Alkane-thiols

Sheen C W, Martensson J, Shi J, Parikh A N and Allara D L A 1992 New class of organized self-assembled monolayers—alkane thiols on GaAs(IOO) J. Am. Chem. Soc. 114 1514-5... 

Hydrogen cyanide and alkane thiols have p/C values in the 9to 10 range and the p/C for acetylene is 26... 

Ethylene oxide Acids and bases, alcohols, air, 1,3-nitroaniline, aluminum chloride, aluminum oxide, ammonia, copper, iron chlorides and oxides, magnesium perchlorate, mercaptans, potassium, tin chlorides, alkane thiols... 

Kruger, D., Fuchs, H., Rousseau, R., Marx, D. and Parinello, M. (2001) Interaction of short-chain alkane thiols and thiolates with small gold clusters Adsorption structures and energetics. Journal of Chemical Physics, 115, 4776-4786. 

The use of tetraoctylammonium salt as phase transfer reagent has been introduced by Brust [199] for the preparation of gold colloids in the size domain of 1-3 nm. This one-step method consists of a two-phase reduction coupled with ion extraction and self-assembly using mono-layers of alkane thiols. The two-phase redox reaction controls the growth of the metallic nuclei via the simultaneous attachment of self-assembled thiol monolayers on the growing clusters. The overall reaction is summarized in Equation (5). 

Careful TEM analyses (with alkane thiols) clearly showed that the big prismatic particles are indeed broken into small particles (Figure 20) upon ligand addition [32]. 

All in aqueous solution at 25°C unless otherwise noted equilibrium constants have dimensions of M. Various alkane thiols, of similar equilibrium reactivity. Methylamine or a primary alkyl amine of similar reactivity. Dimethylamine or a secondary alkyl amine of similar reactivity °Reference 30. Reference 14. RSH is mercaptoethanol. Reference 31. Reference 32. Reference 33. Reference 21. RSH is ethanethiol " Reference 34. Reference 35. Reference 36. Reference 37. RSH is 2-methoxyethanethiol. Reference 38. Reference 39. Reference 40. Reference 23. Reference 41. Reference 31. Reference 42. Reference 5. Reference 43. In ethanol. Reference 44. Reference 45. Reference 46. RNKj is n-butylamine. "Reference 47. 

Fig. II (continued) coordinates corresponding to the various peaks are shown in sketches on the bottom and, by reconstructing all of these, the eventual transport picture in the blobbish sketch above emerges - the current goes through the a system in the alkane thiol end, transfers to the n system to pass through the naphthalene, and then back into the o system through the ether to the other electrode. From [108] copyright 2011 by the National Academy of Sciences...

As well as fluorescence-based assays, artificial membranes on the surface of biosensors offered new tools for the study of lipopeptides. In a commercial BIA-core system [231] a hydrophobic SPR sensor with an alkane thiol surface was incubated with vesicles of defined size distribution generating a hybrid membrane by fusion of the lipid vesicles with the alkane thiol layer [232]. If the vesicles contain biotinylated lipopeptides their membrane anchoring can be analyzed by incubation with streptavidine. Accordingly, experiments with lipopeptides representing the C-terminal sequence of N-Ras show clear differences between single and double hydrophobic modified peptides in their ability to persist in the lipid layer [233]. 

The results summarized above were obtained by using fluorescence based assays employing phospholipid vesicles and fluorescent labeled lipopeptides. Recently, surface plasmon resonance (SPR) was developed as new a technique for the study of membrane association of lipidated peptides. Thus, artificial membranes on the surface of biosensors offered new tools for the study of lipopeptides. In SPR (surface plasmon resonance) systemsI713bl changes of the refractive index (RI) in the proximity of the sensor layer are monitored. In a commercial BIAcore system1341 the resonance signal is proportional to the mass of macromolecules bound to the membrane and allows analysis with a time resolution of seconds. Vesicles of defined size distribution were prepared from mixtures of lipids and biotinylated lipopeptides by extruder technique and fused with a alkane thiol surface of a hydrophobic SPR sensor. 

FIGURE 1.24. Potential-dependent forward and backward rate constants of the ferrocene-ferrocenium couple attached to a gold electrode hy a long-chain alkane thiol assembled together with unsubstituted alkane thiols of similar length. Solid line use of Equations (1.37) to (1.39) with X, = 0.85 eV, ks — 1.25 s 1. Adapted from Figure 4A in reference 65, with permission from the American Association for the Advancement of Science. 

The preparation of thiols by nucleophilic displacement reactions using aqueous potassium or sodium hydrogen sulphide under catalytic conditions is not particularly effective. A limited number of simple alkane thiols have been obtained under mild and neutral conditions in moderate yield (70-80%) from the reaction of bis(n-butyltin) sulphide with bromoalkanes in the presence of a ca. twofold amount of tetra-n-butylammonium fluoride [1], but there has been no exploitation of this procedure. 

The possibilities afforded by SAM-controlled electrochemical metal deposition were already demonstrated some time ago by Sondag-Huethorst et al. [36] who used patterned SAMs as templates to deposit metal structures with line widths below 100 nm. While this initial work illustrated the potential of SAM-controlled deposition on the nanometer scale further activities towards technological exploitation have been surprisingly moderate and mostly concerned with basic studies on metal deposition on uniform, alkane thiol-based SAMs [37-40] that have been extended in more recent years to aromatic thiols [41-43]. A major reason for the slow development of this area is that electrochemical metal deposition with, in principle, the advantage of better control via the electrochemical potential compared to none-lectrochemical methods such as electroless metal deposition or evaporation, is quite critical in conjunction with SAMs. Relying on their ability to act as barriers for charge transfer and particle diffusion, the minimization of defects in and control of the structural quality of SAMs are key to their performance and set the limits for their nanotechnological applications. 

Similar to other fundamental studies on SAMs, alkane thiols on Au(l 11) have also been prevailing in electrochemistry with, however, aromatic thiols receiving increased attention. A major topic has been formation and stability of SAMs and... 

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