Solvatation ionique dans les mélanges eau-acétonitrile. Structure de ceux-ci

Moreau, Colette; Douhéret, Gérard

doi:10.1051/jcp/1974711313

Cited by 19 publications

(13 citation statements)

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“…It is clear that the acetonitrile–water mixture is not a simple homogeneous mixture, but rather is a concentration-dependent structural composition. There are three main concentration regions over the mixture composition range − which can be characterized by different structural patterns. In the first region, the water-rich region of acetonitrile–water mixtures (0 ≤ x MeCN ≤ 0.2), the structure of the acetonitrile–water mixture largely resembles pure water with acetonitrile occupying vacancies in the three-dimensional hydrogen-bond network of water molecules.…”

Section: Resultsmentioning

confidence: 99%

Solvent Effects on pK_aValues of Some Anticancer Agents in Acetonitrile–Water Binary Mixtures

2014

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The solute−solvent interactions of four anticancer drugs, daunorubicin, doxorubicin, vincristine sulfate, and 6-thioguanine, have been studied in acetonitrile− water mixtures up to 50 % acetonitrile by volume fraction using a UV/pH titration method. The acidity constants have been calculated with the STAR (stability constants by absorbance readings) program. The interactions between the four anticancer drugs and the solvent studied, acetonitrile−water mixtures, was identified using the microscopic parameters (Kamlet and Taft's solvatochromic parameters: α, β, and π*). The Kamlet and Taft general equation for pK a1 and pK a2 values of 6-thioguanine, doxorubicin, daunorubicin, and vincristine sulfate was reduced to two terms (the independent term and the hydrogen-bond-donating ability, α) or three terms (the independent term, polarity/polarizability, π*, and the hydrogen-bond-donating ability, α) using linear regression analysis in acetonitrile−water mixtures. The Kamlet and Taft equations can be used to predict the acidity constants of daunorubicin, doxorubicin, vincristine sulfate, and 6-thioguanine at any acetonitrile composition, which would be helpful in practical work during chromatographic method development.

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Section: Resultsmentioning

confidence: 99%

Solvent Effects on pK_aValues of Some Anticancer Agents in Acetonitrile–Water Binary Mixtures

2014

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“…Mixtures of ACN and HOH show a series of unusual properties which can be interpreted in terms of microheterogeneity . , The literature of this field, as well as the variety of experimental information available for ACN−HOH mixtures, has recently been summarized. ,, Both liquids are miscible and colorless but, within an ACN mole fraction range between 0.15∼0.3 and 0.7, are postulated to separate into discrete regions of liquid acetonitrile and liquid water. Estimates for the shape, size, or interconnectivity of these regions are rare, however, with the most tangible description coming from the simulations of Kovacs and Laaksonen .…”

Section: Rationalizing the Solvent Shift On The Basis Of The Solvent ...mentioning

confidence: 99%

“…It is, however, becoming evident that the structural properties of liquids containing ACN are very complex . Water−ACN mixtures exhibit anomalous thermodynamic properties, and this has led to the postulate of microheterogeneity , − in which the solution is thought to separate into regions of ACN and regions of water. Further, from the work of Eisenthal et al, ACN is known to form a thin layer at the liquid−air interface above aqueous solutions ordered akin to the surface of neat acetonitrile, and here we present spectroscopic evidence for two types of ACN environments in aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

The Solvation of Acetonitrile

1999

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Acetonitrile is an extremely important solvent and cosolvent. Despite this, we have no general picture of the nature of mixed liquids containing acetonitrile applicable across-solvent families. We consider the properties of acetonitrile dissolved in 33 solvents, focusing on interpretation of the environment-sensitive solvent shift, Δν, of its CN stretch frequency, ν2. The two major models (dispersive and specific solvation) which have been proposed to interpret Δν are based on diverse experiments with incompatible conclusions. We ascertain the robust features of these models and combine them into a new one in which solvent−solvent and solvent−solute forces compete to determine the structure of the solution and hence Δν. First, Δν is analyzed in terms of solvent repulsive and dielectric effects combined with specific solvation effects. To interpret this specific solvation, 95 MP2 or B3LYP calculations are performed to evaluate structures and CN frequency shifts for CH3CN complexed with one molecule of either water, methanol, ethanol, 2-propanol, tert-butyl alcohol, phenol, benzyl alcohol, acetic acid, trifluoroacetic acid, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, acetonitrile, chloroform, carbon tetrachloride, tetrahydrofuran, formamide, pyridine, or Cl-, as well as 45 parallel calculations for the solvent monomers or dimers. The results are then convolved using known structural properties of the various solutions and/or related neat liquids, leading to an interpretation of the observed solvent shifts. Also, we measure Δν for acetonitrile in aqueous solution using Fourier transform Raman spectroscopy and show that the results are consistent with, but require modification of, microheterogeneity theories for the structure of acetonitrile−water solutions. Although such theories are still in their infancy, we suggest that microheterogeneity could also account for most known properties of acetonitrile−alcohol solutions and, in fact, be a quite general phenomenon.

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“…The formation of regions with enhanced water structure surrounded by a more disordered mixture of water and an analyte was referred to as ''microheterogeneity''. Later, on the basis of excess volumes, viscosity, and the dielectric constant, Moreau and Douhe´ret 17 postulated that there are three regions in the entire composition range of W/ACN where the solution is thought to separate into regions of acetonitrile and regions of water. For molar fractions of acetonitrile x ACN o 0.2, the acetonitrile molecule occupies the cavities between the water molecules without enhancing the water structure, for 0.2 r x ACN r 0.8, microheterogeneous behavior occurs with large aggregates formed and for x ACN 4 0.8, the acetonitrile structure is disrupted by water.…”

Section: Introductionmentioning

confidence: 99%

Solvent structures of mixed water/acetonitrile mixtures at chromatographic interfaces from computer simulations

Braun

Fouqueau

Bemish

et al. 2008

Phys. Chem. Chem. Phys.

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Atomistic simulations are used to characterize the molecular dynamics (MD) of alkyl chains with different functionalizations in different water/acetonitrile mixtures (80/20 and 50/50). Starting from fully equilibrated solvent systems (flat density profile for both components), microheterogeneous structuring of the solvent in the chromatographic system is found for both mixtures. Depending on the functionalization of the alkyl chain (nitrile, amide, nitro, phenyl), differences in the density profiles of the two solvents (water/acetonitrile), the effective width of the stationary phase and the solvent gradients in the overlap region are observed. The solvent mixture (mobile phase) in RPLC is a liquid which is directly involved in the physical process and must be included explicitly. Far from the surface, the solvent displays bulk properties; closer to it the mixed solvent partitions due to the presence of the stationary phase. This creates a gradient in solvent strength perpendicular to the surface which influences the motions of the analyte. The surface is found to define the amount of water that can bind to it and defines its hydrophilic character. Proposals from the literature, such as the existence of persistent water filaments extending from the functionalized silica layer towards the bulk solvent, are discussed. Simulations of acridine orange near a -NH(2)- and -phenol-functionalized surface highlight the different dynamical behaviour (insertion vs. adsorption) of an analyte depending on the functionalization of the surface.

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Solvatation ionique dans les mélanges eau-acétonitrile. Structure de ceux-ci

Cited by 19 publications

References 0 publications

Solvent Effects on pK_aValues of Some Anticancer Agents in Acetonitrile–Water Binary Mixtures

Solvent Effects on pK_aValues of Some Anticancer Agents in Acetonitrile–Water Binary Mixtures

The Solvation of Acetonitrile

Solvent structures of mixed water/acetonitrile mixtures at chromatographic interfaces from computer simulations

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Solvatation ionique dans les mélanges eau-acétonitrile. Structure de ceux-ci

Cited by 19 publications

References 0 publications

Solvent Effects on pKaValues of Some Anticancer Agents in Acetonitrile–Water Binary Mixtures

Solvent Effects on pKaValues of Some Anticancer Agents in Acetonitrile–Water Binary Mixtures

The Solvation of Acetonitrile

Solvent structures of mixed water/acetonitrile mixtures at chromatographic interfaces from computer simulations

Contact Info

Product

Resources

About

Solvent Effects on pK_aValues of Some Anticancer Agents in Acetonitrile–Water Binary Mixtures

Solvent Effects on pK_aValues of Some Anticancer Agents in Acetonitrile–Water Binary Mixtures