Energetics of Chiral Imprinting of Cu(100) by Lysine

Temperature-programmed desorption experiments have been used to probe the adsorption energetics of d - and l -lysine on the chiral Cu(3,1,17) R&S and achiral Cu(100) surfaces. Previous literature has reported the reconstruction of Cu(100) surfaces to form homochiral (3,1,17) R facets upon adsorption of l -lysine at high coverage and after annealing to 430 K ( J. Am. Chem. Soc. 122, 2000, 12584). The implication of that work is that the adsorption energy of l -lysine on Cu(3,1,17) R is greater than on Cu(3,1,17) S and Cu(100), thereby driving the homochiral reconstruction. The results of temperature-programmed desorption measurements test and support this implication. The desorption energies of d - and l -lysine on the Cu(100) surface are significantly lower than those on either of the Cu(3,1,17) R&S surfaces. Furthermore, large enantiospecific differences in desorption kinetics were observed for d - and l -lysine on the Cu(3,1,17) R&S surfaces. This observed enantiospecificity is believed to originate from the enantiospecific interactions of lysine with the chiral kinked steps on these surfaces. The observation that adsorption of l -lysine on Cu(3,1,17) R is energetically preferred over adsorption on Cu(3,1,17) S is consistent with the formation of homochiral (3,1,17) R facets during l -lysine adsorption on Cu(100).