Morphology Control Of Microporous Organic Polymers And Their Catalytic Activity In Pd Catalytic Hydrogenation And Coupling Reactions

Microporous organic polymers(MOPs)which include some competitive characters like large specific surface area,high stability,and easy functionality,are ideal materials for the synthesis of supported palladium-based catalysts.Although recent research on MOPs is mainly focused on the performance control of the material framework structure,morphology and structure are also the key factors that affect catalytic performance.Therefore,synthesizing MOPs with different morphologies and studying its influence mechanism in Pd-catalyzed organic reactions are new ideas for the study of microporous organic polymer materials.In this essay,the aim is to synthesize microporous organic polymers with controllable morphology and explore the utilization of Pd on microporous organic polymers with different morphologies and structures to catalyze simple organic reactions.The specific contents are given as below:1.The porphyrin was self-crosslinked to formed hypercrosslinked microporous organic polymer with irregular morphology by solvent knitting method.A highly dispersed heterogeneous palladium-based catalyst was obtained through coordination of palladium with porphyrin center.This catalyst showed very high activity in the tandem reaction of AB dehydrogenation and R-NO₂ hydrogenation to generate primary amine(R-NH₂)at room temperature.Moreover,it has a high specific surface area,good substrate universality and repeat stability.This research lays the foundation for subsequent research on hypercrosslinked microporous organic polymers with controllable morphology.2.A new hybrid hypercrosslinked polymer was synthesized that constructed PPh₃ on octaphenyl POSS by external cross-linker method and microporous organic polymer with vesicle structure was obtained by HF etching.Based on the strong coordination between triphenylphosphine and palladium metal nanoparticles,a highly dispersed multiphase Palladium-based catalysts can be formed while the size of polymer vesicles can be controlled by changing HF etching time.We explored the effects of catalysts with different vesicle diameters in the Suzuki-Miyaura coupling reaction of chlorobenzene and found that the catalyst with a vesicle diameter of about 100 nm not only had a perfect catalytic activity but also had the ability to recycle 14 times without a significant activity decrease.Thus,it has been demonstrated that the framework and morphology play a major role in the catalysts'excellent performance in Suzuki-Miyaura coupling reaction of aryl chlorides.3.Hollow microporous organic capsules(HMOCs)were obtained by HF etching a microporous organic polymer with a core-shell structure(HCP-Si O₂@PS-DVB).Then the HMOCs load palladium nanoparticles to catalyze the reduction reaction of 4-NP.The microporous shell of the catalyst prevented agglomeration and loss of Pd NPs,and the layered pores connecting the hollow core provided a way for the smooth diffusion of molecules to approach the active site.In addition,the catalyst had an excellent catalytic performance since the yield can reached 99%within 4 minutes,and the catalyst was easy to recycle for using many times.