Monolayers having large in-plane dipole moments: characterization of sulfone-containing self-assembled monolayers of alkanethiols on gold by Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and wetting

Abstract

Monolayers were formed from alkyl chain molecules having large in-plane dipole moments. The molecular species introduced was a sulfone moiety, and it was found that its incorporation strongly affected the molecular conformation within the monolayer. The effect of varying the position of the sulfone group in an otherwise straight alkyl chain, while constant molecular length was maintained, was studied, and the results were compared to those found for an octadecanethiol (ODT). The monolayers were characterized by Fourier transform infrared reflection absorption spectroscopy and X-ray photoelectron spectroscopy and by their wetting properties.

Fluorescent monolayer protected gold nanoparticles – Preparation and structure elucidation

“…3). This result is very consistent with the spectra of the alkanethiol self-assembled monolayers on polycrystalline gold [35] and confirms the presence of a chemical bond between the AuNPs and the thiol moi- eties. We did not observe any signal in the S2p region of nonbonded sulfur (physisorbed thiol molecules) which is at $163.7 eV for S2p 3/2 [33].…”

Mercaptoethane sulfonate protected, water-soluble gold and silver nanoparticles: Syntheses, characterization and their building multilayer films with polyaniline via ion–dipole interactions

“…Fig. 5b illustrates the BE of the Au4f 7/2 and 4f 5/2 doublet are at 83.8 and 87.5 eV, respectively; they are typical values for metallic gold [43]. The absence of Au(I) and Ag(I) reveals there is no metal sulfide on the surface.…”

“…The S2p region in Figs. 5c and 5d is, unfortunately, not characterized by a doublet that arises from spin-orbit coupling (2p 3/2 and 2p 1/2 ), but only the peaks, which are originated from the -SO 3 Na sulfur and the thiol sulfur, can be resolved due to the fact that chemisorption of alkanethiols on gold gives the gold (Au δ+ ) thiolate (RS δ− ) species which lead to the thiol sulfur peak shifting to lower binding energy and that the oxygen is an electron withdrawing group which causes the peak of the -SO 3 Na sulfur shifting to a higher binding energy [43,44]. The difficulty to resolve the S2p 3/2 and S2p 1/2 consists in the weak signals of the S2p spectra, which results from the small scattering cross section of the S and the low amount of material present [42,45].…”

Self‐Assembled Monolayers on Electrodes

“…Considering just the family of w-substituted alkanethiols, the terminal substituent can be an alkane (linear, branched, perfluorinated, perdeuterated), alkene, alkyne, aromatic, halide, ether, alcohol, aldehyde, carboxylic acid, amide, ester, amine or nitrile. 18 -20 The ''body'' of the molecule can contain, for example, heteroatoms, 21 -24 aromatic groups, 25 -27 conjugated unsaturated links 28 -30 and other rigid rod structures, 31 -33 sulfones 24,34 and amides. 35,36 If the SAM is uniform in composition and densely packed, then a single functional group is exposed on the external surface.…”