Porous Polymer Host-guest Interaction And Chiral Induction

Over the past few decades, the field of porous polymers finding applications as novel functional materials has developed rapidly. Porous polymers have been widely used in storage, adsorption, separation and so on. Owing to immense industrial development and scientific progress, porous polymers find practical applications in environmental protection, thereby creating far-flung attention among more and more chemists.PAFs with high specific surface area, high stability and uniform pore size, is one of the rapidly developing materials in recent times. By modifying the surface of PAFs, the application scope becomes wider and more specific. MOFs is also one of the rapidly developing porous materials in recent years. The most important features of MOFs have ordered structure, high surface area and high stability.As a new functional material, MOFs has attracted considerable attention in the academic field. The advantages of MOFs is that rich topological structure, large specific surface, and can be designed, cut, easily modified(post-modification) and so on. It has broad application prospects in the field of luminescence, catalysis, sensor and so on.Porous polymers exhibit permanent porosity and the host-guest chemistry occurs in the pores of these materials. The host and guest interaction helps to form a number of small molecules or clusters in the pore of large molecular skeleton. Porous materials are often used as the host material, such as zeolite, porous carbon, mesoporous silica, MOFs, porous polymer and so on.The host-guest chemistry is often associated with molecular recognition. Under certain conditions through the intermolecular forces, molecular recognition is actually combined with each other to achieve synergies. With the vigorous development of the host-guest chemistry, the applications of molecular recognition in synthetic chemistry, life science, materials science and environmental science are having a great impact upon the development of mankind.PAFs(JUC-Z2, JUC-Z2-SO3H) and MOFs(JUC-32) are the research topics of this paper. We introduce the typical porous polymers and host-guest chemistry in the first chapter of our paper. The second chapter of this paper depicts the modification of JUC-Z2 and their applications in the field of adsorption, molecular recognition. The third chapter of the paper discusses the chiral induction of MOFs with chiral axes. Lastly, we discuss the host-guest interaction between chiral induced crystal(Ψ-JUC-32 å'Œ Φ-JUC-32)and organic molecule in the fourth chapter.In the first chapter, we introduced some typical porous materials. Such as HCPs, PAFs, MOFs ect. The nature of the interaction between host and guest and the supramolecular polymer formed by the interaction of the host and guest are also introduced.In the second chapter, we discuss the post-modification of JUC-Z2 and its application in the adsorption of nitrogen compounds. JUC-Z2 is a porous organic polymer material containing nitrogen atoms. The nitrogen atoms increase the charge density in the polymer backbone and have the interaction with guest molecules. The JUC-Z2 is used as the initial material and the sulfonic acid group is introduced into the backbone of the polymer to adjust the lewis acid base site of the polymer. The thermal stability of the sulfonated polymer JUC-Z2-SO3 H was maintained very well whereas the surface area and pore volume decreased. The sulfonic acid group introduced in the framework increases the interaction between the polymer and the nitrogen organic compounds. The experimental results show that the interaction between these two organic frameworks and organic amine molecules is restricted by the interaction of solvent, acid and alkali. Specifically, firstly in different solvent systems, there is a difference in the adsorption capacity of the polymer to the guest molecules. The stronger the polarity of the solvent, the weaker is the binding ability between the polymer and the guest molecule. This reflects the constraints of the solvent polarity of the host guest chemistry. Secondly, in the solvent system, the adsorption behavior of JUC-Z2 and JUC-Z2-SO3 H on the guest molecules is similar; however there is a big difference in the adsorption capacities of JUC-Z2 and JUC-Z2-SO3 H. The sulfonated polymer JUC-Z2-SO3 H with guest molecula binding ability was stronger than JUC-Z2. It is showed that the Lewis acid base sites of the polymer backbone will affect the interaction between host and guest. Moreover, nitrogen-containing organic molecules have a different alkaline value. The adsorption capacity of polymers on nitrogen molecules is related to the basicity of molecules, only the molecules with the basicity with a certain threshold can interact with polymers. Lastly, adsorption capacity of nitrogen-containing organic small molecules related to the diameter, the smaller the molecular diameter, the stronger the adsorption capacity. This reflects the size effect selective adsorption.In the third chapter, the chiral induction of JUC-32 is introduced. JUC-32 is a MOF with chiral axis. The crystals are usually prepared in the presence of a form of racemic compounds, that is half of crystal is in the form of P4122 and the other half in the form of P4322. The whole crystals does not show chiral bias. By introducing chiral dopants in the process of synthesis, we get the chiral excess of the crystal, named as Ψ-JUC-32 and Φ-JUC-32. The chiral induced crystals in the thermal characterization, the surface area and the macroscopic structure of the crystal are identical with JUC-32. The results of statistical data obtained from the X- ray single crystal diffraction shows that the induced crystals are chiral excess. In this chapter, we find a method to prepare chiral excess metal organic frameworks.The fourth chapter describes chiral excess metal organic frameworks(Ψ-JUC-32 and Φ-JUC-32) of the host-guest interaction with chiral organic small molecula. The experimental results show that the interaction between the chiral metal organic framework and the chiral small molecules is restricted by the solvent polarity, molecular configuration, size and molecular species. Specific as follows:(1) With different values of polarity for different solvents, the interaction of host and guest is different. Greater the polarity of solvent, the weaker is the host-guest interaction;(2) There is a recognition effect in the adsorption of chiral organic molecules by Ψ-JUC-32 and Φ-JUC-32 as host materials. Ψ-JUC-32 crystal easily adsorbs S configuration of the chiral molecules whereas Φ-JUC-32 easily adsorbs R configuration;(3) Molecular size effect studies the relationship between molecular size and polymer pore size(0.6 nm). The experimental results show that the diameter of the guest molecule is more closely related to the size of the polymer. The stronger the interaction, the larger molecular or smaller molecular are not conducive to the interaction between the host and the guest, Φ-JUC-32 as the host material,(R)-(-)-2-amino-1-butanol as guest molecula(0.6 nm), the binding constant is 9.3 M-1; while(R)-(-)- 2- amino-3-methyl-1-butanol(0.7 nm) and(R)-(-)- 1- amino-2-propanol(0.54 nm) as guest molecula, the binding constant is 4.2 and 6.9 M-1, respectively;(4) Chiral excess Ψ-JUC-32 and Φ-JUC-32 crystals ability to identify different types of chiral organic molecules are different. In carbon tetrachloride solution, Ψ-JUC-32 and Φ-JUC-32 as host material,(R)-(-)- 2- amino-3-methyl-1-butanol as guest molecula, the binding constant is 2.0 and 4.2 M-1, having the ability to identify; while(R)-(-)-2- methyl-2,4-pentanediol as guest molecula, Ψ-JUC-32 and Φ-JUC-32 as host material, the binding constant is 1.6 and 1.5 M-1 respectively, having not the ability to identify.In summary, we have chosen the two kinds of porous materials as the research subject, explores the nature and intensity of the interaction between the host material and the guest molecules, by titration method to determine bonding strength and judge the host-guest interaction. At present, we explore some preliminary results are obtained, we can also study other porous materials in future.