Ionic solvents, computational

Margulis, C. J., Stern, H. A., and Berne, B. J., Computer simulation of a green chemistry room-temperature ionic solvent, /. Phys. Ghent. B., 106, 12017-12021, 2002. 

Xu Z, Deng S, Cai W Image charge approximations of reaction fields in solvents with arbitrary ionic strength, / Comput Phys 228(6) 2092—2099, 2009a. 

Using computer simulations, several groups investigated the effect of ionic solvents on catalytic, structural, and dynamic properties of enzymes in these media. MD simulations, in particular, are a valuable tool to gain molecular scale insights of the interactions between various solvents and biomolecules [120,121]. 

Margulis, C. J. 2004 Computational study of imidazolium-based ionic solvents with alkyl substituents of different lengths. Mol. Phys. 102, 829-838. 

Charged particles in polar solvents have soft-repulsive interactions (see section C2.6.4). Just as hard spheres, such particles also undergo an ordering transition. Important differences, however, are that tire transition takes place at (much) lower particle volume fractions, and at low ionic strengtli (low k) tire solid phase may be body centred cubic (bee), ratlier tlian tire more compact fee stmcture (see [69, 73, 84]). For tire interactions, a Yukawa potential (equation (C2.6.11)1 is often used. The phase diagram for the Yukawa potential was calculated using computer simulations by Robbins et al [851. 

Hamiltonian for, solvent effects on, 57 ionic states and, 46-47 LD model for, 51, 52 MO calculations for, computer program for, 72-73... 

In a recent paper. Mo and Gao [5] used a sophisticated computational method [block-localized wave function energy decomposition (BLW-ED)] to decompose the total interaction energy between two prototypical ionic systems, acetate and meth-ylammonium ions, and water into permanent electrostatic (including Pauli exclusion), electronic polarization and charge-transfer contributions. Furthermore, the use of quantum mechanics also enabled them to account for the charge flow between the species involved in the interaction. Their calculations (Table 12.2) demonstrated that the permanent electrostatic interaction energy dominates solute-solvent interactions, as expected in the presence of ion species (76.1 and 84.6% for acetate and methylammonium ions, respectively) and showed the active involvement of solvent molecules in the interaction, even with a small but evident flow of electrons (Eig. 12.3). Evidently, by changing the solvent, different results could be obtained. 

This volume of Modem Aspects covers a wide spread of topics presented in an authoritative, informative and instructive manner by some internationally renowned specialists. Professors Politzer and Dr. Murray provide a comprehensive description of the various theoretical treatments of solute-solvent interactions, including ion-solvent interactions. Both continuum and discrete molecular models for the solvent molecules are discussed, including Monte Carlo and molecular dynamics simulations. The advantages and drawbacks of the resulting models and computational approaches are discussed and the impressive progress made in predicting the properties of molecular and ionic solutions is surveyed. 

The mean ionic activity coefficients of hydrobromic acid at round molalities (calculated by means of Equation 2) are summarized in Tables XI, XII, and XIII for x = 10, 30, and 50 mass percent monoglyme. Values of —logio 7 at round molalities from 0.005 to 0.1 mol-kg-1 were obtained by interpolating a least squares fit to a power series in m which was derived by means of a computer. These values at 298.15° K are compared in Figure 2 with those for hydrochloric acid in the same mixed solvent (I) and that for hydrobromic acid in water (21). The relative partial molal enthalpy (H2 — Hj>) can be calculated from the change in the activity coefficient with temperature, but we have used instead the following equations ... 

Surface complexation model A computer code or geochemical model that provides an explanation and attempts to predict the partitioning of a chemical species between the surface of an adsorbent and the associated solvent. The models consider a number of factors, including pH and ionic strength (see (Langmuir, 1997), 369-395 for details compare with charge distribution multisite complexation model). 

---