Non-electrostatic interactions

In some cases, e.g., the Hg/NaF q interface, Q is charge dependent but concentration independent. Then it is said that there is no specific ionic adsorption. In order to interpret the charge dependence of Q a standard explanation consists in assuming that Q is related to the existence of a solvent monolayer in contact with the wall [16]. From a theoretical point of view this monolayer is postulated as a subsystem coupled with the metal and the solution via electrostatic and non-electrostatic interactions. The specific shape of Q versus a results from the competition between these interactions and the interactions between solvent molecules in the mono-layer. This description of the electrical double layer has been revisited by... 

The non-electrostatic interaction between a solid metal and the constituents in solution (water, ions, etc.) will not be the same as that for mercury. 

The possibility exists to condense DNA through proton donor and proton acceptor non-electrostatic interactions with DNA-grooves. This type of non-electrostatic complex has been developed for sequence-specific binding to DNA. Several prominent works were recently accomplished in this field (Dervan, 1997 Kiclkopf et al., 1998 Minchan et al, 2000). 

A more detailed study of the phase diagram of the polyelectrolyte complex must take into account the non-electrostatic interactions between the two polymers characterized by the Flory interaction parameter %. This inter-... 

The nonpolar (or hydrophobic) component, AGnp may be decomposed into a surface component, which is proportional to the solvent accessible surface area (SASA) of the solute and the component representing the solute-solvent non-electrostatic interactions,57... 

As the data for the Menschutkin reactions indicate, the character of the solute-solvent interactions is more complex than described by Eq. (5-87). It is evident that functions of relative permittivity alone, as given in Eq. (5-87), are not useful for describing the solvent effect on reactions between dipolar reactants, except in certain special cases, such as when a mixture of two solvents is used. In addition to electrostatic forces, non-electrostatic interactions, such as dispersion forces and hydrogen-bonding, must also be involved in Menschutkin reactions. 

Total contribntion of non-electrostatic interactions between solnte and solvent The corresponding experimental activation energies reported for hydrolysis of CH3 COOCH3 in aqneons solntion were 10.45 kcal/mol [61] and 12.2 kcal/mol [62]... 

A variant of [3.6.36] applies to the case where, say positive, charges on the surface act as the sites where specific adsorption of anions may occur, i.e. when the specific adsorption is of the second kind. Then ion pairs are formed, held together by electrostatic and non-electrostatic interactions. Defining 0 as the fraction of [Pg.309]

This calculation relies on the prediction of the dissociation constant of water, K, at elevated temperatures. The prediction involves the dielectric constant of water and a power series consistent with non-electrostatic interactions in the absence of a dielectric medium (12). The dissociation constant of water was calculated based upon the assumption that the entropy of the dissociation of water is the sum of the contributions of the electrostatic and nonelectrostatic interactions. The deviation between the predicted and the experimental (12) values of pK is smaller than 0.01. 

It is assumed that systems with fast decaying non-electrostatic interactions (class 1 of our classification) are very well understood nowadays and that they thus do not pose any problem for theory anymore. It is therefore the range of the Coulomb interactions and its effect on the properties of fluids which is of the main concern. To investigate this effect for fluids of class 2 and 3, trial potentials of a different range, uT, are constructed from the given parent model u so that,... 

The inert electrolytes are, indeed indifferent at low concentrations and near the PZC, For example the values of C potentials and cro are often symmetrical with respect to the PZC and insensitive to the nature of these salts. However certain results, e.g. Hoffmeister s series, studies of uptake of ions from solution, and even shifts in the isoelectric point lEP and PZC suggest non-electrostatic interactions of these ions and surfaces of materials, especially at high concentrations and far from the PZC. These results are shown and briefly discussed next. 

Newcombe, G., Donati, C., Drikas, M., and Hayes, R. (1994). Adsorption onto activated carbon electrostatic and non-electrostatic interactions. Water Supply, 14, 129M2. 

Quaternary Ammonium Ions. In a recent study (17), 1200 EW Nafion has been used to construct a membrane ion selective electrode. The electrode was placed in both the tetrabutylammonium ion and cesium ion forms, and the response characteristics of each form were measured. These electrodes show Nernstian responses, and the tetrabutylammonium ion electrode has no interference from inorganic cations such as Na" ", K" ", and Ca2" ". However, this electrode shows a marked interference with decyltri-methylammonium ion. In addition the cesium ion electrode response is sensitive to the presence of tetrabutylammonium ion and especially dodecyltrimethylammonium ion. Although membrane electrode sensitivities are not in general proportional to thermodynamic selectivity coefficients, the results do indicate that these large, hydrophobic cations are preferred over smaller inorganic cations by the polymer. The authors suggest that the surfactant character of the two asymmetric tetraalkylammonium ions may lead to non-electrostatic interactions with the fluorocarbon regions of the polymer, which would enhance their affinities (17). 

Basic proteins protamine (pKj = 12.4) and histone (pKj = 10.8) did not inhibit attachment. The effect of proteins on attachment were independent of surface charge density on the substratum and thus the decreased attachment in the presence of proteins may be due to non-electrostatic interactions. The behaviour of bovine serum albumin, which has a large number of non-polar side chains, indicates that hydrophobic interactions may be important (Tanford, 84 Goldsack and Chalifux, 85). The effects of hydrophyllic colloids on bacterial floccuTation have been studied by Hodge and Metcalfe (86) and the subject has been reviewed by Harris and Mitchell (87). 

Polyelectrolyte adsorption is a subtle balance of electrostatic and short-range non-electrostatic interactions. For a given combination of charge density, segment charge and non-electrostatic interactions, this balance can be affected by changing the concentration of simple electrolytes [6]. 

The non-electrostatic interactions between starch and cellulose make starch less susceptible to desorption than other polymers. 

The last term can be included in empirically added linear terms which take into account specific (non-electrostatic) interactions in solution. Thus eqn. 2.5.5 is often found in the form, for a 1 1 electrolyte... 

Simple corrections for non-electrostatic interactions have been suggested, wherein atomic-specific parameters are used to describe cavitation, Pauli repulsion, and dispersion [2, 3, 20, 84], These non-electrostatic interactions are then added to Gpoi to obtain the total solvation energy. The most successful examples of this approach are the so-called SMx models of Cramer and Truhlar [27], most of which are not actually PCMs per se but rather generalized Bom models. However, one such model ("SMD") has recently been parameterized for use with lEF-PCM electrostatics [55] and exhibits mean errors of < 1 kcal/mol as compared to experimental solvation... 

To improve the accuracy of implicit-solvent potential energy surfaces, non-electrostatic interactions must be included, although such interactions have received only a brief mention here. The smooth, linear-scaling PCM technology that is discussed here is immediately ready for use in MM/PBSA applications [36, 38], as a replacement for finite-difference electrostatics. Other formulas for the non-electrostatic interactions [47] can also be used in PCM calculations, possibly after some re-parameterization. In general these non-electrostatic interaction formulas depend in some way on the cavity surface area, which is smooth and easily calculable by means of the PCM algorithms discussed herein. 

It is important to understand the nature of the solvent-solute non-electrostatic interaction, U. Assume that the aqueous environment has multiple species labeled by a, and their interactions with each solute atom near the interface can be given by... 

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