Surface reactivity at "chiral" platinum surfaces

The electro-oxidation of D- and L-glucose has been investigated using the chiral electrode Pt{643}(R) and its enantiomorph Pt{643}(S). Both electrodes are demonstrated to be enantioselective. We ascribe this behavior to the inherent (left or right) "handedness" of kink sites present at the surface. In contrast, no difference in D- and L-glucose oxidation could be detected using stepped Pt{211} and Pt{332} electrodes. Stepped surfaces are achiral, since they lack the prerequisite necessary for the observation of chirality, namely kink sites. For Pt{531}, a surface which contains only kink sites, a diastereomeric product excess of similar to 80% is estimated for D- and L-glucose oxidation. This compares with a value of similar to 60% for Pt{643}. Hence, the chiral discrimination appears to scale with the surface density of kink sites. These findings constitute the first experimental proof that chiral discrimination is an intrinsic propel ty of kinked single-crystal surfaces.