pH variation as the switch for chiral recognition in a biomembrane model

Chiral recognition was observed in a biomembrane model. Micellar aggregates formed by N-dodecyl-L-proline were, in fact, able to convert the racemic mixture of a biphenyl derivative into an enantiomerically enriched mixture. The extent of deracemization was established by HPLC on a chiral stationary phase and, in some conditions, resulted in the highest ever observed in these systems. The configuration of the exceeding enantiomer and the extent of enantiomeric enrichment depend on the medium pH. In fact, the exceeding enantiomer has the same configuration at pH 1 and 7, being more abundant at pH 7, whereas it has the opposite configuration at pH 13. The changes in the stereochemical bias are reversible. Copyright © 2005 American Chemical Society.