Solvation shell water molecules

If this occurs it takes place in the first solvation shell. These are water molecules with which the ion interacts strongly and are coordinated to the ion. They thus move with the ion and could be termed bound water. Often all of the first solvation shell water molecules can be considered to be primary solvation, but some workers feel that this need not necessarily be the case. Some water molecules may be in the first solvation shell but are not bound, and do not move with the ion. It becomes necessary to define a criterion for distinguishing bound from unbound molecules, i.e. primary solvation or not. The criterion used will be determined by the experimental technique which is being used to measure it. Unfortunately, different experiments may actually measure different properties. 

At 0 K we have found that the first solvation shell for the two studied clustery is formed by six water molecules octahedrically disposed around each Fe ion, the two octahedrons being staggered face-to-face. Table 1 presents for each cluster the mean distances between both Fe ions and the oxygen atoms of the first solvation shell water molecules, and the... 

In that respect, then, the polarizable continuum estimate of hydration energy of these entities is considerably smaller than the quantum mechanical interaction energy of the molecule plus the appropriate number of first-shell water molecules. In this vein, then, it would be highly inaccurate to equate the interaction energy of a molecule such as imidazole with the molecules in its first solvation shell to the entire solvation energy when computed by a continuum approach. 

DNA waters of solvation play a significant role in the DNA damage process from ionizing radiation. In fiilly hydrated DNA, approximately 8-10 water molecules per nucleotide (T = 8-10 H2O/ nucleotide) form a primary solvation shell of molecules directly in contact with the DNA and its coimtetion. When these molecules are ionized, hole transfer to the DNA molecule is faster than deprotonation... 

Surprisingly, the low solubility of small-sized particles does not stem from a weak interaction of particles with their surrounding water environment (77). For example, the heat of solvation of methane in water at ambient temperature is of similar magnitude as the heat of vaporization of pure liquid methane (80). The positive solvation free energy of small apolar particles at low temperatures is the consequence of negative solvation entropy, which overcompensates for the negative solvation enthalpy. It is widely believed that this entropy penalty is caused by the orientation order introduced to the hydration-shell water molecules as they try to maintain an intact hydrogen bond network (77). Parallel to the entropy decrease observed for low... 

Bad peak shapes may be encountered. This may occur especially if the analyte is a small hydrophobic compound in which the hydrophobic part of the molecule is comparable to that of the acidic moiety. For larger hydrophobic acidic compounds this effect may not be predominant. The anionic form of the acidic compound is strongly solvated by water molecules. If the organic eluent modifier can participate in the analyte solvation, the solvation shell will have some hydrophobicity and may actually... 

The FI2O molecules of these aquo-complexes constitute the iimer solvation shell of the ions, which are, in turn, surrounded by an external solvation shell of more or less uncoordinated water molecules fomiing part of the water continuum, as described in section A2.4.2 above. Owing to the difference in the solvation energies,... 

Consider now the aquo-complexes above, and let v be the distance of the centre of mass of the water molecules constituting the iimer solvation shell from the central ion. The binding mteraction of these molecules leads to vibrations... 

Modem understanding of the hydrophobic effect attributes it primarily to a decrease in the number of hydrogen bonds that can be achieved by the water molecules when they are near a nonpolar surface. This view is confirmed by computer simulations of nonpolar solutes in water [15]. To a first approximation, the magnimde of the free energy associated with the nonpolar contribution can thus be considered to be proportional to the number of solvent molecules in the first solvation shell. This idea leads to a convenient and attractive approximation that is used extensively in biophysical applications [9,16-18]. It consists in assuming that the nonpolar free energy contribution is directly related to the SASA [9],... 

The substituent effects on the H-bonding in an adenine-uracil (A-U) base pair were studied for a series of common functional groups [99JPC(A)8516]. Substitutions in the 5 position of uracil are of particular importance because they are located toward the major groove and can easily be introduced by several chemical methods. Based on DFT calculation with a basis set including diffuse functions, variations of about 1 kcal/mol were found for the two H-bonds. The solvent effects on three different Watson-Crick A-U base pairs (Scheme 100) have been modeled by seven water molecules creating the first solvation shell [98JPC(A)6167]. 

Micelles and reversed micelles are able to solubilize substances which are insoluble in the bulk phase of the system considered. This solubilization is due to a solvation by the amphiphile and concomitantly a change in the order of the solubilized molecules may occur as a consequence of its modified solvation shell. In this sense reversed micelles of detergents in hydrophobic solvents with solubilized water in the core are... 

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