Hierarchy of Intermolecular Interactions in Highly Luminescent Pyrenyl-Pyrazole-Aldehyde

The intricacies of the crystal structure and the hierarchy of intermolecular interactions in a highly luminescent pyrene-pyrazole-aldehyde (PPPcA) are hereby analyzed by means of experimental charge density analysis, periodic DFT calculations, and high-pressure crystallography. Luminescent properties of the material under pressure up to 6 GPa are reported. Several intermolecular interactions in the crystal structure of PPPcA are identified and found to be significant based on their energies and mechanical properties of the material, a pair of C-HmiddotmiddotmiddotO hydrogen bonds in particular. However, the presence of any single strong intermolecular interaction cannot automatically warrant changes in luminescent properties of a crystal, as shown in the present case.