Ionic solvation effects

SOLVATION AND IONIC ASSOCIATION EFFECTS IN THE SELECTIVITY OF ISES RESPONSIVE TO... 

The neutral reactants possess permanent dipoles, the product is ionic, and the transition state must be intermediate in its charge separation, so an increase in solvent polarity should increase the rate. Except for selective solvation effects of the type cited in the preceding section, this qualitative prediction is correct. 

For the electrolyte as a whole, the effects associated with cations and anions crossing the surface layer cancel, and Eq. (7.17) is valid, with both the chemical and the real ionic solvation energies. Next, we describe ways of theoretically calculating the solvation energies of individual ions or of calculating them from indirect experimental data. 

Stuart SJ, Berne BJ (1999) Surface Curvature Effects in the Aqueous Ionic Solvation of the Chloride Ion. J Phys Chem A 103(49) 10300-10307... 

When the gas-phase reactions, such as the relative acidities or basicities were compared with their counterparts in solution (in a solvent such as water) it was generally found16,17 that the energetics in the solvent were strongly affected by solvation effects and particularly the solvation of the ionic reactants. Relationships between the gas-phase and solution-phase reactions and the solvation energies of the reactants are generally obtained through thermodynamic cycles. From the cycle,... 

The important role of thermodynamics in complex formation, ionic medium effects, hydration, solvation, Lewis acid-base interactions, and chelation has been presented in this chapter. Knowledge of these factors are of great value in understanding solvent extraction and designing new and better extraction systems. 

Anderson, J.L. et al.. Surfactant solvation effects and micelle formation in ionic liquids, Chem. Comm., 2444, 2003. 

A solvent, in addition to permitting the ionic charges to separate and the electrolyte solution to conduct an electrical current, also solvates the discrete ions, by ion-dipole or ion-induced dipole interactions and by more direct interactions, such as hydrogen bonding to anions or electron-pair donation to cations. Lewis acidity and basicity of the solvents affect the latter. The redox properties of the ions at an electrode depend on their being solvated, and the solvation effects electrode potentials or polarographic half-wave potentials. 

The method of choice has to be carefully evaluated prior to a simulation study to assess whether a chosen functional is appropriate for a particular system. Ionic solvates are strongly dominated by Coulombic interactions and significant polarization effects are observed resulting from the presence of the charged solute. The unphysical self-interaction inherent to DFT is a striking disadvantage in these cases. Furthermore, the parametrization... 

Comparison of Ionic Solvation Energies in Different Solvents and Solvent Effects on Ionic Reactions and Equilibria... 

Solvation Effects. Many previous accounts of the activity coefficients have considered the connections between the solvation of ions and deviations from the DH limiting-laws in a semi-empirical manner, e.g., the Robinson and Stokes equation (3). In the interpretation of results according to our model, the parameter a also relates to the physical reality of a solvated ion, and the effects of polarization on the interionic forces are closely related to the nature of this entity from an electrostatic viewpoint. Without recourse to specific numerical results, we briefly illustrate the usefulness of the model by defining a polarizable cosphere (or primary solvation shell) as that small region within which the solvent responds to the ionic field in nonlinear manner the solvent outside responds linearly through mild Born-type interactions, described adequately with the use of the dielectric constant of the pure solvent. (Our comments here refer largely to activity coefficients in aqueous solution, and we assume complete dissociation of the solute. The polarizability of cations in some solvents, e.g., DMF and acetonitrile, follows a different sequence, and there is probably some ion-association.)... 

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