Abstract
In a recent paper Ciszek et al. [J.W. Ciszek, M.P. Stewart, J.M. Tour, J. Am. Chem. Soc. 126 (2004) 13172] showed that organic thiocyanates
may be an interesting alternative to the use of thiols for thiolate assemblies. We use scanning tunnelling microscopy (STM),
infrared reflection absorption and sum-frequency generation spectroscopies (IRRAS and SFG) in order to study the adsorption properties
of decyl thiocyanates (DTCN) and compare them to the decanethiol (DT) ones. Firstly, IRRAS measurements show that DTCN
molecules form self-assembled monolayers (SAMs) on gold via a thiolate link with the metallic substrate. Secondly, the DTCN SAM on
gold is less ordered than the DT one as highlighted by SFG spectroscopy. Indeed, the intensities of the methyl vibration modes vanish
while the methylene ones increase when DTCN molecules are adsorbed on the substrate instead of DT. We explain the differences in
SAMs quality on the basis of STM measurements which reveal differences in molecular order and packing.
Original language | English |
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Pages (from-to) | 4052-4057 |
Number of pages | 6 |
Journal | Surface Science |
Volume | 600 |
Issue number | 18 |
Publication status | Published - 2006 |
Keywords
- Sum-frequency generation spectroscopy
- Self-assembled monolayers
- Decyl thiocyanate
- Scanning tunnelling microscopy
- Decanethiol