Chirality is present in biological systems, individual molecules, and crystal structures. To ensure a drug, surface, or crystal is biologically active the correct chiral form must be produced. For thin films, chirality films can be controlled for the first monolayer, but subsequent layers result from intermolecular stacking interactions. This makes control of chirality in thicker films difficult.

Rodolfo Miranda and colleagues, Universidad Autónoma de Madrid, Spain, have studied how adenine layers grow on a Au(111) surface. By using scanning tunnelling microscopy and surface X-ray diffraction experiments, they show that prochiral adenine films self-assemble into homochiral domains of α-adenine. The domains are 15 nm in diameter and exist in films hundreds of nanometers thick. The self-assembled films only expose the chiral and biocompatible faces, making them interesting for enantioselective heterogeneous catalysis.

• Growth of Textured Adenine Thin Films to Exhibit only Chiral Faces
  M. J. Capitán, R. Otero, J. Álvarez, R. Miranda,
  ChemPhysChem 2011.
  DOI: 10.1002/cphc.201001064