Dynamics of structural diffusion in phosphoric acid hydrogen-bond clusters

Suwannakham, Parichart; Sagarik, Kritsana

doi:10.1039/c7ra01829k

Cited by 5 publications

(5 citation statements)

References 52 publications

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“…) occurs on the low energy barrier path. The first transfer occurs in the H-bond (1) of the transition structure CG-[2] 2+, ‡ (Zundel-like structure) with ΔE ‡ = 6.3 kJ mol −1 and ΔE H-bond/CP = −160.0 kJ mol −1 ; similar shared proton structures were found in our previous studies as active intermediates in proton transfer in the O-H + … O H-bonds of H + [H 2 O] 2 and H + [H 3 PO 4 ] 2 for ε = 1 [21,33]. However, the second transfer involves an almost barrierless potential via a transition structure with ΔE H-bond/CP ≈ −269 kJ mol −1 , leading to CG- [3] 2+ with ΔE H-bond/CP = −22.1 kJ mol −1 .…”

Section: Potential Energy Curves For Bifunctional Proton Transfersupporting

confidence: 86%

The Grotthuss mechanism for bifunctional proton transfer in poly(benzimidazole)

2021

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Poly(benzimidazole) (PBI) has received considerable attention as an effective high-temperature polymer electrolyte membrane for fuel cells. In this work, the Grotthuss mechanism for bifunctional proton transfer in PBI membranes was studied using density functional theory and transition state theory. This study focused on the reaction paths and kinetics for bifunctional proton transfer scenarios in neutral ([PBI] 2 ), single (H + [PBI] 2 ) and double-protonated (H 2+ [PBI] 2 ) dimers. The theoretical results showed that the energy barriers and strength for H-bonds are sensitive to the local dielectric environment. For [PBI] 2 with ε = 1, the uphill potential energy curve is attributed to extraordinarily strong ion-pair H-bonds in the transition structure, regarded as a ‘dipolar energy trap’. For ε = 23, the ion-pair charges are partially neutralized, leading to a reduction in the electrostatic attraction in the transition structure. The dipolar energy trap appears to prohibit interconversion between the precursor, transition and proton-transferred structures, which rules out the possibility for [PBI] 2 to be involved in the Grotthuss mechanism. For H + [PBI] 2 and H 2+ [PBI] 2 with ε = 1, the interconversion involves a low energy barrier, and the increase in the energy barrier for ε = 23 can be attributed to an increase in the strength of the protonated H-bonds in the transition structure: the local dielectric environment enhances the donor–acceptor interaction of the protonated H-bonds. Analysis of the rate constants confirmed that the quantum effect is not negligible for the N–H + … N H-bond especially at low temperatures. Agreement between the theoretical and experimental data leads to the conclusion that the concerted bifunctional proton transfer in H 2+ [PBI] 2 in a high local dielectric environment is ‘the rate-determining scenario’. Therefore, a low local dielectric environment can be one of the required conditions for effective proton conduction in acid-doped PBI membranes. These theoretical results provide insights into the Grotthuss mechanism, which can be used as guidelines for understanding the fundamentals of proton transfers in other bifunctional H-bond systems.

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Section: Potential Energy Curves For Bifunctional Proton Transfersupporting

confidence: 86%

The Grotthuss mechanism for bifunctional proton transfer in poly(benzimidazole)

2021

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“….60 Â 10 À14 s À1 , whereas for the same reaction at 3 ¼ 1 (Int2b / TS3 / Int3), k S-Wig f ¼ 1.71 Â 10 8 s À1 , which indicates that acid catalyst (1) (III) is kinetically favorable in a low local dielectric environment. This is in accordance with our previous work, 11,14,24 in which the uctuation of the local dielectric environment was conrmed to govern the kinetics of proton transfer processes; based on this analysis, React / TS1 / Int1 (1,3-dipolar cycloaddition (I)) is kinetically more favorable than React 3 / TS1 3 / Int1 3 (k S-Wig f ¼ 3.44 Â 10 3 and k S-Wig,3 f ¼ 2.44 Â 10 3 s À1 , respectively). Attempt was made to correlate the rate constants obtained from the TST method with the experimental data.…”

Section: Kinetics and Thermodynamics Of The Elementary Reactionssupporting

confidence: 94%

Kinetics and thermodynamics of enzymatic decarboxylation of α,β-unsaturated acid: a theoretical study

et al. 2022

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“…Protons exchange during diffusion of phosphoric acid in hydrogen-bond clusters could not be fully analyzed in an experimental way [ 51 ]. That is why a theoretical study based on the reliable calculation protocol was used in order to propose the underlying mechanism.…”

Section: Summary Of the Chosen Studies Applying Both Aimd And Nmr Parameters Calculationmentioning

confidence: 99%

A Review on Combination of Ab Initio Molecular Dynamics and NMR Parameters Calculations

Mazurek

Szeleszczuk

Pisklak

2021

IJMS

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This review focuses on a combination of ab initio molecular dynamics (aiMD) and NMR parameters calculations using quantum mechanical methods. The advantages of such an approach in comparison to the commonly applied computations for the structures optimized at 0 K are presented. This article was designed as a convenient overview of the applied parameters such as the aiMD type, DFT functional, time step, or total simulation time, as well as examples of previously studied systems. From the analysis of the published works describing the applications of such combinations, it was concluded that including fast, small-amplitude motions through aiMD has a noticeable effect on the accuracy of NMR parameters calculations.

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Dynamics of structural diffusion in phosphoric acid hydrogen-bond clusters

Abstract: For protonated H3PO4 clusters, the Eigen–Zundel–Eigen mechanism is enhanced by fluctuations in the H-bond chain length and local-dielectric environment, and can proceed without the reorientation of H3PO4 molecules as in the case of neat liquid H3PO4.

Cited by 5 publications

References 52 publications

The Grotthuss mechanism for bifunctional proton transfer in poly(benzimidazole)

The Grotthuss mechanism for bifunctional proton transfer in poly(benzimidazole)

Kinetics and thermodynamics of enzymatic decarboxylation of α,β-unsaturated acid: a theoretical study

A Review on Combination of Ab Initio Molecular Dynamics and NMR Parameters Calculations

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