Untitled

Abstract

Electron-electron repulsion energy (<Vee>) is presented as a new molecular descriptor to be employed in QSAR and QSPR studies. Here it is shown that this electronic energy parameter is connected to molecular quantum similarity measures (MQSM), and as a consequence can be considered as a complement to steric and electronic parameters in description of molecular properties and biological responses of organic compounds. The present strategy considers the molecule as a whole, thus there is no need to employ contributions of isolated fragments as in many calculations of molecular descriptors, like log P or the Free-Wilson analysis. The procedure has been tested in a widespread set of molecules: alcohols, alkanamides, indole derivatives and 1-alkylimidazoles. Molecular properties, as well as toxicity, are correlated using <Vee> as a parameter, and extensions to the method are given for handling difficult systems. In almost all studied cases, satisfactory linear relationships were finally obtained.

Genetic neural network modeling of the selective inhibition of the intermediate-conductance Ca2+-activated K+ channel by some triarylmethanes using topological charge indexes descriptors

“…In this sense, they developed the concept of E-states, an electrotopological-state index for atoms in a molecule. More recently, Carbo´-Dorca et al [29] proposed the use of electron-electron repulsion energy, in connection with molecular quantum similarity measures derived from quantum-chemical calculations, as a molecular descriptor in QSAR studies of biological activities [29].…”

Mutagenicity of Aromatic and Heteroaromatic Amines and Related Compounds: A QSAR Investigation

“…Relatively little is known about the importance of this particular molecular descriptor in QSAR development, although it is certainly reasonable that the C À N bond is involved for this data set. Recently, Gironé s et al [65] have shown that the electron-electron repulsion energy of an entire molecule can be connected to so-called molecular quantum similarity measures and these authors found quite acceptable correlations of this descriptor with several biological activities. The a-polarizability also appears in several of our BMLR equations.…”

Use of promolecular ASA density functions as a general algorithm to obtain starting MO in SCF calculations

“…Within the ASA approach 1–7, electronic densities are expressed as a linear combination of spherical 1 s functions: where the coefficients { w i } are restricted to be positive definite in order to assure the physical meaning of the fitted density. A simple but very interesting particular case of the previous development consists in using a promolecular approximation.…”

“…With the parameterized atomic densities \documentclass{article}\pagestyle{empty}\begin{document}$\rho_{a}^{\mathrm{ASA}}(\mathbf{r})$\end{document}, and the nuclear coordinates of any molecular system, PASA density is easily generated by using Eq. (3), producing a reasonable approximation to the molecular density, avoiding the ab initio theoretical calculation of electron density, and permitting the quantum similarity study of large molecular systems such as enzymes 3.…”

“…This is the case of molecular quantum similarity measures, where in order to compute precise measure values, it has been used as a simple, yet accurate approximation to the molecular density function, based on a sum of spherically symmetric atomic densities. Such a theoretical model of electron density fitting has been named atomic shell approximation (ASA) 1–7. Furthermore, when dealing with molecules, a promolecular description of the charge density distribution was employed, based on the sum of atomic ASA densities, which were previously fitted to an ab initio atomic basis set.…”