The ultimate application of functional materials requires successful fabrication of devices. For organic molecules, this usually involves the deposition of organic thin films on surfaces, which often limits the options for subsequent modification and optimization.

Milko E. van der Boom, Weizmann Institute of Science, Rehovot, Israel, and colleagues have demonstrated an innovative approach to modifying the morphology of physical vapor deposited films via non-covalent interactions. Polycrystalline films of 1,4-bis((E)-2-(pyridin-4-yl)vinyl)benzene, a halogen-bond acceptor, can be converted into new co-crystal films upon exposing them to a vapor of triiodotrifluorobenzene, a halogen-bond donor, through N•••I bond formation.

While this strategy utilizes halogen bonding, its scope can be easily extended to include other driving forces, such as hydrogen bonding or π‑π interactions. It enables the stepwise fabrication of multicomponent thin films to create complex yet ordered structures. 

• On-Surface Solvent-Free Crystal-to-Co-crystal Conversion by Non-Covalent Interactions,
  Meital Boterashvili, Michal Lahav, Sreejith Shankar, Antonio Facchetti, Milko E. van der Boom,
  J. Am. Chem. Soc. 2014.
  DOI: 10.1021/ja5066587