Volumetric properties for the monosaccharide (D-xylose, D-arabinose, D-glucose, D-galactose)-NaCl-water systems at 298.15 K

Interactions in saccharide/cation/water systems: Insights from density functional theory

Interactions between saccharides and ions in aqueous solutions are of great importance in many fields (chemistry, physico-chemistry, biology, food industries). Thus, this work proposes to develop a methodology dealing with the characterization and the understanding of interactions between saccharides and cations in presence of water molecules, by a quantum mechanics approach. In the first part, the saccharide hydration properties (xylose, glucose, sucrose) in pure water are determined. Results show that the saccharide coordination numbers, as well as the saccharides hydration enthalpy, increase with the saccharide hydrophilic group number. In the second part, the influence of cations on saccharides hydration properties, and inversely, is evaluated. In saccharide/cation/water systems, the decrease in hydration enthalpy of cations and saccharides shows that both species are dehydrated and that saccharide dehydration depends on the nature of the cation. The dehydration sequence of saccharides was explained from the study of saccharide/cation interactions.

Why Are Saccharides Dehydrated in the Presence of Electrolytes? Insights from Molecular Modeling and Thermodynamic Measurements

The mechanisms governing the interactions of neutral polar solutes with ions in aqueous solutions are still poorly understood, despite the importance of this phenomenon in many fields (chemistry, physicochemistry, biology, food industries). In order to go further through the understanding of the molecular mechanisms governing the ions' specific effects, this paper presents a generic method dealing with the characterization and understanding of interactions between saccharides and ions in aqueous systems. For that, an original approach combining a computational technique and experimental measurements (thermodynamic properties) is proposed to explain and rationalize the relationship between the solute hydration and the physical chemistry of the ions in solution (cation/anion, charge, size, and hydration). These relationships make it possible to evaluate the hydration state of a saccharide, a polar neutral molecule, according to the ionic composition, from the knowledge of the ions' hydration properties. This work proposes new insight into molecular mechanisms governing the polar neutral solute/ion interactions and a new understanding of the hydration phenomenon in electrolytic solutions.

Role of the triple solute/ion/water interactions on the saccharide hydration: A volumetric approach

The aim of this study is to further the understanding of the mechanisms that govern the hydration behavior of neutral solutes, with respect to the ions' properties that are present in a solution. For that, a systematic volumetric study of saccharides (xylose, glucose and sucrose), in the presence of various electrolytes (LiCl, NaCl, KCl, Na₂SO₄, K₂SO₄, CaCl₂, MgCl₂, MgSO₄) has been carried out with density measurements at 298.15 K. From this data, the standard transfer molar volume of the saccharide ΔV_ϕ,S⁰, which characterizes the hydration state of the solute, has been determined. Positive and increasing values of ΔV_ϕ,S⁰ with increasing electrolyte concentrations were obtained. This indicated the dehydration of the saccharide in the presence of the electrolyte, due to the predominance of saccharide/cation interactions. Concerning the influence of the cation, it was shown that saccharides are more dehydrated in the presence of divalent cations than in the presence of monovalent ones. This is because the interactions are stronger between saccharides and divalent cations, in comparison to those with monovalent cations. For a specific cation valence and molality, regardless of the anion, saccharide dehydration increases according to the following sequences: Li⁺< Na⁺< K⁺ and Mg²⁺< Ca²⁺. These saccharide dehydration sequences have been explained by the Gibbs free energy of hydration of the cations, reflecting the cation/water interactions. For a specific cation valence, it was concluded that decreasing cation/water interactions induce the increase of saccharide dehydration. Concerning the influence of the anion, it was also observed that saccharides are more dehydrated in the presence of divalent anions than in the presence of monovalent ones. It was stated that saccharide/cation interactions are modulated by the nature of the anion. The anion impact was again attributed to its capacity to interact with water molecules. It was pointed out that anions with increasing values of Gibbs free energy of hydration cause an increase in saccharide/cation interactions or a decrease in saccharide/anion interactions. Therefore, saccharide dehydration increases.

Polarizable empirical force field for hexopyranose monosaccharides based on the classical Drude oscillator

A polarizable empirical force field based on the classical Drude oscillator is presented for the hexopyranose form of selected monosaccharides. Parameter optimization targeted quantum mechanical (QM) dipole moments, solute-water interaction energies, vibrational frequencies, and conformational energies. Validation of the model was based on experimental data on crystals, densities of aqueous-sugar solutions, diffusion constants of glucose, and rotational preferences of the exocylic hydroxymethyl of d-glucose and d-galactose in aqueous solution as well as additional QM data. Notably, the final model involves a single electrostatic model for all sixteen diastereomers of the monosaccharides, indicating the transferability of the polarizable model. The presented parameters are anticipated to lay the foundation for a comprehensive polarizable force field for saccharides that will be compatible with the polarizable Drude parameters for lipids and proteins, allowing for simulations of glycolipids and glycoproteins.

Volumetric and acoustic properties of D-mannitol in aqueous sodium or magnesium chloride solutions over temperature range of 293.15-313.15K

Apparent molar volumes and apparent molar compressibilities for d-mannitol in (1, 5 and 10) % aqueous sodium or magnesium chloride have been determined from solution density measurements at T=(293.15, 298.15, 303.15, 308.15, 310.15, and 313.15)K and sound velocity measurements at T=(293.15 and 310.15)K as a function of the concentration of sugar alcohol. The limiting apparent molar volumes and limiting apparent molar compressibilities have been obtained from the Masson equation. The corresponding transfer parameters and expansion coefficients were also estimated. These parameters have been discussed in terms of d-mannitol-cosolute (NaCl or MgCl(2)) interactions in aqueous solutions and thus used to understand the mixing effects due to these interactions.

Interactions of calcium nitrate with pyranosides in water: a 13C NMR study

The 13C NMR spectra of methyl alpha- and beta-D-galactopyranosides, and methyl alpha- and beta-D-glucopyranosides were recorded and show that the Delta(deltaC-4) values for methyl alpha- and beta-D-galactopyranosides increase most rapidly, whereas those for methyl alpha- and beta-D-glucopyranosides vary hardly with increasing molality of calcium nitrate. It can be concluded that ax-OH-4 interacts more strongly with Ca2+ than eq-OH-4 group, namely, the Ca2+ ion interaction with ax-OH-4 leads to a stronger deshielding of the C-4 atom. Compared with other C atoms, the chemical shifts of both C-1 and C-5 atoms in these two types of glycosides decrease relatively rapidly as molality of calcium nitrate increases, indicating that the nitrate ion attractions for these glycosides cause a relatively strong enhancing shielding effect of C-1 and C-5 atoms.

Densities, Apparent Molar Volumes, and Interaction Parameters for the Monosaccharide (D-Xylose, D-Arabinose, D-Glucose, D-Galactose)–NaBr–Water Systems at 298.15 K

Densities have been measured for the monosaccharide (D-xylose, D-arabinose, D-glucose and D-galactose)–NaBr–water solutions at 298.15 K. These data have been used to calculate the apparent molar volumes of these saccharides ( V