In many cases, optical isomers, which include many compounds of pharmaceutical interest, are known to exhibit very different bioactivities as well as biotoxicities. Traditionally, the separation of optical isomers has been considered among the most difficult of all separations. Indeed, many optical isomers remain unresolvable using currently available techniques. Carbohydrate-based phases, including derivatized and underivatized cyclodextrins, cellulosic and amylosic phases have been shown to be effective for the liquid chromatographic resolution of some optical isomers. The enantioselectivity of chiral stationary phases based on small carbohydrate bonded ligands will be studied. Initially, the work will focus on maltotriose and maltooligosaccharide bonded phases. Derivatized sugar based phases will also be prepared which incorporate various types of functionalities known to be important in chiral recognition processes. The resultant sorbents will be evaluated as chromatographic chiral stationary phases. Retention as well as chiral recognition mechanisms will be explored by judicious choice of analyte and derivative structural features. Results will be compared to results obtained on the various phases synthesized as part of this project as well as with results obtained on other than carbohydrate-derived chirally selective stationary phases. The proposed work will provide important information regarding the chiral recognition mechanism(s) of these new bonded phases. In addition, it is anticipated that these new phases may also provide some insight into the chiral recognition mechanisms of other carbohydrate-based phases such as the cellulosic and amylosic phases. Understanding the mechanisms responsible for chiral recognition is fundamental to the intelligent design and application of new methodologies for the separation of optical isomers.
