Local Structures of Methanol–Water Binary Solutions Studied by Soft X-ray Absorption Spectroscopy

Nagasaka, Masanari; Mochizuki, Kenji; Leloup, Valentin; Kosugi, Nobuhiro

doi:10.1021/jp4091602

Cited by 83 publications

(102 citation statements)

References 77 publications

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“…[27][28][29][30][31][32] This has been supported by X-ray emission and X-ray absorption studies. [33][34][35] Dielectric relaxation and nuclear magnetic resonance spectroscopies support the clustering explanation while also revealing reduced liquid mobility. [36][37][38][39][40][41] Using Raman spectroscopy, Ben-Amotz et al have concluded that the observed clustering in alcohol-water mixtures is a result of random, rather than hydrophobic, interactions.…”

Section: -17mentioning

confidence: 61%

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Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

Lam

Smith

Saykally

2016

The Journal of Chemical Physics

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While methanol and ethanol are macroscopically miscible with water, their mixtures exhibit negative excess entropies of mixing. Despite considerable effort in both experiment and theory, there remains significant disagreement regarding the origin of this effect. Different models for the liquid mixture structure have been proposed to address this behavior, including the enhancement of the water hydrogen bonding network around the alcohol hydrophobic groups and microscopic immiscibility or clustering. We have investigated mixtures of methanol, ethanol, and isopropanol with water by liquid microjet X-ray absorption spectroscopy on the oxygen K-edge, an atomspecific probe providing details of both inter-and intra-molecular structure. The measured spectra evidence a significant enhancement of hydrogen bonding originating from the methanol and ethanol hydroxyl groups upon the addition of water. These additional hydrogen bonding interactions would strengthen the liquid-liquid interactions, resulting in additional ordering in the liquid structures and leading to a reduction in entropy and a negative enthalpy of mixing, consistent with existing thermodynamic data. In contrast, the spectra of the isopropanol-water mixtures exhibit an increase in the number of broken alcohol hydrogen bonds for mixtures containing up to 0.5 water mole fraction, an observation consistent with existing enthalpy of mixing data, suggesting that the measured negative excess entropy is a result of clustering or micro-immiscibility. Published by AIP Publishing. [http://dx

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Section: -17mentioning

confidence: 61%

“…Note that this is not in agreement with previous finding by Nagasaka et al who observed the absorption onset of methanol and water at the same energy. 34 Significant changes are observed in the pre-edge region of the alcohol spectra (533-535 eV) upon the addition of water (Fig. 2).…”

Section: Resultsmentioning

confidence: 94%

Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

Lam

Smith

Saykally

2016

The Journal of Chemical Physics

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“…According to this interpretation, the presence of the composition-dependent anomalies can be ascribed to the formation of a low entropy cage of water with strong hydrogen-bonds around the alcohol molecules, which in this case would increase the structural ordering of bulk water. These ideas seem to have been confirmed by a series of experimental X-ray diffraction studies, in most cases complemented by molecular simulations [27,28]. In these studies it was found that adding methanol to water, enhances the local three dimensional network of water in the vicinity of the methanol molecules, which explains the decrease in the entropy of mixing and the considerable increase in the heat capacity at low alcohol concentrations.…”

Section: Introductionmentioning

confidence: 74%

Temperature of maximum density and excess properties of short-chain alcohol aqueous solutions: A simplified model simulation study

Furlan¹,

Lomba

Barbosa³

2017

The Journal of Chemical Physics

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We perform an extensive computational study of binary mixtures of water and short-chain alcohols resorting to two-scale potential models to account for the singularities of hydrogen bonded liquids. Water molecules are represented by a well studied core softened potential which is known to qualitatively account for a large number of water's characteristic anomalies. Along the same lines, alcohol molecules are idealized by dimers in which the hydroxyl groups interact with each other and with water with a core softened potential as well. Interactions involving non-polar groups are all deemed purely repulsive. We find that the qualitative behavior of excess properties (excess volume, enthalpy and constant pressure heat capacity) agrees with that found experimentally for alcohols such as t-butanol in water. Moreover, we observe that our simple solute under certain conditions acts as an "structure-maker", in the sense that the temperature of maximum density of the bulk water model increases as the solute is added, i.e. the anomalous behavior of the solvent is enhanced by the solute. PACS numbers:1 arXiv:1701.08670v1 [cond-mat.soft]

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“…[21][22][23][24][25][26][27][28][29] The effects of the local order can also be studied systematically by adsorption to metal surfaces, where different coverages yield structures ranging from gas-like to icelike. 16,17 The spectral changes for variations in pH have also been investigated, [30][31][32] as well as that of supercritical water 33 and water contained in reverse micelles.…”

Section: Introductionmentioning

confidence: 99%

Requirements of first-principles calculations of X-ray absorption spectra of liquid water

Fransson

Zhovtobriukh

Coriani

et al. 2016

Phys. Chem. Chem. Phys.

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1 Abstract A computational benchmark study on X-ray absorption spectra of water has been performed by means of transition-potential density functional theory (TP-DFT), damped time-dependent density functional theory (TDDFT), and damped coupled cluster (CC) linear response theory. For liquid water, using TDDFT with a tailored CAM-B3LYP functional and a polarizable embedding, we find that an embedding with over 2000 water molecules is required to fully converge spectral features for individual molecules, but a substantially smaller embedding can be used within averaging schemes.TP-DFT and TDDFT calculations on 100 MD structures demonstrate that TDDFT produces a spectrum with spectral features in good agreement with experiment, while it is more difficult to fully resolve the spectral features in the TP-DFT spectrum. Similar trends were also observed for calculations of bulk ice. In order to further establish the performance of these methods, small water clusters have been considered also at the CC2 and CCSD levels of theory. Issues regarding the basis set requirements for spectrum simulations of liquid water and the determination of gas-phase ionization potentials are also discussed.2

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Local Structures of Methanol–Water Binary Solutions Studied by Soft X-ray Absorption Spectroscopy

Cited by 83 publications

References 77 publications

Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

Temperature of maximum density and excess properties of short-chain alcohol aqueous solutions: A simplified model simulation study

Requirements of first-principles calculations of X-ray absorption spectra of liquid water

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