Formation of Planar π‑Conjugated Sheets\nin Cocrystals of Bis(iodoethynyl)pyridines and Bipyrimidylalkynes:\nCooperative C–H···N Hydrogen Bonds and sp-C–I···N\nHalogen Bonds

The cocrystallization\nof the ditopic halogen bond donors 2,5-,\n2,6-, 3,5-bis(iodoethynyl)pyridines with the dipyrimidyls 1,2-bis(5-pyrimidyl)ethyne\nand 1,4-bis(5-pyrimidyl)butadiyne is explored. The cocrystal components\nhave complementary shapes and functional groups so that the noncovalent\nC–I···N halogen bonding and C–H···N\nhydrogen bonding interactions are complementary resulting in 1:1 cocrystals\nwith the ditopic halogen bond accepting bipyrimidyls. The cocrystals\nfeature π-stacked planar sheets of alternating bis(iodoalkynes)\nand bipyrimidyls held together in one direction by I···N\nhalogen bonds and in the roughly orthogonal direction by pyridine–pyridine\nand pyrimidine–pyrimidine C–H···N hydrogen\nbonds.