(574h) Enantioselective Reaction Kinetics of Tartaric Acid on Surfaces Vicinal to Cu(111)

The homochirality of living organisms on Earth and the enantiospecific physiological impact of chiral bioactive molecules create the need for processes that yield enantiomerically pure compounds. Enantioselective reactions on intrinsically chiral metal surfaces can provide new insight into the molecular origins of enantioselectivity in chiral catalysis. In this study, we used a high-throughput library in the form of a surface structure spread single crystal (S⁴C) to access a continuum of different crystallographic surface orientations. Coupled with the use of spatially resolved x-ray photoelectron spectroscopy (SR-XPS), we mapped the enantiospecific surface reaction kinetics of tartaric acid decomposition across 169 different surface Cu(hkl) orientations. All 169 orientations lie within a polar angle of 12.4^o from the <111> orientation. These surface orientations span regions of both R- and S- chirality. The enantiospecific decomposition kinetics of D- and L-tartaric acid were measured isothermally at 433 K and the vacancy-mediated, surface explosive decomposition rate constants were estimated on all 169 different surface orientations. The times to reach half coverage, t_1/2, for the decomposition of tartaric acid reveal that the reactivity of both enantiomers is enantiospecific. The t_1/2 values of D- and L- tartaric acid decomposition are larger on surface structures with R- and S- chirality, respectively. This method enables us to obtain a comprehensive understanding of the effect of surface structure on reaction kinetics, which is of critical importance to the optimization of enantioselective processes on chiral surfaces.