Research On The Preparation And Properties Of Functional Covalent Organic Frameworks Materials Based On Imine Linkage

Covalent Organic Frameworks?COFs?are a new type of organic crystalline porous materials with great potential for applications such as adsorption separation,gas storage,sensing,energy storage,catalysis,and drug delivery.Schiff-base reaction is one of the most common reaction types for the synthesis of COFs.When the amine and aldehyde react,an imine bond?C=N?-linked Schiff-base COFs are obtained,while the amine and 2,4,6-trihydroxy-1,3,5-benzenetrialdehyde form a rearranged ketone COFs.COFs materials connected by imine bonds have many excellent physical and chemical properties,and are one of the most popular and widely used categories of COFs materials today.This type of COFs material shows extremely high application value in many scientific research fields and daily production and life.Focusing on the synthesis and characterization of imine-linked COFs based on Schiff-base reaction,the following work has been carried out:?1?A new ligand with benzodifuran group was designed and synthesized,and it was self-assembled with triazine ligand unit by solvothermal method to form a two-dimensional imine-based termed as COFs named as COF-BDF-TAPT.Various techniques including powder X-ray diffraction,fourier transform infrared spectroscopy,transmission electron microscopy,UV-visible absorption spectroscopy have been used to test and analyze the COF for the study of their crystallinity,morphology and absorbance.These measurements confirm that the COFs material has excellent crystallinity,uniform morphology,and strange light absorption.In addition,the COFs could have photocatalytic activity and can be used as a good photocatalytic hydrogen production.In the further work,we would apply it to the photocatalytic hydrogen production and gain a deeper understanding of the application of COFs in photocatalytic hydrogen production.?2?A functional COFs with fluorene group was designed and synthesized,which was named as COF-DPF-Tp.For the study of its crystallinity,morphology and stability,a variety of techniques were used to test and analyze the COFs,such as powder X-ray diffraction,fourier transform infrared spectroscopy,scanning electron microscopy,transmission electron microscopy,gas adsorption/desorption,and so on.Those tests proved that the COFs materials have good crystallinity,uniform morphology,and great stability.?3?A new ligand with Azide group was designed and synthesized,and it was self-assembled with 2,4,6-Trihydroxybenzene-1,3,5-tricarbaldehyde by solvothermal method to form a two-dimensional imine-based COFs named as COF-N₃-Tp.There are many methods like powder X-ray diffraction,Fourier transform infrared spectroscopy,scanning electron microscopy,transmission electron microscopy,thermogravimetric analysis,gas adsorption and desorption were used to test and analyze the COFs for the study of their crystallinity,morphology and stability.The excellent properties of the crystallinity,morphology,and stability of the COF material were confirmed by these measurements.In addition,the COFs material has azide group,a good reactive linker,which allows it to be further modified to obtain the new properties and functions we expected.