Protonic Mobility and Its Importance for Biological Systems*

Riehl, Ν.

doi:10.1111/j.2164-0947.1965.tb02236.x

Cited by 26 publications

(6 citation statements)

References 15 publications

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“…In the kilocycle range, molecular rotation gives rise to a Debye dispersion; the reciprocal of its characteristic angu lar frequency is the relaxation time. The translation of ion states is thought to make only a relatively small contribution to this dispersion (130,131,141). The static dielectric constant is extrapolated from the Debye dispersion curve.…”

Section: Effects Of Trace Inorganics On the Electrical Properties Of Icementioning

confidence: 99%

“…A de tailed quantitative model of ice as a protonic semiconductor has recently been developed by Seidensticker (138). The transfer of energy via hydrogen bonds (130,131) may be of fundamental importance for an understanding of the transmission of nerve impulses and of information storage in the brain; a mechanism for binary storage may be available in the two alternate positions the proton can occupy on the hydrogen bond.…”

Section: Effects Of Trace Inorganics On the Electrical Properties Of Icementioning

confidence: 99%

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Some Effects of Trace Inorganics on the Ice/Water System

Gross

1968

Trace Inorganics in Water

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Trace inorganic impurities cause specific changes in the con ductivity, dielectric constant and dielectric relaxation, ther moelectric power, mechanical relaxation, and the microstruc ture of ice. Most of these effects are explained by changes in the populations of ion defects and valence defects. The freezing potential (Workman-Reynolds effect) occurs when trace amounts (10 -6 M to 10 -3 M) of many inorganic and some organic salts are present in a freezing solution. Selec tive ion incorporation induces a charge layer at the advanc ing phase boundary. Its effect on the overall distribution of impurities between the phases is probably small. The dis tribution coefficient increases with freezing rate. For a given ion species and freezing rate it is a function of all im purity species present in solution, their concentrations, and the shape and surface structure of the phase boundary. Typical values of distribution coefficients for ionic solutes in ice range from 10 -5 to 10 -3 . Traceinorganics are the cause of specific electrochemical phenomena at the phase boundary of growing ice; these are the freezing potential and the preferential incorporation into the solid phase of certain ions over others. The physical and chemical properties of the phases are more or less deeply affected by such interface processes. These processes raise fundamental questions concerning the mechanisms by which solute ions are incorporated into the ice structure and what their positions and effects are once they get there. This paper proposes to review these phenomena, the experimental evidence available, and the theories that have been formulated to account for them. A major difficulty in the critical evaluation of the data is their great sensitivity to the experimental conditions, which are difficult to define completely in most instances.

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Section: Effects Of Trace Inorganics On the Electrical Properties Of Icementioning

confidence: 99%

Section: Effects Of Trace Inorganics On the Electrical Properties Of Icementioning

confidence: 99%

Some Effects of Trace Inorganics on the Ice/Water System

Gross

1968

Trace Inorganics in Water

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“…It has been understood for decades that imidazole molecules shuttle protons through biological membranes. 6 The observa- tion of enhanced acidic proton diffusion coefficients in imidazole/acid mixtures 3 was the first demonstration that imidazole facilitates fast proton hopping in an electrolyte. Since that demonstration, several theoretical studies have shed light on the details of the proton hopping mechanism in imidazole.…”

Section: ■ Introductionmentioning

confidence: 99%

Proton Hopping and Long-Range Transport in the Protic Ionic Liquid [Im][TFSI], Probed by Pulsed-Field Gradient NMR and Quasi-Elastic Neutron Scattering

et al. 2012

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The management of proton conductivity in the protic ionic liquid imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) is investigated via the use of quasi-elastic neutron scattering (QENS) and pulsed-field gradient NMR. The introduction of excess neutral imidazole to [Im][TFSI] leads to enhanced conductivity. We find that proton dynamics in [Im][TFSI] with excess imidazole are characterized by proton hopping that is encompassed in the slower of two translational processes, as identified by QENS. This relatively slow process contributes to long-range diffusion more than the faster process. NMR diffusion measurements show that proton hopping decreases with increasing temperature, but significant proton hopping persists even at the maximum experimental temperature of 120 °C. This, in combination with minimal ion aggregation, leads to high proton conductivity and a high proton transference number over a wide temperature range.

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“…The notion that molecular reorientation is critical for driving proton transport in hydrogen bond media can be traced back to early work from the 1960s . The idea that proton transport in an infinite one-dimensional chain of hydrogen-bonded imidazoles must be followed by a roughly concerted rate-determining reorientation of imidazoles to return the system to its starting configuration , has motivated subsequent simulation studies of imidazole crystals − and imidazole-terminating oligomers [imidazole 2-ethylene (Imi-2EO)]. , However, solid-state nuclear magnetic resonance studies show that ordered crystalline domains actually do not participate in long-range proton transport, but rather, it is disordered or amorphous domains, grain boundaries, and crystal defects, etc., where no consistent hydrogen bond ordering can be assigned, that contribute most to the transport process. , …”

mentioning

confidence: 99%

Elucidating the Proton Transport Pathways in Liquid Imidazole with First-Principles Molecular Dynamics

Long

Atsango

Napoli

et al. 2020

J. Phys. Chem. Lett.

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Imidazole is a promising anhydrous proton conductor with a high conductivity comparable to that of water at a similar temperature relative to its melting point. Previous theoretical studies of the mechanism of proton transport in imidazole have relied either on empirical models or on ab initio trajectories that have been too short to draw significant conclusions. Here, we present the results of multiple time-step ab initio molecular dynamics simulations of an excess proton in liquid imidazole reaching 1 ns in total simulation time. We find that the proton transport is dominated by structural diffusion, with the diffusion constant of the proton defect being ∼8 times higher than that of self-diffusion of the imidazole molecules. By using correlation function analysis, we decompose the mechanism for proton transport into a series of first-order processes and show that the proton transport mechanism occurs over three distinct time and length scales. Although the mechanism at intermediate times is dominated by hopping along pseudo-one-dimensional chains, at longer times the overall rate of diffusion is limited by the re-formation of these chains. These results provide a more complete picture of the traditional idealized Grotthuss structural diffusion mechanism.

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Protonic Mobility and Its Importance for Biological Systems*

Cited by 26 publications

References 15 publications

Some Effects of Trace Inorganics on the Ice/Water System

Some Effects of Trace Inorganics on the Ice/Water System

Proton Hopping and Long-Range Transport in the Protic Ionic Liquid [Im][TFSI], Probed by Pulsed-Field Gradient NMR and Quasi-Elastic Neutron Scattering

Elucidating the Proton Transport Pathways in Liquid Imidazole with First-Principles Molecular Dynamics

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