The chemisorption of specific optically active compounds on metal surfaces can create catalytically active chirality transfer sites. However, the mechanism through which these sites bias the stereoselectivity of reactions (typically hydrogenations) is generally assumed to be so complex that continued progress in the area is uncertain. We show that the investigation of heterogeneous asymmetric induction with single-site resolution sufficient to distinguish stereochemical conformations at the submolecular level is finally accessible. A combination of scanning tunneling microscopy and density functional theory calculations reveals the stereodirecting forces governing preorganization into precise chiral modifier-substrate bimolecular surface complexes. The study shows that the chiral modifier induces prochiral switching on the surface and that different prochiral ratios prevail at different submolecular binding sites on the modifier at the reaction temperature.

Methyl pyruvate undergoes CH bond scission on Pt(111) at room temperature to trigger surface-mediated enol formation and subsequent self-assembly into enol superstructures. This process may be inhibited by performing the experiment below the temperature for CH bond scission or, at room temperature, by using a background pressure of H2. Superstructure formation is not due to a polymerization reaction. Hence, it is unlikely that rate enhancement of the enantioselective hydrogenation of methyl pyruvate on cinchona-modified Pt catalysts is simply due to the absence of a substrate polymerization reaction under reaction conditions.

We investigate the energy and symmetry of Zn and Be dopant-induced acceptor states in GaAs using cross-sectional scanning tunnelling microscopy (STM) and spectroscopy at low temperatures. The ground and first excited states are found to have a nonspherical symmetry. In particular, the first excited acceptor state has a T(d) symmetry. Its major contribution to the STM empty-state images allows us to explain the puzzling triangular shaped contrast observed in the empty-state STM images of acceptor impurities in III-V semiconductors.