Chiral Heterorecognition of Organic Molecules and Inorganic Surfaces

Atomic kinks on surfaces are chiral and may thus be used to distinguish left-handed from right-handed molecules. Two distinct non-mirror-symmetric conformations of D- and L-cysteine were found after adsorption on Au(17~11~9)$^S$. This demonstrates chiral heterorecognition, i.e. enantioselectivity of $S$-kinks on vicinal Au(111). The structures as determined by angle scanned X-ray photoelectron diffraction (XPD) agree well with those from density functional theory (DFT) calculations. The calculations predict adsorption energies of $\approx$2~eV where D-cysteine binds 140~meV stronger than L-cysteine. The classical three point contact model for molecular recognition fails to explain these findings.