Design,Synthesis And Application Of Functional Hydrazone-Based Covalent Organic Frameworks

With the excessive exploitation of fossil fuels and the continuous deterioration of the environment,the scientific community has initiated research on sustainable development and green chemistry.Researchers in various disciplines are working hard to find breakthroughs in this discipline.From the perspective of chemistry and materials science,using the unique properties of porous materials and reducing the use of organic solvents has become a well-established solution.The advent of stripped graphene tape in 2004,which caused a great sensation in the world,2D materials are widely studied due to their unique structure.A large number of 2D materials such as black phosphorus,organic metal materials,and transition metal sulfides have been successively developed.With the gradual expansion of the 2D material family,Covalent Organic Frameworks?COFs?stand out with their simple preparation methods,excellent properties and unique covalent structures.Researchers need to consider how to use COFs to solve the current environmental and energy problems.In the third chapter of this paper,we synthesize the a hydrazone-based hydrophilic TFPT-BMTH.Long chains containing ether bonds were introduced to the structure.We proved that the synthesized TFPT-BMTH is completely consistent with the design through various characterization methods.Due to the influence of long chains in the pores,the specific surface area of TFPT-BMTH is not ideal,but still reaches 603 m²/g.Photophysical performance testing shows that TFPT-BMTH has a suitable band gap and has a strong current response under light.We used TFPT-BMTH as a photocatalyst for the oxidative coupling reaction of benzylamine.Conversion rate calculated by ¹H NMR can reach 99%.Controlled variable experiments prove that the conversion of benzylamine is the function of TFPT-BMTH and light.In photocatalysis experiments,4-methoxybenzaldehyde and4-methoxybenzamide were main products in the 4-methoxybenzylamine oxidative coupling,which is completely different from the imine products of other substituted benzylamines.This result was not found in previous research reports.We performed additional controlled trials on this and again proved the same results.We have explored the mechanism of oxidative coupling reaction of benzylamine.In addition,TFPT-BMTH can be reused.The photocatalytic activity of TFPT-BMTH was still kept after five recycles.After multiple reactions,the basic properties of TFPT-BMTH remain unchanged,which shows its excellent stability.TFPT-BMTH as a heterogeneous catalyst shows the great potential of porous polymers in this field.In the fourth chapter of this paper,we synthesized COF-BMTH,a multifunctional COFs material that can be widely used in different fields.COF-BMTH has a variety of functions,not only as a photocatalyst for the photocatalytic oxidation of phenylboronic acid and its derivatives,but also as a metal fluorescence sensor,which can detect Cu²⁺sensitively,quickly,efficiently,and easily from a large number of metal ions.The fluorescence intensity of COM-BMTH quenches in the presence of copper ions.COF-BMTH is also stable,easy to recycle and reusable.As a photocatalyst,after one round of reaction,COF-BMTH is separated,washed and dried,and then it can be used as a new photocatalyst for catalytic reaction again.After five cycles,the photocatalytic activity of COF-BMTH remains unchanged.PXRD,FTIR,SEM,and TEM characterizations confirmed that the COF-BMTH almost maintained the initial crystallinity,structure,and micromorphology after five recycles.After adding EDTA-2Na to the COF-BMTH@Cu²⁺system,COF-BMTH quickly recovered the initial fluorescence intensity.When Cu²⁺was added to the system again,the fluorescence intensity of COF-BMTH quenched again.After five cycles,COF-BMTH has also maintained a high degree of specificity and selectivity for Cu²⁺.Therefore,COF-BMTH is an excellent COFs material with dual functions.