title: A photochemical mechanism for homochirogenesis.
abstract: Theoretical analysis of one-step and multiple-step photoreactions initiated with circularly polarized light shows that the enantiomeric excess of a chiral reactant approaches +/- 1 as the amount of unreacted reactant approaches 0. The final product never has a large enantiomeric excess at any stage of its formation and slowly decreases to 0 at the completion of the reaction. For multiple-step reactions the behavior of the intermediate photoproducts is much more interesting. During certain stages of the overall reaction both the size of the enantiomer excess and the amount of a given intermediate photoproduct are large. Furthermore, the sign of the enantiomeric excess of an intermediate may change during the course of the reaction. Multiple-step photoreactions initiated with circularly polarized light may be a method by which the exogenous and endogenous synthesis of optically active molecules occurred in the prebiotic universe.
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Pagni
authors.forename: John
authors.initials: J
authors.lastname: Bartmess
mesh_terms: D000465:Algorithms; D000596:Amino Acids / Q000737:chemistry*; D019418:Evolution, Chemical; D005118:Extraterrestrial Environment; D019110:Meteoroids; D000069497:Origin of Life; D010777:Photochemistry; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids