Synthesis And Characterization Of Conjugated Organic Framework Polymers Based On 1,3,5-Triazine

Covalent triazine skeletons?CTFs?are a class of conjugated organic framework?COFs?,which are porous polymers synthesized by aromatic nitrile trimerization.The structure contains a large amount of N atoms and could increase the electron transport properties of the polymers and provides active sites for the modification of polymer.In recent years,more attention has focused on its rich functional properties such as porosity and photoelectricity.CTFs have been widely used in heterogeneous catalysis,photocatalysis,gas storage,toxic organic compound adsorption,electrochemical double-layer supercapacitors,lithium batteries,gas sensors and other fields.Herein,we report the successful synthesis of a CTF rich in cyano groups?CTF-CN?by the solvothermal condensation of 2,3,6,7-tetrabromonapthalene,Na₂?1,1-dicyanoethene-2,2-dithiolate?and 1,3,5-tris-?4-aminophenyl?-triazine at 120oC.Monomer preparation:4-aminobenzonitrile as a raw material,trifluoromethanesulfonic acid was used as a strong acid catalyst,and trimeric cyclization to form a monomer 2,4,6-tris?4-aminophenyl?-1,3,5-triazine?TAPT?;1,4,5,8-naphthalenetetracarboxylic dianhydride?NDA?was brominated in concentrated sulfuric acid and fuming sulfuric acid with bromine to obtain naphthalic anhydride 2,3,6,7-tetrabromonaphthalene dianhydride?TBNDA?containing four bromine atoms;Sodium thiocyanate-containing sodium sulphate was prepared from malononitrile,named 1,1-dicyanoethyl-2,2-dithiodisodium?Na₂?i-mnt??.The structure of the above three monomers was confirmed by Fourier transform infrared spectroscopy?FT-IR?.Polymer synthesis:Synthesis of Polymer CTF-CN by Solvothermal Synthesis and Microwave Assisted Synthesis.In a pyrex tube,n-butanol and mesitylene were added as solvent,TBNDA and Na₂?i-mnt?react at 50 ^oC for 1 h,then TAPT was added to seal the reactor at120°C for 5 day.FT-IR,¹H NMR and X-ray photoelectron spectroscopy?XPS?showed that the polymer was successfully synthesized.Scanning electron microscopy?SEM?and transmission electron microscopy?TEM?showed that the polymer was porous and lamellar amorphous structure.Energy spectrometer?EDS?proved the uniform element distribution of the polymer,and the powder X-ray diffractometer?XRD?proved that the polymer was amorphous.Secondly,the microwave-assisted synthesis of polymer was carried out.The polymer was prepared by reacting DMF with solvent at 300 W and 70°C for 30 min.The structure was determined by FT-IR and its layer structure was characterized by TEM.The microwave-assisted synthesis method greatly improves the synthesis efficiency of the polymer,but the yield is low.The visible light catalytic performance of the polymer was initially explored.The polymer was used to catalyze the hydrogen production of visible light.We explored the hydrogen production effects of different content of cocatalyst,different solvents and different polymer states.The results show that in the 5%Pt,the solvent is TEOA:CH₃OH=10:3,and the hydrogen production can reach the maximum value of 2150?mol·g^-11 without the polymer being ground.Under optimal conditions,the polymer can stably produce hydrogen.