Effect of the aqueous–organic solvent structure on the cobalticenium–cobaltocene redox potential: The redox couple as a basis for determination of the single ion transfer energies

Khanova, L. A.; Topolev, V. V.; Krishtalik, L. I.

doi:10.1016/j.chemphys.2006.05.001

Cited by 21 publications

(16 citation statements)

References 29 publications

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“…Other potential sources of error in the computational prediction of the standard reduction A recent experimental study 117 of the effect of the structure of water on its dielectric response energy and, therefore, on the ion solvation energy predicted a 0.07 V shift for the redox potential of an ionic species because of water structuring effects not accounted for in a continuum approximation, and it is not clear that our CDS terms can account for this kind of effect.…”

Section: Further Discussionmentioning

confidence: 99%

Computational Electrochemistry: The Aqueous Ru³⁺|Ru²⁺ Reduction Potential

et al. 2007

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We present results of density functional calculations for the standard reduction potential of the −10.56 eV to −10.99 eV for n = 6 and from -6.83 eV to -7.45 eV for n = 18, depending on the density functional and basis set quality. The aqueous standard reduction potential is overestimated when only the first solvation shell is treated explicitly and it is underestimated when the first and second solvation shells are treated explicitly.

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Section: Further Discussionmentioning

confidence: 99%

Computational Electrochemistry: The Aqueous Ru³⁺|Ru²⁺ Reduction Potential

et al. 2007

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“…Besides, the change in the dielectric response energy of the Fc + cation upon its transfer from water to DMF has to be taken into account using the Born equation; this correction increases Fc/Fc + potential in DMF by 0.03 V. While Born equation describes well Fc + solvation energy in aprotic solvents, it cannot be applied quantitatively to aqueous solutions: due to its 3D hydrogen bond network, water displays an anomalously strong dielectric response to an ionic charge. The effect of this anomaly on Fc +/0 potential in water was determined as equal to *0.07 V (Khanova et al 2006). Another effect is the pre-existing intraphase potential.…”

Section: Reference Redox Potentialsmentioning

confidence: 99%

Semi-continuum electrostatic calculations of redox potentials in photosystem I

et al. 2008

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The midpoint redox potentials (E(m)) of all cofactors in photosystem I from Synechococcus elongatus as well as of the iron-sulfur (Fe(4)S(4)) clusters in two soluble ferredoxins from Azotobacter vinelandii and Clostridium acidiurici were calculated within the framework of a semi-continuum dielectric approach. The widely used treatment of proteins as uniform media with single dielectric permittivity is oversimplified, particularly, because permanent charges are considered both as a source for intraprotein electric field and as a part of dielectric polarizability. Our approach overcomes this inconsistency by using two dielectric constants: optical epsilon(o)=2.5 for permanent charges pre-existing in crystal structure, and static epsilon(s) for newly formed charges. We also take into account a substantial dielectric heterogeneity of photosystem I revealed by photoelectric measurements and a liquid junction potential correction for E(m) values of relevant redox cofactors measured in aprotic solvents. We show that calculations based on a single permittivity have the discrepancy with experimental data larger than 0.7 V, whereas E(m) values calculated within our approach fall in the range of experimental estimates. The electrostatic analysis combined with quantum chemistry calculations shows that (i) the energy decrease upon chlorophyll dimerization is essential for the downhill mode of primary charge separation between the special pair P(700) and the primary acceptor A(0); (ii) the primary donor is apparently P(700) but not a pair of accessory chlorophylls; (iii) the electron transfer from the A branch quinone Q(A) to the iron-sulfur cluster F(X) is most probably downhill, whereas that from the B branch quinone Q(B) to F(X) is essentially downhill.

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“…The first fac tor is the presence of a network of hydrogen bonds. However, the network is broken almost completely even after an addition of 30 vol % solvent [13]; hence, this factor has no effect in the major fraction of the curve. The second specific factor is the variation of the intraphase potential.…”

Section: Resultsmentioning

confidence: 96%

“…Correspondingly, the approach of common macroscopic electrostatics becomes incorrect. This effect was estimated, when the hydro gen bond network was broken by adding (approxi mately to 30 vol %) aprotic organic solvents [6,13]. For ferricinium, the effect was ~0.1 eV.…”

Section: Introductionmentioning

confidence: 99%

Real energies of ferricinium cation transfer from water to organo-aqueous solvents

Topolev

Krishtalik

2012

Russ J Electrochem

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The redox potentials of ferrocene-ferricinium couple are determined for five organo aqueous systems with respect to a reversible chloride electrode in the same solvent. Combined with the literature data on real (and some chemical) transfer energies of chloride ion, the effective real energies of ferricinium trans fer from water into organo aqueous mixtures are determined. These values do not obey the Born equation. Most probably, this is due to the selective solvation of cation by water and of neutral ferrocene molecule by an organic component.

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Effect of the aqueous–organic solvent structure on the cobalticenium–cobaltocene redox potential: The redox couple as a basis for determination of the single ion transfer energies

Cited by 21 publications

References 29 publications

Computational Electrochemistry: The Aqueous Ru³⁺|Ru²⁺ Reduction Potential

Computational Electrochemistry: The Aqueous Ru³⁺|Ru²⁺ Reduction Potential

Semi-continuum electrostatic calculations of redox potentials in photosystem I

Real energies of ferricinium cation transfer from water to organo-aqueous solvents

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Effect of the aqueous–organic solvent structure on the cobalticenium–cobaltocene redox potential: The redox couple as a basis for determination of the single ion transfer energies

Cited by 21 publications

References 29 publications

Computational Electrochemistry: The Aqueous Ru3+|Ru2+ Reduction Potential

Computational Electrochemistry: The Aqueous Ru3+|Ru2+ Reduction Potential

Semi-continuum electrostatic calculations of redox potentials in photosystem I

Real energies of ferricinium cation transfer from water to organo-aqueous solvents

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Product

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Computational Electrochemistry: The Aqueous Ru³⁺|Ru²⁺ Reduction Potential

Computational Electrochemistry: The Aqueous Ru³⁺|Ru²⁺ Reduction Potential