Direct Visualization of Enantiospecific Substitution of Chiral Guest Molecules into Heterochiral Molecular Assemblies at Surfaces

Site-specific chiral recognition in a two-dimensional heterochiral structure leading to highly enantiospecific substitution by a chiral guest was observed by scanning tunneling microscopy (STM). Thus, in the case of succinic acid (SU) on Cu(110), which forms two chiral motifs denoted D- and L-SU, (R,R)-tartaric acid ((R,R)-TA=R) only substitutes L sites (see picture; in the STM image R appears as “slots” aligned −20° to the [001] direction).