameworks(COFs)are a type of crystalline polymer porous material that offer advantages such as low density,high specific surface area,and easy modification and functionalization.They have been extensively studied and have promising applications in various fields,including gas storage and separation,photovoltaics,energy storage,sensing,and catalysis.COFs exhibit excellent properties and have garnered the attention of numerous chemists.However,there has been limited research on chiral covalent organic frameworks(CCOFs),particularly in their synthesis and catalysis.Therefore,this thesis aims to develop a catalytic asymmetric polymerisation strategy for the synthesis of CCOFs.The CCOFs obtained using this method will be used for chiral catalysis,which will be divided into three parts:1.Direct synthesis,post-synthesis modification,and chiral induction are considered three effective methods for synthesizing CCOFs.However,catalytic asymmetric polymerization,the most important and effective synthetic method for obtaining chiral organics,has not yet been used for the synthesis of CCOFs.Chiral propargylamine-conjugated(S)-DTP-COF were successfully synthesized using chiral catalysts through catalytic asymmetric polymerization at room temperature.This marks the first time that CCOFs have been constructed from achiral monomers using the catalytic asymmetric polymerization strategy,thus enriching and developing a new synthetic method for CCOFs.The chiral propargylamine-conjugated(S)-DTP-COF obtained can serve as a highly active and reusable catalyst for promoting the asymmetric Michael addition reaction.2.Based on the strategy of catalytic asymmetric polymerisation,the photosensitive porphyrin CCOFs-(R)-DTP-COF-QA,containing phase-transfer functional groups,has been synthesised by functionalising organic monomers at room temperature.The first application of CCOFs in asymmetric photocatalysis has been achieved using(R)-DTP-COF-QA as a catalyst.The metal-free(R)-DTP-COF-QA demonstrated exceptional catalytic activity and enantioselectivity in the enantioselective photo-oxidation of sulfide to sulfoxide in air and water under visible light irradiation.Notably,(R)-DTP-COF-QA performed well in the synthesis of the antidrowsiness drug(R)-modafinil,yielding 90%with an ee value of 88%under optimized reaction conditions.3.The synthesis of chiral cyclic carbonates by reacting carbon dioxide with epoxides has become an attractive method for carbon dioxide management.However,reported catalysts suffer from harsh reaction conditions and the need for additional loading of metals or co-catalysts.The imidazolium salt-functionalized CCOFs-(R)-DTP-COF-IM was synthesized using the previous asymmetric polymerization method for the synthesis of CCOFs.An asymmetric A~3-coupling polymerization reaction was carried out at room temperature.The resulting metal-free(R)-DTP-COF-IM-catalyzed asymmetric carbon dioxide cycloaddition reaction exhibited some catalytic activity and enantioselectivity.This method provides guidance for designing CCOFs and future research,and offers an alternative approach for converting CO2 into other value-added products.In this thesis,three types of CCOFs were successfully synthesized using an asymmetric synthesis strategy.The CCOFs were then investigated for their applications in chiral catalysis.This work provides a new strategy for the rational design and synthesis of multifunctional CCOF materials,while also expanding the scope of catalytic applications for CCOFs.