Effect of multivalency on the performance of enantioselective separation media for chiral HPLC prepared by linking multiple selectors to a porous polymer support via aliphatic dendrons.
Chiral stationary phases (CSPs) containing L-proline indananilide chiral selectors attached through a multivalent dendritic linker to monodisperse macroporous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) beads have been prepared using two different approaches. The convergent method involves the preparation of ligands in solution and their subsequent attachment to the support. The divergent approach is based on the stepwise "on-bead" formation of the linker using methods that are typical of solid-phase synthesis. While the convergent CSPs feature well-defined ligands, their loading is relatively low. In contrast, the divergent technique affords CSPs with higher loading but with more limited control over precise ligand architecture. Excellent enantioselectivities characterized by separation factors of up to 31 were achieved for the separation of racemic N-(3,5-dinitrobenzoyl)-alpha-amino acid alkyl amides with these new CSPs under normal-phase HPLC conditions.
Ling
Frank H
FH
Department of Chemistry, University of California, Berkeley, California 94720-1460, and Division of Materials Science, E. O. Lawrence Berkeley National Laboratories, Berkeley, California 94720.
Lu
Victor
V
Svec
Frantisek
F
Fréchet
Jean M J
JM
D000409:Alanine / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D007930:Leucine / Q000737:chemistry; D008024:Ligands; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry; D011392:Proline / Q000737:chemistry; D013237:Stereoisomerism; D013997:Time Factors
D000596:Amino Acids; D008024:Ligands; D011108:Polymers; D011109:Polymethacrylic Acids; C459242:poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate); D011392:Proline; D007930:Leucine; D000409:Alanine