@article {1440, title = {The effects of chloride salts of some cations on the molecular organization of H2O. Towards understanding the Hofmeister series. II}, journal = {Bulletin of the Chemical Society of Japan}, volume = {79}, number = {9}, year = {2006}, note = {ISI Document Delivery No.: 097WCTimes Cited: 7Cited Reference Count: 42Koga, Yoshikata Katayanagi, Hideki Davies, James V. Kato, Hitoshi Nishikawa, Keiko Westh, Peter}, month = {Sep}, pages = {1347-1354}, type = {Article}, abstract = {We use the thermodynamic behaviour of I-propanol (1P) as a probe in ternary 1P-salt-H2O systems to elucidate the effect of a salt on the molecular organization of H2O. For salts, we have chosen CaCl2, NH4Cl, and (CH3)(4)NCl (TMAC). Having fixed the counter anion at Cl-, we compare here mainly the effects of chosen cations on H2O. Together with an earlier study on NaCl, we found that Ca2+, Na+, and NH4+ are hydrated by a number of H2O molecules and leave the bulk H2O away from the hydration shell unperturbed. The hydration numbers were found to be 6.4 +/- 1.6, and 1.2 +/- 0.4, for Ca2+ and NH4+, respectively with the hydration number 5.2 for Na+, the result of a simulation study, chosen as a reference. Thus, a salting out (also referred to as structure making, stabilizing, or kosmotropic) tendency would decrease in the order; Ca2+ > Na+ > NH4+. TMA(+), on the other hand, showed a more hydrophilic characteristics than the probing 1P. Thus, TMA(+) is rather chaotropic (salting in, structure breaking or destabilizing) within this methodology.}, keywords = {AQUEOUS-SOLUTIONS, EXCESS CHEMICAL-POTENTIALS, HEAT-CAPACITIES, INTERMOLECULAR INTERACTIONS, MIXING SCHEMES, PARTIAL MOLAR ENTHALPIES, TETRAALKYLAMMONIUM HALIDES, TETRAMETHYL UREA, THERMODYNAMIC APPROACH, WATER MIXTURES}, isbn = {0009-2673}, url = {://000241479100004}, author = {Koga,Yoshikata and Katayanagi, H. and Davies, J. V. and Kato, H. and Nishikawa, K. and Westh, P.} } @article {4587, title = {Fluctuations in aqueous methanol, ethanol, and propan-1-ol: amplitude and wavelength of fluctuation}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {77}, number = {12}, year = {1999}, note = {ISI Document Delivery No.: 262KYTimes Cited: 29Cited Reference Count: 18}, month = {Dec}, pages = {2039-2045}, type = {Article}, abstract = {Density, heat capacity, and isentropic compressibility data for aqueous methanol, ethanol, and propan-1-ol by Benson{\textquoteright}s group were used to evaluate two kinds of fluctuations; mean-square fluctuation densities; and (mean-square) normalized fluctuations, respectively, in volume, entropy, and cross (entropy/volume) effect. The mean-square fluctuation densities provide measures for the amplitude (intensity) of the fluctuation, while the normalized fluctuations contain information regarding the wavelength (extensity) of the fluctuation. Furthermore, their composition derivatives, the partial molar fluctuations of alcohols were calculated. These quantities signify the effect of additional solute on the respective fluctuations. These data were interpreted in terms of mixing schemes learned earlier in this laboratory by using the data of excess partial molar enthalpy, entropy, and volume, and the respective alcohol-alcohol interaction functions, i.e., the composition derivatives of partial molar quantities.}, keywords = {25-DEGREES-C, and propan-1-ol, aqueous methanol, ETHANOL, fluctuation density, HEAT-CAPACITIES, LIQUID WATER, N-ALCOHOL MIXTURES, NON-ELECTROLYTES, normalized fluctuation, partial molar fluctuations of alcohol, THERMODYNAMICS, VOLUMES}, isbn = {0008-4042}, url = {://000084067500005}, author = {Koga,Yoshikata} } @article {4027, title = {{\textquoteright}Intermolecular interactions{\textquoteright} in aqueous solutions of three components including lysozyme}, journal = {Fluid Phase Equilibria}, volume = {136}, number = {1-2}, year = {1997}, note = {ISI Document Delivery No.: YR149Times Cited: 5Cited Reference Count: 4614th IUPAC Conference on Chemical Thermodynamics (ICCT 97)AUG 25-30, 1996OSAKA, JAPANInt Union Pure \& Appl Chem, Sci Council Japan, Chem Soc Japan, Japan Soc Calorimetry \& Thermal Anal, Atom Energy Soc Japan}, month = {Nov}, pages = {207-221}, type = {Proceedings Paper}, abstract = {Excess partial molar enthalpies were measured in ternary aqueous solutions, tert-butyl alcohol (TBA)DMSO-H2O, and lysozyme (L)-alcohols (A)-H2O. The solute-solute interactions were evaluated as the derivatives of these data with respect to the mole fraction of a solute. In the water-rich region, where the so-called mixing scheme I is operating in binary aqueous solutions of TEA, DMSO or alcohols, two solutes in TBA-DMSO-H2O seem to modify the hydrogen bond network of H2O in an additive manner. Here, mixing scheme I refers to the way in which a solute (hydrophobic) modifies the molecular organization of H2O. Specifically, a solute enhances the hydrogen bond strength of H2O in its immediate vicinity. On the other hand, the probability of hydrogen bond in the bulk away from a solute is reduced, and it is still high enough, however, to keep the hydrogen bond network connected throughout the entire macroscopic: system. As the composition of solute increases, the hydrogen bond probability in the bulk decreases to the point at which the macroscopic bond connectivity is no longer possible. At this point, a new mixing scheme, II, sets in. For L-A-H2O mixtures at infinite dilution of L, the L-A interaction changes drastically from repulsive: to attractive at the boundary between I and II for binary aqueous alcohols. Moreover, a denatured lysozyme interacts with alcohols more strongly than the native form, and is more repulsive in mixing scheme I and more attractive in IT. This behaviour is shown to be consistent with the alcohol-dependent enthalpy of denaturation of lysozyme found by Velicelebi and Sturtevant [Velicelebi and Sturtevant, Biochem. 18 (1979) 1188-86]. (C) 1997 Elsevier Science B.V.}, keywords = {2-BUTOXYETHANOL, BUTYL ALCOHOL, denaturation of lysozyme, enthalpy of, excess partial molar enthalpies, FREE-ENERGIES, HEAT-CAPACITIES, lysozyme-alcohols-H2O, MIXING SCHEME, PARTIAL MOLAR ENTHALPIES, SOLUTE-SOLUTE INTERACTION, TERT-BUTANOL MIXTURES, tert-butyl alcohol-DMSO-H2O, THERMAL EXPANSIVITIES, VAPOR-PRESSURES, WATER-RICH REGION}, isbn = {0378-3812}, url = {://000071465000020}, author = {Koga,Yoshikata and Westh, P. and Trandum, C. and Haynes, C. A.} } @article {3721, title = {Mixing schemes in aqueous solutions of nonelectrolytes: A thermodynamic approach}, journal = {Journal of Physical Chemistry}, volume = {100}, number = {13}, year = {1996}, note = {ISI Document Delivery No.: UC398Times Cited: 92Cited Reference Count: 77}, month = {Mar}, pages = {5172-5181}, type = {Article}, abstract = {Thermodynamic studies were carried out on aqueous solutions of some nonelectrolytes. The quantities proportional to the second derivatives of Gibbs energy were measured directly and in small increments in mole fraction or temperature. Therefore, we were able to differentiate once more with respect to mole fraction or temperature. Generally, the higher the order of the derivative, the more detailed the information it contains. Using these second and third derivatives, an attempt was made at elucidating the mixing schemes, the way in which solute and solvent H2O molecules mix with each other. For the following nonelectrolytes studied so far, 2-butoxyethanol, tert-butyl alcohol, 2-butanone, isobutyric acid, and dimethyl sulfoxide, there are separate regions in the single-phase domain of the temperature-mole fraction field, in each of which the mixing scheme is qualitatively different from those of the other regions. The details of each mixing scheme were elucidated from the behavior of the second and third derivatives of Gibbs energy. In the water-rich region (I), the effect of a solute was suggested to enhance the hydrogen bonds of H2O in the vicinity of the solute but to diminish the hydrogen bond probability of the bulk H2O away from the solute. When the hydrogen bond probability at a certain region of bulk water decreases to that of the percolation threshold, this mixing scheme is no longer operative, and mixing scheme II sets in. The transition from the mixing scheme of region I to that in region (II) was found to accompany anomalies in the third derivatives of Gibbs energy, in contrast to the normal phase transitions which are associated with anomalies in the second derivatives of Gibbs energy. In the intermediate region (II), it was suggested that the solution consists of two kinds of clusters rich in each component. In the solute-rich region (III), at least for the 2-butoxyethanol and dimethyl sulfoxide cases, the clusters of purely solute molecules exist and H2O molecules are {\textquoteright}{\textquoteright}adsorbed{\textquoteright}{\textquoteright} on the surfaces of such clusters.}, keywords = {2-BUTOXYETHANOL WATER, BUTANOL, CORRELATION LENGTH, HEAT-CAPACITIES, KIRKWOOD-BUFF PARAMETERS, LOCAL-STRUCTURE, MIXTURES, PARTIAL MOLAR ENTHALPIES, TERT-BUTYL ALCOHOL, WATER-RICH REGION, X-RAY-SCATTERING}, isbn = {0022-3654}, url = {://A1996UC39800006}, author = {Koga,Yoshikata} } @article {3412, title = {EXCESS PARTIAL MOLAR ENTHALPIES, ENTROPIES, GIBBS ENERGIES, AND VOLUMES IN AQUEOUS DIMETHYLSULFOXIDE}, journal = {Journal of Solution Chemistry}, volume = {24}, number = {1}, year = {1995}, note = {ISI Document Delivery No.: QF279Times Cited: 60Cited Reference Count: 20}, month = {Jan}, pages = {89-102}, type = {Article}, abstract = {The excess partial molar enthalpies, the vapor pressures, and the densities of dimethylsulfoxide (DMSO) - H2O mixtures were measured and the excess partial molar Gibbs energies and the partial molar volumes were calculated for DMSO and for H2O. The values of the excess partial molar Gibbs energies for both DMSO and H2O are negative over the entire composition range. The results for the water-rich region indicated that the presence of DMSO enhances the hydrogen bond network of H2O. Unlike monohydric alcohols, however, the solute-solute interaction is repulsive in terms of the Gibbs energy. This was a result of the fact that the repulsion among solutes in terms of enthalpy surpassed the attraction in terms of entropy. The data in the DMSO-rich region suggest that DMSO molecules form clusters which protect H2O molecules from exposure to the nonpolar alkyl groups of DMSO.}, keywords = {2-BUTOXYETHANOL, 25-DEGREES-C, AQUEOUS DIMETHYLSULFOXIDE, DIMETHYL-SULFOXIDE, ENTROPIES, excess partial molar enthalpies, GIBBS ENERGIES AND VOLUMES, HEAT-CAPACITIES, LIQUID-MIXTURES, MIXING SCHEME, RANGE, SOLUTE-SOLUTE INTERACTION, TRANSITION, WATER-RICH REGION}, isbn = {0095-9782}, url = {://A1995QF27900007}, author = {Lai, J. T. W. and Lau, F. W. and Robb, D. and Westh, P. and Nielsen, G. and Trandum, C. and Hvidt, A. and Koga,Yoshikata} } @article {3400, title = {FLUCTUATIONS IN AQUEOUS-SOLUTIONS OF SOME HYDROPHOBIC SOLUTES}, journal = {Chemical Physics Letters}, volume = {240}, number = {4}, year = {1995}, note = {ISI Document Delivery No.: RG423Times Cited: 13Cited Reference Count: 33}, month = {Jun}, pages = {340-344}, type = {Article}, abstract = {The entropy fluctuation in liquids and solutions is most conveniently normalized to the coarse-grained volume. Hence, [(Delta S/V)(2)] = RC(p)/V-m(2) and [(Delta S/V)(Delta N/N)] = RT alpha(p)/V-m. It was shown to be useful if the response functions, C-p, kappa(T) and alpha(p), and the fluctuations derived from them, were discussed separately in contrasting the peculiar nature of liquid H2O against a typical van der Waals liquid, benzene. The composition dependence of these fluctuations was examined in aqueous solutions of typical hydrophobic solutes, 2-butoxyethanol, 2-butanone and tert-butanol. It was concluded that the above solutes reduce the hydrogen bond probability in H2O up to the crossover point of mixing scheme, x(i)(c).}, keywords = {2-BUTOXYETHANOL, 25-DEGREES-C, FREE-ENERGIES, HEAT-CAPACITIES, MIXING SCHEME, PARTIAL MOLAR ENTHALPIES, TERT-BUTANOL MIXTURES, TRANSITION, VOLUMES, WATER-RICH REGION}, isbn = {0009-2614}, url = {://A1995RG42300015}, author = {Koga,Yoshikata} } @article {3403, title = {Speeds of sound and isothermal compressibilities in the water-rich region of aqueous 2-butoxyethanol and 2-butanone at 25 degrees C}, journal = {Journal of Solution Chemistry}, volume = {24}, number = {11}, year = {1995}, note = {ISI Document Delivery No.: TV702Times Cited: 8Cited Reference Count: 25}, month = {Nov}, pages = {1125-1133}, type = {Article}, abstract = {Speeds of sound were measured at 25 degrees C in the water-rich region of aqueous 2-butoxyethanol (BE) and 2-butanone (BUT). Density, heat capacity, and thermal expansivity data available in literature were used to calculate isothermal compressibilities, kappa(T). The composition derivative, N(partial derivative kappa(T)/partial derivative n(B)), a third derivative of Gibbs free energy, showed a peak anomaly at x(BE) = 0.0175 for BE-H2O, and bend at x(BUT) = 0.033 for BUT-H2O. n(B) (n(BE) or n(BUT)) is the amount of the solute and x(BE) and x(BUT) are the respective mole fractions. The location of these anomalies were the same as those of other third derivatives found earlier for the same aqueous solutions. These anomalies were shown earlier to mark the transition point across which the mixing scheme changes in a qualitative fashion.}, keywords = {2-BUTANONE, 2-BUTOXYETHANOL, anomaly in the third derivative, aqueous solutions, ENTHALPIES, HEAT-CAPACITIES, isothermal compressibility, MIXING SCHEME, MIXTURES, of mixing scheme, PARTIAL MOLAR VOLUMES, RANGE, speed of sound, SYSTEMS, TRANSITION}, isbn = {0095-9782}, url = {://A1995TV70200004}, author = {Koga,Yoshikata and Tamura, K. and Murakami, S.} } @article {3007, title = {EXCESS PARTIAL MOLAR VOLUMES AND THERMAL EXPANSIVITIES IN THE WATER-RICH REGION OF AQUEOUS 2-BUTANONE}, journal = {Journal of Solution Chemistry}, volume = {23}, number = {2}, year = {1994}, note = {ISI Document Delivery No.: NB508Times Cited: 8Cited Reference Count: 22Symposium in Honor of Donald Patterson on His 65th Birthday, at the 76th Congress of the Canadian-Society-for-ChemistryMAY 31-JUN 03, 1993SHERBROOKE, CANADACANADIAN SOC CHEM}, month = {Feb}, pages = {339-349}, type = {Proceedings Paper}, abstract = {Excess partial molar volumes of 2-butanone V(m)E(B) and thermal expansivities alpha(p) were measured in the water-rich region of aqueous 2-butanone. The composition derivatives of both quantities showed anomalies at about X(B) = 0.033 (x(B) is the mole fraction of B). (partial derivative V(m)E(B)/partial derivative n(B))p,T,nW showed a step anomaly, while (partial derivative alpha(p)/partial derivatives n(B))p,T,nw exhibited a peak anomaly. The compositions at which these anomalies occurred match those of the step anomalies observed earlier in (partial derivative H(m)E(B)/partial derivative n(B))p,T,nW and (partial derivative S(m)E(B)/partial derivative n(B))p,T,nW in aqueous 2-butanone. These results are discussed in comparison with those obtained previously for aqueous 2-butoxyethanol.}, keywords = {2-BUTANONE, 2-BUTOXYETHANOL, 25-DEGREES-C, ANOMALIES IN 3RD DERIVATIVES, AQUEOUS, DERIVATIVES, ENTHALPIES, EXCESS PARTIAL MOLAR VOLUMES, fluctuations, FREE-ENERGIES, HEAT-CAPACITIES, MIXING SCHEME, OF GIBBS FREE ENERGY, TERT-BUTANOL MIXTURES, THERMAL EXPANSIVITIES, TRANSITION, TRANSITION OF MIXING SCHEME}, isbn = {0095-9782}, url = {://A1994NB50800016}, author = {Davies, J. V. and Fooks, R. and Koga,Yoshikata} }