Standard Gibbs energies of ion transfer across the water∣2-nitrophenyl octyl ether interface

Wilke, Stefan; Zerihun, Tadesse

doi:10.1016/s0022-0728(01)00640-4

Cited by 84 publications

(111 citation statements)

References 33 publications

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“…3 In the past decade, 2-nitrophenyl n-octyl ether (NPOE) has emerged as a viable alternative, and it is seen as one of the most promising solvents in ion transfer studies across liquid|liquid interfaces. 2,[4][5][6][7][8][9][10][11][12] Compared to the other organic solvents, NPOE has a relatively low solubility in water, a low vapor pressure, and is not known to be highly toxic. 3 In addition, NPOE has a high molar volume and a medium permittivity ( rel ) 24.2), which makes it also a good solvent for ionic solutes.…”

Section: Introductionmentioning

confidence: 99%

“…It has been applied in pharmacology, 2,7,12 and in the design of voltammetric and amperometric sensors and detector devices based on ion transfer. 6,[8][9][10] It is also worth mentioning that a recent study has shown that the solvation properties of nitrobenzene and NPOE toward ionic species are very similar. 11,12 In contrast, few theoretical studies have been devoted to probe such organic solvents.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Study of 2-Nitrophenyl Octyl Ether and Nitrobenzene

et al. 2006

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The pure organic liquids nitrobenzene (NB) and 2-nitrophenyl octyl ether (NPOE) have been studied by means of molecular dynamics simulations. Both solvents are extremely important in various interfacial processes, mainly connected with ion transfer taking place across the interface with water. Thermodynamic (mass density, enthalpy of vaporization, isothermal compressibility, dipole moment) and dynamic (viscosities and self-diffusion coefficients) properties of both liquids have been calculated and are in very good agreement with the experimental data. In the case of NB, several potentials have been tested and the obtained results compared and discussed. In most cases, the OPLS all-atom potential gives results that are in better agreement with available experimental values. Atomic radial distribution functions, dihedral and angle distributions, as well as dipole-orientation correlation functions are used to probe the structure and interactions of the bulk molecules of both organic solvents. These were seen to be very similar in terms of structure and thermodynamics, but quite distinct in terms of dynamic behavior, with NPOE showing a much slower dynamic response than NB. A simulation study of the simple Cl -and K + ions dissolved in both solvents has been also undertaken, revealing details about the diffusion and solvation mechanisms of these ions. It was found that in both liquids the positive potassium ion is solvated by the negative end of the molecular dipole, whereas the negative chloride ion is solvated by the positive end of the dipole.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Study of 2-Nitrophenyl Octyl Ether and Nitrobenzene

et al. 2006

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“…Ionic partition diagrams were first developed by Reymond et al 8 as a representation of the predominance area of the various species of an ionizable compound as a function of the Galvani potential difference and the pH and taking into account the thermodynamic 18 equilibrium governing the distribution of various acid/base forms of molecules involved. Two adjacent areas of predominance are separated by equiconcentration boundary lines.…”

Section: Experimental Validation Of the Electrochemical Cell Based Onmentioning

confidence: 99%

“…8,16,17 However, the high volatility and the toxicity of DCE limit its use and call for its replacement by a more appropriate organic solvent. Given its absence of known toxicity and interesting physicochemical properties (low solubility in water, low vapor pressure), NPOE has recently been introduced as an alternative for DCE in electrochemistry 18,19 and medicinal chemistry. 5,20 In addition, solvatochromic analysis have shown NPOE to be a good candidate to replace DCE in measurements of lipophilicity.…”

mentioning

confidence: 99%

“…5,20 In addition, solvatochromic analysis have shown NPOE to be a good candidate to replace DCE in measurements of lipophilicity. 20,21 Furthermore, it has been shown that for a series of small ions the Gibbs energy of ion transfer from water to DCE directly correlates with the Gibbs energy of ion transfer from water to NPOE, 18,22 suggesting that the standard partition coefficient in NPOE offers a convenient alternative to the one in DCE.…”

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Immobilized pH Gradient Gel Cell To Study the pH Dependence of Drug Lipophilicity

et al. 2006

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An experimental setup to study the pH dependence of standard ion-transfer potentials at the water/NPOE interface is presented. The system is composed of a microhole generated by laser photoablation in a 12-µm polyethylene terephthalate film, the aqueous phase consisting of a commercial immobilized pH gradient gel reswelled in electrolyte solution and a droplet of organic solution. Two electrodes are used, an Ag/AgCl aqueous electrode and an Ag/AgTPBCl organic electrode. This setup is applied to the study of two ionizable compounds (pyridine, 2,4-dinitrophenol). Thermodynamic parameters such as the standard transfer potential, the Gibbs energy of transfer, and the partition coefficients of the ionized forms as well as the neutral forms of these drug compounds are evaluated by differential pulse voltammetry. The data obtained are summarized in ionic partition diagrams, which are a useful tool for predicting and interpreting the transfer behavior of ionized drugs at the liquid/liquid interfaces mimicking the biological membranes.Recently, the electrochemical study of the transfer of ionic species across the interface between two immiscible electrolyte solutions (ITIES) has gained great significance due to its wide applicability in different fields such as ion-selective electrodes for application to amperometric sensors, solvent extraction, drug lipophilicity, and its consequences on drug delivery. 1-4 Unlike numerous traditional chromatographic and potentiometric systems developed to study the distribution of ionic species and giving an indirect access to partition coefficients, voltammetry at the ITIES allowed us to evaluate the standard partition coefficient of both the neutral and the ionized forms. 5,6 The four-electrode system initially introduced by Samec et al. 7 was later used intensively by Reymond et al. 2 to study the transfer of many ionizable drugs at the interface between water and 1,2-dichloroethane (DCE), and the introduction of ionic partition diagrams revealed a most interesting aspect for the study of drug lipophilicity. 8 Indeed, a partition diagram of a specific drug between two immiscible liquids is a representation of the conditions corresponding to the predominance of different forms of the compound (basic, neutral, acid) as a function of the Galvani potential difference and the pH of the aqueous phase. This representation has been revealed to be a useful tool to mimic the passage of a drug through a biological membrane and help understand the action of that drug.However, the initial systems used to study the distribution of ionic species between two immiscible solutions used large ITIES, requiring quite large volumes of each phase 2 . Thus, when only limited amount of species is available, micro-ITIES are more suitable, such as liquid/liquid (L/L) interfaces supported at the tip of micropipets 9,10 or systems using a droplet of organic phase or aqueous phase. 11,12 For example, Gobry et al. 13 reported experiments with an aqueous droplet supported at an Ag/AgCl disk electrode covered wi...

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Voltammetry of Ion Transfer at a Water–Toluene Micro‐ Interface

2016

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Voltammograms of ion transfer at the water (W) j toluenei nterface were recorded for the first time by using am icro-interface electrolytic cell and bis(triphenylphosphoranylidene)ammonium tetrakis [3,5-bis(trifluoromethyl)phenyl]borate (BTPPA + TFPB À ). The high solubility of BTPPA + TFPB À in toluene at room temperature enabled the electrochemical measurements. The potentialw indow at the W j toluene interface is about 1.09 V, which is 0.30 Vl arger than that at the W j 1,2-dichloroethane interface when using 10 mmol dm À3 NaCl as the supporting electrolyte in W. The transfer reactions of quaternary ammonium ions acrosst he W j toluene interface were found to be reversible.F ormal potentials for ion transfer from Wt ot oluene were evaluated, and linear correlations were observed between these formal potentials and the standard potentials reported at the W j nitrobenzene, W j 1,2-dichloroethane,a nd W j 2-nitrophenyl octyl ether interfaces.Voltammetry of ion transfer at the interface between two immiscible electrolyte solutions( VITIES)a llows investigation of ion-transfer reactions across aw ater (W) j organic solution ( O) interface. This allows the determination of the mechanism of distribution of an ion at the interface and the process generating the potential at an ion-selective electrode, and the understanding of electrochemical phenomena occurring in living organisms. [1][2][3][4][5] To date, primarily nitrobenzene (NB) and 1,2-dichloroethane (DCE) have been used as the Os olution for voltammetrics tudies of the W j Oi nterface, because of their low mutual solubility with water and ratherhighd ielectric constant (e, % 10-15), and thus are suitable for as upporting electrolyte (SE). Other Os pecies, such as 2-nitrophenyl octyl ether (NPOE), [6,7] 2,6-dimethylnitrobenzene, [8] o-dichlorobenzene, [9,10] 2-heptanone, [11] 2-octanone, [11,12] chloroform, [13] 1,6-dichlorohexane, [14] 1,4-dichlorobutane, [14] acetophenone, [15] n-octanol, [13,16] a,a,a-trifluorotoluene, [17] 5-nonanone, [12] room temperature ionic liquids (RTIL), [18][19][20] and mixed solvents, [10,21,22] are also useful for VITIES, but the low e ( % 2) of aromatich ydrocarbon solvents, in general,r esultsi nl ow solubility of the SE. The interface between Wa nd an aromatic hydrocarbon such as toluene is utilized in solvente xtraction, [23,24] and over the past several decades the formation of nanoparticles and thin-layer films at the W j toluene interface has been studied extensively. [25][26][27][28][29][30] To the best of our knowledge,h owever,t here are no direct experimental data on VITIES at the W j toluene interface.Use of am icro-electrode and tetrahexylammonium perchlorate (THexA + ClO 4 À )a st he SE enablet he observation of the reversible response for the redox reaction of ferrocene [31] or porphyrins [32,33] in toluene, because the micro-electrode reduces the effect of the ohmic drop. The effect of the addition of the RTIL [trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)-trifluorophosphate, aph4.cph12]t ot oluene has be...

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Standard Gibbs energies of ion transfer across the water∣2-nitrophenyl octyl ether interface

Cited by 84 publications

References 33 publications

Molecular Dynamics Study of 2-Nitrophenyl Octyl Ether and Nitrobenzene

Molecular Dynamics Study of 2-Nitrophenyl Octyl Ether and Nitrobenzene

Immobilized pH Gradient Gel Cell To Study the pH Dependence of Drug Lipophilicity

Voltammetry of Ion Transfer at a Water–Toluene Micro‐ Interface

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