Molecular formulas (upper) arrangement schemes (middle) and STM images at liquid-solution interface(lower) for the mono- bi- and tri-functional building blocks (left to right). For bi-functional molecules, both rectilinear and hexamer structures are represented. The core molecule was hexabenzocoronene (HBC). Width of STM images: 7.8nm, 8.1nm, 17.0 and 8.9nm (left to right). Current imaging mode at a setpoint of ~10pA and a bias of 1.0V.
The spontaneous ordering and assembly of molecules on well-defined surfaces constitutes a promising bottom-up route in our quest for atomically-precise fabrication of functional molecular architectures. We have developed an original approach to the design of self-assembling building blocks tailored so as to form on demand specific hierarchical topographies.
Based on our long-term experience on self-assembly of triphenylene-cored columnar liquid crystals , we conducted a systematic analysis of the important role played by substrate interactions . This led us to a generalization of the 2D molecular sieves . We designed a new molecular unit acting as a functional linking group able to form strong surface-assisted intermolecular “clips”. These non-covalent bondings are based on an interdigitation of alkyl side-chains which strictly mimics alkane epitaxial assembly on HOPG. We have thus realized various target topologies: mono- bi- and tri-functional molecules building blocks forming dimers, chains or 2D networks respectively, each entity further assembling in the most compact structure.
 Surface-Induced Chirality in a Self-Assembled Monolayer of Discotic Liquid Crystal
F. Charra and J. Cousty, Phys. Rev. Lett. 80, 1682 (1998) ;
 Influence of molecular–substrate interaction on the self-assembly of discotic liquid crystals
K. Perronet and F.Charra, Surface Science 551, 213 (2004)
 Single-Molecule Dynamics in a Self-Assembled 2D Molecular Sieve
G. Schull, L. Douillard, C. Fiorini-Debuisschert, F. Charra, F. Mathevet, D. Kreher, A.-J. Attias, Nano Lett. 6, 1360 (2006),
Selectivity of Single-Molecule Dynamics in 2D Molecular Sieves,
G. Schull, L. Douillard, C. Fiorini-Debuisschert, F. Charra, F. Mathevet, D. Kreher, A.-J. Attias, Adv. Mat. 18, 2954 (2006)