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The influence of molecular mobility on the properties of networks of gold nanoparticles and organic ligands.

Authors
  • Devid, Edwin J
  • Martinho, Paulo N
  • Kamalakar, M Venkata
  • Prendergast, Una
  • Kübel, Christian
  • Lemma, Tibebe
  • Dayen, Jean-François
  • Keyes, Tia E
  • Doudin, Bernard
  • Ruben, Mario
  • van der Molen, Sense Jan
Type
Published Article
Journal
Beilstein Journal of Nanotechnology
Publisher
Beilstein-Institut
Publication Date
Jan 01, 2014
Volume
5
Pages
1664–1674
Identifiers
DOI: 10.3762/bjnano.5.177
PMID: 25383278
Source
Medline
Keywords
License
Unknown

Abstract

We prepare and investigate two-dimensional (2D) single-layer arrays and multilayered networks of gold nanoparticles derivatized with conjugated hetero-aromatic molecules, i.e., S-(4-{[2,6-bipyrazol-1-yl)pyrid-4-yl]ethynyl}phenyl)thiolate (herein S-BPP), as capping ligands. These structures are fabricated by a combination of self-assembly and microcontact printing techniques, and are characterized by electron microscopy, UV-visible spectroscopy and Raman spectroscopy. Selective binding of the S-BPP molecules to the gold nanoparticles through Au-S bonds is found, with no evidence for the formation of N-Au bonds between the pyridine or pyrazole groups of BPP and the gold surface. Subtle, but significant shifts with temperature of specific Raman S-BPP modes are also observed. We attribute these to dynamic changes in the orientation and/or increased mobility of the molecules on the gold nanoparticle facets. As for their conductance, the temperature-dependence for S-BPP networks differs significantly from standard alkanethiol-capped networks, especially above 220 K. Relating the latter two observations, we propose that dynamic changes in the molecular layers effectively lower the molecular tunnel barrier for BPP-based arrays at higher temperatures.

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