The chiral covalent-organic framework (CCOF) is a new kind of chiral porous material, which has been broadly applied in many fields owing to its high porosity, regular pores, and structural adjustability. However, conventional CCOF particles have the characteristics of irregular morphology and inhomogeneous particle size distribution, which lead to difficulties in fabricating chromatographic columns and high column backpressure when the pure CCOFs particles are directly used as the HPLC stationary phases. Herein, we used an in situ growth strategy to prepare core–shell composite by immobilizing MDI-β-CD-modified COF on the surface of SiO₂-NH₂. The synthesized MDI-β-CD-modified COF@SiO₂ was utilized as a novel chiral stationary phase (CSP) to explore its enantiomeric-separation performance in HPLC. The separation of racemates and positional isomers on MDI-β-CD-modified COF@SiO₂-packed column (column A) utilizing n-hexane/isopropanol as the mobile phase was investigated. The results demonstrated that column A displayed remarkable separation ability for racemic compounds and positional isomers with good reproducibility and stability. By comparing the MDI-β-CD-modified COF@SiO₂-packed column (column A) with commercial Chiralpak AD-H column and the previously reported β-CD-COF@SiO₂-packed column (column B), the chiral recognition ability of column A can be complementary to that of Chiralpak AD-H column and column B. The relative standard deviations (RSDs) of the retention time and peak area for the separation of 1,2-bis(4-fluorophenyl)-2-hydroxyethanone were 0.28% and 0.79%, respectively. Hence, the synthesis of CCOFs@SiO₂ core–shell composites as the CSPs for chromatographic separation has significant research potential and application prospects.

Molecular organic cage compounds have attracted considerable attention due to their potential applications in gas storage, catalysis, chemical sensing, molecular separations, etc. In this study, a homochiral pentyl cage compound was synthesized from a condensation reaction of (S,S)-1,2-pentyl-1,2-diaminoethane and 1,3,5-triformylbenzene. The imine-linked pentyl cage diluted with a polysiloxane (OV-1701) was explored as a novel stationary phase for high-resolution gas chromatographic separation of organic compounds. Some positional isomers were baseline separated on the pentyl cage-coated capillary column. In particular, various types of enantiomers including chiral alcohols, esters, ethers and epoxides can be resolved without derivatization on the pentyl cage-coated capillary column. The reproducibility of the pentyl cage-coated capillary column for separation was investigated using nitrochlorobenzene and styrene oxide as analytes. The results indicate that the column has good stability and separation reproducibility after being repeatedly used. This work demonstrates that molecular organic cage compounds could become a novel class of chiral separation media in the near future.

A strategy was designed for the molecular imprinting of magnetic nanoparticles with boric acid affinity (MNPs@MIP) which were then used for the selective recognition and isolation of glycoproteins. Fe₃O₄ nanoparticles were prepared by a solvothermal method and direct silanization by the condensation polymerization of aminopropyltriethoxysilane (APTES). Subsequently, phenylboric acid was functionalized by reductive amination between 2,3-difluoro-4-formyl phenylboric acid (DFFPBA) and the amido group. The resultant Fe₃O₄@SiO₂–DFFPBA was then used for the selective adsorption of a glycoprotein template. Finally, a molecularly imprinted layer was covered on the surface nanoparticles by the condensation polymerization of tetraethyl orthosilicate (TEOS). The adsorption capacities of the resultant MNPs@MIP–HRP and MNPs@MIP–OVA to horseradish peroxidase (HRP) or ovalbumin (OVA) were significantly higher than non-imprinted particles (MNPs@NIP). Moreover, the adsorption capacities of MNPs@MIP–HRP and MNPs@MIP–OVA on non-template protein and non-glycoprotein bovine serum albumin (BSA) were significantly lower than those of their respective template proteins, thus indicating that both of the prepared MNPs@MIP exhibited excellent selectivity.