On the hydrophobic effect in water–alcohol mixtures

Catalán, Javier; Díaz-Oliva, Cristina; García-Blanco, Francisco

doi:10.1016/j.chemphys.2019.110467

Cited by 13 publications

(9 citation statements)

References 70 publications

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“…It is closely related to the existence of a hydrophobic effect in ethanol/water mixtures which depends on the size and branching of the hydrocarbon chain in the alcohol. [33] This hydrophobic effect causes the O-H bonds of adjacent water molecules to the ethanol, to not directly point their O-H bonds towards the β-CH 3 group of ethanol.…”

Section: A Theoretical Model Of Ethanol/water Mixturesmentioning

confidence: 99%

An experimental FTIR-ATR and computational study of H-bonding in ethanol/water mixtures

Zeinalipour-Yazdi

Loizidou

2021

Chemical Physics

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Section: A Theoretical Model Of Ethanol/water Mixturesmentioning

confidence: 99%

An experimental FTIR-ATR and computational study of H-bonding in ethanol/water mixtures

Zeinalipour-Yazdi

Loizidou

2021

Chemical Physics

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“…In Figure 16, we have shown the translational diffusion coefficients of the cations Li + (Figure 16a), Na + (Figure 16b), K + (Figure 16c), and Cs + (Figure 16d) as a function of the inverse of the shear viscosity of the binary mixture at ethanol compositions 0, 5,10,15,20,25,30,40,60,80, and 100%. The direction of black arrows in the figures shows the diffusion values varying from 0 to 100% ethanol compositions.…”

Section: Comparison Of Charged and Uncharged Solutesmentioning

confidence: 99%

“…The water–alcohol mixtures by themselves have attracted a great deal of theoretical, experimental, and computational studies. − The seminal review of Franks and Ives investigates the molecular origin of the anomalous behavior of amphiphilic solutes in water–alcohol systems. In a series of studies, Banerjee et al , showed that the anomalies follow a pattern, and different behavior was observed at low and high concentrations of the solute in the binary mixture.…”

Section: Introductionmentioning

confidence: 99%

Rigid Cations Induce Enhancement of Microheterogeneity and Exhibit Anomalous Ion Diffusion in Water–Ethanol Mixtures

Nair

Bagchi

2021

J. Phys. Chem. B

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Because of the amphiphilic nature of ethanol in the aqueous solution, ions cause an interesting microheterogeneity where the water molecules and the hydroxy groups of ethanol preferentially solvate the ions, while the ethyl groups tend to occupy the intervening space. Using computer simulations, we study the dynamics of rigid monovalent cations (Li+, Na+, K+, and Cs+) in aqueous ethanol solutions with chloride as the counterion. We vary both the size of the ions and the composition of the mixture to explore size- and composition-dependent ion diffusion. The relative stability of enhanced microheterogeneous configurations makes ion diffusion slower than what would be surmised by using the bulk properties of the mixture, using the Stokes–Einstein relation. We study the structure through partial radial distribution functions and the stability through coordination number fluctuations. The ion diffusion coefficient exhibits sharp re-entrant behavior when plotted against viscosity varied by composition. Our studies reveal multiple anomalous features of ion motion in this mixture. We formulate a mode-coupling theory (MCT) that takes into account the interaction between different dynamical components; MCT can incorporate the effects of heterogeneous dynamics and nonlinearity in composition dependence that arise from the feedback between mutually dependent ion–solvent dynamics.

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“…The description of what this “re-ordering” is has attracted intense discussion since the work of Franks and co-workers, ,− but it has been suggested that the increase in ordering is due to some sort of water and alcohol cluster formation (water-rich and alcohol-rich regions). This has led to discussions that focus on the role of the hydrophobic effect in these mixtures, and measures of the temperature-dependencies of hydration shell structures of water solvating short-chain alcohols . The relation to the hydrophobic effect can be difficult to contextualize due to the competing interactions (hydrophobic vs hydrophilic), the changing physical properties of the mixtures, along with the many subtleties of the hydrophobic effect, and yet the macroscopic solubility of the liquids.…”

Section: Introductionmentioning

confidence: 99%

Dipolar Dispersion Forces in Water–Methanol Mixtures: Enhancement of Water Interactions upon Dilution Drives Self-Association

2022

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Mixtures of short-chain alcohols and water produce anomalous thermodynamic and structural quantities, including molecular segregation into water-rich and alcohol-rich components. Herein, we used molecular dynamics simulations with polarizable models to investigate interactions that could drive the self-association of water molecules in mixtures with methanol (MeOH). As water was diluted with MeOH, significant changes in the distribution of molecules and solvation properties occurred, where water exhibited a clear preference for self-association. When common structural quantities were analyzed, it was found that there was a clear reduction in water–water hydrogen bonding and tetrahedral order (both in terms of typical bulk behavior), contrary to the observed water self-association. However, when dipolar dispersion forces between all molecules as a function of system composition were analyzed, it was found that water–water dipolar interactions became significantly stronger with dilution (6-fold stronger interaction in 75% MeOH compared to 0% MeOH). This was only observed for water, where MeOH–MeOH interactions became weaker as the systems were more dilute in MeOH. These forces result from specific dipole orientations, likely occurring to adopt lower energy configurations (i.e., head-to-tail or antiparallel). For water, this may result from lost other interactions (e.g., hydrogen bonding), leading to more rotational freedom between the dipole moments. These intriguing changes in dipolar interactions, which directly result from structural changes, can therefore explain, in part, the driving force for water self-association in MeOH–water mixtures.

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On the hydrophobic effect in water–alcohol mixtures

Cited by 13 publications

References 70 publications

An experimental FTIR-ATR and computational study of H-bonding in ethanol/water mixtures

An experimental FTIR-ATR and computational study of H-bonding in ethanol/water mixtures

Rigid Cations Induce Enhancement of Microheterogeneity and Exhibit Anomalous Ion Diffusion in Water–Ethanol Mixtures

Dipolar Dispersion Forces in Water–Methanol Mixtures: Enhancement of Water Interactions upon Dilution Drives Self-Association

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