K W Hipps - Supramolecular Structures of Coronene and Alkane Acids at the Au(111)−Solution Interface:  A Scanning Tunneling Microscopy Study

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      Publication Details (including relevant citation   information):

      Gyarfas, Brett J., Wiggins, Bryan, Zosel, Monica, Hipps, K. W.   Langmuir 2005 21 (3) 919-923

      Abstract: Scanning tunneling microscopy (STM) is   utilized to study the solution−solid interface formed between   Au(111) and solutions of coronene in hexanoic, heptanoic, and   octanoic acids. In all three cases adsorbed coronene is observed   and lays flat on the metal surface. Heptanoic and hexanoic acid   solutions produce a hexagonal symmetry monolayer. For the   heptanoic and hexanoic cases, dipole-image dipole interactions   and H bonding stabilize a surface structure in which 12 acid   molecules surround each coronene and produce a coronene spacing   of 1.45 nm. In the case of octanoic acid as solvent, the   incorporation of the solvent into the monolayer is not as   strongly favored. The coronene spacing can range from   close-packed (1.2 nm) with no solvent presumed present in the   monolayer, to 1.50 nm with up to 12 solvent molecules surrounding   each coronene. The close-packed regions have hexagonal symmetry,   as do those with the largest (1.5 nm) spacing. Heptanoic acid   solutions give the clearest STM images and are associated with   the most stable two-component monolayer. The present paper   demonstrates that non-covalent interactions at the solution−metal   interface can lead to complex multicomponent monolayer   structures.

      Address (URL): http://dx.doi.org/10.1021/la047726j