Synthesis And Performance Of Carbazole-based Imine Covalent Organic Frameworks

Covalent Organic Frameworks(COFs)are a class of crystalline porous polymers constructed by the linkers and covalent linkages.For more than ten years,because of their regular and adjustable pore structure,low density and large specific surface area,COFs have received widespread attention in the fields of gas adsorption and separation,drug delivery,catalysis,sensing,energy storage,etc.The types of linkages,multienvironment stability and mass production will limited practical applications of COFs for a long time.Among them,the construction of a new linkage depends on a new reversible reaction together with a new topology.This dissertation will use the special geometric structure of carbazole derivatives to synthesize new C2 symmetric monomers and their COFs with new topological structures,and provide a new way to diversify the topology of COFs.In Chapter 2,first five monomers synthesized and characterized by NMR and FTIR.Then the synthesis conditions of COFs based on synthesized monomers were explored,and five imine COFs were successfully synthesized.COF-P1,COF-P2 and COF-P3 came from the reaction of 9-(4-aminophenyl)-3,6-carbazole diamine as a substrate with 2,5-dimethoxy-1,4-phthalaldehyde,2,5-dihydroxy-1,4-phthalaldehyde and 2,3-dimethoxy-1,4-benzenedialdehyde,respectively.COF-P4 and COF-P5 grew out of the reaction of 1,3,5-benzenetricarboxylic hydrazid as a substrate with 2,5-dimethoxy-1,4-phthalaldehyde and 1,3,5-tris(p-formylphenyl)benzene,respectively.In Chapter 3,on the base of PXRD,FTIR,BET,TGA and the molecular simulation,the obtained COFs all present an AA stacking structure of two-dimensional layers.It is found that COF-P1,COF-P2 and COF-P3 have two-dimensional new topological structures of symbiosis of eight-membered and four-membered rings,and their BET specific surface areas are 777.918,199.921 and 493.718 m2/g,respectively.The results of CO2/N2 separation experiments based on the IAST model show that the separation factors of COF-P1,COF-P2 and COF-P3 are 44.93,41.17 and 44.26,respectively,which can well meet the CO2 separation requirements at 273 K in a gas composition of 15:85(flue gas composition).Calculations show that all three COFs have an adsorption heat suitable for CO2 adsorption and separation,too.In addition,the drug loading testes of these three COFs show that they all have good drug loading,especially COF-P1 has a better drug loading rate of rhodamine isothiocyanate B at 71.71%.The adsorption experiments of selected dyes show that both COF-P4 and COF-P5 have good adsorption capacity for methylene blue among the four dyes,and the adsorption capacity were 110.03 and 92.65 mg/g in 2 h,respectively.