| Porous materials are defined as substances that contain accessible voids and possess some unusual properties, such as diverse compositions and structures, high surface areas, tunable pore diameters and so on. Porous materials have attracted considerable research interest owing to their potential applications in gas adsorption and storage, molecular separation, catalysis, etc. In particular, the research in this area has been dominated by metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and porous organic polymers (POPs) in recent years. Chiral nematic mesoporous silica (CNMS) is a novel inorganic mesoporous material, which is synthesized by using nanocrystalline cellulose (NCC) as template through evaporation-induced self-assembly of tetramethoxysilane (TMOS). Not only chiral nematic organization of NCC suspensions is replicated in CNMS, but also chiral nanoporous structures generated by cellulose at multiple levels are imprinted. Porous organic cages (POCs), represent as a novel porous organic molecular materials, are packed by discrete molecules with shape-persistent and permanent cavities. With the development of dynamic covalent chemistry (DCC), many organic molecular cages have been synthesized in one step by the formation of reversible covalent bonds. At present, most mesoporous materials have been used as support materials for the preparation of chiral stationary phases (CSPs) through coating or chemical bonding chiral selector. To the best of our knowledge, chiral inorganic mesoporous materials and chiral porous organic cages were directly used as chromatographic CSPs have not been reported so far. In order to explore novel CSPs with high separation efficiency and selectivity and expand the application of chiral porous materials in the field of chromatographic chiral separation, CNMS and chiral POCs were directly used as CSPs for high-resolution gas chromatographic (GC) and high-performance liquid chromatographic (HPLC) enantioseparations in this dissertation. The main contents are summarized as follows:In the preface section, the basic concepts of chirality, the significance of chiral resolution and the main methods of chiral resolution were presented. The chiral stationary phases of GC and HPLC were introduced. The syntheses and some applications of mesoporous materials and POCs were reviewed. Finally, we pointed out purpose and significance of the dissertation.CNMS has attracted widespread attention due to its nematic structure, chirality, large pore size, high temperature resistance, low cost, and ease of preparation. CNMS for high-resolution GC separations was investigated in part two. We prepared CNMS capillary column by a dynamic coating method. The experimental results showed that the column not only gives good selectivity for the separation of linear alkanes, aromatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and isomers, but also offers excellent enantioselectivity for chiral compounds. Compared enantioseparations to commercial β-DEX 120 and Chirasil-L-Val columns, the CNMS coated capillary column exhibits chiral recognition complementarity, short elution times, and resisting high-temperature application in GC. This work indicates that CNMS could soon become very attractive for separations.CNMS was also used as stationary phase for HPLC separation of positional isomers in part three. The high resolution of aminophenol, dihydroxybenzene, nitroaniline, nitrophenol, chloroaniline, bromoaniline, iodoaniline, dinitrobenzene, nitrochlorobenzene and nitrobromobenzene were performed by CNMS column, respectively. The effects of mobile phase composition, injected analyte mass and column temperature were investigated. The relative standard deviations (RSDs) for five replicate separations of positional isomers were 0.10-0.43% for retention time and 0.5-3.9% for peak area. The CNMS column has better selectivity than that of commercial β-cyclodextrin HPLC columns. In addition, the column also exhibited recognition ability toward racemates.Porous organic molecular cages as a new type of porous materials have attracted a tremendous attention for their potential applications in recent years. A homochiral POC CC3-R with interconnected 3D diamondoid chiral pore channel networks was synthesized and used as stationary phase for high-resolution GC in the fourth section. The column was prepared by a static coating method diluting CC3-R with a polysiloxane OV-1701 in dichloromethane. A large number of optical isomers have been resolved without derivatization, including chiral alcohols, diols, amines, alcohol amines, esters, ketones, ethers, halohydrocarbons, organic acids, amino acid methyl esters, and sulfoxides. Compared with the widely used commercial β-DEX 120 and Chirasil-L-Val columns, the CC3-R coated capillary column offered more preeminent enantioselectivity. In addition, CC3-R also exhibited good selectivity for the separation of isomers, linear alkanes, alcohols, and aromatic hydrocarbons. The excellent resolution ability, repeatability, and thermal stability make CC3-R a promising candidate as a novel stationary phase and first prove useful commercially for GC. It opens a new gateway for the application of porous organic molecules in the field of separation science.We explored an imine-linked POC CC10 diluted with a polysiloxane OV-1701 as a novel stationary phase for high-resolution GC in section five. A wide variety of enantiomers including chiral alcohols, esters, ketones, ethers, halohydrocarbons, epoxides and organic acids have been resolved on the coated capillary column. The fabricated column complements to commercial β-DEX 120 column and our recently reported CC3-R column, which indicates that the excellent chiral recognition ability of CC10 is interesting academically and practical application. CC10 can also be used to separate n-alkanes, n-alcohols, Grob mixture, and positional isomers with good selectivity.CC5, a homochiral POC with large internal cavity, was also used as stationary phase for preparing capillary GC column in chapter six. The column not only shows excellent selectivity for the separation of positional isomers, but also offers good chiral resolution ability for amino acid derivatives, alcohols, amines, esters, ethers, ketones, epoxy compounds, etc. It holds good chiral recognition complementarity of CC3-R coated column. Therefore, CC5 as a GC stationary phase has potential practical application.In the seventh section, the main researches and results of this dissertation were summarized, and the application of porous materials in the field of separation was prospected. |
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