The Preparation Of Covalent Organic Frameworks And Its Absorption Properties

Covalent organic frameworks(COFs)represent a new type of crystalline porous materials based on various building blocks into two-or three-dimensional porous crystalline structures connected by strong reversible covalent bonds.They are pre-designable in terms of the molecular building blocks employed.The pore structure of COFs materials can be controlled by the change the geometry of diverse monomers during the synthesis,and the pore size can be tuned by the method of ion exchange,too.COFs materials show promise for various applications in the field of gas adsorption and storage,proton conduction,drug delivery,adsorption of organic analytes,and fluorescent sensors because of their crystalline and periodic structure with high surf-ace area and thermal stability.In this study,a series of[HC?C]x-TPB-DMTP-COFs(DMTA/BPTA at different molar ratios correspond to x=0,0.17,0.5 and 1)were designed and synthesized by combining aldehyde group units 2,5-bis(2-propynyloxy)terephthalaldehyde,2,5-dihydroxy-terephthalaldehyde and 1,3,5-tri-(4-aminophenyl)benzene based on the imidization reaction.Then,[PrNH2]x-TPB-DMTP-COFs was synthesized with 3-azidopylamine via click chemistry.The resultant COFs materials were further characterized by FT-IR,PXRD,TGA,Nitrogen sorption isotherm,and SEM,respectively.Finally,the adsorption properties of COFs were investigated by the adsorption experiments of the Allure red AC,Sunset yellow,Rhodamine B dyes,and trinitrotoluene,respectively.The results indicated that the adsorption amounts of Rhodamine B on[HC?C]0.17-TPB-DMTP-COFs and[PrNH2]0.17-TPB-DMTP-COFs were higher than that of other dyes.Moreover,the chemical modification has a significant effect to the materials'adsorption property.The adsorption amount of[PrNH2]0.17-TPB-DMTP-COFs to Rhodamine B was 70.47mg/g,which was higher than that of[HC?C]0.17-TPB-DMTP-COFs(64.51mg/g).In addition,[PrNH2]0.5-TPB-DMTP-COFs also showed a better binding property to trinitrotoluene than[HC?C]0.5-TPB-DMTP-COFs,the binding amounts were 21.03mg/g and 1.5 mg/g,respectively.It can be seen that the functionalized modification can increase the adsorption amounts of COFs to the Allure red AC,Sunset yellow and Rhodamine B dyes and trinitrotoluene.The resultant materials showed a potential application for the aforementioned targets.