Coadsorption of ferrocene-terminated and unsubstituted alkanethiols on gold: electroactive self-assembled monolayers

Chidsey, Christopher E. D.; Bertozzi, Carolyn R.; Putvinski, T. M.; Mujsce, A. M.

doi:10.1021/ja00167a028

Cited by 1,040 publications

(1,258 citation statements)

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“…38 In that work, a direct, nonpolar CH 2 linkage to the ferrocene was also examined and shown to result in much broader, nonideal voltammograms, even at coverages as low as 10%. It was hypothesized that the more polar linkage prevented the formation of aggregates of redox species.…”

Section: Resultsmentioning

confidence: 99%

Rate of Interfacial Electron Transfer through the 1,2,3-Triazole Linkage

et al. 2006

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The rate of electron transfer is measured to two ferrocene and one iron tetraphenylporphyrin redox species coupled through terminal acetylenes to azide-terminated thiol monolayers by the Cu(I)-catalyzed azide-alkyne cycloaddition (a Sharpless "click" reaction) to form the 1,2,3-triazole linkage. The high yield, chemoselectivity, convenience, and broad applicability of this triazole formation reaction make such a modular assembly strategy very attractive. Electron-transfer rate constants from greater than 60,000 to 1 s −1 are obtained by varying the length and conjugation of the electron-transfer bridge and by varying the surrounding diluent thiols in the monolayer. Triazole and the triazole carbonyl linkages provide similar electronic coupling for electron transfer as esters. The ability to vary the rate of electron transfer to many different redox species over many orders of magnitude by using modular coupling chemistry provides a convenient way to study and control the delivery of electrons to multielectron redox catalysts and similar interfacial systems that require controlled delivery of electrons.

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Section: Resultsmentioning

confidence: 99%

Rate of Interfacial Electron Transfer through the 1,2,3-Triazole Linkage

et al. 2006

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“…The high surface coverage for the SWCNT/ FMCA compared to SWCNT/FDCA suggests that the FMCA species probably coordinates more with SWCNTs via ester bonds as described above compared to its FDCA counterparts. It is known from Chidsey and co-workers 2,36,37 that high concentration of ferrocene adsorbates leads to asymmetric and broad voltammograms, hence high DE p values. Thus, the higher surface coverage shown by the FMCA-based electrode (Table 1) may further explain the poor DE p and E fwhm values of the SWCNT/FMCA compared to its SWCNT/FDCA counterpart.…”

Section: Heterogeneous Electron Transfer Dynamics In 05 M H 2 So 4 Smentioning

confidence: 99%

Heterogeneous electron transfer kinetics and electrocatalytic behaviour of mixed self-assembled ferrocenes and SWCNT layers

Nkosi

Pillay

Ozoemena

et al. 2010

Phys. Chem. Chem. Phys.

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The electron transfer dynamics and electrocatalytic behaviour of ferrocene-terminated self-assembled monolayers (SAMs), co-adsorbed with single-walled carbon nanotubes (SWCNTs) on a gold electrode, have been interrogated for the first time. Ferrocene monocarboxylic acid (FMCA) or ferrocene dicarboxylic acid (FDCA) was covalently attached to the cysteamine (Cys) monolayer to form Au-Cys-FMCA and Au-Cys-FDCA, respectively. The same covalent attachment strategy was used to form the mixed SWCNTs and ferrocene-terminated layers (i.e. Au-Cys-SWCNT/FMCA and Au-Cys-SWCNT/FDCA). Using cyclic voltammetry and electrochemical impedance spectroscopy, the impact of neighbouring SWCNTs on the electron transfer dynamics of the ferrocene molecular assemblies in an acidic medium (0.5 M H 2 SO 4 ) and in a solution of an outer-sphere redox probe ([Fe(CN) ) was explored. The electron transfer rate constants in both media essentially decreased as Au-Cys-FMCA 4 Au-Cys-SWCNT/FDCA 4 Au-Cys-FDCA 4 Au-Cys-SWCNT/FMCA. This trend has been interpreted in terms of several factors such as the locations of the ferrocene species in a range of environments with a range of potentials, the proximity/interactions of the ferrocenes with one another, and electrostatic interaction or repulsion existing between the negatively-charged redox probe and the modified electrodes. The thiocyanate ion (SCN À ) was used as a model analyte to examine the influence of the neighbouring SWCNTs on the electrocatalytic ability of the ferrocene assemblies. The Au-Cys-SWCNT/FDCA showed the best catalytic activity (in terms of onset potential and catalytic peak current height) for the oxidation of SCN À , possibly due to the repulsive interactions between the negatively charged SCN À and high number of surface -COOH species at the SWCNT/FDCA. This study has provided some useful insights as to how CNTs co-assembled with ferrocene-terminated thiols could impact on the electron transfer kinetics as well as the electrocatalytic detection of the self-assembled ferrocene layers.

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“…Through-bond tunneling is the electrontransfer mechanism that operates for Au-SAM-redox centers [25], [26] and [76]. Such through-bond process is easily established by reversible cyclic voltammetric plots, indicating that such redox centers can easily exchange electron with the underlying electrode surface vial tunneling [25], [26], [76], [77] and [78]. Thus, we can reasonably assume that efficient through-bond tunneling takes place between redox-active CoTAPc and gold at the Au-AET-SWCNT-CoTAPc electrode.…”

Section: Proposed Electron-transfer Mechanismmentioning

confidence: 99%