The goals of this proposed research are to develop the first widely applicable multimodal chiral stationary phase, development of novel enantiomeric separation methods for compounds that cannot be resolved directly by any known means (particularly those containing few, if any functional groups) and to understand the chiral recognition and racemic separation process. More specifically, our work will focus on ordered media (i.e., CD derivatives, micelles, and so on). The principal types of compounds that will be studied are drugs and related compounds of interest to the biomedical community as well as compounds of environmental importance (e.g., pesticides, pheromones, etc.). This work is of great value to the health and welfare of the population as a whole because nearly 30% of all prescribed drugs consist of racemic mixtures. Other """"""""natural-products"""""""" frequently contain significant amounts of """"""""enantiomeric impurities"""""""" as well. These result from racemization during isolation and purification. These chiral, enantiomeric impurities frequently are responsible for a drug's side effects or can limit the effectiveness of the desired isomer. In addition to developing and understanding new analytical methods we will develop effective preparative-scale methods for resolving enantiomers. Preliminary data suggests that these have a high probability of success. The analytical liquid and gas chromatographic methods will make use of several unusual CD derivatives and a number of chiral bile acids. Three very different approaches will be used for large-scale separations. These are: chiral hollow-fiber membranes, centrifugal countercurrent chromatography and chiral foam flotation. A significant portion of this work will involve the use of statistical mechanical calculations and calorimetry to refine and evaluate our models and results. X-ray crystallography will allow structure determination of chiral selectors (such as derivatized cyclodextrins, CDs) and complexes. These can be projected and manipulated through the use of computer graphics and energy minimization calculations.
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