Gold-disulphide monolayers

The mechanism of formation of gold-thiol monolayers has been intensively investigated over the last decade. A detailed record of these studies is given in a recent review. Formation of monolayers from thiols is understood best, although some information on adsorption of disulphides and sulphides is also available. XPS analyses of the sulphur 2p peak in monolayers indicate that adsorption of thiols and disulphides on gold produces thiolate species, Raman spectra of monolayers of disulphides and thiols,... 

Beer and co-workers have investigated this concept using self-assembled monolayers of the l,l -bis(alkyl-iV-amido)ferrocene 106 on gold electrodes [72]. The pendant disulphide groups serve to covalently anchor the receptor to the gold surface. In electrochemical experiments on 106 in acetonitrile/dichloro-methane solution, anion-induced cathodic shifts of the ferrocene/ferrocenium... 

Viana, A. S. Kalaji, M. Abrantes, L. M. Self-assembled monolayers of Vitamin B12 disulphide derivatives on gold. Electrochimica Acta (2002) 47(10) 1587-1594. 

Liquid crystalline azobenzene polymers can undergo photoisomerization on irradiation at 360 or 450 nm on gold films. This permits changing the refractive index of the film depending upon the wavelength used136. A study has examined the photopolymerization of p-styrene sulphonate counteranions associated with monolayers of disulphide amphiphiles as self-assembled monolayers on gold137. 

The ability of disulphides and thiols to self-assemble on gold surfaces was discovered by Nuzzo and Allara in 198310, and in the 1990s these films have probably become the most studied monolayers worldwide. There are several reasons for such popularity. Sulphur has a very strong affinity for gold, and self-assembly proceeds rapidly to give... 

H. Schonherr, F.J.B. Kremer, S. Kumar, J.A. Rego, H. Wolf, H. Ringsdorf, M. Jaschke, FL-J. Butt, E. Bamberg, Self-assembled monolayers of discotic liquid crystalline thioethers, discoid disulphides and thiols on gold molecular engineering of ordered surfaces. J. Am. Chem. Soc. 118, 13051-13057 (1996)... 

More interestingly, electron transfer reaction of cytochrome c and other redox proteins occurs with fast rates at modified electrodes. The most efficient electrode surface promoters tend to be bifunctional molecules containing surface-active functional groups (thiol, disulphide, or pyridyl) which bind the promoter to the electrode surface and weakly basic or anionic functional groups (such as pyridyl nitrogen, carboxy-late, sulphonate or phosphate) which can bind the positively charged cytochrome c [188-190,204-211]. For instance, if a gold electrode is modified with 4,4 -bipyridine, this promoter forms a monolayer at the... 

Cordas CM, Viana AS, Leopold S, Montforts FP, Abrantes LM (2003) Self-assembled monolayer of an rron(lll) porphyrin disulphide derivative on gold. Electrochem Comm 5 36-41... 

Viana AS, Leupold S, Montforts FP, Abrantes LM (2005) Self-assembled monolayers of a disulphide-derivatised cobalt-porphyrin on gold. Electrochim Acta 50 2807-2813... 

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