Vicinal water structural influence

Sun et al. (1986) have observed that various types of clay exhibit the same influence on the vicinal water. They concluded that a substrate independence exists. Packer (1977) also noted the substrate independence of water-structuring effects. He quotes Woessner s NMR studies showing that the ratio of the deuteron-to-proton splittings for water, oriented by proximity to a clay surface (3.75), appears independent of the type of clay and that the same ratio is found for water in oriented collagen, Li-DNA, and rayon. Thus, Packer suggests that it is merely the presence of a static surface and not its nature that matters in producing dynamic orientation of that water, and that the predominant effect is water-water interaction. The importance of the paradoxical effect lies in the prediction that vicinal water occurs at all solid interfaces and must, therefore, also occur in cellular systems—the cellular interior offers vast structural areas for the induction of vicinal water. 

The hydrophobic effect is a term describing the influence of relatively nonpolar (lipophilic) substances on the collective behavior of water molecules in their vicinity. The common expression is that water is more structured or organized when in contact with a lipophilic solute. This behavior was observed in a cellular automata model of a solute in water,42,43 which led to a study in more detail.44 The hydrophobic effect was modeled by systematically increasing the breaking probability, PB(WS), value, encoding an increasing probability of a solute molecule, S, not to associate with water. 

The kinetics of decomposition of nickel formate [6,7] are sensitive both to the experimental conditions [8] and the reactant structure, ar-time curves for the isothermal decomposition (about 450 K) are usually [8], though not invariably [9], sigmoid and there is microscopic evidence [6] that reaction proceeds through nucleation and growth. The induction period [6] and the shape of the subsequent acceleratory process [8] are influenced by the rapidity with which product water vapour is removed from the vicinity of the reactant. Data fit the Prout-Tompkins equation with , about 100 kJ mol". ... 

The variations observed in the spectra with changing water content (figure 4) imply a modification of the environment of the ferrous ion below 6 % water. [Fe(H20)6]2+ complexes are progressively dehydrated, but it is difficult to establish a precise, quantitative correlation between the hyperfine parameters and the number of water molecules in the vicinity of the ion. The influence of the structure of the Nafion itself becomes increasingly felt as the water concentration decreases, and certainly leads to a very broad distribution of environments for the ferrous ion, as may be seen from the variation in linewidth as the water content approaches zero. 

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