Fabrication of Chiral Stationary Phases via Continuous Assembly of Polymers for Resolution of Enantiomers by Liquid Chromatography

Precise stereochemical determination of chiral molecules is highly important, especially in the pharmaceutical industry where one enantiomer may have a therapeutic effect while the other has detrimental effects. Herein, the continuous assembly of polymers (CAP) mediated via ring-opening metathesis polymerization (ROMP) is used to fabricate immobilized-type chiral stationary phases (CSPs) - as cross-linked thin films on solid supports - for enantiomeric separation. Optically active polysaccharides (chitosan and amylose) with aromatic substituents were pre-functionalized with pendent norbornene groups and subsequently employed as macrocross-linkers in the CAP(ROMP) process, building cross-linked films from initiator-functionalized mesoporous silica particles. The immobilized cross-linked films on mesoporous silica particles can act as CSPs. Therefore, the chiral recognition abilities of the CSPs were explored by liquid chromatography (LC). It was found that CSPs with higher amount of polysaccharide cross-linked films - made from multiple CAP reactions - have better chiral separation capabilities. This work demonstrates the versatility of the CAP approach to fabricate CSPs to tailor specific separation needs.