Chiral Metal-organic Cages And Porous Organic Polymer Materials Used As Stationary Phases For Chromatography

Porous materials are a class of functional materials with large porosity,specific surface area,and adjustable pore size.Porous materials have attracted widespread attention due to their characteristics,which have been widely used in catalysis,sensing,molecular recognition and separation,etc.In recent years,people are particularly interested in the research of metal-organic frameworks(MOFs)and covalent organic frameworks(COFs).In addition,there are also many reports on porous organic polymers(POPs)and metal-organic cages(MOCs).POPs are a kind of organic porous materials composed of light elements.They possess low skeleton density and large specific surface area.MOCs are discrete supramolecular materials formed by the coordination self-assembly of metal central ions and organic building blocks.The MOCs'topology and internal cavity can be regulated by changing their metal centers or organic ligands.Therefore,it can be designed and prepared into various composite materials.In this paper,one chiral POP material and two chiral MOC materials were synthesized and used as chromatographic stationary phases to prepare chiral columns.Their chiral separation performance for racemic compounds was mainly studied.The details are as follows:(1)Firstly,the basic concept of chirality,the significance and methods of chiral separation were introduced.Secondly,the types of chiral stationary phases(CSPs)in high-performance liquid chromatography(HPLC)and gas chromatography(GC)were introduced.In addition,the synthetic methods and related applications of POPs and MOCs materials were described.(2)A chiral porous organic polymer(COP-1)was synthesized using Boc-3-(4-biphenylyl)-L-alanine as the chiral building block and used as CSP for HPLC.The chiral compounds and positional isomers were separated under normal-phase liquid chromatography(NPLC)and reversed-phase liquid chromatography(RPLC).The results demonstrated that the COP-1 packed chiral column showed excellent chiral recognition ability for a variety of chiral compounds such as alcohols,amines,aldehydes,ketones,esters and organic acids.The chiral resolution ability has certain complementarity for this chromatographic column under NPLC and RPLC,which can effectively expand its application range.(3)A chiral MOC UMOP-1-1S-(+)-Cam was synthesized by post-modification of achiral MOC.Then,a novel composite material UMOP-1-1S-(+)-Cam@Si O₂was prepared by bonding chiral MOC UMOP-1-1S-(+)-Cam on the carboxyl-functionalized silica gel.The separation performance of the prepared composite material as CSP for HPLC was investigated.There are twenty racemates and four positional isomers were successfully separated on UMOP-1-1S-(+)-Cam@Si O₂ packed column,which indicating that the chromatographic column has good separation selectivity.(4)A chiral metal-organic tetrahedral cage[Fe₄L₆](Cl O₄)₈ was synthesized by the subcomponent self-assembly strategy,which was mixed with polysiloxane(OV-1701)as stationary phase for preparing a GC capillary column via a static coating method.Eighteen racemates were resolved on the chiral column,indicating that the chiral MOC[Fe₄L₆](Cl O₄)₈has excellent chiral resolution capability.In addition,four positional isomers were well separated on this column.