title: Changes in the Enantiomeric Composition of Chiral Mixtures Upon Adsorption on a Non-Chiral Surface.
abstract: The adsorption of propylene oxide, a chiral molecule, on a Pt(111) single-crystal surface was studied as a function of enantiomeric composition by temperature programmed desorption (TPD) and molecular beams. Two opposing trends were observed leading to variations in the enantiomeric excess (ee) of the chemisorbed layers with respect to the composition of the gas-phase mixtures: a kinetic effect dominant during the initial uptake, with a preference toward the formation of enantiopure layers, and a steady-state effect seen after approximately monolayer half-saturation, at which point the preference is toward racemization. These effects may account for important phenomena such as the bias toward one chirality in biological systems and the selective crystallization of some chiral compounds, and may also be used in practical applications for chemical separations and catalysis.
authors.affiliation: Department of Chemistry and UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA.
authors.forename: Stavros
authors.initials: S
authors.lastname: Karakalos
authors.affiliation: Department of Chemistry and UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA.
authors.forename: Junghyun
authors.initials: J
authors.lastname: Hong
authors.affiliation: Department of Chemistry and UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA. zaera@ucr.edu.
authors.forename: Francisco
authors.initials: F
authors.lastname: Zaera
keywords: adsorption; chiral amplification; enantiomeric excess; molecular beam; temperature programmed desorption