Alkanethiolates, gold

S. J. Green, J. J. Stokes, G. D. Wignall, G. L. GUsh, M. D. Porter, N. D. Evans, and R. W. Murray, Alkanethiolate gold cluster molecules with core diameters from 1.5 to 5.2 nm Core and monolayer properties as a function of core size, Langmuir 14,17—30 (1998). 

Maitani MM, Daniel TA, Cabarcos OM, Allara DL (2009) Nascent metal atom condensation in self-assembled monolayer matrices coverage-driven morphology transitions from buried adlayers to electrically active metal atom nanofilaments to overlayer clusters during aluminum atom deposition on alkanethiolate/gold monolayers. J Am Chem Soc 131 (23) 8016-8029... 

Murray, Alkanethiolate gold cluster molecules with cotc diameters from 1.5 to 5.2 nm core and monolayer properties as a fimction of cote size. Langmuir 14, 17-30 (1998)... 

The alkanethiol-gold interaction (RSH/Au or R1R2S/AU where R = alkyl chain. Figure 8a) whether spontaneous or electrochemically induced, from solution or vapor deposition, is widely exploited due to ease of fabrication, degree of perfection, and thickness control with 0.1 nm... 

Alkanethiols and other sulfur-bearing hydrocarbons covalently attach to metal surfaces alkanethiol onto gold is the most widely studied of these systems [27-29,31,32,45]. These SAMs are ordered provided the alkane chain contains nine or more carbons [32]. Binary solutions of two alkanethiols also appear... 

The self-assembly of alkanethiols on gold has been an important topic in surface chemistry over die last few years [39] and STM has contributed significantly to our understanding of these systems. In particular, the... 

Laibinis P E, Flickman J J, Wrighton M S and Whitesides G M 1989 Orthogonal self-assembled monolayers— alkanethiols on gold and alkane carboxylic-acids on alumina Science 245 845-7... 

Flahner G, Wdll C, Buok M and Grunze M 1993 Investigation of intermediate steps in the self-assembly of n-alkanethiols on gold surfaoes by soft-x-ray speotrosoopy Langmuirs 1955-8... 

Liedberg B and Tengvall P 1995 Moleoular gradients of -substituted alkanethiols on gold preparation and oharaoterization Langmuir 3821-7... 

Atre S V, Liedberg B and Allara D L 1995 Chain length dependenoe of the struoture and wetting properties in binary oomposition monolayers of OH and CHj-terminated alkanethiolates on gold Langmuir 3882-93... 

DiMilla P A, Folkers J P, Biebuyck H A, Harter R, Lopez G P and Whitesides G M 1994 Wetting and protein adsorption of the self-assembled monolayers of alkanethiolates which are supported on transparent films of gold J. Am. Chem. Soc. 116 2225-6... 

Terril R H ef a/1995 Monolayers in three dimensions NMR, SAXS, thermal and eleotron hopping studies of alkanethiol stabilized gold olusters J. Am. Chem. Soc. 117 12 537... 

Hosteler M J ef a/1996 Monolayers in three dimensions synthesis and eleotroohemistry of w-funotionalized alkanethiolate stabilized gold oluster oompounds J. Am. Chem. Soc. 118 4212... 

Hostetler M J, Stokes J J and Murray R W 1996 Infrared speotrosoopy of three-dimensional self-assembled monolayers n-alkanethiolate monolayers on gold oluster oompounds Langmuir M 3604... 

Organosulfur Adsorbates on Metal and Semiconductor Surfaces. Sulfur compounds (qv) and selenium compounds (qv) have a strong affinity for transition metal surfaces (206—211). The number of reported surface-active organosulfur compounds that form monolayers on gold includes di- -alkyl sulfide (212,213), di- -alkyl disulfides (108), thiophenols (214,215), mercaptopyridines (216), mercaptoanilines (217), thiophenes (217), cysteines (218,219), xanthates (220), thiocarbaminates (220), thiocarbamates (221), thioureas (222), mercaptoimidazoles (223—225), and alkaneselenoles (226) (Fig. 11). However, the most studied, and probably most understood, SAM is that of alkanethiolates on Au(lll) surfaces. 

Fig. 11. Surface-active organosulfur compounds that form monolayers on gold (a) alkanethiol (b) dialkyl disulfide (c) dialkyl sulfide (d) alkyl xanthate ...

Chemisorption of alkanethiols as well as of di- -alkyl disulfides on clean gold gives indistinguishable monolayers (251) probably forming the Au(l) thiolate species. A simple oxidative addition of the S—S bond to the gold surface is possibly the mechanism in the formation of SAMs from disulfides ... 

In the alkanethiol case, the reaction may be considered formally as an oxidative addition of the S—H bond to the gold surface, followed by a reductive elimination of the hydrogen. When a clean gold surface is used, the proton probably ends as a molecule. Monolayers can be formed from the gas phase (241,255,256), in the complete absence of oxygen ... 

Eig. 12. Hexagonal coverage scheme for alkanethiolates on Au(lll), where (0) gold atoms and (Oj are sulfur atoms. 

The above stm study also discovered a facile transport of surface gold atoms in the presence of the Hquid phase, suggesting that the two-step mechanism does not provide a complete picture of the surface reactions, and that adsorption/desorption processes may have an important role in the formation of the final equiHbrium stmcture of the monolayer. Support for the importance of a desorption process comes from atomic absorption studies showing the existence of gold in the alkanethiol solution. The stm studies suggest that this gold comes from terraces, where single-a tomic deep pits are formed (281—283). 

---