Synthesis And Properties Of Covalent Organic Framework Materials Based On Triazine And Triptycene

Covalent organic frameworks（COFs）are an emerging class of organic materials with periodic structural units connected by covalent bonds.COFs have received extensive attention due to their ordered channel structures,low density,adjustable pores and high chemical and thermal stability.Among them,triazine-based COFs and triptycene-based COFs have become a research hotspot in recent years due to their unique structural advantages of high nitrogen content andπ-πconjugation,as well as their unique optoelectronic properties.Therefore,designing and synthesizing novel covalent organic framework polymers and making full use of their structural advantages to explore the further applications has important research significance.In this paper we designed and synthesized 1,3,5-tris（4-aminophenyl）triazine（TAPT）and2,3,6,7-tetrabromonaphthalic anhydride（TBNDA）two monomers,and then synthesized triazine-based COF（TATB）and triptycene-based COF（tatp-NDA）,and their properties have been studied.The main research contents are as follows:（1）TAPT was synthesized by the cyclization of 4-aminobenzonitrile using trifluoromethanesulfonic acid as a catalyst.The reaction was stirred at 0℃ for 24 h under an inert N₂ atmosphere and then the molecular structure of TAPT was confirmed by FT-IR and¹H NMR.Naphthalic anhydride（NDA）and 1,3-dibromo-5,5-dimethylhydantoin was selected as raw materials.In a mixed solvent of concentrated sulfuric acid and trifluoroacetic acid,the H atom at the end of the NDA was replaced by bromine group.After,TBNDA was synthesized and its molecular structure was determined by FT-IR.（2）The solvothermal method was used to synthesize TATB and tatp-NDA.Using TAPT and TBNDA as monomers,TATB was synthesized in a mixed solvent of mesitylene and n-butanol.The molecular structure of TATB was determined by FT-IR,¹³C NMR and XPS.SEM indicated that TATB was in the form of microspheres with rough surfaces and diameters of 0.5-2μm.TGA test demonstrated that the decomposition temperature of TATB was higher than 600℃.Using 2,6,14-triamino triptycene（tatp）and NDA as monomers and propionic acid was injected as a catalyst at 170℃,tatp-NDA was synthesized in DMF solution.The molecular structure was confirmed by FT-IR and ¹³C NMR.SEM and TEM revealed that tatp-NDA was composed of microspheres about 1μm,and the surface was rough.The specific surface area and porosity tests showed that tatp-NDA was dominated by microporous structure with a little mesoporous structure.The electronic structure of tatp-NDA was investigated by UV-Vis DRS measurements.The analysis revealed that tatp-NDA had a direct band gap of 1.74 eV,indicating its semiconductor nature.（3）TATB/GCE was used for the detection of 1-naphthol in water samples.EIS and CC tests show that TATB/GCE had an increased electron transfer rate and an increased active area.The CV test results revealed that TATB/GCE showed an enhanced electrochemical response signal of 1-naphthol,and the detection limit was 5.0 n M.In view of the rough microporous structure of tatp-NDA,rhodamine B was selected as the target pollutant,and the adsorption and photocatalytic degradation properties of tatp-NDA were explored.The test results of UV-Vis spectroscopy indicated that tatp-NDA had a good adsorption and photocatalytic degradation performance.The quenching free radical method explored the photocatalytic degradation mechanism and proved that^·O₂^-played a major role in the degradation process.HRMS identified the degradation intermediates and proved that the degradation process was N-deethyl.