Assembly, Diffusion and Rotation of Organic Molecules on a Gold Surface

The interplay between molecules and surfaces has become a rich playground to study a wide variety of phenomena. Advances in deposition procedures, scanning probe techniques, and theoretical modeling and simulation have allowed us to explore many different avenues, like many-body effects, the on-surface synthesis of new molecules, or the motion of molecules on surfaces. Here, we study theoretically two different organic molecules on a gold (111) surface. For the first one, acetylbiphenyl (ABP), we show how after deposition the ABP molecule diffuses along the main directions of the Au(111) surface, revealing the directionality of the molecule-surface interactions driven just by van der Waals forces. This diffusion leads the molecules to form robust supramolecular assemblies stabilized by gold adatoms. For the second molecule, DMBI-P, we show how the molecule is dissociated after deposition, getting anchored to the surface and forming a molecule-rotor that presents a unidirectional motion at 5 K.