Voltammetric determination of extreme standard Gibbs ion transfer energy

Olaya, Astrid J.; Méndez, Manuel A.; Cortés‐Salazar, Fernando; Girault, Hubert H.

doi:10.1016/j.jelechem.2010.03.030

Cited by 108 publications

(138 citation statements)

References 33 publications

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“…No contribution originating from the motion of nuclei (except for the deformation of geometries of fragments following the dissociation) was included in the BDEs. ) is initially present only in the aqueous phase, however, since it is a highly lipophilic anion, it transfers with a proton to the organic phase thereby polarizing the interface positively (water vs oil), 29 which favors the adsorption of both P 4+ and [P 4+ /P 4− ]. As soon as both phases are in contact, the color of the organic phase changes from yellow to dark red associated to the oxidation of TTF to TTF .…”

Section: Methodsmentioning

confidence: 99%

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

et al. 2011

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ABSTRACT:The self-assembly of the oppositely charged watersoluble porphyrins, cobalt tetramethylpyridinium porphyrin (CoTMPyP 4+ ) and cobalt tetrasulphonatophenyl porphyrin (CoTPPS 4− ), at the interface with an organic solvent to form molecular "rafts", provides an excellent catalyst to perform the interfacial four-electron reduction of oxygen by lipophilic electron donors such as tetrathiafulvalene (TTF). The catalytic activity and selectivity of the self-assembled catalyst toward the four-electron pathway was found to be as good as that of the Pacman type cofacial cobalt porphyrins. The assembly has been characterized by UV−visible spectroscopy, Surface Second Harmonic Generation, and Scanning Electron Microscopy. Density functional theory calculations confirm the possibility of formation of the catalytic CoTMPyP 4+ / CoTPPS 4− complex and its capability to bind oxygen.

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Section: Methodsmentioning

confidence: 99%

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

et al. 2011

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“…In such a system, as the interface is polarised positively (water vs. oil) the interfacial capacitor becomes charged (water (+)|organic (À)) until the polarisation is strong enough for either an aqueous cation or an organic anion to cross the interface, which can be measured as a current. Here, the Gibbs energy of transfer of Li + from water to 1,2-dichloroethane (1,2-DCE) is equal to 63 AE 4 kJ mol À1 and that of TB À equal to À65 AE 4 kJ mol À1 , 5 and therefore the potential window is limited by the transfer of Li + . Inversely, when we polarise the interface negatively, we charge the interfacial capacitor (water (À)|organic (+)) until the polarisation is strong enough for an aqueous anion or an organic cation to cross the interface.…”

Section: Polarised Itiesmentioning

confidence: 99%

Molecular electrocatalysis at soft interfaces

Méndez

Partovi‐Nia

Hatay

et al. 2010

Phys. Chem. Chem. Phys.

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“…Thus, a concentration of 10 µM BTPPACl in the aqueous and oil phase gives a potential difference of ∆ o w φ ) -0.70 V, under the same assumptions as before, and by using the literature value of ∆ o w φ BTPPA+ 0 . 45 The results for the negatively polarized interface are shown in Figure 6 (left). With focus on the complexes formed with the 10+ lysozyme the data from these experiments are compared (Table 1) to that of the interface that is not polarized.…”

Section: Inmentioning

confidence: 99%

Interfacial Complexes between a Protein and Lipophilic Ions at an Oil−Water Interface

et al. 2010

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The interaction between an intact protein and two lipophilic ions at an oil-water interface has been investigated using cyclic voltammetry, impedance based techniques and a newly developed method in which the biphasic oil-water system is analyzed by biphasic electrospray ionization mass spectrometry (BESI-MS), using a dualchannel electrospray emitter. It is found that the protein forms interfacial complexes with the lipophilic ions and that it specifically requires the presence of the oil-water interface to be formed under the experimental conditions. Furthermore, impedance based techniques and BESI-MS with a common ion to polarize the interface indicated that the Galvani potential difference across the oil-water interface significantly influences the interfacial complexation degree. The ability to investigate protein-ligand complexes formed at polarized liquid-liquid interfaces is thus a new analytical method for assessing potential dependent interfacial complexation using a structure elucidating detection principle.The behavior of biological macromolecules at liquid-liquid interfaces has important implications in the pharmaceutical sciences. It is for example well-known that proteins adsorb at a wide variety of interfaces, 1-4 a process that can have unwanted consequences such as a loss of therapeutic activity due to denaturation and aggregation. 4,5 Two-phase systems are at equilibrium generally associated with an interfacial potential difference, 6 in the following referred to as the Galvani potential difference between a water (w) and oil (o) phase at equilibrium; ∆ o w φ. The value of ∆ o w φ can influence adsorption kinetics and/ or adsorption isotherms. 7 Electrochemistry at Interfaces between two immiscible electrolyte solutions (ITIES) provides an effective methodology for studying potential dependent adsorption and ion transfer processes. [8][9][10][11][12] In relation to protein research, electrochemistry at ITIES have been used to study protein adsorption, 13 protein adsorption kinetics, 7 the effects on transfer of aqueous ions, 14 and the assisted transfer of proteins to the oil phase. [15][16][17][18] Recently, electrochemistry at ITIES has been used for detecting proteins in solution by means of a protein assisted transfer of organic anions into the water phase at positive potentials. [19][20][21][22] A suggested mechanism for the organic anion transfer involves the formation of a protein-anion complex at the interface. 22 Usually electrospray ionization mass spectrometry (ESI-MS) involves an aqueous solution which by application of a high voltage is sprayed into a mass analyzer. Recently, the development of a new biphasic electrospray interface has allowed interfacial complexes in two phase systems to be analyzed using a mass spectrometer; the new technique is termed biphasic electrospray mass spectrometry (BESI-MS). [23][24][25][26] The combined use of BESI-MS and electrochemistry at ITIES is attractive as it allows studying quantitative mechanistic aspects of adsorption and ion transfer pro...

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Voltammetric determination of extreme standard Gibbs ion transfer energy

Cited by 108 publications

References 33 publications

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

Molecular electrocatalysis at soft interfaces

Interfacial Complexes between a Protein and Lipophilic Ions at an Oil−Water Interface

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