Synthesis Methods Exploration And Properties Study Of Several Porous Organic Frameworks (POFs) Materials

Materials have been attracting more and more attention these years as thefundamental for human beings’ development and existence. During the improvingresearch of the materials, porous material, featured as large BET, high porosity,low density high permeability, assembility and high adsorption etc., had playedan important role in the potential application of gas adsorption-desorption, cleanenergy storage, carbon capture, sensors, catalysis, supra-capacitors,photo-electric materials and biological carriers. In recent years, the PorousOrganic Frameworks （POFs） with light frameworks, permanent assessable tunnelstructure and high stability has become a researching hotspot. Composed withorganic molecule covalently, the frameworks have a more light density and morestable structure. But when it comes to the gas adsorption, the whole-carbonframeworks of POFs suffer the low adsorption enthalpy because of the lack of sites.On the other hand, the Covalent Organic Frameworks （COFs） constructed withpolyborates suffer low chemical stability. In that case, the introduction of theheteroatom into POFs for a more stable framework structure has become a new spot.Additionally, development of constructing the POFs, design of the synthesis towardnovel POFs are the main aim of this research. At the same time, improving synthesismethod, shorten the reaction duration, improving the productivity and lowering the cost should be urgent.（1） Combining traditional molecular sieve structural construct unit, a newsynthesis method was described in this article. That is, to construct novel polyphenylene ether-type POFs—JUC-Z6featuring high stability and large BET usingpoly-node organic unit via Cu catalyzing Ullmann type cross-coupling reaction.The structure was characterized by EA, IR and sNMR. Powder X-ray diffractionpatterns simulated spontaneously based on a structure model of dia-c5topologyis going well with the experiment result, one can conclude that the material ishighly ordered. TGA showed good thermal stability of JUC-Z6. N2adsorption showeda BET of191m2g^-1and a Langmiur BET of242m2g^-1. And the pore size distributionshowed a1.36nm which coincided with the experimental result （1.48nm）. The lowpressure adsorption showed that JUC-Z6had good adsorption toward H2, CO2and CH4,which is31.23cm3g^-1for H2at77K,1bar,5.08cm3g^-1for methane at273K,1bar,20.48cm3g^-1for CO2at273K and1bar. Correspondingly, the Qst toward H2, CH4,CO2were4.3kJ mol^-1,4.1kJ mol^-1and33.7kJ mol^-1, respectively.（2） Aside from the main trend of POFs structural design, we combinedtraditional cross-coupling structure with, for the first time, the long chain linerpolymer-poly（4-bromo-styrene） and triple node organic unit--tris （4-bromophenyl） amine. We successfully synthesized light, covalently connectedporous organic framework JUC-Z7via Yamamoto type Ullmann cross-coupling reaction.The structure was characterized with IR, pXRD, SEM, TEM. The N2adsorption showedthe BET decreased with the increase of PBS ratio. The Pore size distribution showeda bigger pore size than JUC-Z2, plus, JUC-Z7-80gave the mesopores at3.97nm.Low pressure adsorption showed that JUC-Z7have good adsorption toward CO2and CH4.With the increase of PBS ratio of the raw reactant, JUC-Z7showed a decreaseadsorption ability toward H2, CO2and CH4. The Qst didn’t show much difference forCH4while a decrease for CO2.（3） For the first time, we introduce microwave into POFs synthesis. By tuning microwave heating duration, we produced PAF^-1-MW and JUC-Z4-MW materials.The structure was characterized by IR, pXRD, SEM TEM. N2adsorption showed anincrease of BET with a longer microwave treatment. However, after30minutes, therewas no obvious increase in BET. Pore size distribution showed a pore size of1.27nm for PAF^-1-MW while1.41nm for JUC-Z4-MW with0.7nm supermicro pores. We alsoperformed low pressure adsorption toward the optimum30minutes samples. The resultshowed that both PAF^-1-MW30and JUC-Z4-MW30have good adsorption toward H₂, CO₂and CH4, while JUC-Z4-MW30have higher Qst toward CO₂and CH₄.In summary, the design and synthesis of novel porous organic frameworks willboost the development and application of porous organic frameworks, which willshed light on the clean energy storage, carbon capture and photoelectronicmaterials based on the light porous organic frameworks materials.