Self-assembled organic monolayers terminated in perfluoroalkyl pentafluoro-lambda(6)-sulfanyl (-SF5) chemistry on gold

Citation

Winter, R.; Nixon, P. G.; Gard, G. L.; Graham, D. J.; Castner, D. G.; Holcomb, N. R.; & Grainger, D. W. (2004). Self-assembled organic monolayers terminated in perfluoroalkyl pentafluoro-lambda(6)-sulfanyl (-SF5) chemistry on gold. Langmuir: the ACS journal of surfaces and colloids, 20(14), 5776-5781.

Abstract

Recently synthesized (Winter, R.; Nixon, P. G.; Gard, G. L.; Radford, D. H.; Holcomb, N. R.; Grainger, D. W. J. Fluorine Chem. 2001, 107, 23-30) SF5-terminated perfluoroalkyl thiols (SF5(CF2)nCH2CH2SH, where n = 2, 4, and 6) and a symmetric SF5-terminated dialkyl disulfide ([SF5-CH=CH-(CH2)8-S-]2) were assembled as thin films chemisorbed onto gold surfaces. The adsorbed monolayer films of these SF5-containing molecules on polycrystalline gold were compared using ellipsometry, contact angle, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and infrared spectroscopy (FTIR) surface analytical methods. The resulting SF5-dialkyl disulfide monolayer film shows moderate angle dependence in depth-dependent XPS analysis, suggesting a preferentially oriented film. The SF5-terminated perfluoroalkyl thiols exhibit angular-dependent XPS compositional variance depending on perfluoroalkyl chain length, consistent with improved film assembly (increasingly hydrophobic, fewer defects, and more vertical chain orientation increasing film thickness) with increasing chain length. Tof-SIMS measurements indicate that both full parent ions for these film-forming molecules and the unique SF5 terminal group are readily detectable from the thin films without substantial contamination from other adsorbates.

Keyword(s)

Fluorocarbons
gold
Mass Spectrometry
Membranes, Artificial
Molecular Conformation
Sensitivity and Specificity
Spectrophotometry
Spectroscopy, Fourier Transform Infrared
Sulfhydryl Compounds
Surface Properties
X-Rays

Reference Type

Journal Article

Secondary Title

Langmuir: the ACS journal of surfaces and colloids

Author(s)

Winter, R.
Nixon, P. G.
Gard, G. L.
Graham, D. J.
Castner, D. G.
Holcomb, N. R.
Grainger, D. W.

Year Published

2004

Date Published

1089072000

Volume Number

20

Issue Number

14

Pages

5776-5781