Formation of a 2D phase in the electrochemical reduction of 4,4′-bipyridine on mercury in the presence of iodide ions via a desorption-nucleation, reorientation-nucleation mechanisms

Gómez, Lorenzo Martínez; Ruiz, Juan; Camacho, Luis; Rodríguez‐Amaro, Rafael

doi:10.1016/j.jelechem.2003.11.006

Cited by 5 publications

(12 citation statements)

References 17 publications

(28 reference statements)

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“…Examples described in recent reports include both nonfaradaic transitions [4][5][6][7] and faradaic ones [8][9][10][11][12]. The voltammetric peak position, wave-shape, and dependence on the time-scale of the experimental parameters, such as a potential scan rate, tell us a plenty of information of thermodynamics and kinetics.…”

Section: Introductionmentioning

confidence: 99%

Formation of viologen radical cation condensed phase through two-dimensional molecular organization process on an HOPG electrode surface in binary viologen solutions

Tanaka

Sagara

2008

Journal of Electroanalytical Chemistry

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Viologens possessing long alkyl chains are condensed to monolayers of their radical cations upon one-electron reduction on a basal plane of a highly-oriented pyrolytic graphite (HOPG) electrode in contact with not only one-component viologen aqueous solutions but also binary mixtures. For three types of binary mixtures of viologen including ten different combinations, the condensed phase formation processes were described using the results of voltammetric measurements. First, in the case of the binary mixture of symmetric di-alkyl viologens (dA) with different chain lengths, two-dimensional (2D) phase separation into two domains took place in the course of cathodic potential scan in a certain range of the solution molar fraction when the chain length difference is two methylene units or more. Second, in the case of the mixture of a dA and its both-end carboxylated derivative (bis-carboxylated viologen: bC), either pure bC condensed phase or dA + bC well-mixed phase covered the entire surface area.Third, in the case of the mixture of dA and bC with far different chain lengths, the molar fraction dependent condensation processes took place while bC always dominates the phase formation behavior. The implications of these results were discussed as typical 2D molecular nano-organization processes in the terms of homo-and hetero-intermolecular interactions on the HOPG surface.

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Section: Introductionmentioning

confidence: 99%

Formation of viologen radical cation condensed phase through two-dimensional molecular organization process on an HOPG electrode surface in binary viologen solutions

Tanaka

Sagara

2008

Journal of Electroanalytical Chemistry

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] This phenomenon has been understood as being a two-dimensional (2D) faradaic phase transition. One-electron reduction of viologen to mono-radical mono-cation is accompanied by the formation of the condensed phase.…”

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confidence: 99%

Molecular Structure Dependence of the Phase Transition Spike Response of Viologens at an HOPG Electrode Using Bisviologen and Carboxylated Viologen

Sagara

Fujihara

Tada

2005

J. Electrochem. Soc.

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Behavior of a bisviologen and a carboxylated viologen in their faradaic phase transition at a highly ordered pyrolytic graphite (HOPG) electrode between a gas-like adsorption layer and a two-dimensional condensed phase was studied. Bisviologen (bis-V) possesses two 4,4′ -bipyridinium moieties, and a carboxylated viologen (V-COOH) does carboxyl groups at both terminals of the alkyl chains. The results of the voltammetric measurements were compared with heptyl viologen (HV) with a focus on the intermolecular lateral interaction among radical cations of the viologens in the condensed phase. It was found that the intermolecular attractive interaction between neighboring reduced forms of bis-V is stronger than that of HV, indicating that intermolecular stacking of two radical cation moieties per molecule appears dominant over the negative effect of the possible chance of the presence of out-of-gear molecule pairs due to the mismatch in the neighboring molecule stacking upon the transition. The potential width of the bistable region of the phase transition for V-COOH exceeded 120mV in an acidic medium due to the effective positive contribution of hydrogen bonding to the intermolecular attraction in the condensed phase on the hydrophobic basal plane of the HOPG electrode, while the contribution vanished in a basic medium. These results revealed that the voltammetric spike response of the phase transition can be a direct measure of the strength of two-dimensional intermolecular interaction on the electrode surface. Characteristics of the phase transition behavior of V-COOH were also described in regard to temperature, concentration, and potential sweep rate dependencies. Implications of these characteristics were discussed in consideration of the dynamics of the assembling process of reduced forms of V-COOH into the condensed layer. In the tests of the additives, only trimesic acid among the carboxylic acids used exhibited the activity as a hydrogen bonding inhibitor.

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“…The j − t curves for the first step were analyzed in previous work . The chronoamperometric behavior of this system can be explained in the light of a mathematical model that assumes a desorption−nucleation mechanism involving molecular reorientation and is described later on.…”

Section: Resultsmentioning

confidence: 99%

“…j 1 ( t ) was obtained as described in a previous paper, in the light of the model based on the desorption−nucleation-reorientation mechanism, using to the expression where θ( t ) is the time-dependent surface coverage by randomly adsorbed BpyH 2 2+ −counterion pairs; S 1 ( t ) is the time-dependent surface coverage by molecules involved in the nucleation and growth (NG) process; k d and k i are the rate constants of adsorption and desorption, respectively, of BpyH 2 2+ −counterion pairs; and k r is the reorientation rate constant for BpyH 2 2+ .…”

Section: Resultsmentioning

confidence: 99%

“…However, the chronoamperometric study exposed a complex behavior that cannot be accurately described by available models. Recently, our group developed a mathematical model based on a desorption−nucleation, reorientation−nucleation mechanism that accounts for the behavior of this system provided the phase formation processes involved are well resolved (below 18 °C) …”

Section: Introductionmentioning

confidence: 99%

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Chronoamperometric Study of the Films Formed by 4,4‘-Bipyridyl Cation Radical Salts on Mercury in the Presence of Iodide Ions: Consecutive Two-Dimensional Phase Transitions

Gómez

Camacho

et al. 2004

Langmuir

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Formation of a 2D phase in the electrochemical reduction of 4,4′-bipyridine on mercury in the presence of iodide ions via a desorption-nucleation, reorientation-nucleation mechanisms

Cited by 5 publications

References 17 publications

Formation of viologen radical cation condensed phase through two-dimensional molecular organization process on an HOPG electrode surface in binary viologen solutions

Formation of viologen radical cation condensed phase through two-dimensional molecular organization process on an HOPG electrode surface in binary viologen solutions

Molecular Structure Dependence of the Phase Transition Spike Response of Viologens at an HOPG Electrode Using Bisviologen and Carboxylated Viologen

Chronoamperometric Study of the Films Formed by 4,4‘-Bipyridyl Cation Radical Salts on Mercury in the Presence of Iodide Ions: Consecutive Two-Dimensional Phase Transitions

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