Issue 17, 2010

Structural characterization of self-assembled monolayers of pyridine-terminated thiolates on gold

Abstract

Self-assembled monolayers (SAMs) fabricated on Au(111) substrates from a homologous series of pyridine-terminated organothiols have been investigated using ultra high vacuum infrared reflection adsorption spectroscopy (UHV-IRRAS), X-ray photoelectron spectroscopy (XPS), scanning tunnelling microscopy (STM) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. A total of 4 different pyridine-based organothiols have been investigated, consisting of a pyridine unit, one or two phenyl units, a spacer of between one and three methylene units and, finally, a thiol unit. For all pyridine-terminated thiols the immersion of Au-substrates in the corresponding ethanolic solutions was found to result in the formation of highly ordered and densely packed SAMs. For an even number of the methylene spacers between the SH group and the aromatic moieties, the SAM unit-cell is rather large, Image ID:b924246p-t1.gif, whereas in case of an odd number of methylene units a smaller unit cell is adopted, Image ID:b924246p-t2.gif. The tilt angle of the molecules amounts to 15°. In contrast to expectation, the pyridine-terminated organic surfaces exposed by the corresponding SAMs showed a surprisingly strong resistance with regard to protonation.

Graphical abstract: Structural characterization of self-assembled monolayers of pyridine-terminated thiolates on gold

Article information

Article type
Paper
Submitted
17 Nov 2009
Accepted
08 Feb 2010
First published
04 Mar 2010

Phys. Chem. Chem. Phys., 2010,12, 4459-4472

Structural characterization of self-assembled monolayers of pyridine-terminated thiolates on gold

J. Liu, B. Schüpbach, A. Bashir, O. Shekhah, A. Nefedov, M. Kind, A. Terfort and C. Wöll, Phys. Chem. Chem. Phys., 2010, 12, 4459 DOI: 10.1039/B924246P

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