Graphical abstract

Gas-phase equilibrium adsorption of _d- and _l-serine (Ser) mixtures and _d- and _l-phenylalanine (Phe) mixtures has been studied on the naturally chiral Cu{3,1,17}^R&S surfaces. ¹³C labeling of the _l enantiomers (_*l-Ser and _*l-Phe) has enabled mass spectrometric enantiodiscrimination of the species desorbing from the surface following equilibrium adsorption. On the Cu{3,1,17}^R&S surfaces, both equilibrium adsorption and the thermal decomposition kinetics of the _d and _*l enantiomers exhibit diastereomerism. Following exposure of the surfaces to _d/*l mixtures, the relative equilibrium coverages of the two enantiomers are equal to their relative partial pressures in the gas phase, θ_d/θ_*l = P_d/P_*l. This implies that adsorption is not measurably enantiospecific. The decomposition kinetics of Ser are enantiospecific whereas those of Phe are not. Comparison of these results with those for aspartic acid, alanine, and lysine suggests that enantiospecific adsorption on the naturally chiral Cu surfaces occurs for those amino acids that have side chains with functional groups that allow strong interactions with the surface. There is no apparent correlation between amino acids that exhibit enantiospecific adsorption and those that exhibit enantiospecific decomposition kinetics.