Structural aspects of the topological model of the hydrogen bond in water on auto-dissociation <i>via</i> proton transfer

Lentz, Jesse; Garofalini, Stephen H.

doi:10.1039/c8cp02592d

Cited by 18 publications

(35 citation statements)

References 62 publications

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“…Extending the evaluations to simulations of water nanoconfined in amorphous silica resulted in the simulations showing the change in volume with decreasing pore size seen experimentally. 12,16 Simulations of hydrogen bond lifetimes of water molecules in bulk water gave a time constant of 2.1 ps, 47 consistent with the experimental data. 48…”

supporting

confidence: 77%

“…Such an effect has been used in femtosecond pump‐probe spectroscopies to determine lifetimes of H‐bonds in water and reorientation times . Molecular dynamics simulations using the potential used in the current work similarly showed the dependence of the shortening of the H‐bond length on the elongation of the covalent OH bond length and the decrease in the high‐frequency OH stretch vibration …”

Section: Resultsmentioning

confidence: 55%

“…The first peak, indicative of the covalent OH bond, is shown in Figure A, showing an elongation of the covalent OH bond length for those glasses containing increasing concentrations of SiOH. Previous studies show that an increase in longer distance covalent OH bonds occurs simultaneously with a decrease in the hydrogen bond (H‐bond) length . Figure B shows the PDFs at longer distances for each system.…”

Section: Resultsmentioning

confidence: 90%

“…[51][52][53][54][55] Molecular dynamics simulations using the potential used in the current work similarly showed the dependence of the shortening of the H-bond length on the elongation of the covalent OH bond length and the decrease in the high-frequency OH stretch vibration. 47 Figure 9 shows the high-frequency OH stretching mode of the H 2 O and SiOH 7.7 systems performed at 80 K. Clearly, there is an increase at the lower end of the vibrational spectrum in the glasses containing the high concentration of SiOH, consistent with the shortening of the H-bond length and concomitant increase in the covalent OH bond length and weakening of the covalent OH bond. Such results are also consistent with the data by Sulpizi et al regarding the vibrational spectra of silanols 56 as well as further discussions regarding internal silanols.…”

Section: F I G U R E 4 a Ring Size Distribution In The Three Systemsmentioning

confidence: 82%

“…Previous studies show that an increase in longer distance covalent OH bonds occurs simultaneously with a decrease in the hydrogen bond (H-bond) length. 47 Figure 8B shows the PDFs at longer distances for each system. Consistent with the elongation of the covalent bonds is the decrease in the H-bond length, as shown in the first peak in Figure 8B (such results will be relevant to the results regarding the vibrational spectra presented below).…”

Section: F I G U R E 4 a Ring Size Distribution In The Three Systemsmentioning

confidence: 99%

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Molecular mechanism of the expansion of silica glass upon exposure to moisture

2019

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Molecular dynamics simulations show that the expansion of silica glass occurs by the presence of the hydroxyl (SiOH) groups present in the glass as opposed to intact water (H2O) molecules, providing an accurate molecular description of the experimentally observed volume changes in silica glass exposed to water. Using a robust and accurate reactive potential, the simulations show that the expansion is caused by the rupture of siloxane (Si–O–Si) linkages in the glass via reactions with water molecules, forming SiOHs. Such reactions remove smaller rings and form larger rings, with a decrease in the overall number of rings smaller than a prescribed large ring size in comparison to dry glasses. This change in ring structure overcomes the inherently stronger hydrogen bonding in the glasses containing SiOH in comparison to the glasses containing predominantly intact H2O molecules. This stronger H‐bonding of the SiOH also causes a shift to lower frequencies in the high‐frequency OH vibrational spectrum for the silanols, as shown in previous ab‐initio calculations. This introduces a question about assuming the lower frequency part of the high‐frequency peak is only due to intact H2O molecules. A slight decrease in volume occurred in the glasses containing the largest concentration of intact H2O molecules. There is no change in the ring size distribution between the H2O glasses and dry glasses. Rather, the slight decrease in volume in the H2O system is caused by a decrease in siloxane bond angles caused by the formation of H‐bonds between the H2O molecules and the glass O in the siloxane cages surrounding the H2O molecules.

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supporting

confidence: 77%

Section: Resultsmentioning

confidence: 55%

Section: Resultsmentioning

confidence: 90%

Section: F I G U R E 4 a Ring Size Distribution In The Three Systemsmentioning

confidence: 82%

Section: F I G U R E 4 a Ring Size Distribution In The Three Systemsmentioning

confidence: 99%

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Molecular mechanism of the expansion of silica glass upon exposure to moisture

2019

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Facile Proton Transport in Ammonium Borosulfate—An Unhumidified Solid Acid Polyelectrolyte for Intermediate Temperatures

et al. 2020

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metal-organic frameworks (MOFs), [12-18] and finally covalent organic frameworks (COFs). [19-23] Typically, solid acids display high proton conductivity above a superprotonic transition temperature occurring at >135 °C, [8] but are virtually insulating at lower temperatures, and are often susceptible to degradation under operating conditions. [9] Impregnated organic polymers such as PBI-H 3 PO 4 generally operate at 150-200 °C and show good fuel tolerance, but suffer from acid leaching. [11] Development of CP/MOF electrolytes has led to the discovery of a number of materials that exhibit proton conductivities of 10-100 mS cm −1 under conditions that require active humidification; however, materials that operate under anhydrous conditions are uncommon. [24] Here, we present the discovery that ammonium borosulfate, NH 4 [B(SO 4) 2 ], a solid acid coordination polymer, is a good ionic conductor at modest temperatures (100-200 °C), without active humidification (ambient, <2.5 % RH). As a condensed salt of the molecular superacid H[B(HSO 4) 4 ], its crystal structure presents an infinite, hydrogen-bonded NH•••O•••HN network between interstitial NH 4 + cations and 1D anionic chains of 1 ∞ [B(SO 4) 4/2 ] − that upon initial examination appears promising for long-range proton transfer. [25] According to previously reported calculations of borosulfate pK a values, NH 4

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Recent advances in quantum‐mechanical molecular dynamics simulations of proton transfer mechanism in various water‐based environments

Sakti

Nishimura

Nakai

2019

WIREs Comput Mol Sci

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Proton transfer in water‐based environments occurs because of hydrogen‐bond interaction. There are many interesting physicochemical phenomena in this field, causing fast structural diffusion of hydronium and hydroxide ions. During the last few decades, to support experimental observations and measurements, quantum‐mechanical molecular dynamics (QMMD) simulations with reasonable accuracy and efficiency have significantly unraveled structural, energetic, and dynamical properties of excess proton in aqueous environments. This review summarizes the state‐of‐the‐art QMMD studies of proton transfer processes in aqueous solutions and complex systems including bulk liquid water, ice phases, and confined water in nanochannel/nanoporous materials as well as reports on CO2 scrubbing by amine‐based chemical absorption. This article is categorized under: Structure and Mechanism > Reaction Mechanisms and Catalysis Molecular and Statistical Mechanics > Molecular Dynamics and Monte‐Carlo Methods Electronic Structure Theory > Semiempirical Electronic Structure Methods Theoretical and Physical Chemistry > Reaction Dynamics and Kinetics

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Structural aspects of the topological model of the hydrogen bond in water on auto-dissociation via proton transfer

Cited by 18 publications

References 62 publications

Molecular mechanism of the expansion of silica glass upon exposure to moisture

Molecular mechanism of the expansion of silica glass upon exposure to moisture

Facile Proton Transport in Ammonium Borosulfate—An Unhumidified Solid Acid Polyelectrolyte for Intermediate Temperatures

Recent advances in quantum‐mechanical molecular dynamics simulations of proton transfer mechanism in various water‐based environments

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