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    Surface Science Monday Sessions
       Session SS1-MoA

Paper SS1-MoA8
Enantiospecific Properties of Chiral Surfaces

Monday, October 29, 2001, 4:20 pm, Room 120

Session: Innovations in Surface Science
Presenter: J.D. Horvath, Carnegie Mellon University
Authors: J.D. Horvath, Carnegie Mellon University
A.J. Gellman, Carnegie Mellon University
Correspondent: Click to Email

Chirality is an omnipresent feature of the biochemical and biophysical world. The handedness of the important molecules that form the basis of life creates the need for enantiomeric purity in the chemicals used for pharmaceutical and other bio-active purposes. Many of the processes used for synthesis and preparation of enantiomerically pure compounds rely on the use of chiral surfaces. This represents in interesting and important new opportunity for surface science. I will describe some of the recently discovered, enantiospecific physical and chemical properties of chiral surfaces prepared from simple high Miller Index metal surfaces. The kinked step structures of such surface are chiral. As an example, the heats of adsorption of small chiral molecules such as propylene oxide (CH@sub 3@CH(O)CH@sub 2@) and R-3-methylcyclohexanone are sensitive to the handedness of surfaces such as Cu(643). This has been observed using thermally programmed desorption measurements which reveal that the desorption kinetics of these chiral molecules are enantiospecific on chiral surfaces. They do not exhibit enantiospecificity on achiral surfaces such as Cu(111). Similarly, the orientation of chiral molecules on chiral surfaces can be shown to depend on the relative handedness of adsorbate and substrate. This has been shown by study of the infrared reflection absorption spectra of 2-butanoxy groups on the Ag(643) surface. The intensities of the absorptions by R- and S-2-butanoxy groups are dependent on the handedness of the Ag(643) substrate. Understanding and controlling these enantiospecific properties poses some extremely interesting challenges for surface chemistry and surface physics that can have broad impact in the chemical and life sciences.