Isotope Effect on Fractional Dilatability of Solute Water as an Indicator of the H-Bonding Ability of an Aprotic Dipolar Solvent

Volumetric properties of (water+hexamethylphosphoric triamide) from (288.15 to 308.15)K

“…À15 kJ Á mol À1 , (3) for fitting the experimental data from this work}; s, reference [19]; h, reference [26]; e, reference [30]; 4, reference [31]. on the average [7,[46][47][48]. As follows from table 2 and figure 2, the most stable H-bonded structure is formed in the mixed solvent (water + HMPT) of 3:1 stoichiometry at each of temperatures studied.…”

Water as a solute in nitromethane: Effect of H2O–D2O isotope substitution on the solution volumetric properties between 278.15K and 318.15K

“…Water dissolved in the aprotic dipolar solvent present a rare opportunity for studying both the state and specific features of solute molecules being hydrogen-non-bonded in the three-dimensional network characteristic of the ''pure" aqueous component and the nature of their effect on the structure and thermodynamic properties of the surrounding (solvating) medium [1][2][3][4][5][6][7]. Here, the point is that the aprotic dipolar solvent is such a dissolving medium, whose structural packing contains molecules that do not form strong hydrogen bonds (due to the absence of proton-donating centers) but allows sufficiently strong specific interactions (via H-bonding) with molecules of an electron-accepting protic solute, which in this case is water [3].…”

“…Here, the point is that the aprotic dipolar solvent is such a dissolving medium, whose structural packing contains molecules that do not form strong hydrogen bonds (due to the absence of proton-donating centers) but allows sufficiently strong specific interactions (via H-bonding) with molecules of an electron-accepting protic solute, which in this case is water [3].…”

“…At the same time, although thermodynamics does not yield directly the structural aspects of the intermolecular interaction, one can derive meaningful inferences from thermodynamic properties such as partial volume and enthalpy function as well as their derivatives (partial expansibility, compressibility and heat capacity) indirectly [2][3][4]7,8]. From this viewpoint, approaches that cause ''minimal perturbation" of a solution structure seem to be most informative for the specified thermodynamic studies.…”

“…Based on the results of previous investigations [3,[9][10][11][12][13][14], such an experimental approach primarily includes a combination of precision densimetry and H 2 O-D 2 O isotope substitution methods. The first method provides a set of volumetric characteristics that adequately reflect structure-packing rearrangements occurring during water dissolution (solvation); the second (due to the quantum nature of the D 2 O-H 2 O isotope effect [15]) allows one to establish at the molecular level the role of hydrogen bonds in structure-forming effects, which are manifested in the volumetric and other thermodynamic properties [2,3,[16][17][18][19].…”