Synthesis,Characterization And Heterogeneous Catalytic Performance Of Salen-porphyrin-based Conjugated Microporous Polymers

In recent years,with the rapid development of the global population and economy,the resulting environmental pollution and resource depletion have been highly concerned.To develop effective ways to solve this problem,scientists'research interests have been focused on sustainable development and green chemistry.From the polymer materials point of view,the development of heterogeneous catalytic systems for use in environmentally friend media such as water and/or its co-solvents is one of the most effective strategies.Compared with the heterogeneous catalyst,the homogeneous catalyst has the advantages of excellent activity,high selectivity and uniform active site in the catalytic reaction.However,the heterogeneous catalysts are difficult to be separated from the reaction system,and cannot be easily scaled up for industrial applications with the low recycling efficiency.Furthermore,their potential toxicity could pollute the products and the environment.Therefore,it is important to design and synthesize heterogeneous catalysts with high catalytic activity and environmental friendliness.Conjugated microporous polymer materials have been attractive in heterogeneous catalysis due to their high surface area,permanent porosity and adjustable structure.In the third chapter of this thesis,we prepare a Salen-porphyrin-based conjugated microporous polymer?SP-CMP?by aldehyde-pyrrole polycondensation and characterized it in detail.SP-CMP has a specific surface area of 482 m² g^–1 with the pore size of 0.5?0.8 and 1.1 nm,which is a microporous material.Since the skeleton structure of SP-CMP is composed of Salen and porphyrin units having metal chelating sites,the material could be used as a good carrier for palladium nanoparticles.Therefore,we further loaded uniformly dispersed palladium nanoparticlesonthemicroporousstructureofSP-CMP.Palladium nanoparticle-loaded SP-CMP?Pd@SP-CMP?was used to catalyze the Suzuki–Miyaura and Heck–Mizoroki coupling reactions in water.The catalytic results showed excellent catalytic activity,wide substrate suitability and good recyclability.As a heterogeneous catalyst,this material demonstrates the enormous potential of organic porous materials in the field of heterogeneous catalysis.In the fourth chapter of this thesis,we synthesized a Salen-porphyrin based conjugated microporous polymer?CMP-Zn?by acid-catalyzed condensation polymerization of dialdehyde derivative of Salen-Zn and pyrrole,and further characterized it with spectra technologies.The material has high thermal and chemical stability,a large specific surface area and a rich microporous channel.CMP-Zn also showed a higher adsorption capacity of carbon dioxide(77.2 mg g^–1 at 273 K 1 bar)and an adsorption heat of 13.65 kJ mol^–1.In addition,CMP-Zn was applied to catalyze the chemical fixation of CO₂ in cycloaddition reactions with various epoxides and Knoevenagel condensation reaction between aromatic aldehyde and malononitrile.The material has demonstrated excellent catalytic activity and wide substrate suitability.Moreover,catalytic cycling experiments have also shown that the material also has good recycling properties and maintains good catalytic activity after eight cycles.