Electrostatic Potential Topology for Probing Molecular Structure, Bonding and Reactivity.

Shridhar R Gadre,Cherumuttathu H Suresh,Neetha Mohan

doi:10.3390/molecules26113289

Abstract

Following the pioneering investigations of Bader on the topology of molecular electron density, the topology analysis of its sister field viz. molecular electrostatic potential (MESP) was taken up by the authors’ groups. Through these studies, MESP topology emerged as a powerful tool for exploring molecular bonding and reactivity patterns. The MESP topology features are mapped in terms of its critical points (CPs), such as bond critical points (BCPs), while the minima identify electron-rich locations, such as lone pairs and π-bonds. The gradient paths of MESP vividly bring out the atoms-in-molecule picture of neutral molecules and anions. The MESP-based characterization of a molecule in terms of electron-rich and -deficient regions provides a robust prediction about its interaction with other molecules. This leads to a clear picture of molecular aggregation, hydrogen bonding, lone pair–π interactions, π-conjugation, aromaticity and reaction mechanisms. This review summarizes the contributions of the authors’ groups over the last three decades and those of the other active groups towards understanding chemical bonding, molecular recognition, and reactivity through topology analysis of MESP.

Highlights

The computation of accurate molecular wave functions and their analysis has remained a challenge for theoretical chemists over the years due to the enormous dimensionality of the problem
For a given molecular framework, the molecular electrostatic potential (MESP) is calculated by subtracting out the electronic contribution from the corresponding positive nuclear potential (Equation (5))
molecular electron density (MED) at a reference point is proportional to the Laplacian of the MESP at that point, through the Poisson equation (Equation (8))

Summary

Introduction

The computation of accurate molecular wave functions and their analysis has remained a challenge for theoretical chemists over the years due to the enormous dimensionality of the problem. Several 3D molecular scalar fields derived from the 3N-dimensional wave function have been explored by theoretical as well as experimental chemists to understand the structure, bonding, and reactivity patterns of molecules. Many of these 3D scalar fields, such as the molecular electron density (MED) in position and momentum spaces and the molecular electrostatic potential (MESP), are experimentally amenable, thereby providing a vital bridge between experiment and theory. Since the focus of the present review is on MESP, we do not attempt to review such studies

MESP Topology

Recent Studies on MESP Topology and Algorithm Development

Concluding Remarks and Future Outlook