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Koyakkat M, Ishida T, Fujita K, Shirota H. Low-Frequency Spectra of Hydrated Ionic Liquids with Kosmotropic and Chaotropic Anions. J Phys Chem B 2024; 128:4171-4182. [PMID: 38640467 DOI: 10.1021/acs.jpcb.4c01255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2024]
Abstract
In this study, we investigated the water concentration dependence of the intermolecular vibrations of two hydrated ionic liquids (ILs), cholinium dihydrogen phosphate ([ch][dhp]) and cholinium bromide ([ch]Br), using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES). The anions of the former and latter hydrated ILs are kosmotropic and chaotropic, respectively. We found that the spectral peak of ∼50 cm-1 shifted to the low-frequency side in hydrated [ch][dhp], indicating the weakening of its intermolecular interactions. In contrast, no change in the peak frequency of the low-frequency band at ∼50 cm-1 was observed with increasing water concentration in hydrated [ch]Br. The vibrational density of states (VDOS) spectra generated from molecular dynamics (MD) simulations were in qualitative agreement with the experimental results. Decomposition analysis of the VDOS spectra for each component revealed that the red shift of the low-frequency band in the hydrated [ch][dhp] upon water addition was essentially due to the contributions of anions and water rather than that of the cholinium cation. We also found from the low-frequency spectra of the two hydrated ILs that they differed in the concentration dependence of the 180 cm-1 band, which is assigned as a hindered translational motion of water molecules combined to form O···O stretching motions. From the relationship between the peak frequency of the low-frequency band and the bulk parameter, which is the square root of the surface tension divided by the density, we found that the peak frequency in the hydrated IL with kosmotropic [dhp]- depends on the bulk parameter, similar to the case for an aqueous solution of the typical deep eutectic solvent reline. However, the peak frequency of the hydrated IL with chaotropic Br- is constant with the bulk parameter.
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Affiliation(s)
- Maharoof Koyakkat
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Tateki Ishida
- Institute for Molecular Science and Research Center for Computational Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Kyoko Fujita
- Department of Pathophysiology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Hideaki Shirota
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
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2
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Ando M, Tashiro A, Kawano M, Peng Y, Takamuku T, Shirota H. Exploring the Microscopic Aspects of 1-Methyl-3-octylimidazolium Tetrafluoroborate Mixtures with Formamide, N-Methylformamide, and N, N-Dimethylformamide by Multiple Spectroscopic Techniques and Computations. J Phys Chem B 2023; 127:3870-3887. [PMID: 37093658 DOI: 10.1021/acs.jpcb.2c09102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
The microscopic aspects of 1-methyl-3-octylimidazolium tetrafluoroborate ([MOIm][BF4]) mixtures with formamide (FA), N-methylformamide (NMF), and N,N-dimethylformamide (DMF) were investigated using spectroscopic techniques of femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES), FT-IR, and NMR. Molecular dynamics simulations and quantum chemistry calculations were also performed. According to fs-RIKES, the first moment of the low-frequency spectrum bands mainly originating from the intermolecular vibrations in the [MOIm][BF4]/FA and [MOIm][BF4]/DMF systems changed gradually with the molecular liquid mole fraction XML but that in the [MOIm][BF4]/NMF system was constant up to XNMF = 0.7 and then gradually increased in the range of XNMF ≥ 0.7. Excluding the contribution of the 2D hydrogen-bonding network due to the presence of FA in the low-frequency spectrum band, the XML dependence of the normalized first moment of the low-frequency band in the [MOIm][BF4]/FA and [MOIm][BF4]/NMF systems revealed that the normalized first moment did not remarkably change in the range of XML < 0.7 but drastically increased in XML ≥ 0.7. FT-IR results indicated that the amide C═O band shifted to the low-frequency side with increasing XML for the three mixtures due to the hydrogen bonds. The imidazolium ring C-H band also showed a similar tendency to the amide C═O band. 19F NMR probed the microenvironment of [BF4]- in the mixtures. The [MOIm][BF4]/NMF and [MOIm][BF4]/DMF systems showed an up-field shift of the F atoms of the anion with increasing XML, and the [MOIm][BF4]/FA system exhibited a down-field shift. Steep changes in the chemical shifts were confirmed in the region of XML > 0.8. On the basis of the quantum chemistry calculations, the observed chemical shifts with increasing XML were mainly attributed to the many-body interactions of ions and amides for the [MOIm][BF4]/FA and [MOIm][BF4]/DMF systems. Meanwhile, the long distance between the cation and the anion was due to the high dielectric medium for the [MOIm][BF4]/NMF system, which led to an up-field shift.
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Affiliation(s)
- Masatoshi Ando
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Atsuya Tashiro
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Honjo-machi, Saga 840-8502, Japan
| | - Masahiro Kawano
- Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Honjo-machi, Saga 840-8502, Japan
| | - Yue Peng
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Toshiyuki Takamuku
- Faculty of Science and Engineering, Saga University, Honjo-machi, Saga 840-8502, Japan
| | - Hideaki Shirota
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
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Shirota H, Rajbangshi J, Koyakkat M, Baksi A, Cao M, Biswas R. Low-frequency spectra of reline and its mixtures with water: A comparative study based on femtosecond Raman-induced Kerr effect spectroscopy and molecular dynamics simulations. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2022.114504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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4
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Ando M, Ohta K, Ishida T, Koido R, Shirota H. Physical Properties and Low-Frequency Polarizability Anisotropy and Dipole Responses of Phosphonium Bis(fluorosulfonyl)amide Ionic Liquids with Pentyl, Ethoxyethyl, or 2-(Ethylthio)ethyl Group. J Phys Chem B 2023; 127:542-556. [PMID: 36602430 DOI: 10.1021/acs.jpcb.2c07466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This study compared the physical properties, e.g., glass transition temperature, melting point, viscosity, density, surface tension, and electrical conductivity, and the low-frequency spectra under 200 cm-1 of three synthesized ionic liquids (ILs), triethylpentylphosphonium bis(fluorosulfonyl)amide ([P2225][NF2]), ethoxyethyltriethylphosphonium bis(fluorosulfonyl)amide ([P222(2O2)][NF2]), and triethyl[2-(ethylthio)ethyl]phosphonium bis(fluorosulfonyl)amide ([P222(2S2)][NF2]), at various temperatures using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES) and terahertz time-domain spectroscopy (THz-TDS). The [P222(2S2)][NF2] had the highest viscosity and glass transition temperature, whereas the [P222(2O2)][NF2] had the lowest. Among the three ILs, the [P222(2S2)][NF2] had the highest density and surface tension, and the [P222(2O2)][NF2] had the highest electrical conductivity. The RIKES and THz-TDS spectral line shapes for the three ILs varied significantly. For the [P2225][NF2], molecular dynamics simulations successfully reproduced the line shapes of the experimental spectra and indicated that the RIKES spectrum was mainly due to the cation and cross-term and their rotational motions, whereas the THz-TDS spectrum was mainly due to the anion and its translational motion. This shows that it is desirable to utilize both fs-RIKES and THz-TDS methods to reveal molecular motions at the low-frequency domain. The [P222(2S2)][NF2] had higher frequency peaks and broader bands in the low-frequency spectra via fs-RIKES and THz-TDS than those for the [P2225][NF2] and [P222(2O2)][NF2].
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Affiliation(s)
- Masatoshi Ando
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Kaoru Ohta
- Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Tateki Ishida
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science and Research Center for Computational Science, 38 Nishigonaka, Myodaiji, Okazaki 444-8585, Japan
| | - Ryohei Koido
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Hideaki Shirota
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
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5
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Biswas A, Mallik BS. Multiple Ensembles of the Hydrogen-bonded Network in Ethylammonium Nitrate versus Water from Vibrational Spectral Dynamics of SCN- Probe. Chemphyschem 2022; 23:e202200497. [PMID: 35965410 DOI: 10.1002/cphc.202200497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/05/2022] [Indexed: 11/12/2022]
Abstract
We performed classical molecular dynamics simulations to monitor the structural interactions and ultrafast dynamical and spectral response in the protic ionic liquid, ethylammonium nitrate (EAN) and water using the nitrile stretching mode of thiocyanate ion (SCN-) as the vibrational probe. The normalized stretch frequency distribution of nitrile stretch of SCN- attains an asymmetric shape in EAN, indicating the existence of more than one hydrogen-bonding environment in EAN. We computed the 2D IR spectrum from classical trajectories, applying the response function formalism. Spectral diffusion dynamics in EAN undergo an initial rattling of the SCN - inside the local ion-cage occurring at a timescale of 0.10 ps, followed by the breakup of the ion-cage activating molecular diffusion at 7.86 ps timescale. In contrast, the dynamics of structural reorganization occur at a timescale of 0.58 ps in H 2 O. Hence, the time dependence of the frequency-frequency correlation function decay hints at the local molecular structure and ultrafast ion dynamics of the SCN - probe. The loss of frequency correlation read from the peak shape changes in the 2D correlation spectrum as a function of waiting time is faster in H 2 O than in EAN due to the enhanced structural ordering and higher viscosity of the latter. We provide an atomic-level interpretation of the solvation environment around SCN - in EAN and water, which indicates the multiple ensembles of the hydrogen bond network in EAN.
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Affiliation(s)
- Aritri Biswas
- IITH: Indian Institute of Technology Hyderabad, Chemistry, INDIA
| | - Bhabani S Mallik
- IITH: Indian Institute of Technology Hyderabad, Chemistry, Kandi, 502285, Sangareddy, INDIA
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Kodis G, Ertem MZ, Newton MD, Matyushov DV. Reorganization Energy of Electron Transfer in Ionic Liquids. J Phys Chem Lett 2022; 13:3297-3303. [PMID: 35389644 DOI: 10.1021/acs.jpclett.2c00733] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Bandshape analysis of charge-transfer optical bands in room-temperature ionic liquids (ILs) was performed to extract the reorganization energy of electron transfer. Remarkably, the reorganization energies in ILs are close to those in cyclohexane. This result runs against common wisdom in the field since conducting ILs, which are characterized by an infinite static dielectric constant, and nonpolar cyclohexane fall to the opposite ends of the polarity scale based on their dielectric constants. Theoretical calculations employing structure factors of ILs from molecular dynamics simulations support the low values of the reorganization energy. Standard dielectric arguments do not apply to solvation in ILs, and nonergodic reorganization energies are required for a quantitative analysis.
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Affiliation(s)
- Gerdenis Kodis
- Department of Physics and School of Molecular Sciences, Arizona State University, PO Box 871504, Tempe, Arizona 85287-1504, United States
| | - Mehmed Z Ertem
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Marshall D Newton
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Dmitry V Matyushov
- Department of Physics and School of Molecular Sciences, Arizona State University, PO Box 871504, Tempe, Arizona 85287-1504, United States
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Friesen S, Fedotova MV, Kruchinin SE, Bešter-Rogač M, Podlipnik Č, Buchner R. Hydration and counterion binding of aqueous acetylcholine chloride and carbamoylcholine chloride. Phys Chem Chem Phys 2021; 23:25086-25096. [PMID: 34747952 DOI: 10.1039/d1cp03543f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The hydration and Cl- ion binding of the neurot†ransmitter acetylcholine (ACh+) and its synthetic analogue, carbamoylcholine (CCh+), were studied by combining dilute-solution conductivity measurements with dielectric relaxation spectroscopy and statistical mechanics calculations at 1D-RISM and 3D-RISM level. Chloride ion binding was found to be weak but not negligible. From the ∼30 water molecules coordinating ACh and CCh+ only ∼1/3 is affected in its rotational dynamics by the cation, with the majority - situated close to the hydrophobic moieties - only retarded by a factor of ∼2.5. At vanishing solute concentration cations and the ∼3-4 H2O molecules hydrogen bonding to the CO group of the solute exhibit similar rotational dynamics but increasing concentration and temperature markedly dehydrates ACh+ and CCh+.
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Affiliation(s)
- Sergej Friesen
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany.
| | - Marina V Fedotova
- G. A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Kademicheskaya st. 1, 153045 Ivanovo, Russian Federation.
| | - Sergey E Kruchinin
- G. A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Kademicheskaya st. 1, 153045 Ivanovo, Russian Federation.
| | - Marija Bešter-Rogač
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia.
| | - Črtomir Podlipnik
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia.
| | - Richard Buchner
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany.
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Ando M, Shirota H. Low-Frequency Spectra of 1-Methyl-3-octylimidazolium Tetrafluoroborate Mixtures with Poly(ethylene glycol) by Femtosecond Raman-Induced Kerr Effect Spectroscopy. J Phys Chem B 2021; 125:12006-12019. [PMID: 34694116 DOI: 10.1021/acs.jpcb.1c07079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This is the first report on low-frequency spectra of ionic liquid (IL)/polymer mixtures using femtosecond Raman-induced Kerr effect spectroscopy. We studied mixtures of 1-methyl-3-octylimidazolium tetrafluoroborate ([MOIm][BF4]) and poly(ethylene glycol) (PEG) with Mn = 400 (PEG400) at various concentrations. To elucidate the unique features of the IL/polymer mixture system, mixtures of PEG400 with a molecular liquid, 1-octhylimidazole (OIm), which is a neutral analog of the cation, were also studied. In addition, mixtures of [MOIm][BF4] with ethylene glycol (EG) and poly(ethylene glycol) with Mn = 4000 (PEG4000) were also investigated. The first moments of broad low-frequency spectra, mainly due to intermolecular vibrations for the [MOIm][BF4]/PEG400 and OIm/PEG400, increased slightly with increasing concentration of PEG400, indicating that microscopic intermolecular interactions, in general, are slightly enhanced. We also compared the [MOIm][BF4] mixtures with EG, PEG400, and PEG4000 at concentrations of 5 and 10 wt % PEG or EG. The low-frequency spectra of samples with the same concentrations were quite similar, but a comparison of the normalized spectra showed that the spectral intensity in the low-frequency region below ∼50 cm-1 of the [MOIm][BF4] mixtures with PEG400 and PEG4000 is somewhat lower than that of the [MOIm][BF4] mixtures with EG. Although the effect of the polymer is small compared to other polymer solution systems, this feature is attributed to a suppression of translational motion in the mixtures of [MOIm][BF4] with PEG compared to the mixtures of [MOIm][BF4] with EG due to the greater mass of PEG than EG. Density, surface tension, viscosity, and electrical conductivity were also estimated. From Walden plots, it was found that the [MOIm][BF4]/PEG4000 system showed more ideal electrical conductive behavior than the [MOIm][BF4]/PEG400 and [MOIm][BF4]/EG systems.
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Affiliation(s)
- Masatoshi Ando
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Hideaki Shirota
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
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Ausín D, Parajó JJ, Trenzado JL, Varela LM, Cabeza O, Segade L. Influence of Small Quantities of Water on the Physical Properties of Alkylammonium Nitrate Ionic Liquids. Int J Mol Sci 2021; 22:7334. [PMID: 34298957 PMCID: PMC8306069 DOI: 10.3390/ijms22147334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/28/2021] [Accepted: 07/02/2021] [Indexed: 11/16/2022] Open
Abstract
This paper presents a comprehensive study of two alkylammonium nitrate ionic liquids. As part of this family of materials, mainly ethylammonium nitrate (EAN) and also propylammonium nitrate (PAN) have attracted a great deal of attention during the last decades due to their potential applications in many fields. Although there have been numerous publications focused on the measurement of their physical properties, a great dispersion can be observed in the results obtained for the same magnitude. One of the critical points to be taken into account in their physical characterization is their water content. Thus, the main objective of this work was to determine the degree of influence of the presence of small quantities of water in EAN and PAN on the measurement of density, viscosity, electrical conductivity, refractive index and surface tension. For this purpose, the first three properties were determined in samples of EAN and PAN with water contents below 30,000 ppm in a wide range of temperatures, between 5 and 95 °C, while the last two were obtained at 25 °C. As a result of this study, it has been concluded that the presence of water is critical in those physical properties that involve mass or charge transport processes, resulting in the finding that the absolute value of the average percentage change in both viscosity and electrical conductivity is above 40%. Meanwhile, refractive index (≤0.3%), density (≤0.5%) and surface tension (≤2%) present much less significant changes.
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Affiliation(s)
- David Ausín
- Departamento de Física, Facultade de Ciencias, Campus da Zapateira, Universidade da Coruña, 15071 A Coruña, Spain; (D.A.); (O.C.)
| | - Juan J. Parajó
- Grupo de Nanomateriais, Fotónica e Materia Branda, Departamento de Física de Partículas y Departamento de Física Aplicada, Universidade de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain; (J.J.P.); (L.M.V.)
- Departamento de Química e Bioquímica, CIQUP-Centro de Investigaçao em Química da Universidade do Porto, Universidade do Porto, P-4169-007 Porto, Portugal
| | - José L. Trenzado
- Departamento de Física, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas Gran Canaria, Spain;
| | - Luis M. Varela
- Grupo de Nanomateriais, Fotónica e Materia Branda, Departamento de Física de Partículas y Departamento de Física Aplicada, Universidade de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain; (J.J.P.); (L.M.V.)
| | - Oscar Cabeza
- Departamento de Física, Facultade de Ciencias, Campus da Zapateira, Universidade da Coruña, 15071 A Coruña, Spain; (D.A.); (O.C.)
| | - Luisa Segade
- Departamento de Física, Facultade de Ciencias, Campus da Zapateira, Universidade da Coruña, 15071 A Coruña, Spain; (D.A.); (O.C.)
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Johnson CA, Parker AW, Donaldson PM, Garrett-Roe S. An ultrafast vibrational study of dynamical heterogeneity in the protic ionic liquid ethyl-ammonium nitrate. I. Room temperature dynamics. J Chem Phys 2021; 154:134502. [PMID: 33832238 DOI: 10.1063/5.0044822] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using ultrafast two-dimensional infrared spectroscopy (2D-IR), a vibrational probe (thiocyanate, SCN-) was used to investigate the hydrogen bonding network of the protic ionic liquid ethyl-ammonium nitrate (EAN) in comparison to H2O. The 2D-IR experiments were performed in both parallel (⟨ZZZZ⟩) and perpendicular (⟨ZZXX⟩) polarizations at room temperature. In EAN, the non-Gaussian lineshape in the FTIR spectrum of SCN- suggests two sub-ensembles. Vibrational relaxation rates extracted from the 2D-IR spectra provide evidence of the dynamical differences between the two sub-ensembles. We support the interpretation of two sub-ensembles with response function simulations of two overlapping bands with different vibrational relaxation rates and, otherwise, similar dynamics. The measured rates for spectral diffusion depend on polarization, indicating reorientation-induced spectral diffusion (RISD). A model of restricted molecular rotation (wobbling in a cone) fully describes the observed spectral diffusion in EAN. In H2O, both RISD and structural spectral diffusion contribute with similar timescales. This complete characterization of the dynamics at room temperature provides the basis for the temperature-dependent measurements in Paper II of this series.
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Affiliation(s)
- Clinton A Johnson
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, USA
| | - Anthony W Parker
- Central Laser Facility, STFC, Rutherford Appleton Laboratory, Harwell Campus, Didcot, United Kingdom
| | - Paul M Donaldson
- Central Laser Facility, STFC, Rutherford Appleton Laboratory, Harwell Campus, Didcot, United Kingdom
| | - Sean Garrett-Roe
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, USA
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11
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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.
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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.
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Shirota H, Ando M, Kakinuma S, Takahashi K. Ultrafast Dynamics in Nonaromatic Cation Based Ionic Liquids: A Femtosecond Raman-Induced Kerr Effect Spectroscopic Study. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2020. [DOI: 10.1246/bcsj.20200198] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hideaki Shirota
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Masatoshi Ando
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Shohei Kakinuma
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Kotaro Takahashi
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
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13
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Abe H, Koyama Y, Kishimura H, Matsuishi K. High-pressure crystal polymorph of the protic ionic liquid: Ethylammonium nitrate. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113959] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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14
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Polok K, Beisert M, Swiątek A, Maity N, Piatkowski P, Gadomski W, Miannay FA, Idrissi A. Dynamics in the BMIM PF 6/acetonitrile mixtures observed by femtosecond optical Kerr effect and molecular dynamics simulations. Phys Chem Chem Phys 2020; 22:24544-24554. [PMID: 33094298 DOI: 10.1039/d0cp03847d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have performed the measurements of the optical Kerr effect signal time evolution up to 4 ns for a mixture of 1-alkyl-3-methyl-imidazolium hexafluorophosphate (BMIM PF6) ionic liquid and acetonitrile in the whole mole fractions range. The long delay line in our experimental setup allowed us to capture the complete reorientational dynamics of the ionic liquid. We have analysed the optical Kerr effect signal in the time and frequency domains with help of molecular dynamics simulations. In our approximation of the slow picosecond dynamics with a multi-exponential decay, we distinguish three relaxation times. The highest two are assigned to the reorientation of the cation and acetonitrile molecules that are in the vicinity of the imidazolium ring. The third one is recognized as originating from cation rotations and reorientation of acetonitrile molecules in the bulk or in the vicinity of the aliphatic chains of the cation. With help of the simulation we interpret the intermolecular band in the reduced spectral density, obtained from Kerr signal, as follows: its low-frequency side results from oscillations of one of the components in the cage formed by its neighbors, while the high-frequency side is attributed to the librations of the cation and acetonitrile molecule as well as the intermolecular oscillations of system components involved in specific interactions. We use this assignment and concentration dependence of the spectra obtained from velocity and angular velocity correlations to explain the mole fraction dependence of Kerr reduced spectral density.
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Affiliation(s)
- Kamil Polok
- Faculty of Chemistry, Laboratory of Spectroscopy and Intermolecular Interactions, University of Warsaw, Żwirki i Wigury 101, Warsaw 02-089, Poland.
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15
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Ghorai PK, Matyushov DV. Equilibrium Solvation, Electron-Transfer Reactions, and Stokes-Shift Dynamics in Ionic Liquids. J Phys Chem B 2020; 124:3754-3769. [DOI: 10.1021/acs.jpcb.0c01773] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Pradip Kr. Ghorai
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Dmitry V. Matyushov
- Department of Physics and School of Molecular Sciences, Arizona State University, PO Box 871504, Tempe, Arizona 85287, United States
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16
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Hefter G, Buchner R. Dielectric relaxation spectroscopy: an old-but-new technique for the investigation of electrolyte solutions. PURE APPL CHEM 2020. [DOI: 10.1515/pac-2019-1011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Abstract
The use of dielectric relaxation spectroscopy (DRS) for studying electrolyte solutions is reviewed, focussing on the authors’ investigations over the last three decades. It is shown that this often-overlooked technique provides powerful insights into the nature of ion-ion and ion-solvent interactions. DRS is revealed to be particularly useful for detection of weak ion association and, due to its unique ability to detect solvent-separated species, the quantitation of ion pairing. It is demonstrated that DRS correctly determines chemical speciation for ion-paired systems where major spectroscopic techniques (NMR, Raman, UV-vis) fail. DRS also provides important insights into ion solvation. In aqueous solutions, it has been used to build up a coherent set of ‘effective’ hydration numbers for ions based on the dynamics of proximate water molecules, and has a unique ability to detect ‘slow’ water resulting from hydrophilic and hydrophobic hydration of solutes. DRS has been especially useful for characterising the behaviour of ionic liquids (ILs), e.g. showing they possess rather low dielectric constants and, surprisingly, contain no significant concentrations of ion pairs. Neat ILs and their mixtures with molecular solvents are shown by ultra-broadband DRS to exhibit extremely complicated behaviour especially at frequencies in the THz region.
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Affiliation(s)
- Glenn Hefter
- Chemistry Department , Murdoch University , Murdoch , WA 6150 , Australia
| | - Richard Buchner
- Institute for Physical and Theoretical Chemistry, University of Regensburg , D-93040 Regensburg , Germany
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17
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Hunger J, Roy S, Grechko M, Bonn M. Dynamics of Dicyanamide in Ionic Liquids is Dominated by Local Interactions. J Phys Chem B 2019; 123:1831-1839. [PMID: 30717596 PMCID: PMC6398149 DOI: 10.1021/acs.jpcb.8b10849] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
The
dynamics of probe molecules is commonly used to investigate
the structural dynamics of room-temperature ionic liquids; however,
the extent to which this dynamics reflects the dynamics of the ionic
liquids or is probe specific has remained debated. Here, we explore
to what extent the vibrational and rotational dynamics of the dicyanamide
anion, a common ionic liquid anion, correlates with the structural
relaxation of ionic liquids. We use polarization-resolved, ultrafast
infrared spectroscopy to probe the temperature- and probe-concentration-dependent
dynamics of samples with small amounts of 1-ethyl-3-methylimidazolium
([emim]+) dicyanamide ([DCA]−) dissolved
in four [emim]+-based ionic liquids with tetrafluoroborate
([BF4]−), bis(trifluoromethylsulfonyl)imide
([NTf2]−), ethylsufate ([EtSO4]−), and triflate ([OTf]−) as
anions. The transient spectra after broad-band excitation at 2000–2300
cm–1, resonant with the symmetric and antisymmetric
C≡N stretching vibrations, initially contain oscillatory signatures
due to the vibrational coherence between both modes. Vibrational population
relaxation occurs on two distinct time scales, ∼6–7
and ∼15–20 ps. The vibrational dynamics is rather insensitive
to the details of the ionic liquid anion and temperature, except for
the slow vibrational relaxation component. The decay of the excitation
anisotropy, a measure of the rotational dynamics of [DCA]−, markedly depends on temperature, and the obtained decay time exhibits
an activation energy of ∼15–21 kJ/mol. Remarkably, neither
the rotation time nor the activation energy can be simply explained
by the variation of the macroscopic viscosity. Hence, our results
suggest that the dynamics of dicyanamide is only in part representative
of the ionic liquid structural dynamics. Rather, the dynamics of the
probe anion seems to be determined by the specific interaction of
[DCA]− with the ionic liquid’s ions for the
class of [emim]+-based ionic liquids studied here.
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Affiliation(s)
- Johannes Hunger
- Max Planck Institute for Polymer Research , Ackermannweg 10 , 55128 Mainz , Germany
| | - Soham Roy
- Max Planck Institute for Polymer Research , Ackermannweg 10 , 55128 Mainz , Germany.,Graduate School Materials Science in Mainz , Staudingerweg 9 , 55128 Mainz , Germany
| | - Maksim Grechko
- Max Planck Institute for Polymer Research , Ackermannweg 10 , 55128 Mainz , Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research , Ackermannweg 10 , 55128 Mainz , Germany
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18
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Moreno-Gómez N, Vargas EF, Buchner R. Hydration and Counterion Binding of an Aminomethylated Resorcin[4]arene. J Phys Chem B 2019; 123:1840-1846. [DOI: 10.1021/acs.jpcb.8b11900] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nicolás Moreno-Gómez
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, D-93040 Regensburg, Germany
- Laboratorio de Termodinámica de Soluciones, Departamento de Química, Universidad de Los Andes, Cr. 1 No. 18 A-12, Bogotá, Colombia
| | - Edgar F. Vargas
- Laboratorio de Termodinámica de Soluciones, Departamento de Química, Universidad de Los Andes, Cr. 1 No. 18 A-12, Bogotá, Colombia
| | - Richard Buchner
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, D-93040 Regensburg, Germany
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19
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Philippi F, Rauber D, Zapp J, Präsang C, Scheschkewitz D, Hempelmann R. Multiple Ether-Functionalized Phosphonium Ionic Liquids as Highly Fluid Electrolytes. Chemphyschem 2019; 20:443-455. [PMID: 30480374 DOI: 10.1002/cphc.201800939] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/22/2018] [Indexed: 11/11/2022]
Abstract
Ionic liquids (ILs) are promising electrolytes, although their often high viscosity remains a serious drawback. The latter can be addressed by the introduction of multiple ether functionalization. Based on the highly atom efficient synthesis of tris(2-ethoxyethyl) phosphine, several new phosphonium ionic liquids were prepared, which allows studying the influence of the ether side chains. Their most important physicochemical properties have been determined and will be interpreted using established approaches like ionicity, hole theory, and the Walden plot. There is striking evidence that the properties of phosphonium ionic liquids with the methanesulfonate anion are dominated by aggregation, whereas the two triple ether functionalized ILs with the highest fluidity show almost ideal behavior with other factors being dominant. It is furthermore found that the deviation from ideality is not significantly changed upon introduction of the ether side chains, although a very beneficial impact on the fluidity of ILs is observed. Multiple ether functionalization therefore proves as a powerful tool to overcome the disadvantages of phosphonium ionic liquids with large cations.
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Affiliation(s)
- Frederik Philippi
- Physical Chemistry, Saarland University, Campus B 2 2, 66123, Saarbrücken, Germany
| | - Daniel Rauber
- Physical Chemistry, Saarland University, Campus B 2 2, 66123, Saarbrücken, Germany.,Transfercentre Sustainable Electrochemistry, Saarland University and KIST Europe, Am Markt, Zeile 3, 66125, Saarbrücken, Germany
| | - Josef Zapp
- Pharmaceutical Biology, Saarland University, Campus B 2 3, 66123, Saarbrücken, Germany
| | - Carsten Präsang
- Krupp-Chair of General and Inorganic Chemistry, Saarland University, 66123, Saarbrücken, Germany
| | - David Scheschkewitz
- Krupp-Chair of General and Inorganic Chemistry, Saarland University, 66123, Saarbrücken, Germany
| | - Rolf Hempelmann
- Physical Chemistry, Saarland University, Campus B 2 2, 66123, Saarbrücken, Germany.,Transfercentre Sustainable Electrochemistry, Saarland University and KIST Europe, Am Markt, Zeile 3, 66125, Saarbrücken, Germany
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20
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Kakinuma S, Shirota H. Femtosecond Raman-Induced Kerr Effect Study of Temperature-Dependent Intermolecular Dynamics in Pyrrolidinium-Based Ionic Liquids: Effects of Anion Species. J Phys Chem B 2019; 123:1307-1323. [DOI: 10.1021/acs.jpcb.8b10269] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Shaukat S, Fedotova MV, Kruchinin SE, Bešter-Rogač M, Podlipnik Č, Buchner R. Hydration and ion association of aqueous choline chloride and chlorocholine chloride. Phys Chem Chem Phys 2019; 21:10970-10980. [DOI: 10.1039/c9cp01016e] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Choline hydration occurs predominantly via its hydroxyl group, and weak contact ion pair formation with Cl− is via the onium moiety.
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Affiliation(s)
- Saadia Shaukat
- Institute of Physical and Theoretical Chemistry
- University of Regensburg
- 93040 Regensburg
- Germany
| | - Marina V. Fedotova
- G.A. Krestov Institute of Solution Chemistry
- Russian Academy of Sciences
- 153045 Ivanovo
- Russian Federation
| | - Sergey E. Kruchinin
- G.A. Krestov Institute of Solution Chemistry
- Russian Academy of Sciences
- 153045 Ivanovo
- Russian Federation
| | - Marija Bešter-Rogač
- Faculty of Chemistry and Chemical Technology
- Večna pot 113
- University of Ljubljana
- SI-1000 Ljubljana
- Slovenia
| | - Črtomir Podlipnik
- Faculty of Chemistry and Chemical Technology
- Večna pot 113
- University of Ljubljana
- SI-1000 Ljubljana
- Slovenia
| | - Richard Buchner
- Institute of Physical and Theoretical Chemistry
- University of Regensburg
- 93040 Regensburg
- Germany
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22
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Dasari S, Mallik BS. Nondiffusive Rotational Jump Dynamics in Ethyl Ammonium Nitrate. J Phys Chem B 2018; 122:9738-9746. [PMID: 30272452 DOI: 10.1021/acs.jpcb.8b06372] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sathish Dasari
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy 502 285, Telangana, India
| | - Bhabani S. Mallik
- Department of Chemistry, Indian Institute of Technology Hyderabad, Kandi, Sangareddy 502 285, Telangana, India
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23
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Nazet A, Buchner R. Dielectric response and transport properties of alkylammonium formate ionic liquids. J Chem Phys 2018; 148:193836. [DOI: 10.1063/1.5013097] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Andreas Nazet
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
| | - Richard Buchner
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
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24
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Kakinuma S, Ramati S, Wishart JF, Shirota H. Effects of aromaticity in cations and their functional groups on the temperature dependence of low-frequency spectrum. J Chem Phys 2018; 148:193805. [DOI: 10.1063/1.5010066] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Shohei Kakinuma
- Department of Nanomaterial Science, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Sharon Ramati
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - James F. Wishart
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Hideaki Shirota
- Department of Chemistry, Chiba University, 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan
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25
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Kakinuma S, Shirota H. Femtosecond Raman-Induced Kerr Effect Study of Temperature-Dependent Intermolecular Dynamics in Molten Bis(trifluoromethylsulfonyl)amide Salts: Effects of Cation Species. J Phys Chem B 2018; 122:6033-6047. [DOI: 10.1021/acs.jpcb.8b03302] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Abstract
Ionic liquids are liquid salts at ambient temperature composed of organic cations and organic/inorganic anions. Outstanding physical and chemical properties of ionic liquids lead to increasing application in scientific and industrial field. Ionic liquids have been already investigated by different spectroscopic techniques, including terahertz (THz) time-domain spectroscopy. The usual THz frequency range extends up to 2-3 THz, a relatively narrow band, which can only show the intermolecular vibrational modes. Here, we report about broadband THz spectroscopy of ionic liquids up to 13 THz. Bandwidth of intermolecular absorption band presents an unexpected behavior and strong sharp intramolecular absorptions are shown. In addition, we found violation of the approximation of harmonic oscillator used to predict the peak shift of intermolecular absorption band.
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Affiliation(s)
- Sen Mou
- Dipartimento di Fisica "Ettore Pancini" , Università di Napoli "Federico II", Complesso Universitario di Monte Sant'Angelo , via Cintia , 80126 Napoli , Italy
| | - Andrea Rubano
- Dipartimento di Fisica "Ettore Pancini" , Università di Napoli "Federico II", Complesso Universitario di Monte Sant'Angelo , via Cintia , 80126 Napoli , Italy.,ISASI-Institute of Applied Sciences and Intelligent Systems , Consiglio Nazionale delle Ricerche , via Campi Flegrei 34 , 80078 Pozzuoli , Italy
| | - Domenico Paparo
- ISASI-Institute of Applied Sciences and Intelligent Systems , Consiglio Nazionale delle Ricerche , via Campi Flegrei 34 , 80078 Pozzuoli , Italy
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27
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Matyushov DV, Newton MD. Electrode reactions in slowly relaxing media. J Chem Phys 2017; 147:194506. [DOI: 10.1063/1.5003022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Dmitry V. Matyushov
- Department of Physics and School of Molecular Sciences, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287-1504, USA
| | - Marshall D. Newton
- Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA
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28
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Mou S, Rubano A, Paparo D. Complex Permittivity of Ionic Liquid Mixtures Investigated by Terahertz Time-Domain Spectroscopy. J Phys Chem B 2017; 121:7351-7358. [DOI: 10.1021/acs.jpcb.7b04706] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sen Mou
- Dipartimento di
Fisica “Ettore Pancini”, Università di Napoli “Federico II”, Complesso universitario di Monte Sant’Angelo,
via Cintia, 80126 Napoli, Italy
| | - Andrea Rubano
- Dipartimento di
Fisica “Ettore Pancini”, Università di Napoli “Federico II”, Complesso universitario di Monte Sant’Angelo,
via Cintia, 80126 Napoli, Italy
- ISASI−Institute
of Applied Sciences and Intelligent Systems, Consiglio Nazionale delle Ricerche, via Campi Flegrei 34, 80078 Pozzuoli, Italy
| | - Domenico Paparo
- ISASI−Institute
of Applied Sciences and Intelligent Systems, Consiglio Nazionale delle Ricerche, via Campi Flegrei 34, 80078 Pozzuoli, Italy
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29
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Ramakrishnan G, González-Jiménez M, Lapthorn AJ, Wynne K. Spectrum of Slow and Super-Slow (Picosecond to Nanosecond) Water Dynamics around Organic and Biological Solutes. J Phys Chem Lett 2017; 8:2964-2970. [PMID: 28612605 DOI: 10.1021/acs.jpclett.7b01127] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Water dynamics in the solvation shell of solutes plays a very important role in the interaction of biomolecules and in chemical reaction dynamics. However, a selective spectroscopic study of the solvation shell is difficult because of the interference of the solute dynamics. Here we report on the observation of heavily slowed down water dynamics in the solvation shell of different solutes by measuring the low-frequency spectrum of solvation water, free from the contribution of the solute. A slowdown factor of ∼50 is observed even for relatively low concentrations of the solute. We go on to show that the effect can be generalized to different solutes including proteins.
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Affiliation(s)
| | | | - Adrian J Lapthorn
- School of Chemistry, WestCHEM, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Klaas Wynne
- School of Chemistry, WestCHEM, University of Glasgow , Glasgow G12 8QQ, United Kingdom
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30
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Reichenbach J, Ruddell SA, González-Jiménez M, Lemes J, Turton DA, France DJ, Wynne K. Phonon-like Hydrogen-Bond Modes in Protic Ionic Liquids. J Am Chem Soc 2017; 139:7160-7163. [PMID: 28511538 DOI: 10.1021/jacs.7b03036] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Gigahertz- to terahertz-frequency infrared and Raman spectra contain a wealth of information concerning the structure, intermolecular forces, and dynamics of ionic liquids. However, these spectra generally have a large number of contributions ranging from slow diffusional modes to underdamped librations and intramolecular vibrational modes. This makes it difficult to isolate effects such as the role of Coulombic and hydrogen-bonding interactions. We have applied far-infrared and ultrafast optical Kerr effect spectroscopies on carefully selected ions with a greater or lesser degree of symmetry in order to isolate spectral signals of interest. This has allowed us to demonstrate the presence of longitudinal and transverse optical phonon modes and a great similarity of alkylammonium-based protic ionic liquids to liquid water. The data show that such phonon modes will be present in all ionic liquids, requiring a reinterpretation of their spectra.
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Affiliation(s)
- Judith Reichenbach
- School of Chemistry, WestCHEM, University of Glasgow , Glasgow G12 8QQ, U.K
| | - Stuart A Ruddell
- School of Chemistry, WestCHEM, University of Glasgow , Glasgow G12 8QQ, U.K
| | | | - Julio Lemes
- School of Chemistry, WestCHEM, University of Glasgow , Glasgow G12 8QQ, U.K
| | - David A Turton
- School of Chemistry, WestCHEM, University of Glasgow , Glasgow G12 8QQ, U.K
| | - David J France
- School of Chemistry, WestCHEM, University of Glasgow , Glasgow G12 8QQ, U.K
| | - Klaas Wynne
- School of Chemistry, WestCHEM, University of Glasgow , Glasgow G12 8QQ, U.K
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31
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Nazet A, Weiß L, Buchner R. Dielectric relaxation of nitromethane and its mixtures with ethylammonium nitrate: Evidence for strong ion association induced by hydrogen bonding. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2016.09.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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32
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Abstract
Vibrational spectroscopy has continued use as a powerful tool to characterize ionic liquids since the literature on room temperature molten salts experienced the rapid increase in number of publications in the 1990's. In the past years, infrared (IR) and Raman spectroscopies have provided insights on ionic interactions and the resulting liquid structure in ionic liquids. A large body of information is now available concerning vibrational spectra of ionic liquids made of many different combinations of anions and cations, but reviews on this literature are scarce. This review is an attempt at filling this gap. Some basic care needed while recording IR or Raman spectra of ionic liquids is explained. We have reviewed the conceptual basis of theoretical frameworks which have been used to interpret vibrational spectra of ionic liquids, helping the reader to distinguish the scope of application of different methods of calculation. Vibrational frequencies observed in IR and Raman spectra of ionic liquids based on different anions and cations are discussed and eventual disagreements between different sources are critically reviewed. The aim is that the reader can use this information while assigning vibrational spectra of an ionic liquid containing another particular combination of anions and cations. Different applications of IR and Raman spectroscopies are given for both pure ionic liquids and solutions. Further issues addressed in this review are the intermolecular vibrations that are more directly probed by the low-frequency range of IR and Raman spectra and the applications of vibrational spectroscopy in studying phase transitions of ionic liquids.
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Affiliation(s)
- Vitor H Paschoal
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil
| | - Luiz F O Faria
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil
| | - Mauro C C Ribeiro
- Laboratório de Espectroscopia Molecular, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo , Av. Prof. Lineu Prestes 748, São Paulo 05508-000, Brazil
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33
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Kakinuma S, Ishida T, Shirota H. Femtosecond Raman-Induced Kerr Effect Study of Temperature-Dependent Intermolecular Dynamics in Imidazolium-Based Ionic Liquids: Effects of Anion Species and Cation Alkyl Groups. J Phys Chem B 2017; 121:250-264. [DOI: 10.1021/acs.jpcb.6b11009] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Tateki Ishida
- Department
of Theoretical and Computational Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
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34
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Shirota H, Kakinuma S, Takahashi K, Tago A, Jeong H, Fujisawa T. Ultrafast Dynamics in Aromatic Cation Based Ionic Liquids: A Femtosecond Raman-Induced Kerr Effect Spectroscopic Study. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2016. [DOI: 10.1246/bcsj.20160085] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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35
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Rumble CA, Kaintz A, Yadav SK, Conway B, Araque JC, Baker GA, Margulis C, Maroncelli M. Rotational Dynamics in Ionic Liquids from NMR Relaxation Experiments and Simulations: Benzene and 1-Ethyl-3-Methylimidazolium. J Phys Chem B 2016; 120:9450-67. [DOI: 10.1021/acs.jpcb.6b06715] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher A. Rumble
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Anne Kaintz
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sharad K. Yadav
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Brian Conway
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Juan C. Araque
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Gary A. Baker
- Department
of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Claudio Margulis
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Mark Maroncelli
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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36
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Patil AB, Bhanage BM. Modern ab initio valence bond theory calculations reveal charge shift bonding in protic ionic liquids. Phys Chem Chem Phys 2016; 18:15783-90. [PMID: 27229870 DOI: 10.1039/c6cp02819e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nature of bonding interactions between the cation and the anion of an ionic liquid is at the heart of understanding ionic liquid properties. A particularly interesting case is a special class of ionic liquids known as protic ionic liquids. The extent of proton transfer in protic ionic liquids has been observed to vary according to the interacting species. Back proton transfer renders protic ionic liquids volatile and to be considered as inferior ionic liquids. We try to address this issue by employing modern ab initio valence bond theory calculations. The results indicate that the bonding in the cation and the anion of a prototypical ionic liquid, ethylammonium nitrate, is fundamentally different. It is neither characteristic of covalent/polar covalent bonding nor ionic bonding but rather charge shift bonding as a resonance hybrid of two competing ionic molecular electronic structure configurations. An investigation of other analogous protic ionic liquids reveals that this charge shift bonding seems to be a typical characteristic of protic ionic liquids while the ionic solid analogue compound ammonium nitrate has less charge shift bonding character as compared to protic ionic liquids. Further the extent of charge shift bonding character has been found to be congruent with the trends in many physicochemical properties such as melting point, conductivity, viscosity, and ionicity of the studied ionic liquids indicating that percentage charge shift character may serve as a key descriptor for large scale computational screening of ionic liquids with desired properties.
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Affiliation(s)
- Amol Baliram Patil
- Department of Chemistry, Institute of Chemical Technology, Mumbai, 400019, India.
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Shirota H, Kakinuma S, Itoyama Y, Umecky T, Takamuku T. Effects of Tetrafluoroborate and Bis(trifluoromethylsulfonyl)amide Anions on the Microscopic Structures of 1-Methyl-3-octylimidazolium-Based Ionic Liquids and Benzene Mixtures: A Multiple Approach by ATR-IR, NMR, and Femtosecond Raman-Induced Kerr Effect Spectroscopy. J Phys Chem B 2016; 120:513-26. [DOI: 10.1021/acs.jpcb.5b10917] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hideaki Shirota
- Department
of Nanomaterial Science and Department of Chemistry, Chiba University, 1-33
Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Shohei Kakinuma
- Department
of Nanomaterial Science and Department of Chemistry, Chiba University, 1-33
Yayoi, Inage-ku, Chiba 263-8522, Japan
| | - Yu Itoyama
- Department
of Chemistry and Applied Chemistry, Graduate School of Science and
Engineering, Saga University, Honjo-machi, Saga 840-8502, Japan
| | - Tatsuya Umecky
- Department
of Chemistry and Applied Chemistry, Graduate School of Science and
Engineering, Saga University, Honjo-machi, Saga 840-8502, Japan
| | - Toshiyuki Takamuku
- Department
of Chemistry and Applied Chemistry, Graduate School of Science and
Engineering, Saga University, Honjo-machi, Saga 840-8502, Japan
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Stoppa A, Nazet A, Buchner R, Thoman A, Walther M. Dielectric response and collective dynamics of acetonitrile. J Mol Liq 2015. [DOI: 10.1016/j.molliq.2015.03.045] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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