title: Does the surface matter? Hydrogen-bonded chain formation of an oxalic amide derivative in a two- and three-dimensional environment.
abstract: We report on a multi-technique investigation of the supramolecular organisation of N,N-diphenyl oxalic amide under differently dimensioned environments, namely three-dimensional (3D) in the bulk crystal, and in two dimensions on the Ag(111) surface as well as on the reconstructed Au(111) surface. With the help of X-ray structure analysis and scanning tunneling microscopy (STM) we find that the molecules organize in hydrogen-bonded chains with the bonding motif qualitatively changed by the surface confinement. In two dimensions, the chains exhibit enantiomorphic order even though they consist of a racemic mixture of chiral entities. By a combination of the STM data with near-edge X-ray absorption fine-structure spectroscopy, we show that the conformation of the molecule adapts such that the local registry of the functional group with the substrate is optimized while avoiding steric hindrance of the phenyl groups. In the low coverage case, the length of the chains is limited by the Au(111) reconstruction lines restricting the molecules into fcc stacked areas. A kinetic Monte Carlo simulated annealing is used to explain the selective assembly in the fcc stacked regions.
authors.affiliation: Physik Department E20, TU München, Munich, Germany. fklapp@ph.tum.de
authors.forename: Florian
authors.initials: F
authors.lastname: Klappenberger
authors.forename: Marta E
authors.initials: ME
authors.lastname: Cañas-Ventura
authors.forename: Sylvain
authors.initials: S
authors.lastname: Clair
authors.forename: Stéphane
authors.initials: S
authors.lastname: Pons
authors.forename: Uta
authors.initials: U
authors.lastname: Schlickum
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Qu
authors.forename: Thomas
authors.initials: T
authors.lastname: Strunskus
authors.forename: Alessio
authors.initials: A
authors.lastname: Comisso
authors.forename: Christof
authors.initials: C
authors.lastname: Wöll
authors.forename: Harald
authors.initials: H
authors.lastname: Brune
authors.forename: Klaus
authors.initials: K
authors.lastname: Kern
authors.forename: Alessandro
authors.initials: A
authors.lastname: De Vita
authors.forename: Mario
authors.initials: M
authors.lastname: Ruben
authors.forename: Johannes V
authors.initials: JV
authors.lastname: Barth