Electrostatic potentials mapped on Hirshfeld surfaces provide direct insight into intermolecular interactions in crystals

Ab initio electrostatic potentials for molecules can readily be mapped onto their Hirshfeld surfaces and displayed within a crystal packing diagram. In this manner the close molecular contacts in the crystal can be rationalized and discussed in terms of the electrostatic complementarity of touching surface patches in adjacent molecules. By way of example a detailed discussion is given of molecular electrostatic potentials for a large number of small, symmetric, cyclic molecules that crystallize in space groupsP41212 or P43212, with a focus on the qualitative insight that can be obtained and the ways in which this complements the intermolecular electrostatic energies recently reported for some of these materials.