title: Supramolecular self-assembly of π-conjugated hydrocarbons via 2D cooperative CH/π interaction.
abstract: Supramolecular self-assembly on well-defined surfaces provides access to a multitude of nanoscale architectures, including clusters of distinct symmetry and size. The driving forces underlying supramolecular structures generally involve both graphoepitaxy and weak directional nonconvalent interactions. Here we show that functionalizing a benzene molecule with an ethyne group introduces attractive interactions in a 2D geometry, which would otherwise be dominated by intermolecular repulsion. Furthermore, the attractive interactions enable supramolecular self-assembly, wherein a subtle balance between very weak CH/π bonding and molecule-surface interactions produces a well-defined "magic" dimension and chirality of supramolecular clusters. The nature of the process is corroborated by extensive scanning tunneling microscopy/spectroscopy (STM/S) measurements and ab initio calculations, which emphasize the cooperative, multicenter characters of the CH/π interaction. This work points out new possibilities for chemical functionalization of π-conjugated hydrocarbon molecules that may allow for the rational design of supramolecular clusters with a desired shape and size.
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Tennessee 37831, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Chengbo
authors.initials: C
authors.lastname: Han
authors.forename: Scott R
authors.initials: SR
authors.lastname: Horton
authors.forename: Miguel
authors.initials: M
authors.lastname: Fuentes-Cabrera
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.forename: Wenchang
authors.initials: W
authors.lastname: Lu
authors.forename: Jerry
authors.initials: J
authors.lastname: Bernholc
authors.forename: Petro
authors.initials: P
authors.lastname: Maksymovych
authors.forename: Minghu
authors.initials: M
authors.lastname: Pan
mesh_terms: D002244:Carbon / Q000737:chemistry*; D003198:Computer Simulation; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D046911:Macromolecular Substances / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D002244:Carbon; D006859:Hydrogen