We will describe Electrostatic Tuning Maps (ETMs) and their extension to different properties. Initially, ETMs were developed to understand the effect of an electrostatic environment on the absorption wavelength of a molecule and were called Electrostatic Spectral Tuning Maps (ESTMs). These maps were constructed by moving a point charge around the van der Waals surface of a molecule and performing excited-state quantum mechanical (QM) computations in the presence of the point charge at each position. The results were then represented with colors indicating the magnitude of the excitation energy shift caused by the charge, producing a colored surface map that intuitively visualizes the effect of charges on a molecule's absorption wavelength.<br/>ETMs are numerically computed from a series of QM calculations. Therefore, it is possible to extend the approach to properties other than excitation energies. For instance, instead of plotting excitation energies, absorption strengths can be plotted to generate "oscillator strength tuning maps." Alternatively, water molecules can be used instead of point charges to generate several molecule-water pair structures that can be optimized to find potential hydrogen-bonding interactions. Such "hydrogen-bonding maps" were used to predict how hydrogen-bonding interactions affect a molecule's vibrational frequencies. Most recently, by using a surface that is closer to the molecule and moving a proton on this surface, we generated "basicity maps" showing the areas on a molecule that are most basic.<br/>The calculation of ETMs is largely automated and user-friendly, making them useful tools for researchers and chemistry students alike. We are working on extending their utility by making ETMs easy to compute and by making it possible to generate ETMs for different observables.

Visualization of properties through electrostatic tuning maps

ACS Spring 2022

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