6A, 6B-β-Cyclodextrin-Hexasiloxane Copolymers: Enantiomeric Separations by a β-Cyclodextrin-Containing Rotoxane Copolymer

초록

6A, 6B-Bis-O-[p-(allyloxy)phenyl]per-O-methyl-β-cyclodextrin, prepared from β-cyclodextrin (CD) by a five-step process, has two isomeric forms. Form A has the two p-(allyioxy)phenyl substituents directed away from the CD cavity, while form B is a rotoxane with one p-(allyloxy)-phenyl group in the CD cavity. CD-hexasiloxane copolymers were prepared by treating each form with 1, 1, 3, 3, 5, 5, 7, 7, 9, 9, 11, 11-dodecamethylhexasiloxane (with Si-H functions on each end) using a platinum catalyst These copolymeric stationary phases were coated on fused silica capillaiy columns and found to separate enantiomeric solutes in gas chromatography (GC). The copolymer prepared from form A separated both enantiomeric hydrocarbons and polar solutes. Rotoxane copolymer prepared from form B separated only polar solutes. Since form B copolymer is a rotoxane with the benzene part of the copolymer in the cavity, these results show that an open CD cavity is necessary for interaction and enantiomeric resolution of nonpolar hydrocarbons; however, polar solutes interact effectively with the polar CD rim or exterior surface. © 1995, American Chemical Society. All rights reserved.