Self-assembly of amino acids on the Cu(001) surface

The major results of a series of our recent investigations on the self-assembly of amino acids on the Cu(001) surface are reviewed in the present paper. It has been found that all eight amino acids studied here adsorb on the surface in their anionic forms and that for most of them, three distinctly different phases of the adsorbates may form, that is, the 2D gas, intermediate and solid phases. In the gas phase, the intermolecular interactions are repulsive and the molecules are “standing” on their carboxylate group “feet” and can diffuse frequently on the surface. In the intermediate phase, the intermolecular interactions are also repulsive and the molecules are also “standing” on the surface; however, the molecules align into short rows. In the solid phase, the molecules “lie” down with their main chain and, in some cases, also the side chain attached to the surface, whereas, hydrogen bonds are likely responsible for stabilization of this phase. In addition to the formation of these phases, some amino acid adsorbates may cause magnificent step faceting and bunching or even chiral restructuring of the surface morphology. These results may have applications in nano-scale materials, nano-technology and probably, also in chiral separations or enantioselective heterogeneous catalysis.