Tripodal Binding Units for Self-Assembled Monolayers on Gold: A Comparison of Thiol and Thioether Headgroups

Citation

Weidner, Tobias; Ballav, Nirmalya; Siemeling, Ulrich; Troegel, Dennis; Walter, Tim; Tacke, Reinhold; Castner, David G.; & Zharnikov, Michael (2009). Tripodal Binding Units for Self-Assembled Monolayers on Gold: A Comparison of Thiol and Thioether Headgroups. The Journal of Physical Chemistry C, 113(45), 19609-19617.

Abstract

Whereas thiols and thioethers are frequently used as binding units of oligodentate precursor molecules to fabricate self-assembled monolayers (SAMs) on coinage metal and semiconductor surfaces, their use for tridentate bonding configuration is still questionable. Against this background, novel tridentate thiol ligands, PhSi(CH2SH)3 (PTT) and p-Ph?C6H4Si(CH2SH)3 (BPTT), were synthesized and used as tripodal adsorbate molecules for the fabrication of SAMs on Au(111). These SAMs were characterized by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The PTT and BPTT films were compared to the analogous systems comprised of the same tripodal ligands with thioether instead of thiol binding units (anchors). XPS and NEXAFS data suggest that the binding uniformity, packing density, and molecular alignment of the thiol-based ligands in the respective SAMs are superior to their thioether counterparts. In addition, the thiol-based films showed significantly lower levels of contamination. Significantly, the quality of the PTT SAMs on Au(111) was found to be even higher than that of the films formed from the respective monodentate counterpart, benzenethiol. The results obtained allow for making some general conclusions on the specific character of molecular self-assembly in the case of tridentate ligands.

Reference Type

Journal Article

Secondary Title

The Journal of Physical Chemistry C

Author(s)

Weidner, Tobias
Ballav, Nirmalya
Siemeling, Ulrich
Troegel, Dennis
Walter, Tim
Tacke, Reinhold
Castner, David G.
Zharnikov, Michael

Year Published

2009

Date Published

1257984000

Volume Number

113

Issue Number

45

Pages

19609-19617

ISSN/ISBN

1932-7447

DOI

Tripodal Binding Units for Self-Assembled Monolayers on Gold10.1021/jp906367t