title: Self-assembly of indole-2-carboxylic acid at graphite and gold surfaces.
abstract: Model systems are critical to our understanding of self-assembly processes. As such, we have studied the surface self-assembly of a small and simple molecule, indole-2-carboxylic acid (I2CA). We combine density functional theory gas-phase (DFT) calculations with scanning tunneling microscopy to reveal details of I2CA assembly in two different solvents at the solution/solid interface, and on Au(111) in ultrahigh vacuum (UHV). In UHV and at the trichlorobenzene/highly oriented pyrolytic graphite (HOPG) interface, I2CA forms epitaxial lamellar structures based on cyclic OH⋯O carboxylic dimers. The structure formed at the heptanoic acid/HOPG interface is different and can be interpreted in a model where heptanoic acid molecules co-adsorb on the substrate with the I2CA, forming a bicomponent commensurate unit cell. DFT calculations of dimer energetics elucidate the basic building blocks of these structures, whereas calculations of periodic two-dimensional assemblies reveal the epitaxial effects introduced by the different substrates.
authors.affiliation: Centre Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: De Marchi
authors.affiliation: Centre Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Daling
authors.initials: D
authors.lastname: Cui
authors.affiliation: Centre Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Josh
authors.initials: J
authors.lastname: Lipton-Duffin
authors.affiliation: Département de Génie physique, École Polytechnique de Montréal, C.P. 6079, Succ. Centre Ville, Montréal, Quebec H3C 3A7, Canada.
authors.forename: Clara
authors.initials: C
authors.lastname: Santato
authors.affiliation: Centre Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: MacLeod
authors.affiliation: Centre Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Federico
authors.initials: F
authors.lastname: Rosei