Molecular electrostatics potential guided

Tomasi, J. 1981. Use of the Electrostatic Potential as a Guide to Understanding Molecular Properties. In Chemical Applications of Atomic and Molecular Electrostatic Potentials. Plenum Press, New York. 

Molecular electrostatic potential The molecular electrostatic potential (MEP) associated with a molecule arises from the distribution of electrical charges of the nuclei and electrons of a molecule. The MEP is quantum mechanically defined in terms of the spatial coordinates of the charges on the nuclei and the electronic density function p(r) of the molecule. As the MEP is the net result of the opposing effects of the nuclei and the electrons, electrophiles will be guided to the regions of a molecule where the MEP is most negative. The MEP is a useful quantity in the study of molecular recognition processes. 

Murray, Politzer, and their co-workers have developed several descriptors based on features of the molecular electrostatic potential surface (EPS) that can be used to characterize a variety of chemical and physical properties, including pK s [26,199,231]. In studies of the acidities of substituted azoles and anilines they showed that values of the most negative surface potentials (Vrma) and the minimum local ionization energy on the molecular surface (Is,min) showed strong correlations (r 0.97) with the pK s of these compounds. Later, Ma et al. [27] found that Is,jjn and several other EPS descriptors provided good models of the pK variations in substituted phenols and benzoic acids. Sakai and co-workers [232] have shown that Vmin yields an excellent fit (r = 0.996) for the aqueous pK s of a set of 22 amines. These studies demonstrate that features of the molecular electrostatic potential surfaces of acids can offer useful guides for pK, estimatioa... 

The Electrostatic Potential as a Guide to Molecular Interactive Behavior... 

The book covers a gamut of related topics such as methods for determining atoms-in-molecuies, population analysis, electrostatic potential, molecular quantum similarity, aromaticity, and biological activity. It also discusses the role of reactivity concepts in industrial and other practical applications. Whether you are searching for new products or new research projects, this is the ultimate guide for understanding chemical reactivity. 

This chapter introduces and illustrates isosurface displays of molecular orbitals, electron and spin densities, electrostatic potentials and local ionization potentials, as well as maps of the lowest-unoccupied molecular orbital, the electrostatic and local ionization potentials and the spin density (on top of electron density surfaces). Applications of these models to the description of molecular properties and chemical reactivity and selectivity are provided in Chapter 19 of this guide. 

Because atomic charge is not a quantum mechanical observable, we must use some indirect method to calculate these values. Moreover, since we lack experimental results to guide us, other methods of validating our assignments must be devised. Accurate reproduction of some observable, whether experimentally measured (dipole moment) or determined directly from the wavefunction (electrostatic potential, molecular moments, etc.), increases our confidence in the reliability of the assigned charges. 

The average local ionization energy 7(r) has many interesting and significant aspects and applications. It is related to local temperature and atomic shell structure, it is linked to electronegativity and shows promise as a measure of local polarizability. It permits the characterization of bonds and radical sites, and - in conjunction with volume -the prediction of molecular and group polarizabilities. Finally, it is an effective guide to reactivity towards electrophiles, especially when complemented by the electrostatic potential. All of these areas continue to be studied. 

Rolitzer, R Murray, J. S. 2009. The electrostatic potential as a guide to molecular interactive behavior. In Chemical Reactivity Theory A Density Functional View, edited by R. K. Chattaraj, 243-254. Boca Raton, FL CRC Riess. 

Murray, J. S. Concha, M. C. Politzer, P. 2011. Molecular surface electrostatic potentials as guides to Si-O-N angle contraction tunable o-holes. J. Mol. Model. 17 2151-2157. 

The distinct roles of electrostatics in guiding different types of molecular interactions, can also be inferred fi om Figure 6, which shows iso-potential contour maps for the yeast cytochrome c and cytochrome c peroxidase and for the two identical monomers of bacterial desulforedoxin. Each pair of interacting molecules is shown oriented as in the... 

The electrostatic potential V r) that is created in the space around a molecule by its nuclei and electrons is a well-established guide to chemical reactivity and molecular interactive behavior. " Unlike many of the other quantities used now and earlier as indices of reactivity, e.g., atomic charges, the electrostatic potential is a real physical property, one that can be determined experimentally by diffraction methods as well as computationally. However, V r) is most commonly obtained computationally. With the recent advances in computer technology, it is currently being applied to a variety of significant chemical systems. 

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