Quantitative assessment of the difference in free standard energy of reaction between two enantiomers of a chiral molecule and a chiral surface using a convection-diffusion model coupled to surface reactions

Bieri, M., Bürgi, T.
Université de Neuchâtel, Neuchâtel, Switzerland

Chiral surfaces and interfaces have received considerable interest in recent years due to their importance in separationand sensing of enantiomers, their application in heterogeneous enantioselective catalysis and their possibly decisive role for the origin of biochemical homochirality.

In the present work, the interaction of proline with self-assembled monolayers (SAMs) of L-glutathione was investigated by a combination of attenuated total reflection infrared (ATR-IR) spectroscopy and modulation excitation spectroscopy (MES). The latter technique selectively enhances differences in the interactions of the praline enantiomers and the L-glutathione SAM.

By applying a convection-diffusion model coupled to adsorption and desorption it was possible to extract relative adsorption and desorption rates from the experimental data for the two enantiomers of proline, fully accounting for mass transport within the ATR-IR flow-through reactor. The results show that in particular the desorption kinetics is different for the two enantiomers. Therefore, the L-glutathione SAM can discriminate between enantiomers, D-proline being stronger bound.