Solvation hydrophobic

Finally, the liquid-vapor interface probes hydrophobic effects around solutes of infinite diameter, fn particular, the surface 

Altogether, these results lead to concern not only for simulations of micelles and membranes, but also for all hydrophobic association including that involved in protein folding. In particular, the SSDQOl results support a more extensive tetrahedral network. 

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Solvation and especially hydration are rather complex phenomena and little is known about them. Depending on the kind of molecular groups, atoms or ions interacting with the solvent, one can differ between lyo- or hydrophilic and lyo-or hydrophobic solvation or hydration. Due to these interactions the so-called liquid structure is changed. Therefore it seems to be unavoidable to consider, at least very briefly, the intermolecular interactions and the main features of liquids, especially water structure before dealing with solvation/hydration and their effects on the formation of ordered structures in the colloidal systems mentioned above. 

Huang, D.M. Geissler, P.L. Chandler, D., Scaling of hydrophobic solvation free energies, J. Phys. Chem. B 2001,105, 6704-6709... 

Gallicchio, E. Kubo, M. M. Levy, R. M., Enthalpy-entropy and cavity decomposition of alkane hydration free energies numerical results and implications for theories of hydrophobic solvation, J. Phys. Chem. B 2000,104, 6271-6285... 

Hydrocarbons in water give rise to hydrophobic solvation shells in which the water structure is thoroughly disturbed though still forming a solvation shell around a spherical solute. An example of a calculated situation of this type is shown in Fig. 2.69. 

Water is well known for its unusual properties, which are the so-called "anomalies" of the pure liquid, as well as for its special behavior as solvent, such as the hydrophobic hydration effects. During the past few years, a wealth of new insights into the origin of these features has been obtained by various experimental approaches and from computer simulation studies. In this review, we discuss points of special interest in the current water research. These points comprise the unusual properties of supercooled water, including the occurrence of liquid-liquid phase transitions, the related structural changes, and the onset of the unusual temperature dependence of the dynamics of the water molecules. The problem of the hydrogen-bond network in the pure liquid, in aqueous mixtures and in solutions, can be approached by percolation theory. The properties of ionic and hydrophobic solvation are discussed in detail. 

Gill SJ, Dec SF, Olofsson G, Wadsd I. Anomalous heat-capacity of hydrophobic solvation. J. Phys. Chem. 1985 89 3758-3761. Muller N. Search for a realistic view of hydrophobic effects. Acc. Chem. Res. 1990 23 23-28. 

Southall NT, Dill KA. The mechanism of hydrophobic solvation depends on solute radius. J. Phys. Chem. B 2000 104 1326-1331. Lee CY, McCammon JA, Rossky PJ. The structure of fiq-uid water at an extended hydrophobic surface. J. Chem. Phys. 1984 80 4448-4455. 

The basic effects responsible for the properties of electrolyte solutions are ion solvation, ion 2issociation to ion pairs and higher ion aggregates with and without inclusion of solvent molecules. FTIR (Fourier transform infrared) and MW (microwave) spectra are a valuable source of information on ion-solvent and ion-ion interactions and yield factual knowledge on the structure and dynamics of electrolyte solutions. The efficiency of these methods is exemplified for solvation in aptotic and protic solvents, hydrophobic solvation, association to charged and neutral ion aggregates, and stability of ion pairs. 

Studies on structure and dynamics of liquids have recently been extended to solvate structure of ions in non-aqueous solutions, and to the structure of complexes with relatively complicated ligands. We can also handle special problems like hydrophobic solvation is. Diffraction studies have been performed on new solvents as e.g. trifluoroethanol [23] and tetramethyl urea [26], and on solvent mixtures [27-30]. More recently the preferential solvation of ions has been subjected by an XD investigation in MgCh-water-methMol ternary systems [31], and the solvation structure around the cations proved to undergo the change of solvent molecules proportionally to the relative concentration of the two solvents. 

Frank, H. S., Evans, M. W. (1945). Free volume and entropy in condensed systems. Journal of Chemical Physics, 13, 507-532. Gill, S. J., Dec, S. F., Olofsson, G., Wadso, I. (1985). Anomalous heat capacity of hydrophobic solvation. Journal of Physical Chemistry, 89, 3758-3761. 

Hermann, R.B. (1997) Modeling hydrophobic solvation of nonspherical systems comparison of use of molecular surface area with accessible surface area./. Comput. Chem., 18, 115-125. 

SouthaU, N.T., Dill, K.A. The mechanism of hydrophobic solvation depends on solute radius. 

SA Osaka, N., Okabe, S., Karino, T., Hirabara, Y., Aoshima, S., and Shibayama, M., Micro- and macrophase separations of hydrophobically solvated block copolymer aqueous solutions induced by pressure and temperature. Macromolecules, 39, 5875, 2006. 

Horinek, D., Herz, A., Vrbka, L., Sedhneier, F., Mamatkulov, S.I., Nelz, R.R. Specific ion adsorption at the air/water interface the role of hydrophobic solvation. Chtan. Phys. Lett. 479,... 

Levesque M, VuiUeumier R, Borgis D Scalar fundamental measure theory for hard spheres in three dimensions application to hydrophobic solvation, J Chem Phys 137(3) 034115, 2012. 

Hydrophobic Solvation Near the Critical Temperature of Water... 

So far we have considered the insertion of a single nonpolar molecule into water. This is sometimes called hydrophobic hydration or hydrophobic solvation. Now consider bringing two nonpolar solutes together in w-ater. This is called hydrophobic interaction. 

The solvent molecules within the innermost circle are virtually fixed in orientation toward the ion. Those within the next circle are less strongly oriented, but more closely packed, while those beyond are undisturbed, (b) Hydrophobic solvation. The innermost solvent molecules form a cage around the nonpolar solute, hydrogen-bonded to each other. As in the ionic case, these are surrounded by a region of disturbed structure, beyond which the solvent is normal. 

Other workers have used various methods (MC, MD, integral equations) to investigate thermodynamic aspects of hydrophobic solvation (Abraham, 1982 Durrell and Wallqvist, 1996 Guillot et al., 1991). Some have examined effects of solute size or curvature (Ashbaugh and Paulaitis, 1996 Chau et al., 1996 Okazaki et al, 1981 Tanaka, 1987). Others have focused on specific aspects such as heat capacity (Madan and Sharp, 1996), volume, and compressibility (Matubayasi and Levy, 1996). 

We have seen that AG is almost independent of m dne to the cancelation of two effects (micelle aggregation vs. micelle stability). Such cancelation does not necessarily take place in the two terms, A77°, and that compose AG ,. It seems that the dependence of A77°, with n and m follows a trend similar to that of p n and m have opposing effects), while follows the trend of In(CMC) (n and m leading to concurring effects). Although speculative, this makes sense from a molecular point of view in aqueous solutions at 298 K, it is known that the micellization process is entropically driven by gains in the entropy of water, when hydrophobic solvation of individual surfactant molecules is compared with the favorable solvation of micelles. This means that... 

Grunwald-Winstein-type analyses (using ici) for the solvolysis of extremely crowded tertiary alkyl chlorides having a neopentyl or a (l-adamantyl)methyl group at the reaction centre show that they behave as fcc substrates. The solvolytic behaviour of various crowded alkyl derivatives and the origins of dispersions of data points of aqueous organic solvents in Grunwald-Winstein type correlations are discussed in detail. A possible role of hydrophobic solvation is tentatively raised. 

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