Structure-sensitive enantiospecific adsorption on naturally chiral Cu(hkl)^{R and S} surfaces

The desorption kinetics of a chiral compound, R-3-methylcyclohexanone (R-3MCHO), have been measured on both enantiomers of seven chiral Cu(hkl)^{R and S} surfaces and on nine achiral Cu single crystal surfaces with surface structures that collectively span the various regions of the stereographic triangle. The naturally chiral surfaces have terrace-step-kink structures formed by all six possible combinations of the three low Miller index microfacets. The chirality of the kink sites is defined by the rotational orientation of the (1 1 1), (1 0 0) and (1 1 0) microfacets forming the kink. R-3MCHO adsorbs reversibly on these Cu surfaces and temperature programmed desorption has been used to measure its desorption energetics from the chiral kink sites. The desorption energies from the R- and S-kink sites are enantiospecific, $\Delta \Delta E_{\text{des}}^{S-R}=\Delta E_{\text{des}}^S-\Delta E_{\text{des}}^R\ne 0$, on the chiral surfaces. The magnitude of the enantiospecificity is $\left|\Delta \Delta E_{\text{des}}^{S-R}\right|$  ≈  1 kJ mol⁻¹ on all seven chiral surfaces. However, the values of $\Delta \Delta E_{\text{des}}^{S-R}$ are sensitive to elements of the surface structure other than just their sense of chirality as defined by the rotational orientation of the low Miller index microfacets forming the kinks; $\Delta \Delta E_{\text{des}}^{S-R}$ changes sign within the set of surfaces of a given chirality. (paper)