Cocrystals assembled from iodoperfluorobenzene and flexible NTPO via halogen and π-hole bonds.

Two binary cocrystals of 1,4-diiodotetrafluorobenzene (1,4-DITFB, CFI) and 1,3,5-trifluoro-2,4,6-triiodobenzene (1,3,5-TITFB, CFI) with the flexible 2-{[(naphthalen-2-yl)methyl]sulfanyl}pyridine 1-oxide (NTPO, CHNOS) molecule were successfully prepared and characterized by X-ray diffraction and quantum chemistry calculation methods. X-ray diffraction analysis reveals that the conformation of the flexible NTPO molecule has been changed significantly after introducing the 1,4-DITFB or 1,3,5-TITFB molecule into the NTPO lattice. Also the formation of the binary cocrystals is driven mainly by robust C-I...O-N halogen bonds and π-hole...π-bond interactions, and they possess `sandwich' structural frameworks. Moreover, interaction energy analysis and AIM analysis were used to explore the contribution of different fragments to the structural stability and the corresponding electronic properties, which reveals that the robust halogen bonds with shorter bonding lengths [2.768 (4) and 2.789 (3) Å] are suggested to be covalent to a certain degree.