Kink sites on high Miller index surfaces are either left-or right-handed and can be thought of as chiral, when the step lengths on either side of the kink site are unequal. A silver single crystal was oriented and cut to expose the Ag(643) surface on one side and the Ag(6 h4 h3 h) surface on the other side. A system is proposed for naming these surfaces as Ag(643) S and Ag(643) R , respectively , in analogy with the CahnIngold-Prelog rules used in the nomenclature of organic stereoisomers. The left hand/right hand relationship of the two surfaces was manifested by the direction of the splitting of the low-energy electron diffraction (LEED) spots. The interaction of the enantiomers of a chiral alcohol ((R)-2-butanol and (S)-2-butanol) with each surface was studied using temperature-programmed desorption (TPD) measurements in order to ascertain the magnitude of the effect of surface chirality on the heats of adsorption. Desorption of the alcohols following exposure to the clean surfaces was molecular and exhibited first-order kinetics. No difference was observed between (R)-and (S)-2-butanol in either desorption temperature (225 K) or peak shape. Upon exposure to preoxidized surfaces, the alcohols deprotonated to form (R)-and (S)-2-butanoxide, both of which decomposed upon heating via -hydride elimination. The decomposition product, 2-butanone, desorbed at 282 K. Again, no difference in the reaction kinetics of the enantiomeric alkoxides was observed on the two surfaces. From these results it can be concluded that the difference in (a) the heat of adsorption of the enantiomeric alcohols and (b) the difference in the energy barrier to -hydride elimination for the enantiomeric alkoxides is less than 0.1 kcal/mol.
Chiral organic surfaces were generated via adsorption of the pure enantiomers of heptahelicene, a helically shaped aromatic hydrocarbon, on a Ni(111) surface in ultra high vacuum. Time-of-flight secondary mass spectrometry (ToF-SIMS) revealed that the molecule stays intact at room temperature. The formation of a two-dimensionally ordered structure at monolayer coverage is observed via low-energy electron diffraction (LEED) and scanning tunnelling spectroscopy (STM). For creation of a chiral metal film, the chiral organic monolayer was subjected to subsequent metal physical vapour deposition. Differences in morphology of grown copper and palladium films were only observed when heptahelicene was adsorbed prior to deposition. No screw dislocations with preferred handedness were observed when the pure enantiomers were used.
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