Electrostatic potential general

If we are comparing reactions which have approximatively the same steric requirements, the first term is roughly constant. If the species are very polar the second term will dominate, and the reaction is charge controlled. This means for example that an electrophihc attack is likely to occur at the most negative atom, or in a more general sense, along a path where the electrostatic potential is most negative. If the molecules are non-polar, the third term in (15.1) will dominate, and the reaction is orbital controlled. 

Functionalized polyelectrolytes are promising candidates for photoinduced ET reaction systems. In recent years, much attention has been focused on modifying the photophysical and photochemical processes by use of polyelectrolyte systems, because dramatic effects are often brought about by the interfacial electrostatic potential and/or the existence of microphase structures in such systems [10, 11], A characteristic feature of polymers as reaction media, in general, lies in the potential that they make a wider variety of molecular designs possible than the conventional organized molecular assemblies such as surfactant micelles and vesicles. From a practical point of view, polymer systems have a potential advantage in that polymers per se can form film and may be assembled into a variety of devices and systems with ease. 

Besides the electrostatic potential effect on reactivity, functionalized polyelectrolytes have a variety of interesting features worthy of study. If a polyelectrolyte is covalently modified with highly hydrophobic functional groups, it provides an unusual opportunity to study the chemical reactions of normally otherwise water insoluble functional groups in aqueous solution. Furthermore, a structural organization via hydrophobic interactions may occur in aqueous solution [25 — 31], which is of general scientific importance and is worth studying for its own sake. 

The relation between the spatial distribution of the electrostatic potential /(jc) and the spatial distribution of charge density Qy(x) can be stated, generally, in terms of Poisson s differential equation. 

In addition to the nearest-neighbor interaction, each ion experiences the electrostatic potential generated by the other ions. In the literature this has generally been equated with the macroscopic potential 0 calculated from the Poisson-Boltzmann equation. This corresponds to a mean-field approximation (vide infra), in which correlations between the ions are neglected. This approximation should be the better the low the concentrations of the ions. 

Although Eq. (3.1) is an exact formula for the electrostatic potential due to a set of nuclei ZA and an electronic density p(r), the latter [p(r)] is generally obtained computationally from an ab initio or semi-empirical wave function or, more recently, from density functional procedures and is therefore necessarily approximate. It follows that the resulting V(r) is also approximate. 

Our electrostatic potential analyses of TCDD, 22-25, and a number of other dibenzo-p-dioxins have allowed us to make some generalizations about the F(r) pattern that appears to lead to high biological activity for this class of halogenated aromatics. These are listed below ... 

In recent years, we have extended the nature of our analysis to include certain statistically defined features of the surface electrostatic potential. Our purpose has been to expand the capabilities of V(r) for quantitatively describing macroscopic properties that reflect non-covalent molecular interactions. This has led to the development of the General Interaction Properties Function (GIPF), described by Eq. (3.7) ... 

Murray, J. S., T. Brinck, P. Lane, K. Paulsen, and P. Politzer. 1994. Statistically-Based Interaction Indices Derived From Molecular Surface Electrostatic Potentials A General Interaction Properties Function (GIPF). J. Mol. Struct. (Theochem) 307, 55. 

The Finite Difference Method (FD)168 169. This is a general method applicable for systems with arbitrary chosen local dielectric properties. In this method, the electrostatic potential (RF) is obtained by solving the discretized Poisson equation ... 

An Example Focusing on the General Patterns of Molecular Electrostatic Potentials - Toxicity of Dibenzo-p-dioxins and Analogs... 

Statistical Characterization of the Molecular Surface Electrostatic Potential - the General Interaction Properties Function (GIPF)... 

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