Preparation and Enantioseparation Performance of Mixed-Type Polysaccharide-Based Chiral Stationary Phases

Amylose tris(phenylcarbamate) ( A1 ), cellulose tris(phenylcarbamate) ( C1 ) and cellulose tris(3,5-dimethyl phenylcarbamate) ( C2 ) were synthesized by " one-pot” method. The structures of the derivatives were quantitatively characterized by ¹H-NMR. The regular structure and complete substitution of the derivatives were confirmed. The obtained amylose and cellulose derivatives were then coated on the macroporous silica gel, giving rise to mixed-type chiral stationary phases (CSPs) by two mixing ways. Their enantioseparation abilities for ten chiral compounds were evaluated by HPLC. The chiral recognition abilities of the obtained mixed-type CSPs were compared with those of several single polysaccharide-based CSPs (commercialized coated-type CSP derived from C2 ), including A1 , C1 and Chiralcel OD. The results showed that the mixed-type CSPs, especially those mixing with A1 and C2 , exhibited higher enantioseparation performance for some chiral compounds, which could be ascribed to the combined enantioseparation abilities derived from the cellulose and amylose derivatives with different higher order structures in the mixed-type CSPs. The mixing methods, either before or after coating process, had no remarkable influences on the chiral recognition ability of the obtained CSPs. However, some mixed-type CSPs showed decreased enantioseparation abilities for a few chiral compounds, which have opposite elution orders on the two single CSPs. This work suggests that the mixed CSPs is probably more efficient for the improvement on the chiral recognition abilities in case both single CSPs follow the similar recognition mechanism.