Temperature and Overpotential Dependence of Long‐Range Electron Transfer across a Self‐Assembled Monolayer with Pendant Ruthenium Redox Centers

Finklea, Harry O.; Ravenscroft, Melissa S.

doi:10.1002/ijch.199700022

Cited by 20 publications

(11 citation statements)

References 35 publications

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“…Reorganization energies of both the oxidized and reduced forms can be obtained from Tafel plots of redox couples attached to self-assembled monolayers (SAMs) on electrodes [24][25][26][27][28][29][30][31][32][33][34][35][36]. In this work, we describe the electron tranfer kinetics of 4-amino-TEMPO Å coupled to a SAM with pendant carboxylic acid moieties.…”

Section: Introductionmentioning

confidence: 99%

Reorganization energies of TEMPO/TEMPO+ in water

Finklea

Madhiri

2008

Journal of Electroanalytical Chemistry

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Section: Introductionmentioning

confidence: 99%

Reorganization energies of TEMPO/TEMPO+ in water

Finklea

Madhiri

2008

Journal of Electroanalytical Chemistry

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“…The aligned orientation of alkanethiol molecules is one of the most attractive features of the self-assembled monolayers (SAMs) of such molecules. The monolayers of various types of alkanethiol derivatives with covalently tethered electroactive groups have been investigated in detail. − In such SAMs, it is expected that the orientation of the electroactive moiety, lateral interaction among the active centers, and microenvironment for them are highly regulated. The structure of the SAM may be governed by a number of factors including alkyl chain length, counterion involved in the redox reaction, and surface density of the thiol.…”

Section: Introductionmentioning

confidence: 99%

Voltammetric and Electroreflectance Study of Thiol-Functionalized Viologen Monolayers on Polycrystalline Gold: Effect of Anion Binding to a Viologen Moiety

et al. 1999

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The monolayers of thiol-functionalized viologens, i.e., dihexafluorophosphate salts of N-butyl-N‘-(4-mercaptobutyl)-4,4‘-bipyridinium (C4V2+C4SH) and N-pentyl-N‘-(5-mercaptopentyl)-4,4‘-bipyridinium (C5V2+C5SH), on a polycrystalline gold electrode were characterized in several aqueous electrolyte solutions using cyclic voltammetry and electroreflectance (ER) spectroscopy. The voltammetric response for the viologen dication/radical cation couple (V2+/V•+) in Na2SO4, K2SO4, KPF6, or KF solution was found to be electrolyte anion dependent. However, considerable differences due to the electrolyte anion or the alkyl chain length in the fractional content of dimer forms in the V•+ state and the average orientation of the V•+ moiety, both estimated from the results of ER spectral measurements, were not observed. A large voltammteric peak width was observed in KF solution. Because the voltammetric measurements suggested a strong and weak binding to the viologen moiety respectively for PF6 - and F- ions, the dependence of voltammetric response on the concentration of PF6 - was investigated quantitatively for a monolayer of C4V2+C4SH in the mixed solutions of KPF6 and KF at a constant ionic strength. It was found that one PF6 - ion additionally binds to a viologen moiety upon the oxidation of V•+ to V2+. The ratio of the binding constant to V2+ and V•+ was estimated to be approximately 1.2 × 104 M-1 at an ionic strength of electrolyte of 0.4 M. The absence of considerable dependence of the PF6 - binding on the ionic strength was suggested by voltammetric measurements in the solutions containing solely KPF6. The electron-transfer rate constants for the monolayers were estimated to be no less in the order of magnitude than 1 × 104 s-1.

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“…Chidsey and co-workers reported on this class of eSAM in 1990, , and they showed that it is possible to correlate the shift in the redox potential of the ferrocene moiety to the length of the alkyl chain. Subsequently, eSAMs have been extensively studied to better understand SAM structure and functionality, − electrochemical desorption of alkylthiols, − the formation and exchange of alkylthiol SAMs, ,, and fundamental aspects of electron transfer. ,− One conclusion that has emerged from these types of studies is that eSAMs containing exclusively ferrocene-terminated alkylthiols are disordered. , Consequently, mixed monolayers, composed of ferrocene-terminated alkylthiols and non-electroactive, shorter chain alkylthiols, are typically employed to improve ordering within the monolayer. , Additionally, the Schmittel and Plaxco groups have recently demonstrated that ferrocene-terminated eSAMs can decompose over the span of just minutes due to the instability of the ferrocenium redox state. − Despite this instability, eSAMs consisting of ferrocene-terminated alkylthiols are considered to be well-defined model systems.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic Surface Titrations of Electroactive Thin Films

Anderson

Crooks

2017

Langmuir

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We report the use of microfluidic surface titrations (MSTs) for studying electroactive self-assembled monolayers (eSAMs) and other thin films. The technique of MST utilizes a microfluidic generation-collection dual channel electrode (DCE) configuration to quantify the charge associated with electroactive thin films that might or might not be in direct contact with an electrode surface. This technique allows for quantitative measurement of surface coverages, Γ, as low as 30 pmol cm for electrodeposited Cu thin films. Additionally, we show that it is possible to quantify Γ for ferrocene (Fc)-terminated alkylthiols in mixed-monolayer eSAMs. Interestingly, MSTs sometimes reveal a two-fold higher eSAM concentration compared to direct electrochemical measurements. This finding suggests that in these instances not all the constituent Fc-moieties of the eSAM are in sufficiently close proximity to the surface to be addressable via direct electrochemistry.

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Temperature and Overpotential Dependence of Long‐Range Electron Transfer across a Self‐Assembled Monolayer with Pendant Ruthenium Redox Centers

Cited by 20 publications

References 35 publications

Reorganization energies of TEMPO/TEMPO+ in water

Reorganization energies of TEMPO/TEMPO+ in water

Voltammetric and Electroreflectance Study of Thiol-Functionalized Viologen Monolayers on Polycrystalline Gold: Effect of Anion Binding to a Viologen Moiety

Microfluidic Surface Titrations of Electroactive Thin Films

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