Synthesis And Properties Of Stable Three-Dimensional Quinoline Covalent Organic Frameworks

Covalent organic frameworks（COFs）are periodic polymers formed by covalently linking organic building blocks based on topological design principles.COFs materials have good crystallinity and porosity.The stable covalent bonds in COFs are composed of a series of light elements,which give them good thermal stability and low density.Based on the dimension of the building unit,we can classify COFs into two-dimensional（2D）or three-dimensional（3D）COFs.In 2D COFs,the framework material is formed by layered stacking between 2D flakes.In 3D COFs,the framework structure can be extended to three-dimensional forms because the building units contain sp3-hybridized carbon atoms or silicon atoms.Based on the above characteristics,3D COFs have shown excellent application potential in gas storage,photocatalysis,sensing,and energy storage.This paper mainly explores the construction strategy of 3D COFs.Firstly,tetra（4-aminophenyl）methane（TAPM）was used as the tetrahedral construction unit to react with2,3-dimethoxy-p-benzaldehyde（2,3-DMTPA）and 2,5-dimethoxy-p-benzaldehyde（2,5-DMTAP）respectively.Two new 3D COFs（COF-1 and COF-2）were constructed by one pot method.And a quinoline-linked 3D COF（COF-3）was also directly synthesized by a one-pot method.Second,the imine-linked（COF-1）was converted into a more stable quinoline-linked 3D COF（COF-4）by post-modification.Due to the existence of the quinoline ring,the stability of COF is significantly improved compared with imine linked COF,thus broadening the practical application conditions of 3D COFs.The main research contents of this paper are as follows:In chapter 1,the development of 3D COFs in recent years was briefly describes,introduces the research progress of post-modification method and one-pot method in the construction strategy of COFs,and explains the basis for the topic selection of this paper.In chapter 2,we designed and synthesized two imine-linked 3D COFs（COF-1 and COF-2）by means of a one-pot method using TAPM and two linear aldehyde-based monomers（2,3-DMTPA and 2,5-DMTAP）as building blocks.A quinoline ring-linked 3D COF（COF-3）was directly constructed from a multi-component monomer by a one-pot method,and the structures of the three COFs were characterized,and the stability of COF-3 in different chemical environments were discussed.In chapter 3,we converted COF-1 to COF-4 with quinoline linkages by means of a post-modification method.Meanwhile,the structure and stability of COF-4 were characterized.The results showed that COF-4 had great crystallinity and porosity.Meanwhile,COF-4 showed high chemical stability in different chemical environments.In chapter 4,this paper is briefly summarized,and the possible development direction of COFS materials is prospected...