Enantiospecific Chemisorption of Amino Acids on Step Decorated Chiral Cu Surfaces

Highly stepped metal surfaces can define intrinsically chiral structures, and can potentially be used to separate chiral molecules. The decoration of steps on these surfaces with additional metal atoms may be one potential avenue for improving the enantiospecificity of those surfaces. Density functional theory (DFT) calculations have been performed to study the enantiospecific chemisorption of amino acids adsorbed on the pure, Pd-decorated, and Au-decorated Cu(643) surfaces. Negligible differences in adsorption energies for the most stable minima of enantiomers of alanine were found on these surfaces. There are, however, measureable energy differences between the two enantiomers of both serine and cysteine in their most stable states for all surfaces. For serine and cysteine in (3) adsorption geometries, no enhancement in enantiospecificity upon the step decoration is observed, while for those in (4) geometries, it is improved, especially on Au-decorated surface. Our results provide initial information on how tuning the chemistry of intrinsically chiral surfaces can affect the enantiospecific adsorption of amino acids on these surfaces.