Supramolecular interactions of anthraquinone networks on Au(111): Hydrogen bonds and van der Waals interactions

Intermolecular interactions of supramolecular structures were studied in anthraquinone molecules on Au(1 1 1) using scanning tunneling microscopy. Molecular chains of linear and zigzag structures were observed and explained with simple models of hydrogen bonds. In two-dimensional islands, square and chevron structures were observed, and their molecular models were reproduced by density functional theory calculations. Square structures were made of four hydrogen bonds per molecule, whereas chevron structures were explained with four hydrogen bonds per molecule and additional van der Waals interactions. Our study shows that van der Waals interactions play cooperative roles in determining the hydrogen bonded networks of the system. (C) 2012 Elsevier B.V. All rights reserved.