Tracking the Chiral Recognition of Adsorbed Dipeptides at theSingle-Molecule Level

Herein we report on the direct observation of chiral recognition events of adsorbed diphenylalanine by scanning tunneling microscopy (STM). The interaction among individual di-d-phenylalanine (d-Phe-d- Phe) molecules and the discrimination of d-Phe-d-Phe from its enantiomer l-Phe-l-Phe on Cu(110) is followed by STM and rationalized by using first principles and classical molecular dynamics techniques. We find that the stereoselective assembly of adsorbed di-phenylalanine enantiomers into molecule pairs and chains takes place through mutually induced conformational changes, thereby illustrating at the single-molecule level the more than half a century old prediction of Pauling.