Amplification of optical activity by crystallization in the presence of tailor-made additives. The ?inversion rule?

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Abstract
Experiments are described in which enantiomerically pure dimers, trimers and oligomers, generated from non chiral monomers by crystallization and topochemical reaction in suitably designed chiral crystals, induce preferential crystallization of the sarent monomer in the enantiomorphous chiral phase of opposite absolutute configuration. (We coin the term “inversion rule” for this effect). A general mechanism of amplification of optical activity by crystallization is proposed on the basis of these results, involving selective adsorption of resolved impurities on the surface of chiral crystals of similar stereochemistry, resulting in a decrease of the growth rate of the affected enantiomer and consequent preferential crystallization of the antipode. The implications of this mechanism to the generation and amplification of chiralily in a closed system are discussed.