Single-column analysis strategy of star hydroxypropyl cyclodextrin polymer chiral stationary phase to the simultaneous separation of three-pair chiral alkaloid enantiomers

The inherent presence of structurally similar stereoisomers in natural products poses great challenges for chiral quality control in pharmaceutical and botanical industries, particularly in differentiating the pharmacological activity of high-purity enantiomers. Multi-column methods are commonly used to separate multiple pairs of enantiomeric components, serious impact on the separation efficiency. To address this issue, a star hydroxypropyl cyclodextrin polymer (Star-HPCD) mixed-mode ligand with higher selectivity was designed to achieve both chiral recognition and structural selectivity. Sil-Star-HPCD chiral stationary phase (Sil-Star-HPCD CSP) enabled the simultaneous separation of three pairs of quinoline alkaloid stereoisomers during a single chromatographic run with a separation factor (α) greater than 1.5, significantly improving the analytical efficiency. Compared with the linear polymer structures, the supramolecular structure formed by star-shaped polymer significantly reduces the steric hindrance and improves the ligand density, which provides a prerequisite for adequate chiral recognition. Complementary evidence from molecular simulations and chiral NMR revealed multiple interactions at the molecular level for this single-column separation results. This work establishes a new strategy for the preparation of functionalized chiral ligands through structural design, which facilitates efficient stereoisomer analysis and chiral quality control in natural products.