1. Molecular Shape Directed Crystalline Architectures
Kraig A. Wheeler
Department of chemistry, Eastern Illinois University
Quasiracemates – Materials that mimic the molecular recognition behavior of “true” racemic compounds. Prepared from isosteric, chemically unique, compounds that differ in handedness.
Reconstructing L. Pasteur’s 1853 account of his peculiar three-component crystals confirmed the identities of the two crystalline phases as ammonium (+)-bitartrate (central crystal) and a quasiracemate of ammonium (+)-bitartrate/(-)-bimalate (adjoining crystal laths). A crystal structure of the quasiracemate shows that (+)-bitartrate and (-)-bimalate components organize in approximate inversion related molecular assemblies with each bitartrate and bimalate component forming homomeric catemeric motifs. The bitartrate strand is isostructural in the quasiracemate and (+)-bitartrate phases, and likely serves as the primary
structural contributor to the intergrowth of these crystalline phases. Notable program highlights include:
Pasteur’s Quasiracemate : components differing by OH and H chemical functions form approximate inversion related assemblies.
Epitaxial Growth : three-component crystals derived from moieties of (+)-bitartrate and (+)-bitartrate / (-)-bimalate.