The influence of molecular mobility on the properties of networks of gold nanoparticles and organic ligands
Journal article, 2014
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.
gold nanoparticles
aromatic capping ligands
molecular charge transport
surface enhanced Raman spectroscopy
self-assembly
Author
E. J. Devid
Leiden University
P. N. Martinho
University of Lisbon
Karlsruhe Institute of Technology (KIT)
Venkata Kamalakar Mutta
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
U. Prendergast
Dublin City University
C. Kubel
Karlsruhe Institute of Technology (KIT)
Karlsruhe Nano Micro Facility
T. Lemma
Dublin City University
J. F. Dayen
University of Strasbourg
T. E. Keyes
Dublin City University
B. Doudin
University of Strasbourg
M. Ruben
University of Strasbourg
Karlsruhe Institute of Technology (KIT)
S. J. van der Molen
Leiden University
Beilstein Journal of Nanotechnology
21904286 (eISSN)
Vol. 5 1 1664-1674Subject Categories
Materials Engineering
Nano Technology
DOI
10.3762/bjnano.5.177