The crystal packing of a strongly dipolar piperazinedione

A strongly dipolar piperazine-2,5-dione was synthesized in enantiomerically pure form, crystallized from DMSO, and the supramolecular organization of the crystals determined by X-ray crystallography. In contrast with non-polar or weakly polar piperazinediones of similar molecular topography, which form tapes by reciprocal intermolecular amide-to-amide hydrogen bonding, the strongly dipolar piperazinedione participated in hydrogen bonding with occluded DMSO. The dipoles of the piperazinedione molecules were aligned and were opposed by the dipoles of the DMSO molecules. The cocrystals exhibited second harmonic generation when subjected to pulsed irradiation.