Ring structure analysis of ethanol–water mixtures

Gereben, Orsolya

doi:10.1016/j.molliq.2015.08.010

Cited by 26 publications

(36 citation statements)

References 47 publications

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“…Similarly to the aforementioned recent studies of water-ethanol mixtures [9,10,11], the basis of the present analyses is our preceding extensive molecular dynamics (MD) investigation [12]. There, a series of MD simulations for ethanol-water mixtures with 20 to 80 mol % ethanol contents, for pure ethanol and water was performed with one ethanol and three different water force fields.…”

Section: Introductionmentioning

confidence: 93%

“…Analyses of the hydrogen-bonded clusters/network was performed by our own C++ computer code, specifically developed for this purpose, using a depth-first search algorithm for identifying clusters (see also Refs. [9,10,11]). The term 'cluster' is applied only for molecules connected by hydrogen bonds (i.e., lone molecules are not considered as clusters).…”

Section: Cluster Analysesmentioning

confidence: 99%

“…Detailed discussions concerning these preliminaries have been provided in the introductory parts of our very recent publications [9,10,11], so these are not repeated here. In these recent works, H-bond connectivities [9], ring formation and statistics [10], and the 'lacunarity' [11] have been analyzed. To complete our extensive investigations on water-ethanol mixtures, here characteristics of cluster formation and percolation observable in these systems are presented.…”

Section: Introductionmentioning

confidence: 99%

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Cluster formation and percolation in ethanol-water mixtures

Gereben

Pusztai

2017

Chemical Physics

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Results of systematic molecular dynamics studies of ethanol-water mixtures, over the entire concentration range, were reported previously to agree with experimental X-ray diffraction data. These simulated systems are analyzed in this work to examine cluster formation and percolation, using four different hydrogen bond definitions. Percolation analyses revealed that each mixture (even the one containing 80 mol % ethanol) is above the 3D percolation threshold, with fractal dimensions, d f , between 2.6 to 2.9, depending on concentration.Monotype water cluster formation was also studied in the mixtures: 3D water percolation can be found in systems with less than 40 mol % ethanol, with fractal dimensions between 2.53 and 2.84. These observations can be put in parallel with experimental data on some thermodynamic quantities, such as the excess partial molar enthalpy and entropy.

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Section: Introductionmentioning

confidence: 93%

Section: Cluster Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cluster formation and percolation in ethanol-water mixtures

Gereben

Pusztai

2017

Chemical Physics

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“…14 Despite considerable effort in both experiment and theory, significant disagreement remains regarding the microscopic details of this effect. 14,[16][17][18] Different models for the structure of these liquid mixtures have been proposed to address this behavior, including the enhancement of the water hydrogen bonding network around the alcohol hydrophobic groups [14][15][16][17][18][19][20][21][22] and microscopic immiscibility or clustering. [23][24][25][26][27][28][29][30][31][32][33][34] The response of hydrogen-bonded networks to changing thermodynamic variables (and also, constituents) is a key issue in many areas of natural sciences, particularly in chemistry and biology: this has a great deal to do with how living organisms react to decreasing/increasing temperatures.…”

Section: Introductionmentioning

confidence: 99%

Variations of the Hydrogen Bonding and Hydrogen-Bonded Network in Ethanol–Water Mixtures on Cooling

2018

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Molecular dynamics computer simulations have been conducted for ethanol-water liquid mixtures in the water-rich side of the composition range, with 10, 20, and 30 mol % of alcohol, at temperatures between room temperature and the experimental freezing point of the given mixture. All-atom-type (optimized potential for liquid simulations) interatomic potentials have been assumed for ethanol, in combination with two kinds of rigid water models (SPC/E and TIP4P/2005). Both combinations have provided excellent reproductions of the experimental X-ray total structure factors at each temperature; this yielded a strong basis for further structural analyses. Beyond partial radial distribution functions, various descriptors of hydrogen-bonded assemblies, as well as of the hydrogen-bonded network have been determined. A clear tendency was observed toward that an increasing proportion of water molecules participate in hydrogen bonding with exactly two donor and two acceptor sites as temperature decreases. Concerning larger assemblies held together by hydrogen bonding, the main focus was put on the properties of cyclic entities: it was found that, similarly to methanol-water mixtures, the number of hydrogen-bonded rings has increased with lowering temperature. However, for ethanol-water mixtures, the dominance of 5-fold rings, and not 6-fold rings, could be observed.

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“…In most cases, analogous non-ideal behaviour is more pronounced (showing minima or maxima) in the low alcohol concentration region. Despite the large efforts in order to construct a well-defined atomistic picture [20][21][22][23][24][25][26][27] and a molecular-scale understanding of the behavior, no single, widely accepted model exists for these liquid mixtures.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependent dynamics in water-ethanol liquid mixtures

Pothoczki

Pusztai

Bakó

2018

Journal of Molecular Liquids

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Temperature dependent hydrogen bond energetics and dynamical features, such as the diffusion coefficient and reorientational times, have been determined for ethanol-water mixtures with 10, 20 and 30 mol % of ethanol. Concerning pairwise interaction energies between molecules, it is found that water-water interactions become stronger, while ethanol-ethanol ones become significantly weaker in the mixtures than the corresponding values characteristic to the pure substances. Concerning the diffusion processes, for all concentrations the activation barrier of water and ethanol molecule become very similar to each other. Reorientation motions of water and ethanol become slower as ethanol concentration is increasing. Characteristic reorientational times of water in the mixtures are substantially longer than these values in the pure substance. On the other hand, this change for ethanol is only moderate. The reorientation motions of water (especially the ones related to the H-bonded interaction) become very similar for those of ethanol in the mixtures.

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Ring structure analysis of ethanol–water mixtures

Cited by 26 publications

References 47 publications

Cluster formation and percolation in ethanol-water mixtures

Cluster formation and percolation in ethanol-water mixtures

Variations of the Hydrogen Bonding and Hydrogen-Bonded Network in Ethanol–Water Mixtures on Cooling

Temperature dependent dynamics in water-ethanol liquid mixtures

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