Core-shell Composites Used In High Performance Liquid Chromatography Separation

Covalent organic frameworks(COFs)and metal-organic frameworks(MOFs)as novel porous materials have been paid much attention in chiral resolution field owing to their favorable properties such as high surface area,multifunctionality and high thermal and chemical stability.However,the synthesized COFs have the disadvantages such as iregular shape,low density,light weight and nonuniform particle sizes,and the synthesized MOFs also have the shortcomings of irregular shape and wide size distribution.These disadvantages limit the application of COFs and MOFs in high performance liquid chromatography.In order to overcome above drawbacks for the application in HPLC,core-shell composites which combined the advantageous characteristics of two materials were designed and synthesized.In this paper,the synthesized core-shell composites were used as stationary phases in HPLC separation.The specific contents are as follows:The first part mainly introduced chirality and chiral resolution.High-performance liquid chromatography and chiral stationary phases were briefly recommended.In addition,the applications of COFs,MOFs and core-shell composites in chromatographic separation were also emphasized.In the second part,?-CD COF was immobilized on the surface of amino-functionalized SiO₂ microspheres by situ-growth strategy to prepare a core-shell microsphere?-CD-COF@SiO₂.The prepared core-shell microsphere was used as HPLC stationary phase to pack chiral?-CD-COF@SiO₂ columns.The chiral resolution ability of chiral?-CD-COF@SiO₂ columns were investigated by a series of chiral compounds.The effect of HPLC conditions on the separation performance and the reproducibility of the column were also discussed.The results showed that the prepared chiral?-CD-COF@SiO₂ column had excellent chiral resolution ability for24 chiral compounds with good reproducibility.A core-shell composite[Cu₂(D-cam)₂(4,4'-bpy)]_n@SiO₂ was prepared by growing of chiral MOF[Cu₂(D-cam)₂(4,4'-bpy)]_n on the surface of amino-functionalized SiO₂ microspheres in the third part.The synthesized core-shell composite was used as chiral stationary phase in HPLC for chiral separation.The results indicated that 13 chiral compounds were separated on the chiral column.In the fourth part,TPA-COF was grown on the surface of the pre-synthesized MOF NH₂-MIL-125 to synthesize a core-shell composite NH₂-MIL-125@TPA-COF with outstanding properties of MOFs and COFs.The prepared core-shell composite NH₂-MIL-125@TPA-COF was used as a novel HPLC stationary phase to prepared a column.The experimental results exhibited that the NH₂-MIL-125@TPA-COF column had good separation ability toward 10 position isomers.