title: Propagation of biochirality: crossovers and nonclassical crystallization kinetics of aspartic acid in water.
abstract: All experimental procedures discussed could be treated as a screening tool for probing the existence of molecular association among the chiral molecules and the solvent system. The molecular association phases of a racemic conglomerate solution (CS) and a racemic compound solution (RCS), and the templating effect of aspartic acid solid surface were observed to minimize the chance of redissolving racemic conglomerate and racemic compound aspartic acid in water and reforming an RCS in crossovers experiments. Only 1 %wt% of l-aspartic acid was adequate enough to induce a transformation from a racemic compound aspartic acid to a racemic conglomerate aspartic acid. This would make the propagation of biochirality more feasible and sound. However, tetrapeptide, (l-aspartic acid)4 , failed to induce enantioseparation as templates purely by crystallization. Nonclassical crystallization theory was needed to take into account the existence of a CS. Fundamental parameters of the crystallization kinetics such as the induction time, interfacial energy, Gibbs energetic barrier, nucleation rate, and critical size of stable nuclei of: (i) racemic compound aspartic acid, (ii) racemic compound aspartic acid seeded with 1 %wt% l-aspartic acid, (iii) racemic conglomerate aspartic acid, and (iv) l-aspartic acid were evaluated and compared with different initial supersaturation ratios. Morphological studies of crystals grown from the crystallization kinetics were also carried out.
authors.affiliation: Department of Chemical and Materials Engineering, National Central University, Jhong-Li City, Taiwan, R.O.C.
authors.forename: Tu
authors.initials: T
authors.lastname: Lee
authors.forename: Yu Kun
authors.initials: YK
authors.lastname: Lin
authors.forename: Ya Chung
authors.initials: YC
authors.lastname: Tsai
authors.forename: Hung Lin
authors.initials: HL
authors.lastname: Lee
mesh_terms: D000409:Alanine / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry*; D003460:Crystallization; D007700:Kinetics; D013237:Stereoisomerism; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D001224:Aspartic Acid; D000409:Alanine
keywords: aspartic acid; crossovers; enantioseparation; racemic compound solution; racemic conglomerate solution; templating effect; tetrapeptide