COLL 494 |
| Louis A. Clark1, Shaji Chempath2, and Randall Q. Snurr2. (1) Department of Bioengineering, University of California, Berkeley, CA 94720, (2) Department of Chemical Engineering, Northwestern University, 2145 Sheridan Road, E-136, Evanston, IL 60208 |
| A scheme is proposed for the transformation of certain achiral porous solids into chiral solids. At least two materials with racemic mixtures of chiral pores are now available. The UCSB-7 materials and the beta type zeolite have pores that can be described as mixtures of opposite-handed helices. Molecular simulations indicate that enantiomers of some molecules adsorb predominantly in pores of a distinct handedness. Subsequent oligomerization of these molecules would block one of two pore types and yield a solid with exploitable chirality. Adsorption simulations indicate that sizable segregation of tight-fitting racemic mixtures occurs. For example, when isomers of 1,2-dimethyl-cyclobutane are adsorbed in UCSB-7 at 300K a potential energy difference of 4.6 kJ/mol leads to a composition in one pore that is approximately 3/4 of one racemate and 1/4 of the other. Simulations allow us to examine other potential selective pore-blockers and their relative placement in the two solids, as well as their diffusion rates. |
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Chiral Surfaces
Division of Colloid and Surface Chemistry |