https://doi.org/10.1007/s11224-025-02635-y
Molecular electrostatic potential (MESP) analysis has emerged as a powerful and chemically intuitive framework for visualizing and interpreting electronic structure features such as delocalization, aromaticity, and lone pair localization. This review highlights how the topography of the scalar field of MESP—defined through its minima and critical points (CPs), particularly (3, + 3) CPs—serves as a spatially resolved descriptor that captures subtle electronic phenomena often obscured in orbital-based or magnetic criteria. Applications to benzenoid hydrocarbons, linear acenes, heteroaromatics, and fused aromatic–antiaromatic hybrids illustrate how MESP reflects patterns of π-electron delocalization, including effects of curvature, strain, and fusion defects. In parallel, recent developments have shown that MESP topography can rigorously identify localized lone pairs based on the curvature and directionality of negative-valued CPs, offering a physically observable distinction from delocalized π-regions. These lone pair signatures have proven valuable in understanding noncovalent interactions such as hydrogen bonding, lone pair–π contacts, and coordination to electrophiles, with strong correlations between MESP minima and interaction energies. The review also emphasizes the unique advantage of MESP as a geometry-sensitive, scalar field approach that bridges empirical chemical intuition with quantum mechanical observables. Overall, MESP topography unifies the analysis of delocalized and localized electron distributions, providing a versatile platform for interpreting reactivity, guiding ligand design, and probing structure–function relationships in molecular systems.
