1
|
Hinz Y, Beerwerth J, Böhmer R. Anion dynamics and motional decoupling in a glycerol-choline chloride deep eutectic solvent studied by one- and two-dimensional 35Cl NMR. Phys Chem Chem Phys 2023; 25:28130-28140. [PMID: 37818622 DOI: 10.1039/d3cp03668e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Chlorine-35 is among the few nuclides that provide an experimental handle on the anion dynamics in choline based deep eutectic solvents. By combining several nuclear magnetic resonance (NMR) techniques, the present work examines the Cl- motions within glyceline, a glycerol : choline chloride 2 : 1 solution, in a large temperature range down to the glass transition temperature Tg. The applied methods include spin relaxometry, second-order line shape analysis, as well as two-dimensional central-transition exchange and stimulated-echo spectroscopy. The finding of unstructured central-transition NMR spectra characterized by a relatively small average quadrupolar coupling attests to a highly disordered, essentially nondirectional anionic coordination in glyceline. For temperatures larger than about 1.3Tg the chlorine motions are well coupled to those of the glycerol and the choline moieties. At lower temperatures the local translational anion dynamics become Arrhenian and increasingly faster than the motion of glyceline's matrix molecules. Upon further cooling, the overall ionic conductivity continues to display a super-Arrhenius behavior, implying that the choline cations rather than the Cl anions dominate the long-range charge transport also near Tg.
Collapse
Affiliation(s)
- Yannik Hinz
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Joachim Beerwerth
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Roland Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| |
Collapse
|
2
|
Popov I, Zhu Z, Young-Gonzales AR, Sacci RL, Mamontov E, Gainaru C, Paddison SJ, Sokolov AP. Search for a Grotthuss mechanism through the observation of proton transfer. Commun Chem 2023; 6:77. [PMID: 37087505 PMCID: PMC10122652 DOI: 10.1038/s42004-023-00878-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 04/04/2023] [Indexed: 04/24/2023] Open
Abstract
The transport of protons is critical in a variety of bio- and electro-chemical processes and technologies. The Grotthuss mechanism is considered to be the most efficient proton transport mechanism, generally implying a transfer of protons between 'chains' of host molecules via elementary reactions within the hydrogen bonds. Although Grotthuss proposed this concept more than 200 years ago, only indirect experimental evidence of the mechanism has been observed. Here we report the first experimental observation of proton transfer between the molecules in pure and 85% aqueous phosphoric acid. Employing dielectric spectroscopy, quasielastic neutron, and light scattering, and ab initio molecular dynamic simulations we determined that protons move by surprisingly short jumps of only ~0.5-0.7 Å, much smaller than the typical ion jump length in ionic liquids. Our analysis confirms the existence of correlations in these proton jumps. However, these correlations actually reduce the conductivity, in contrast to a desirable enhancement, as is usually assumed by a Grotthuss mechanism. Furthermore, our analysis suggests that the expected Grotthuss-like enhancement of conductivity cannot be realized in bulk liquids where ionic correlations always decrease conductivity.
Collapse
Affiliation(s)
- Ivan Popov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
- Department of Chemistry, University of Tennessee, Knoxville, TN, USA
| | - Zhenghao Zhu
- Department of Chemical & Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA
| | | | - Robert L Sacci
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Eugene Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Catalin Gainaru
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Stephen J Paddison
- Department of Chemical & Biomolecular Engineering, University of Tennessee, Knoxville, TN, USA.
| | - Alexei P Sokolov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
- Department of Chemistry, University of Tennessee, Knoxville, TN, USA.
| |
Collapse
|
3
|
Hinz Y, Böhmer R. Deuteron magnetic resonance study of glyceline deep eutectic solvents: Selective detection of choline and glycerol dynamics. J Chem Phys 2022; 156:194506. [PMID: 35597634 DOI: 10.1063/5.0088290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Glyceline, a green solvent considered for various electrochemical applications, represents a multi-component glass former. Viewed from this perspective, the choline cation and the hydrogen bond donor glycerol, the two major constituents forming this deep eutectic solvent, were studied using nuclear magnetic resonance in a selective manner by means of suitably deuteron-labeled isotopologues. Carried out from far above to far below the glass transition temperature, measurements and analyses of the spin-lattice and spin-spin relaxation times reveal that the reorientational dynamics of the components, i.e., of glycerol as well as of chain deuterated choline chloride are slightly different. Possible implications of this finding regarding the hydrogen-bonding pattern in glyceline are discussed. Furthermore, the deuterated methyl groups in choline chloride are exploited as sensitive probes of glyceline's supercooled and glassy states. Apart from spin relaxometry, a detailed line shape analysis of the CD3 spectra yields valuable insights into the broad intermolecular and intramolecular energy barrier distributions present in this binary mixture.
Collapse
Affiliation(s)
- Yannik Hinz
- Experimental Physics III, Technical University Dortmund, D-44221 Dortmund, Germany
| | - Roland Böhmer
- Experimental Physics III, Technical University Dortmund, D-44221 Dortmund, Germany
| |
Collapse
|
4
|
Hoffmann L, Beerwerth J, Adjei-Körner M, Fuentes-Landete V, Tonauer CM, Loerting T, Böhmer R. Oxygen NMR of high-density and low-density amorphous ice. J Chem Phys 2022; 156:084503. [DOI: 10.1063/5.0080333] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using oxygen-17 as a nuclear probe, spin relaxometry was applied to study the high-density and low-density states of amorphous ice, covering temperatures below and somewhat above their glass transitions. These findings are put in perspective with results from deuteron nuclear magnetic resonance and with calculations based on dielectrically detected correlation times. This comparison reveals the presence of a wide distribution of correlation times. Furthermore, oxygen-17 central-transition echo spectra were recorded for wide ranges of temperature and pulse spacing. The spectra cannot be described by a single set of quadrupolar parameters, suggesting a distribution of H–O–H opening angles that is broader for high-density than for low-density amorphous ice. Simulations of the pulse separation dependent spin-echo spectra for various scenarios demonstrate that a small-step frequency diffusion process, assigned to the presence of homonuclear oxygen–oxygen interactions, determines the shape evolution of the pulse-separation-dependent spectra.
Collapse
Affiliation(s)
- Lars Hoffmann
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - Joachim Beerwerth
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | | | - Violeta Fuentes-Landete
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - Christina M. Tonauer
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - Thomas Loerting
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
| | - Roland Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| |
Collapse
|
5
|
Schulz A, Lunkenheimer P, Loidl A. Lithium-salt-based deep eutectic solvents: Importance of glass formation and rotation-translation coupling for the ionic charge transport. J Chem Phys 2021; 155:044503. [PMID: 34340372 DOI: 10.1063/5.0055493] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Lithium-salt-based deep eutectic solvents, where the only cation is Li+, are promising candidates as electrolytes in electrochemical energy-storage devices, such as batteries. We have performed broadband dielectric spectroscopy on three such systems, covering a broad temperature and dynamic range that extends from the low-viscosity liquid around room temperature down to the glassy state approaching the glass-transition temperature. We detect a relaxational process that can be ascribed to dipolar reorientational dynamics and exhibits the clear signatures of glassy freezing. We find that the temperature dependence of the ionic dc conductivity and its room-temperature value also are governed by the glassy dynamics of these systems, depending, e.g., on the glass-transition temperature and fragility. Compared to the previously investigated corresponding systems, containing choline chloride instead of a lithium salt, both the reorientational and ionic dynamics are significantly reduced due to variations in the glass-transition temperature and the higher ionic potential of the lithium ions. These lithium-based deep eutectic solvents partly exhibit significant decoupling of the dipolar reorientational and the ionic translational dynamics and approximately follow a fractional Debye-Stokes-Einstein relation, leading to an enhancement of the dc conductivity, especially at low temperatures. The presented results clearly reveal the importance of decoupling effects and of the typical glass-forming properties of these systems for the technically relevant room-temperature conductivity.
Collapse
Affiliation(s)
- A Schulz
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
| | - P Lunkenheimer
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
| | - A Loidl
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
| |
Collapse
|
6
|
Ahlmann S, Münzner P, Moch K, Sokolov AP, Böhmer R, Gainaru C. The relationship between charge and molecular dynamics in viscous acid hydrates. J Chem Phys 2021; 155:014505. [PMID: 34241375 DOI: 10.1063/5.0055179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Oscillatory shear rheology has been employed to access the structural rearrangements of deeply supercooled sulfuric acid tetrahydrate (SA4H) and phosphoric acid monohydrate, the latter in protonated (PA1H) and deuterated (PA1D) forms. Their viscoelastic responses are analyzed in relation to their previously investigated electric conductivity. The comparison of the also presently reported dielectric response of deuterated sulfuric acid tetrahydrate (SA4D) and that of its protonated analog SA4H reveals an absence of isotope effects for the charge transport in this hydrate. This finding clearly contrasts with the situation known for PA1H and PA1D. Our analyses also demonstrate that the conductivity relaxation profiles of acid hydrides closely resemble those exhibited by classical ionic electrolytes, even though the charge transport in phosphoric acid hydrates is dominated by proton transfer processes. At variance with this dielectric simplicity, the viscoelastic responses of these materials depend on their structural compositions. While SA4H displays a "simple liquid"-like viscoelastic behavior, the mechanical responses of PA1H and PA1D are more complex, revealing relaxation modes, which are faster than their ubiquitous structural rearrangements. Interestingly, the characteristic rates of these fast mechanical relaxations agree well with the characteristic frequencies of the charge rearrangements probed in the dielectric investigations, suggesting appearance of a proton transfer in mechanical relaxation of phosphoric acid hydrates. These findings open the exciting perspective of exploiting shear rheology to access not only the dynamics of the matrix but also that of the charge carriers in highly viscous decoupled conductors.
Collapse
Affiliation(s)
- S Ahlmann
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - P Münzner
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - K Moch
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - A P Sokolov
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - R Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - C Gainaru
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| |
Collapse
|
7
|
Reuter D, Münzner P, Gainaru C, Lunkenheimer P, Loidl A, Böhmer R. Translational and reorientational dynamics in deep eutectic solvents. J Chem Phys 2021; 154:154501. [DOI: 10.1063/5.0045448] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- D. Reuter
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
| | - P. Münzner
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - C. Gainaru
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - P. Lunkenheimer
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
| | - A. Loidl
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
| | - R. Böhmer
- Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| |
Collapse
|
8
|
Pabst F, Wojnarowska Z, Paluch M, Blochowicz T. On the temperature and pressure dependence of dielectric relaxation processes in ionic liquids. Phys Chem Chem Phys 2021; 23:14260-14275. [PMID: 34159979 DOI: 10.1039/d1cp01636a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular dynamics of ionic liquids in an electric field can be decomposed into contributions from translational motions of ions, rotational motions of permanent dipoles and - in the case of ions equipped with long alkyl-chains - motions of ionic aggregates. The discrimination of these contributions in the dielectric spectrum is quite involved, resulting in numerous controversies in the literature. Here, we use dielectric spectroscopy at ambient and elevated pressures of up to 550 MPa to monitor the changes of the observed processes in five supercooled ionic liquids with octyl-chains independent of pressure and temperature. In most of the ionic liquids under investigation two dynamical processes are observed, one of them is identified as the ion hopping process, which we describe by the MIGRATION model. It turns out that this process is closely connected to the glass transition step as measured by differential scanning calorimetry. Concerning the second process, we rule out motions of aggregated ions to be its origin by comparison of our results with X-ray scattering literature data at elevated pressure. Instead, we tentatively ascribe it to dipolar reorientations and show that the dielectric strength of this slow process decreases as a function of increasing relaxation time, i.e. for decreasing temperatures and increasing pressures. We compare this behavior with literature data of other ion conducting systems and discuss its microscopic origin.
Collapse
Affiliation(s)
- Florian Pabst
- TU Darmstadt, Institut für Physik kondensierter Materie, 64289 Darmstadt, Germany.
| | - Zaneta Wojnarowska
- Institute of Physics, University of Silesia in Katowice, SMCEBI, 75 Pulku Piechoty 1A, Chorzow 41-500, Poland
| | - Marian Paluch
- Institute of Physics, University of Silesia in Katowice, SMCEBI, 75 Pulku Piechoty 1A, Chorzow 41-500, Poland
| | - Thomas Blochowicz
- TU Darmstadt, Institut für Physik kondensierter Materie, 64289 Darmstadt, Germany.
| |
Collapse
|
9
|
Thomann CA, Münzner P, Moch K, Jacquemin J, Goodrich P, Sokolov AP, Böhmer R, Gainaru C. Tuning the dynamics of imidazolium-based ionic liquids via hydrogen bonding. I. The viscous regime. J Chem Phys 2020; 153:194501. [DOI: 10.1063/5.0026144] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- C. A. Thomann
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - P. Münzner
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - K. Moch
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - J. Jacquemin
- Faculté des Sciences et Techniques, Université de Tours, 37200 Tours, France
- QUILL Center, The Queen’s University of Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
| | - P. Goodrich
- QUILL Center, The Queen’s University of Belfast, Belfast BT9 5AG, Northern Ireland, United Kingdom
| | - A. P. Sokolov
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37916, USA and Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
| | - R. Böhmer
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - C. Gainaru
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| |
Collapse
|
10
|
Sen S. Dynamics in inorganic glass-forming liquids by NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 116:155-176. [PMID: 32130956 DOI: 10.1016/j.pnmrs.2019.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/08/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
Dynamical NMR spectroscopy provides unique mechanistic understanding of the transport and relaxation processes in glass-forming liquids over timescales typically ranging from ~10-9 s to ~102 s, and thus has been used extensively in the past to study the dynamical behavior of polymeric and organic glass-forming liquids. However, reports in the literature of similar studies on inorganic glass-forming liquids have remained somewhat limited due to the experimental challenges. In this contribution we present a review of the high-temperature NMR spectroscopic studies of atomic and molecular dynamics in a wide variety of inorganic glass-forming liquids including oxides, halides and chalcogenides as well as select ionic liquids and molten salts. The significance of these dynamical processes in understanding the nature of the liquid-to-glass transition and their connection with the macroscopic transport properties of these liquids are discussed.
Collapse
Affiliation(s)
- Sabyasachi Sen
- Department of Materials Science & Engineering, University of California at Davis, Davis, CA 95616, USA.
| |
Collapse
|
11
|
Hoffmann L, Beerwerth J, Greim D, Senker J, Sternemann C, Hiller W, Böhmer R. Reorientational dynamics of trimethoxyboroxine: A molecular glass former studied by dielectric spectroscopy and 11B nuclear magnetic resonance. J Chem Phys 2020; 152:034503. [PMID: 31968976 DOI: 10.1063/1.5129769] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, trimethoxyboroxine (TMB) is identified as a small-molecule glass former. In its viscous liquid as well as glassy states, static and dynamic properties of TMB are explored using various techniques. It is found that, on average, the structure of the condensed TMB molecules deviates from threefold symmetry so that TMB's electric dipole moment is nonzero, thus rendering broadband dielectric spectroscopy applicable. This method reveals the super-Arrhenius dynamics that characterizes TMB above its glass transition, which occurs at about 204 K. To extend the temperature range in which the molecular dynamics can be studied, 11B nuclear magnetic resonance experiments are additionally carried out on rotating and stationary samples: Exploiting dynamic second-order shifts, spin-relaxation times, line shape effects, as well as stimulated-echo and two-dimensional exchange spectroscopy, a coherent picture regarding the dynamics of this glass former is gained.
Collapse
Affiliation(s)
- Lars Hoffmann
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - Joachim Beerwerth
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - Dominik Greim
- Anorganische Chemie III, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - Jürgen Senker
- Anorganische Chemie III, Universität Bayreuth, D-95440 Bayreuth, Germany
| | - Christian Sternemann
- DELTA/Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - Wolf Hiller
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - Roland Böhmer
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| |
Collapse
|
12
|
Münzner P, Hoffmann L, Böhmer R, Gainaru C. Deeply supercooled aqueous LiCl solution studied by frequency-resolved shear rheology. J Chem Phys 2019; 150:234505. [DOI: 10.1063/1.5100600] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Philipp Münzner
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - Lars Hoffmann
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - Roland Böhmer
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| | - Catalin Gainaru
- Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany
| |
Collapse
|