Anomale H+‐ und OH−‐Ionenbeweglichkeit im Wasser

Gierer, Alfred; Wirtz, K.

doi:10.1002/andp.19494410129

Cited by 12 publications

(24 citation statements)

References 24 publications

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“…Because of the high solvation energy of the reaction H + + H 2 O → H 3 O + , a proton combines with a water molecule and quickly forms a hydronium; the reverse process rarely occurs due to the high energy barrier. Similarly, because of the exothermal properties of the reactions, H 3 O + cations continue to combine with water molecules to form cations of H 5 While it is assumed that protons are transported in water by the mobility of H 5 O 2 + cations, Kuznetsov et al [46] pointed out that the experimental data [47,48] show that the excess proton mobility reaches maximum near 422 K and decreases as the temperature increases. This agrees well with the protonated water cluster weights evaluated by Gierer and Wirtz [48], which show that the weight of H 5 O 2 + decreases quadratically as the temperature increases and nearly disappears at 672 K, above which proton transport through Zundel cations is the not the dominant mechanism.…”

Section: Other Factors Affecting Proton Mobilitymentioning

confidence: 97%

Ab initio simulation on the mechanism of proton transport in water

Han

Zhou

Liu

2006

Journal of Power Sources

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Section: Other Factors Affecting Proton Mobilitymentioning

confidence: 97%

Ab initio simulation on the mechanism of proton transport in water

Han

Zhou

Liu

2006

Journal of Power Sources

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“…Proton transfer normally occurs at hydrogen bonds (179, 230, 289, 365, 399, 434), although proton transfer in the absence of hydrogen bonds was reported recently in π -stacked structures (183). Because of its special conduction mechanism, proton mobility in water is about five times greater than that of other ions.…”

Section: Definitions and Backgroundmentioning

confidence: 99%

“…Also in contrast to proton transfer in bulk water, breaking a hydrogen bond is not a necessary precondition to proton transfer in a water wire (452). In any case, essential features of HBC or Grotthuss conduction are that protons are transferred via hydrogen bond rearrangement (179, 230, 279) and that the identity of the conducted proton may change with each proton transfer event (31, 90). One proton enters the channel, and a different proton emerges from the other end, as evident in FIGURE 1.…”

Section: Definitions and Backgroundmentioning

confidence: 99%

Voltage-Gated Proton Channels: Molecular Biology, Physiology, and Pathophysiology of the H_VFamily

DeCoursey

2013

Physiological Reviews

204

268

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Voltage-gated proton channels (HV) are unique, in part because the ion they conduct is unique. HV channels are perfectly selective for protons and have a very small unitary conductance, both arguably manifestations of the extremely low H+ concentration in physiological solutions. They open with membrane depolarization, but their voltage dependence is strongly regulated by the pH gradient across the membrane (ΔpH), with the result that in most species they normally conduct only outward current. The HV channel protein is strikingly similar to the voltage-sensing domain (VSD, the first four membrane-spanning segments) of voltage-gated K+ and Na+ channels. In higher species, HV channels exist as dimers in which each protomer has its own conduction pathway, yet gating is cooperative. HV channels are phylogenetically diverse, distributed from humans to unicellular marine life, and perhaps even plants. Correspondingly, HV functions vary widely as well, from promoting calcification in coccolithophores and triggering bioluminescent flashes in dinoflagellates to facilitating killing bacteria, airway pH regulation, basophil histamine release, sperm maturation, and B lymphocyte responses in humans. Recent evidence that hHV1 may exacerbate breast cancer metastasis and cerebral damage from ischemic stroke highlights the rapidly expanding recognition of the clinical importance of hHV1.

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“…[6] and results in Eqs. (10) and (11). The reduced electrostatic potential ÈR; z ewR; z= k B T e= k B T g e ug; z expÀigR is plotted in Fig.…”

Section: Appendix A: Modified Pb Equation: Ions Of Finite Sizementioning

confidence: 99%

The effect of water content on proton transport in polymer electrolyte membranes

Commer

Cherstvy

Spohr³

et al. 2002

Fuel Cells

104

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We investigate proton transport in a polymer electrolyte membrane using continuum theory and molecular dynamics (MD) computer simulations. Specifically our goal is to understand the possible molecular origin of the effect of water content on the activation energy (AE) and pre‐exponential factor of proton conductivity, in comparison with experimental observations reported for Nafion, where a decrease of AE with increasing water content has been observed. We study proton diffusion in a single pore, using a slab‐like model. We find that although the average proton diffusion coefficient is several times smaller in a narrow pore than in a wide water‐rich pore, its AE is almost unaffected by the pore width. This contradicts an earlier proposed conjecture that the sizable Coulomb potential energy barriers near the lattice of immobile point‐like SO3– groups increase the AE in a narrow pore. Here we show that these barriers become smeared out by thermal motion of SO3– groups and by the spatial charge distribution over their atoms. This effect strongly diminishes the variation of the AE with pore width, which is also found in MD simulations. The pre‐exponential factor for the diffusion process, however, decreases, indicating a limited number of pathways for proton transfer and the freezing out of degrees of freedom that contribute to the effective frequency of transfer. Decreasing the pore size diminishes bulk‐like water regions in the pore, with only less mobile surface water molecules remaining. This hampers proton transfer. The increase of AE takes place only if the thermal motion of the SO3– head groups freezes out simultaneously with decreasing water content, but the effect is not profound. The stronger effect observed experimentally may thus be associated with some other rate‐determining consecutive process, concerned with polymer dynamics, such as opening and closing of connections (bridges) between aqueous domains in the membrane under low water content.

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Anomale H⁺‐ und OH⁻‐Ionenbeweglichkeit im Wasser

Cited by 12 publications

References 24 publications

Ab initio simulation on the mechanism of proton transport in water

Ab initio simulation on the mechanism of proton transport in water

Voltage-Gated Proton Channels: Molecular Biology, Physiology, and Pathophysiology of the H_VFamily

The effect of water content on proton transport in polymer electrolyte membranes

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Anomale H+‐ und OH−‐Ionenbeweglichkeit im Wasser

Cited by 12 publications

References 24 publications

Ab initio simulation on the mechanism of proton transport in water

Ab initio simulation on the mechanism of proton transport in water

Voltage-Gated Proton Channels: Molecular Biology, Physiology, and Pathophysiology of the HVFamily

The effect of water content on proton transport in polymer electrolyte membranes

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Product

Resources

About

Anomale H⁺‐ und OH⁻‐Ionenbeweglichkeit im Wasser

Voltage-Gated Proton Channels: Molecular Biology, Physiology, and Pathophysiology of the H_VFamily