Generation and amplification of optical activity by crystallization: the system nickel α-amino caprolactam/lysine.

Abstract

A number of possible model systems for the spontaneous generation and amplification of net chirality in chemical systems by the process of crystallization are presented. In one of these a chiral resolved product (S') [or (R') generated from crystals of a multimolecular complex {S n} or {R n}, forms by ligand exchange diastereomeric complexes (S n-1 S') and (R n-1 S') which act as growth inhibitors of the parent conglomerate crystals, but at different extents. The Nickel complex of α-amino caprolactam (ACL) grown in ethanol, in basic conditions, has been investigated as an appropriate system for such a model. Kinetic, structural and morphological studies shed light on the mechanism of the asymmetric induction and demonstrated the feasibility of a complete cycle of generation and amplification of net chirality in this chemical system or others of the same type.