No abstract

Chirality at surfaces has become a strong focus within the surface science community. A particular motivation is the prospect of using heterogeneous catalysis over chiral solid surfaces for asymmetric synthesis, a prospect which has clear relevance to the pharmaceutical industry. Small amino acids adsorbed on Cu surfaces have emerged as important model systems for studying the interaction of chiral molecules with metal surfaces. In this article, we review the current state of knowledge of these systems, and present the results of new experimental studies of alanine overlayers on Cu{311} and {531} surfaces. Our work on Cu{311} helps us to understand the interplay between different manifestations of chirality, especially ''footprint chirality'', in the overlayers. Cu{531} is an intrinsically chiral surface orientation; our data reveal strongly enantiospecific alanine-induced restructuring of this surface. This points the way towards a promising route for obtaining strongly enantiospecific interactions with chiral adsorbates.

Scanning tunneling microscopy (STM) has been used to investigate the structure of the ordered methanethiolate overlayer formed on Ag(111) by reaction at room temperature with dimethyl disulfide. High-resolution images show an ordered structure with three inequivalent atomic-scale protrusions within each ( radical7 x radical7)R19 degrees surface unit mesh which can be reconciled with methanethiolate species on a regular lateral submesh, similar to that proposed in the multilayer ( radical7 x radical7)R19 degrees -S sulfide phase previously reported. STM imaging during dynamic dosing also provides evidence for a significant change in the outermost layer Ag atom density, consistent with a reconstructed surface model. Possible models for this reconstruction are presented and discussed in the light of available information.