Thiol monolayers

Porter M D, Bright T B, Allara D L and Chidsey C E D 1987 Spontaneously organized molecular assemblies. 4. Structural characterization of normal-alkyl thiol monolayers on gold by optical ellipsometry, infrared-spectroscopy, and electrochemistry J. Am. Chem. Soc. 109 3559-68... 

Bertilsson L and Liedberg B 1993 Infrared study of thiol monolayers assemblies on gold—preparation, oharaoterization, and funotionalization of mixed monolayers Langmuir 3 141-9... 

Ruths, M., Boundary Eriction of Aromatic Self-Assembled Monolayers Comparison of Systems with One or Both Sliding Surfaces Covered with a Thiol Monolayer," Langmuir, Vol. 19,2003,pp.67-88. 

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). 

Fig. 13 Self-assembled linkage of ferrocene-modified glucose oxidase (GOD) on thiol monolayer...

Jadzinsky PD, Calero G, Ackerson CJ et al (2007) Structure of a thiol monolayer - protected gold nanoparticle at 1.1 A resolution. Science 318 430-433... 

Gold particulate films have been formed under thiol monolayers spread on aqueous HAuC14 solutions by exposure to carbon monoxide exposure [110]. 

Fig. 94. Absorption spectra of gold particulate films formed under thiol monolayers spread on aqueous HAuC14 solutions exposed to CO prior (a) and subsequent (b) to annealing at 140 °C for 10 min (unpublished results)...

Adsorption has been used as a means of purposely modifying the electrode surface to form a chemically modified electrode [10]. This topic has received such attention since the first edition of this book that a separate chapter on modified electrodes is included in this edition (Chap. 13). An example is the self-assembly of a mixed thiol monolayer on a gold electrode such as the one illustrated in Figure 2.20 [11]. 

An innovative method to remove CTAB from gold nanorod surfaces and at the same time to protect them with thiols has been carried out by a place-exchange reaction inside an ionic exchange polymer. The trapping of gold nanorods inside polymer beads allows sufficient time for a stable thiol monolayer to form on the gold nanorod surface.257... 

Frequently, e.g. in the case of alkane thiol monolayers, the electrode is modified with a low-dielectric-constant layer. Film formation causes the Helmholtz layer to change from a mixture of ions and solvent with a high dielectric constant to an ion-free, often organic, layer with a low dielectric constant. The interfacial capacitance... 

Figure 4.9 Dependence of the reciprocal of the interfacial capacitance on the number of methylene groups, n, within alkane thiol monolayers. The symbols represent capacitances obtained from cyclic voltammograms, with filled symbols indicating data obtained at 10 mV s 1, and empty symbols those obtained at 100 mV s 1 M KC1 A, 1 M HC104 0,1 M NaF. Reprinted...

Table 4.1 Advancing contact angles on derivatized thiol monolayers on gold. HD = hexadecane.

The [Ru(NHs)5 pyridine]2+/3+ redox center exhibits well-defined, nearly ideal voltammetry across a wide range of electrolyte compositions, scan rates and temperatures. Despite the headgroups having comparable sizes, the saturation surface coverage is less than that found for ferrocene alkane thiol monolayers. This behavior is thought to reflect electrostatic repulsion between the polycationic redox centers and the need to incorporate counterions into the monolayer in both... 

Chidsey [30], Weber and Creager [31] and Murray and co-workers [32] have modeled non-adiabatic heterogeneous electron transfer for long-chain alkane thiol monolayers by using an expression similar to Equation (5.3), except that the energy-dependent prefactor in the tunneling probability expression is excluded. 

In this review, we will consider the adsorption of a single species coadsorption phenomena will not be considered, since it is generally impossible to divide the flow of charge among several species. We will present the thermodynamics on which the concept of the electrosorption valency is based, discuss methods by which it can be measured, and explain its relation to the dipole moment and to partial charge transfer. The latter can be explained within an extension of the Anderson-Newns model for adsorption, which is useful for a semi-quantitative treatment of electrochemical adsorption. Our review of concepts and methods will be concluded by a survey of experimental data on thiol monolayers, which nowadays are adsorbates of particular interest. 

The most common procedure for estimating X consists in measuring the thermodynamically significant electrosorption valency l and in evaluating its extrathermodynamic contributions k vkw and g of Eqs. (26) and (27) in order to extract the X value. A more direct extrathermodynamic procedure that relies exclusively on the Gouy-Chapman theory can be applied to the important class of self-assembled thiol monolayers anchored to a metal surface. 

IV. ELECTROSORPTION VALENCY AND PARTIAL CHARGE TRANSFER COEFFICIENT IN SELF-ASSEMBLED THIOL MONOLAYERS... 

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