Direct Organocatalytic Enantioselective Functionalization of SiO_x Surfaces

Abstract

Traditional methods to prepare chiral surfaces involve either the adsorption of a chiral molecule onto an achiral surface, or adsorption of a species that forms a chiral template creating lattices with long range order. To date only limited alternative strategies to prepare chiral surfaces have been studied. In this manuscript a “bottom‐up” approach is developed that allows the preparation of chiral surfaces by direct enantioselective organocatalytic reactions on a functionalized silicon oxide supported self‐assembled monolayer (SAM). The efficient catalytic generation of enantiomerically enriched organic surfaces is achieved using a commercially available homogeneous isothiourea catalyst that promotes an enantioselective Michael‐lactonization process upon a silicon‐oxide supported SAM functionalized with a reactive trifluoroenone group. Chiral atomic force microscopy (χ‐AFM) is used to probe the enantiomeric enrichment of the organic films by measurement of the force distributions arising from interaction of d‐ or l‐cysteine‐modified AFM tips and the organic films.