(700e) Enantioselective Separation of Aspartic Acid On Naturally Chiral Cu (3 1 17)R&S Surfaces

Production of enantiomerically pure chemicals is a major concern in pharmaceutical industries because left- and right-handed enantiomers of chemicals have significantly different physiological impact when ingested.  One strategy for producing enantiomerically pure chemicals is to employ chiral surfaces for enantioselective chemical processes.  In this work, enantioselective adsorption of aspartic acid on naturally chiral Cu (3 1 17)^R&S surfaces was investigated in UHV using temperature programmed desorption.  We have developed a novel technique in which the two enantiomers can be differentiated using mass spectroscopy by incorporation of ¹³C labels.  Exposure of a racemic mixture of D- and *L-aspartic acid to the naturally chiral surfaces results in enantioselective equilibrium adsorption with an enantiomeric excess of ~40%.  This is the first categorical demonstration of enantiospecific adsorption and separation on naturally chiral metal surfaces.  This result implies that the enantiospecific interactions between chiral molecules and naturally chiral surfaces can serve as the basis for enantioselective separations or enantioselective catalysis.