Measurements and Utilization of Consistent Gibbs Energies of Transfer of Single Ions: Towards a Unified Redox Potential Scale for All Solvents

Radtke, Valentin; Gebel, Niklas; Priester, Denis; Ermantraut, Andreas; Bäuerle, Monika; Himmel, Daniel; Stroh, Regina; Koslowski, Thorsten; Leito, Ivo; Krossing, Ingo

doi:10.1002/chem.202200509

Cited by 7 publications

(15 citation statements)

References 103 publications

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“…These results support the findings from our recent publication [21] that the LJPs occurring in cells using [N 2225 ][NTf 2 ] as salt bridge is independent of the solvated ions in the halfcells, neither on its nature nor on its concentration (if not too high). If this were the case, the measured solubility products would not agree with the values described in the literature.…”

Section: Solubility Productssupporting

confidence: 92%

“…For an increased accuracy of the values, the knowledge of the sum x = LJPS 1 + LJPS 2 is necessary. However, since there are both experimental and theoretical (quantum chemical) indications [21] that x could be so small as to be negligible, we considerpending experimental verification -the values given here to be the most reliable published values so far.…”

Section: Discussionmentioning

confidence: 78%

“…If the LJPs at both ends of the ILSB depended only on Δ tr G°([N 2225 ] + , S 1 !S 2 ) and Δ tr G°([NTf 2 ] À , S 1 !S 2 ), as suggested, [21] since S 1 = S 2 = S holds in cell III, the two LJPs would cancel completely, and E III would directly lead to the solubility constant K sp = a(Ag + , S) a(Cl À , S).…”

Section: Cell IIImentioning

confidence: 77%

“…The Gibbs transfer energies of Ag + ions between water, MeCN, PC, and DMF were published earlier. [21,28,29] Here, the Gibbs energies for the transfer from ethanol and methanol have been additionally determined. Figure 1 shows the extended network of the half-cells containing the Ag + (solv)/Ag redox system measured with cell I and now within the solvents S = H 2 O, AN, PC, DMF, EtOH, and MeOH.…”

Section: Silver-ion Transfermentioning

confidence: 99%

“…[39]; [b] from Ref. [21].Values in italics are calculated from values of the first five rows of the corresponding column, i.e., calculated from Gibbs transfer energies from water to the relevant solvents.…”

mentioning

confidence: 99%

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The Unified Redox Scale for All Solvents: Consistency and Gibbs Transfer Energies of Electrolytes from their Constituent Single Ions

Radtke

Priester

Heering

et al. 2023

Chemistry A European J

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We have devised the unified redox scale EabsH2O, which is valid for all solvents. The necessary single ion Gibbs transfer energy between two different solvents, which only can be determined with extra‐thermodynamic assumptions so far, must clearly satisfy two essential conditions: First, the sum of the independent cation and anion values must give the Gibbs transfer energy of the salt they form. The latter is an observable and measurable without extra‐thermodynamic assumptions. Second, the values must be consistent for different solvent combinations. With this work, potentiometric measurements on silver ions and on chloride ions show that both conditions are fulfilled using a salt bridge filled with the ionic liquid [N2225][NTf2]: if compared to the values resulting from known pKL values, the silver and chloride single ion magnitudes combine within a uncertainty of 1.5 kJ mol−1 to the directly measurable transfer magnitudes of the salt AgCl from water to the solvents acetonitrile, propylene carbonate, dimethylformamide, ethanol, and methanol. The resulting values are used to further develop the consistent unified redox potential scale EabsH2O that now allows to assess and compare redox potentials in and over six different solvents. We elaborate on its implications.

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Section: Solubility Productssupporting

confidence: 92%

Section: Discussionmentioning

confidence: 78%

Section: Cell IIImentioning

confidence: 77%

Section: Silver-ion Transfermentioning

confidence: 99%

mentioning

confidence: 99%

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The Unified Redox Scale for All Solvents: Consistency and Gibbs Transfer Energies of Electrolytes from their Constituent Single Ions

Radtke

Priester

Heering

et al. 2023

Chemistry A European J

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Measurements and Utilization of Consistent Gibbs Energies of Transfer of Single Ions: Towards a Unified Redox Potential Scale for All Solvents

Radtke

Gebel

Priester

et al. 2022

Chemistry A European J

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Utilizing the “ideal” ionic liquid salt bridge to measure Gibbs energies of transfer of silver ions between the solvents water, acetonitrile, propylene carbonate and dimethylformamide results in a consistent data set with a precision of 0.6 kJ mol−1 over 87 measurements in 10 half‐cells. This forms the basis for a coherent experimental thermodynamic framework of ion solvation chemistry. In addition, we define the solvent independent peabsH2normalO ‐ and the EabsH2normalO values that account for the electronating potential of any redox system similar to the pHabsH2normalO value of a medium that accounts for its protonating potential. This EabsH2normalO scale is thermodynamically well‐defined enabling a straightforward comparison of the redox potentials (reducities) of all media with respect to the aqueous redox potential scale, hence unifying all conventional solvents′ redox potential scales. Thus, using the Gibbs energy of transfer of the silver ion published herein, one can convert and unify all hitherto published redox potentials measured, for example, against ferrocene, to the EabsH2normalO scale.

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Rigorous pH measurement in non-aqueous solution: measurement method and reference values in ethanol

Bastkowski,

Heering,

Uysal

et al. 2023

Anal Bioanal Chem

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The recently introduced unified pH ($${\mathrm{pH}}_{\mathrm{abs}}^{{\mathrm{H}}_{2}\mathrm{O}}$$ pH abs H 2 O ) concept enables rigorous pH measurements in non-aqueous and mixed media while at the same time maintaining comparability to the conventional aqueous pH scale. However, its practical application is hindered by a shortage of reference $${\mathrm{pH}}_{\mathrm{abs}}^{{\mathrm{H}}_{2}\mathrm{O}}$$ pH abs H 2 O values. In order to improve this situation, the European Metrology Research Project (EMPIR) UnipHied (“Realisation of a UnipHied pH scale”) launched an interlaboratory comparison among highly experienced electrochemistry expert laboratories to assign the first such reference $${\mathrm{pH}}_{\mathrm{abs}}^{{\mathrm{H}}_{2}\mathrm{O}}$$ pH abs H 2 O values by adopting an extensive statistical treatment of the reported measurement data: to phosphate buffer in water–ethanol mixture (50 wt% of ethanol) and ammonium formate buffer in pure ethanol. Two different measurement setups — one capable of being easily adopted in industrial applications — have been used to demonstrate the robustness of $${\mathrm{pH}}_{\mathrm{abs}}^{{\mathrm{H}}_{2}\mathrm{O}}$$ pH abs H 2 O measurement. This is an important step towards wider adoption of the $${\mathrm{pH}}_{\mathrm{abs}}^{{\mathrm{H}}_{2}\mathrm{O}}$$ pH abs H 2 O concept in practice, like liquid chromatography, biofuels analysis and electrocatalysis.

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Measurements and Utilization of Consistent Gibbs Energies of Transfer of Single Ions: Towards a Unified Redox Potential Scale for All Solvents

Cited by 7 publications

References 103 publications

The Unified Redox Scale for All Solvents: Consistency and Gibbs Transfer Energies of Electrolytes from their Constituent Single Ions

The Unified Redox Scale for All Solvents: Consistency and Gibbs Transfer Energies of Electrolytes from their Constituent Single Ions

Measurements and Utilization of Consistent Gibbs Energies of Transfer of Single Ions: Towards a Unified Redox Potential Scale for All Solvents

Rigorous pH measurement in non-aqueous solution: measurement method and reference values in ethanol

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