Derivation of fused-sphere molecular surfaces from properties of the electrostatic potential distribution

Abstract

The distribution of molecular electrostatic potential (MEP) on a surface is a common model used to describe simultaneously steric properties (e.g., size, shape) and reactive properties (e.g., electro- and nucleophilic positions) of a molecule. In this work, we analyze some relations between these two properties. In particular, we explore the possible definition of an optimum fused-sphere molecular surface from properties of the MEP distribution. With this goal, we study how several statistical descriptors of the two-dimensional MEP distribution change upon shrinking or enlarging a van der Waals surface. We find that some of the descriptors exhibit critical points in terms of a scaling factor. We use this property to define effective atomic radii. In particular, we find that a reasonable molecular envelope is defined as the surface having the lowest (i.e., most negative) average negative MEP, with the largest possible dispersion about the mean. We discuss the resulting atomic radii and compare them with others in the literature derived from only steric considerations. The present results expand the scope of fused-sphere surfaces for modeling microscopic or structural molecular properties. © 1996 by John Wiley & Sons, Inc.