Synthesis And Performance Of Several Examples Of Imine-Bonded C Ovalent Organic Frameworks Based On Azines

Covalent Organic Frameworks(COFs)are a kind of crystalline ordered porous polymers formed by thermodynamically controlled reversible polymerization reaction to result in linkages,which connect organic small molecules with a certain symmetry.Due to the characteristics of uniform pores,low density,high crystallinity,good stability,pre-design and modifiability,etc.,COFs have broad application prospects in gas storage and separation,catalysis,photoelectricity,fluorescence detection and biomedicine.However,COFs will still face some challenges for a long time in the future,such as the development of new linkages,the synthesis of multienvironmentally stable COFs,and the mass production of COFs.Based on the theoretical guidance of dynamic covalent chemistry,phenothiazine and pyrazine were introduced into COFs monomers for the first time and successfully used to synthesize new COFs.In Chapter two,three 2-connected,three 3-connected and two 4-connected linkers were synthesized and used to construct six new 2D COF materials.COF-H1 and COFH2 came from the condensation reaction of the substrate 10-(4-aminophenyl)-3,7phenothiazine diamine together with 1,3,5-tris(3-hydroxy-4-formylphenyl)benzene and 1,3,5-tris(4-formylphenyl)benzene,respectively.COF-H3 grew out of the condensation reaction of 2,3,5,6-tetra(4-formylphenyl)pyrazine and pphenylenediamine.COF-H4 and COF-H5 were obtained based on the condensation reaction of 2,3,5,6-tetrakis(4-aminophenyl)pyrazine with 2,3dihydroxyterephthalaldehyde and 2,5-dihydroxyterephthal aldehyde,respectively.COF-H6 was prepared by the reaction of 1,3,5-tris(3-hydroxy-4-formylphenyl)benzene and 1,3,5-benzenetricarboxylic acid hydrazide.The results of Material Studio software simulation and PXRD analysis show that the obtained COFs are all 2D porous materials with AA stacking structure.Characterization methods such as PXRD,FT-IR,N2 adsorption-desorption,TGA and SEM were also used to characterize and analyze their structure,thermal stability,pore characteristics and morphology.Multi-environmental stability experiments show that COF-H4 and COF-H5 have a wide range of pH tolerance.In Chapter three,the application of synthesized COF materials in the fields of CO2 adsorption and dye adsorption was explored.The CO2 adsorption isotherms of COFH1,COF-H2,COF-H3 and COF-H6 show that they respectively have the good effect of CO2 adsorption with moderate adsorption heat at 273 and 298 K.In particular,the CO2 adsorption capacity for COF-H3 reaches 43.82 cm3 g-1 at 273 K.Dye adsorption experiments exhibit that COF-H4 and COF-H5 have good adsorption effects on rhodamine B,methylene blue,Congo red and gentian violet.Especially for Congo Red,the adsorption equilibrium can be reached within 5 minutes with the adsorption capacity of 485 and 361 mg g-1,respectively.The dye removal rates of the five-cycle experiments remained basically unchanged,indicating that both COF-H4 and COF-H5 have good recycling and regeneration capabilities.