2D Self-Assembly and Catalytic Homo-coupling of the Terminal Alkyne 1,4-Bis(3,5-diethynyl-phenyl)butadiyne-1,3 on Ag(111)

Borja Cirera, Yi Qi Zhang, Svetlana Klyatskaya, Mario Ruben, Florian Klappenberger, Johannes V. Barth

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

The covalent linking of terminal alkynes is a promising approach for the bottom-up fabrication of novel, carbon-rich or all-carbon materials, which was recently extended towards interfacial architectures. Here we report the synthesis of a novel organic species (1,4-bis(3,5-diethynylphenyl)butadiyne-1,3) and employ it to engineer self-assembled supramolecular layers and covalent networks on the Ag(111) surface. Samples are prepared in-situ under ultra-high vacuum conditions and examined at the molecular level with scanning tunneling microscopy. After evaporating the two-fold symmetric molecule onto the substrate at temperatures below 300K and subsequent cooling to 5K we find highly regular supramolecular phases commensurate with the underlying silver surface and stabilized mainly by weak, non-covalent interactions originating from the terminal ethynyl moieties. Annealing at temperatures between 350 and 500K triggers catalytic conversions with the pertaining covalent coupling reactions resulting in small aggregates or irregular polymeric networks. Our detailed analysis of the binding motifs demonstrates that two competing reaction pathways dominate the covalent linking processes. The first is the Glaser-Hay-type homo-coupling of two alkyne terminations leading to a linear butadiyne bridge. The second is the connection of a butadiyne group to a laterally attacking terminal alkyne, converting the attacked ethyne to ethene moieties, which presents a major obstacle for the production of regular networks.

Original languageEnglish
Pages (from-to)3281-3288
Number of pages8
JournalChemCatChem
Volume5
Issue number11
DOIs
StatePublished - Nov 2013

Keywords

  • Alkynes
  • Glaser-Hay-type homo-coupling
  • Heterogeneous catalysis
  • Nanochemistry
  • Oligomerization
  • Self-assembly

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