Discerning the Impact of Noncovalent Interactions via Simulated Crystal Growth: A Structural Study of Aromatic Esters

The synthesis and structural characterization of seven systematically varied aromatic esters are reported. The compounds are analyzed using single-crystal X-ray diffraction, dynamic scanning calorimetry, and variable-temperature viscometry. The state of the compounds, i.e., liquid and solid, is controlled, in part, via sterics of the ester functionalities which influence the presence of specific noncovalent interactions in the solid state. Two distinct conformational polymorphs are observed in the solid state. To rationalize the formation of the conformational polymorphs, the intermolecular forces of the crystalline structures were studied via Hirshfeld surface analysis, leading to the conclusion that the unique geometries are controlled by a combination of halogen contacts, pi interactions, and interactions involving the nitro group on the aromatic rings. These conclusions are further examined via computational studies of the conformers, analysis of packing efficiency, and assessment of the structure of the energy frameworks for the crystalline solids. Finally, the information derived from the analysis of the interactions is used to simulate the growth of the crystals, helping to rationalize the conclusions about which interactions are responsible for the phase behavior of the compounds.