Voltammetry at 115-180 K for self-assembled ferrocene-tagged alkanethiol monolayers on gold and silver electrodes in butyronitrile/ethyl chloride solvent

Curtin, Larry S.; Peck, Stephen; Tender, Leonard M.; Murray, Royce W.; Rowe, Gary K.; Creager, Stephen E.

doi:10.1021/ac00052a013

Cited by 55 publications

(27 citation statements)

References 35 publications

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“…A Janis/Leybold closed cycle helium cryostat was employed in which the electrochemical cell is mounted directly on the cold head of the cryostat. The electrode configuration has been reported previously 11 . Electrochemical equipment was locally constructed and of conventional design.…”

Section: Methodsmentioning

confidence: 99%

Cyclic Voltammetric Analysis of Ferrocene Alkanethiol Monolayer Electrode Kinetics Based on Marcus Theory

Tender¹,

Carter²,

Murray³

1994

Anal. Chem.

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242

234

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Theory for electrode kinetics of surface-immobilized monolayers in cyclic voltammetry is developed based on the Marcus free energy-rate relation. Numerical calculations show that when the applied overpotential exceeds ~30% of the reorganizational energy of the electrode reaction, voltammetry predicted from Marcus theory differs from that based on classical Butler-Volmer kinetics with regard to wave shape, peak currents and their dependence on potential sweep rate, and variation of peak potential with potential sweep rate. Estimates of the standard rate constant, A®, can be made from Epak data without exact knowledge of reorganizational energies.Examples are given of evaluating A® for monolayers of ferrocene alkanethiols chemisorbed on Au(lll) electrodes, when the monolayers are highly ordered, and kinetically monodisperse, and when they are somewhat disordered, and kinetically disperse on bulk gold electrodes at room and 150 K temperatures.Theory enabling measurement of heterogeneous electrontransfer rates from cyclic voltammetric oxidation-reduction peak potential separations, AEpeak, was presented some time ago by Nicholson and Shain1 for diffusing and by Laviron2 for diffusionless (i.e., surface bound) electrochemical systems. This methodology is appealing by its ease of application; standard electron-transfer rate constants (A°) result from analysis of the dependence of AE^v alues on potential sweep rate using numerically generated working curves1 or explicit expressions.2 These theoretical formulations are based on the Butler-Volmer3 free energy-rate relation, which in the context of modern electron-transfer theory due to Marcus,4 assumes that the applied potential (free energy, overpotential, = E -E°') is much smaller than the electrode reaction's reorganizational energy barrier ( ). This paper will describe the theoretical and experimental behavior of cyclic voltammetry of nondiffusing (immobilized) electrode reactants when is not negligible in comparison to , i.e., in or approaching what is commonly referred to as the Marcus inverted region.4•5 This contribution is made in the context of recent potential step experiments6•7 with electroactive, self-assembled monolayers in which the ratio / is not small. Cochemisorption of a mixture of the alkanethiols CH3(CH2)i5SH and CpFeCpC02(CH2),6SH

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Section: Methodsmentioning

confidence: 99%

Cyclic Voltammetric Analysis of Ferrocene Alkanethiol Monolayer Electrode Kinetics Based on Marcus Theory

Tender¹,

Carter²,

Murray³

1994

Anal. Chem.

Self Cite

242

234

View full text Add to dashboard Cite

show abstract

“…Developing the relationships between the molecular structure of the surface and its macroscopic properties required developing new protocols and techniques. Surface reflectance infrared spectroscopy, 27 transmission electron microscopy, 28 scanning probe microscopy, 29,30 contact angle goniometry, 31 contact angle titration, 32,33 ellipsometry, X-ray photoelectron spectroscopy, 34 and electrochemistry [35][36][37][38] established the broad characteristics of the formation and structure of SAMs of alkanethiolates on gold.…”

Section: Bridging Molecules To Surfaces Using Alkanethiolate Samsmentioning

confidence: 99%

Molecular engineering of Surfaces Using Self-Assembled Monolayers

2005

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The self-assembly of molecules into structurally organized monolayers (SAMs) uses the flexibility of organic chemistry and coordination chemistry to generate well-defined, synthetic surfaces with known molecular and macroscopic properties. The process of designing monolayers with a specified structure gives a high level of control over the molecular-level composition in the direction perpendicular to a surface; soft lithographic technique gives useful (if lower) resolution in the plane of the surface. Alkanethiolates adsorbed on gold, silver, mercury, palladium and platinum are currently the best-defined systems of SAMs. They provide substrates for a number of applications-from studies of wetting and electron transport to patterns for growing mammalian cells. SAMs have made organic surfaces a central part of surface science. Understanding the principles by which they form, and connecting molecular-level structure with macroscopic properties, opens a wide range of areas to study and exploitation.

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“…30%. Complex 4 was previously synthesized by Cattabriga and also Creager to study SAMs on mercury, gold, and silver.…”

Section: Resultsmentioning

confidence: 99%

“…From our failed attempts to obtain 10 and 14 utilizing the Creager approach, we conclude that short-chain ketoalkyl bromide precursors, such as FcCO(CH 2 ) 2 Br, are significantly less stable than their longer chain ( n ≥ 4) counterparts and that Clemmensen reduction is not suitable for carbonyl reduction of ferrocenoylbromoalkanes if the carbon side chain length possesses three carbon atoms or less. Other reducing methods are known, , but we searched here for an alternative synthetic protocol to obtain the desired ferrocenoylbromoalkanes 10 and 14 .…”

Section: Resultsmentioning

confidence: 99%

A DFT-Elucidated Comparison of the Solution-Phase and SAM Electrochemical Properties of Short-Chain Mercaptoalkylferrocenes: Synthetic and Spectroscopic Aspects, and the Structure of Fc–CH₂CH₂–S–S–CH₂CH₂–Fc

et al. 2016

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Facile synthetic procedures to synthesize a series of difficult-to-obtain mercaptoalkylferrocenes, namely, Fc(CH2)nSH, where n = 1 (1), 2 (2), 3 (3), or 4 (4) and Fc = Fe(η(5)-C5H5)(η(5)-C5H4), are reported. Dimerization of 1-4 to the corresponding disulfides 19-22 was observed in air. Dimer 20 (Z = 2) crystallized in the triclinic space group P1̅. Dimers 20-22 could be reduced back to the original Fc(CH2)nSH derivatives with LiAlH4 in refluxing tetrahydrofuran. Density functional theory (DFT) calculations showed that the highest occupied molecular orbital of 1-4 lies exclusively on the ferrocenyl group implying that the electrochemical oxidation observed at ca. -15 < Epa < 76 mV versus FcH/FcH(+) involves exclusively an Fe(II) to Fe(III) process. Further DFT calculations showed this one-electron oxidation is followed by proton loss on the thiol group to generate a radical, Fc(CH2)nS(•), with spin density mainly located on the sulfur. Rapid exothermic dimerization leads to the observed dimers, Fc(CH2)n-S-S-(CH 2)nFc. Reduction of the ferrocenium groups on the dimer occurs at potentials that still showed the ferrocenyl group ΔE = Epa,monomer - Epc,dimer ≤ 78 mV, indicating that the redox properties of the ferrocenyl group on the mercaptans are very similar to those of the dimer. (1)H NMR measurements showed that, like ferrocenyl oxidation, the resonance position of the sulfhydryl proton, SH, and others, are dependent on -(CH2)n- chain length. Self-assembled monolayers (SAMs) on gold were generated to investigate the electrochemical behavior of 1-4 in the absence of diffusion. Under these conditions, ΔE approached 0 mV for the longer chain derivatives at slow scan rates. The surface-bound ferrocenyl group of the metal-thioether, Fc(CH2)n -S-Au, is oxidized at approximately equal potentials as the equivalent CH2Cl2-dissolved ferrocenyl species 1-4. Surface coverage by the SAMs is dependent on alkyl chain length with the largest coverage obtained for 4, while the rate of heterogeneous electron transfer between SAM substrate and electrode was the fastest for the shortest chain derivative, Fc-CH2-S-Au.

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Voltammetry at 115-180 K for self-assembled ferrocene-tagged alkanethiol monolayers on gold and silver electrodes in butyronitrile/ethyl chloride solvent

Cited by 55 publications

References 35 publications

Cyclic Voltammetric Analysis of Ferrocene Alkanethiol Monolayer Electrode Kinetics Based on Marcus Theory

Cyclic Voltammetric Analysis of Ferrocene Alkanethiol Monolayer Electrode Kinetics Based on Marcus Theory

Molecular engineering of Surfaces Using Self-Assembled Monolayers

A DFT-Elucidated Comparison of the Solution-Phase and SAM Electrochemical Properties of Short-Chain Mercaptoalkylferrocenes: Synthetic and Spectroscopic Aspects, and the Structure of Fc–CH₂CH₂–S–S–CH₂CH₂–Fc

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Voltammetry at 115-180 K for self-assembled ferrocene-tagged alkanethiol monolayers on gold and silver electrodes in butyronitrile/ethyl chloride solvent

Cited by 55 publications

References 35 publications

Cyclic Voltammetric Analysis of Ferrocene Alkanethiol Monolayer Electrode Kinetics Based on Marcus Theory

Cyclic Voltammetric Analysis of Ferrocene Alkanethiol Monolayer Electrode Kinetics Based on Marcus Theory

Molecular engineering of Surfaces Using Self-Assembled Monolayers

A DFT-Elucidated Comparison of the Solution-Phase and SAM Electrochemical Properties of Short-Chain Mercaptoalkylferrocenes: Synthetic and Spectroscopic Aspects, and the Structure of Fc–CH2CH2–S–S–CH2CH2–Fc

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A DFT-Elucidated Comparison of the Solution-Phase and SAM Electrochemical Properties of Short-Chain Mercaptoalkylferrocenes: Synthetic and Spectroscopic Aspects, and the Structure of Fc–CH₂CH₂–S–S–CH₂CH₂–Fc