Does urea modify microheterogeneous nature of ionic amide deep eutectics? Clues from non-reactive and reactive solute-centered dynamics

Dinda, Sirshendu; Sil, Arnab; Das, Anuradha; Tarif, Ejaj; Biswas, Ranjit

doi:10.1016/j.molliq.2021.118126

Cited by 11 publications

(11 citation statements)

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“…However, dynamic heterogeneity has been previously reported as an important characteristic of DESs, resulting in the fractional dependence of the solute reorientation time scale on viscosity. 23 A previous report on a nonionic DES predicts that depending on the structure and the intermolecular interactions of the probe, it would selectively reside in a specific nanodomain of the heterogeneous DES. 31 As ethaline DES is also heterogeneous, 48,49 there could indeed be a scenario where a solute would be located in a different domain.…”

Section: Resultsmentioning

confidence: 99%

“…20−22 Due to the diverse intermolecular interactions within DES components, the formation of heterogeneous nanostructures in a DES has been reported. 23,24 Although bulk viscosity has been measured for different deep eutectic systems, it is highly unlikely that uniform viscosity is maintained across the heterogeneous nanostructures. It is still unknown if a solute dissolved in a DES nanodomain would sense the bulk DES viscosity or domain-specific effective viscosity.…”

Section: ■ Introductionmentioning

confidence: 99%

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Does Viscosity Drive the Dynamics in an Alcohol-Based Deep Eutectic Solvent?

2022

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Deep eutectic solvents, consisting of heterogeneous nanodomains of hydrogen-bonded networks, have evolved into a range of viscous fluids that find applications in several fields. As viscosity is known to influence the dynamics of other neoteric solvents like ionic liquids, understanding the effect of viscosity on deep eutectic solvents is crucial to realize their full potential. Herein, we combine polarization-selective pump–probe spectroscopy, two-dimensional infrared spectroscopy, and molecular dynamics simulations to elucidate the impact of viscosity on the dynamics of an alcohol-based deep eutectic solvent, ethaline. We compare the solvent fluctuation and solute reorientation time scales in ethaline with those in ethylene glycol, an ethaline constituent. Interestingly, we find that the solute’s reorientation apparently scales the bulk viscosity of the solvent, but the same is not valid for the overall solvation dynamics. Using the variations in the estimated intercomponent hydrogen bond lifetimes, we show that a dissolved solute does not sense the bulk viscosity of the deep eutectic solvent; instead, it senses domain-specific local viscosity determined by the making and breaking of the hydrogen bond network. Our results indicate that understanding the domain-specific local environment experienced by the dissolved solute is of utmost importance in deep eutectic solvents.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Does Viscosity Drive the Dynamics in an Alcohol-Based Deep Eutectic Solvent?

2022

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“…20 An important characteristic of DESs�"dynamic heterogeneity"� is suggested by the fractional dependence of a solute's solvation ⟨τ s ⟩ or rotation ⟨τ r ⟩ time on viscosity η and temperature T, which scales as ⟨τ s/r ⟩ ∝(η/T) p with an exponent 0.4 < p < 0.7. 31 In contrast, conventional Stokes− Einstein and Stokes−Einstein−Debye would predict p = 1. Multi-or stretched-exponential relaxation of dynamic structure factors observed in MD simulations explain this viscosity dependence through the existence of spatially varying relaxation rates, reinforcing the idea of a high degree of solution heterogeneity and the formation of domains.…”

Section: ■ Introductionmentioning

confidence: 97%

“…DESs have been studied with a range of approaches, including dielectric, − viscoelastic, , nuclear magnetic , and ultrasonic relaxation, , optical Kerr effect spectroscopy, fluorescence measurements, − wide-angle and quasi-elastic neutron scattering, simulated X-ray scattering structure function calculations, − empirical potential structure refinement (EPSR), and molecular dynamics (MD) simulations. ,, For instance, femtosecond Raman-induced Kerr-effect spectroscopy measurements allowed, in some cases, direct observation of intermolecular hydrogen bonding . An important characteristic of DESs“dynamic heterogeneity”is suggested by the fractional dependence of a solute’s solvation ⟨τ s ⟩ or rotation ⟨τ r ⟩ time on viscosity η and temperature T , which scales as ⟨τ s/r ⟩ ∝(η/ T ) p with an exponent 0.4 < p < 0.7 . In contrast, conventional Stokes–Einstein and Stokes–Einstein–Debye would predict p = 1.…”

Section: Introductionmentioning

confidence: 99%

Structure, Organization, and Heterogeneity of Water-Containing Deep Eutectic Solvents

et al. 2022

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The spectroscopy and structural dynamics of a deep eutectic mixture (KSCN/acetamide) with varying water content is investigated from 2D IR (with the C–N stretch vibration of the SCN– anions as the reporter) and THz spectroscopy. Molecular dynamics simulations correctly describe the nontrivial dependence of both spectroscopic signatures depending on water content. For the 2D IR spectra, the MD simulations relate the steep increase in the cross-relaxation rate at high water content to the parallel alignment of packed SCN– anions. Conversely, the nonlinear increase of the THz absorption with increasing water content is mainly attributed to the formation of larger water clusters. The results demonstrate that a combination of structure-sensitive spectroscopies and molecular dynamics simulations provides molecular-level insights into the emergence of heterogeneity of such mixtures by modulating their composition.

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“…20 An important characteristic of DESs -"dynamic heterogeneity" -is suggested by the fractional dependence of a solutes solvation τ s or rotation τ r time on viscosity η and temperature T , which scales as τ s/r ∝ (η/T ) p with an exponent 0.4 < p < 0.7. 31 In contrast, conventional Stokes-Einstein and Stokes-Einstein-Debye would predict p = 1. Multior stretched-exponential relaxation of dynamic structure factors observed in MD simulations explain this viscosity dependence through the existence of spatially varying relaxation rates, reinforcing the idea of a high degree of solution heterogeneity and the formation of domains.…”

Section: Introductionmentioning

confidence: 97%

Structure, Organization and Heterogeneity of Water-Containing Deep Eutectic Solvents

Töpfer,

Pasti,

Das

et al. 2022

Preprint

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The spectroscopy and structural dynamics of a deep eutectic mixture (KSCN/ acetamide) with varying water content is investigated from 2D IR (with the C-N stretch vibration of the SCN − anions as the reporter) and THz spectroscopy. Molecular dynamics simulations correctly describe the non-trivial dependence of both spectroscopic signatures depending on water content. For the 2D IR spectra, the MD simulations relate the steep increase in the cross relaxation rate at high water content to parallel alignment of packed SCN − anions. Conversely, the non-linear increase of the THz absorption with increasing water content is mainly attributed to the formation of larger water clusters. The results demonstrate that a combination of structure sensitive spectroscopies and molecular dynamics simulations provides molecular-level insights into emergence of heterogeneity of such mixtures by modulating their composition.

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Does urea modify microheterogeneous nature of ionic amide deep eutectics? Clues from non-reactive and reactive solute-centered dynamics

Cited by 11 publications

References 84 publications

Does Viscosity Drive the Dynamics in an Alcohol-Based Deep Eutectic Solvent?

Does Viscosity Drive the Dynamics in an Alcohol-Based Deep Eutectic Solvent?

Structure, Organization, and Heterogeneity of Water-Containing Deep Eutectic Solvents

Structure, Organization and Heterogeneity of Water-Containing Deep Eutectic Solvents

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