Hydrogen bond-directed co-crystals of (±)-1,1′-binaphthalene-2,2′-diol with aromatic diimines: Structures and selectivity

As a result of mutual recognition, 1,1′-binaphthalene-2,2′-diol(binol) (1) and various aromatic diimines including 2,9-dimethyl-1,10-phenanthroline (2), 4,5-diazafluoren-9-one (3), 4,4′-dimethyl-2,2′-bipyridine (4), 4,4′-bipyridine (5), and 5-nitro-1,10-phenanthroline (6) formed well-defined co-crystals 2a, 3a, 4a, 5a and 6a, respectively. In 2a, 3a, 5a and 6a, the components form discrete aggregates, whereas in 4a, the components form infinite one-dimensional arrays. The crystal structures of these co-crystals are all stabilized by O-H···O and O-H···N hydrogen bonds as well as C-H···π and π···π interactions. Remarkably, a preferential co-crystal of 1,10-phenanthroline-5,6-dione (7) over 1,10-phenanthroline (8) and other diimines with binol is established through competitive crystallization and guest-exchange experiments.