Coexistence of one- and two-dimensional supramolecular assemblies of terephthalic acid on Pd(111) due to self-limiting deprotonation.
The adsorption of terephthalic acid [C(6)H(4)(COOH)(2), TPA] on a Pd(111) surface has been investigated by means of scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure spectroscopy under ultrahigh vacuum conditions at room temperature. We find the coexistence of one- (1D) and two-dimensional (2D) molecular ordering. Our analysis indicates that the 1D phase consists of intact TPA chains stabilized by a dimerization of the self-complementary carboxyl groups, whereas in the 2D phase, consisting of deprotonated entities, the molecules form lateral ionic hydrogen bonds. The supramolecular growth dynamics and the resulting structures are explained by a self-limiting deprotonation process mediated by the catalytic activity of the Pd surface. Our models for the molecular ordering are supported by molecular mechanics calculations and a simulation of high resolution STM images.
Cañas-Ventura
M E
ME
Institut de Physique des Nanostructures, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland. marta.canasventura@empa.ch
Klappenberger
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F
Clair
S
S
Pons
S
S
Kern
K
K
Brune
H
H
Strunskus
T
T
Wöll
Ch
Ch
Fasel
R
R
Barth
J V
JV