Self-Assembly of amino-thiols via gold-nitrogen links and consequence for in situ elongation of molecular wires on surface-modified electrodes

Ashwell, Geoffrey J., Williams, Aled T., Barnes, Susan A., Chappell, Sarah L., Phillips, Laurie J., Robinson, Benjamin J., Urasinska-Wojcik, Barbara, Wierzchowiec, Piotr, Gentle, Ian R. and Wood, Barry J. (2011) Self-Assembly of amino-thiols via gold-nitrogen links and consequence for in situ elongation of molecular wires on surface-modified electrodes. Journal of Physical Chemistry C: Nanomaterials and Interfaces, 115 10: 4200-4208. doi:10.1021/jp200006j


Author Ashwell, Geoffrey J.
Williams, Aled T.
Barnes, Susan A.
Chappell, Sarah L.
Phillips, Laurie J.
Robinson, Benjamin J.
Urasinska-Wojcik, Barbara
Wierzchowiec, Piotr
Gentle, Ian R.
Wood, Barry J.
Title Self-Assembly of amino-thiols via gold-nitrogen links and consequence for in situ elongation of molecular wires on surface-modified electrodes
Journal name Journal of Physical Chemistry C: Nanomaterials and Interfaces   Check publisher's open access policy
ISSN 1932-7447
Publication date 2011-03
Sub-type Article (original research)
DOI 10.1021/jp200006j
Volume 115
Issue 10
Start page 4200
End page 4208
Total pages 9
Place of publication Washington, DC United States
Publisher American Chemical Society
Collection year 2012
Language eng
Formatted abstract
The stepwise synthesis of molecular wires on goldnanoparticles and gold electrodes has been performed using amino-terminated and aldehyde-terminated thiols as
anchoring groups to provide surface-active sites for imino coupling. X-ray photoelectron spectroscopy provides evidence that 4-mercaptoaniline (1) binds via either substituent, Au-S-C6H4-NH2 (N 1s, 400.1 eV) or Au-N(H2)-C6H4-SH (N 1s, 399.1 eV), therefore depleting the number of reactive amine sites at the surface. In contrast, 4-[(4-mercaptophenylimino)methyl]benzaldehyde (2) binds exclusively via a thiolate link (Au-S-wire-CHO) and, in relation to the former, highlights the significance of the second substituent. Amines compete with thiols for self-assembly on gold andmay even bond via deprotonated nitrogen. For instance, 4-{(E)-1,3-dihydro-2H-benzimidazol- 2-thione-5-yl)imino]methyl}benzaldehyde (3) binds via a nitrogen of the imidazole ring and the self-assembledmonolayer (SAM) exhibits a 2.2 eV shift of the N 1s binding energy (SAM, 398.3 eV; solid sample, 400.5 eV) compared with a 1.0 eV shift for 1. Its in situ formed molecular wires with one to five bridged anthraquinone units exhibit symmetrical current-voltage characteristics, but the behavior alters to rectifying when the electron-accepting sequence is terminated by a 4-(dimethylamino)-1-naphthalene donor. Forward bias corresponds to electron flow from cathode to acceptor and from donor to anode, but the electrical asymmetry is dependent upon the number of bridging units. Molecules with two anthraquinones exhibit an optimum rectification ratio of 55 at ±1 V.
Keyword Crystal-structure
Gold (iii) complexes
Template synthesis
Click chemistry
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
School of Chemistry and Molecular Biosciences
 
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Created: Sun, 27 Mar 2011, 00:08:28 EST