|Molecular Engineering at Surfaces|
1D supramolecular nanograting fabricated by H-bond mediated self-assembly of PVBA molecules on a Ag(111) surface.
|In this example, we studied the ordering of 4-[trans-2-(pyrid-4-yl-vinyl)] benzoic acid (PVBA) at the noble metal surfaces Ag(111). The PVBA represents a chiral species, when deposited on a surfaces. It was found that homochiral molecules self-assemble in supramolecular chiral hydrogen-bonded twin chains [right picture], which order in nanogratings [left picture]. The supramolecular chirality within one domain of the nanograting, the length of which is in the µm range, is strictly correlated over the entire domains without intimate molecular contact. Model simulations indicate that the underlying mesoscopic chiral resolution is associated with twin chains acting as chiroselective templates for transient molecular attachment, which process mediates the gratings’ evolution.|
Metallosupramolecular nanostructures self-assemble after the deposition of Fe and TPA-molecules on a Au(111) surface.
|The second example shows the result of first experiments concerning nanopatterning of metallosupramolecular assembly on a metal surface. For this purpose, we took advantage of the naturally textured Au(111) surface in order to obtain a selective growth of metallic nano-dots at well ordered sites on the surface. These nanostructures [white spots, right picture] were used as reservoirs of metal atoms for the local coordination with Terephthalic Acid (TPA) molecules [smaller yellow dots, right picture]. The metal-terephthalate system resulting from the reaction of TPA with metal atoms can be seen as a building block involved in a supramolecular structure stabilized by metal-ligand bonds. The tuning of the deposition parameters allows the steering of different metal-organic architectures. The localization of the reaction and the local anisotropy of the metal atom reservoir pattern favor one-dimensional (1D) growth of metal-organic supramolecular architectures as it is shown in the left picture.|
Additional STM data are shown and described in the Functional Molecules Salon of the Exhibition of J. V. Barth.
"Steering molecular organization and host–guest interactions using two-dimensional
nanoporous coordination systems"
S. Stepanow, M. Lingenfelder, A. Dmitriev, H. Spillmann, E. Delvigne, N. Lin, X. Deng, C. Cai, J.V. Barth, and K. Kern,
Nature Mat. 3, 229 (2004) (pdf).
"Supramolecular architectures and nanostructures at metal surfaces"
J.V. Barth, J. Weckesser, N. Lin, A. Dmitriev, and K. Kern,
Appl. Phys. A 76, 645 (2003) (pdf).
"Stereochemical Effects in Supramolecular Self-Assembly at Surfaces:
1-D versus 2-D Enantiomorphic Ordering for PVBA and PEBA on Ag(111)"
J.V. Barth, J. Weckesser, G. Trimarchi, M. Vladimirova, A. De Vita, C. Cai, H. Brune, Peter Günter, and K. Kern,
J. AM. CHEM. SOC. 124, 7991 (2002) (pdf).
"Mesoscopic correlation of supramolecular chirality in one-dimensional hydrogen-bonded assemblies"
Weckesser, A. De Vita, J.V. Barth, C. Cai, and K. Kern,
Phys. Rev. Lett. 87, 096101 (2001) (pdf).
"Building supramolecular nanostructures at surfaces by hydrogen
J.V. Barth, J. Weckesser, C. Cai, P. Günter, L. Bürgi, O. Jeandupeux, and K. Kern,
Angewandte Chemie 112, 1285 (2000) (pdf);
Angewandte Chemie Int. Ed. 39, 1230 (2000) (pdf).
E-mail : johannes.barth
E-mail : florian.klappenberger