Quantitative analysis of intermolecular interactions in cocrystals and a pair of polymorphous cocrystal hydrates from 1,4-dihydroquinoxaline-2,3-dione and 1H-benzo[d]imidazol-2(3H)-one with 2,5-dihydroxy-1,4-benzoquinones: A combined X-ray structure and theoretical analysis

Cocrystallization experiments of the cyclic amides (lactams) 1,4-dihydroquinoxaline-2,3-dione (DHQ) and 1H-benzo[d]imidazol-2(3H)-one (BIM) with the anilic acids 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (CA) and 2,5-dihydroxy-1,4-benzoquinone (AA) yielded a total of five cocrystals and cocrystal hydrates, i.e., (DHQ)2CA (I), (DHQ)2CA·2H2O in form of two polymorphs (IA·2H2O and IB·2H2O), (BIM)2CA (II) and (BIM)2AA (III). The products were characterized by single-crystal X-ray diffraction (SCXRD) and Hirshfeld surface analysis, which were accomplished by DFT, PIXEL, QTAIM, and MESP calculations to assess the intermolecular interaction energies and related parameters. In accordance with the pKa-rule, hydrogen atom transfer between the proton donor and acceptor molecules used in this study was not observed. In the molecular packing, the cyclic amides are always involved in at least one double-bridged homodimeric hydrogen bonding motif based on N–H···O=C interactions. In addition, all five crystal structures exhibit heterosynthons with O–HCA/AA···O=CDHQ/BIM and/or N–HDHQ/BIM···O=CCA/AA hydrogen bonds and π-stacking interactions, through which the molecular components are linked in the three-dimensional space. The crystal structures are further stabilized by C–H···Cl, C–H···O and C–H···π interactions. Quantification of the intermolecular interaction energies by PIXEL, DFT, and QTAIM calculations afforded results consistent with the experimental crystal structures.