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2008-09-02 - Article/Dans un journal avec peer-review - Anglais - 9 page(s)

Linares M., Iavicoli P., Psychogyopoulou K., Beljonne David , De Feyter S., Amabilino D.B., Lazzaroni Roberto , "Chiral Expression at the Solid-Liquid Interface: A Joint Experimental and Theoretical Study of the Self-Assembly of Chiral Porphyrins on Graphite" in Langmuir, 24, 17, 9566-9574

  • Edition : American Chemical Society, Washington (DC)
  • Codes CREF : Chimie des surfaces et des interfaces (DI1327)
  • Unités de recherche UMONS : Chimie des matériaux nouveaux (S817)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
Texte intégral :

Abstract(s) :

(Anglais) The chiral organization of an enantiopure functional molecule on an achiral surface has been studied with the aim of understanding the influence of stereogenic centers on the self-assembly in two dimensions. A chiral tetra meso-amidophenyl-substituted porphyrin containing long hydrophobic tails at the periphery of the conjugated p-electron system was prepared for this purpose. Scanning tunneling microscopy (STM) images of the compound at the graphite-heptanol interface reveal a chiral arrangement of the molecules, with the porphyrin rows tilted by 13° with respect to the normal to the graphite axes. In terms of molecular modeling, a combination of molecular dynamics simulations on systems constrained by periodic boundary conditions and on unconstrained large molecular aggregates has been applied to reach a quantitative interpretation on both the density of the layer and its orientation with respect to the graphite surface. The results show clearly that (i) the methyl groups of the stereogenic point toward the graphite surface and (ii) the porphyrin molecules self-assemble into an interdigitated structure where the alkyl chains align along one of the graphite axes and the porphyrin cores are slightly shifted with respect to one another. The direction of this shift, which defines the chirality of the monolayer, is set by the chirality of the stereogenic centers. Such an arrangement results in the formation of a dense chiral monolayer that is further stabilized by hydrogen bonding with protic solvents.

Notes :
  • (Anglais) Publié en ligne le 24 juillet 2008
Identifiants :
  • DOI : 10.1021/la8017419