Synthesis, Characterization And Photocatalytic Performance Of Hydrazone- And Imine-based Covalent Organic Frameworks

With the development of porous materials,Covalent Organic Frameworks（COFs）as a new type of porous polymer materials have received widespread attention from researchers.Since the COF materials was first reported by Yaghi’s group in 2005,numerous researchers have conducted in-depth research on it.Up to now,COF materials have been widely used in the fields of gas adsorption and separation,catalysis,sensing,and photoelectric application.This paper mainly studies the application of COF materials in the field of photocatalysis.The COF materials have the characteristics of regular crystal structure,high specific surface area,fixed porosity,excellent stability,good light absorption and electrical conductivity.We think that COF materials can be used as an excellent heterogeneous photocatalyst.Today,COF materials are not widely used in photocatalysis,especially in organic synthesis.The main research of this paper is divided into the following two contents:In the third chapter of the paper,we successfully synthesized a series of two-dimensional multi-component covalent organic framework materials（[HC≡C]x-TFB-COFs）by using different molar ratios of 2,5-bis（prop-2-ynyloxy）-terephthaloyl hydrazide（BPTH）,2,5-dimethoxyterephthaloyl hydrazide（DMTH）and 1,3,5-triformylbenzene（TFB）as building units.The characterization analysis was performed,and the results showed that the[HC≡C]10-TFB-COF has the best photoelectric performance,the material also exhibits high thermal and chemical stability,The comparative experiments were carried out,and the results showed high catalytic performance of[HC≡C]10-TFB-COF in both the catalytic cross-dehydrogenation coupling reaction and the arylboronic acid oxidative hydroxylation reaction.The material also showed a wide range of substrate suitability and reusability.The obtained results demonstrated the great potential of COF materials as a heterogeneous catalystin the field of photocatalysis.In the fourth chapter of this paper,a novel two-dimensional covalent organic framework material（TMFPT-COF）with imine linkage was synthesized by using1,3,5-tris-（3-methoxy-4-formylphenyl）-2,4,6-triazine and hydrazine hydrate as building units,and its characterization and performance studies were further performed.It was found that the specific surface area of the TMFPT-COF was as high as 1407 m²g^-1.Under the conditions of 273 K and 1 bar,the material showed a high adsorption capacity for CO₂ with a value of 38.2 cm³g^-1.In view of the material’s large specific surface area,good stability,and excellent photoelectric performance,the TMFPT-COF was empolyed as a photocatalyst to catalyze the 2-arylphenyl isocyanide cyclization reaction.As a result,the material showed high catalytic performance with moderate catalytic activity and broad substrate applicability.After five times of recycling,it still maintained a stable structure and good catalytic activity.