Co-crystals of 9,9′-bianthracene-10,10′-dicarboxylic acid with linear bidentate basic ligand molecules: synthesis, crystal structure, and properties based on the layer structure exfoliated by water

Co-crystals of 9,9′-dianthracene-10,10′-dicarboxylic acid ( 1 ) with the linear bidentate bases 9,9′-biacridine ( bac ), phenazine ( phez ), 4,4′-dipyridine ( dpy ), and DABCO ( dabco ) were synthesized. In the crystal structures of the co-crystals of 1 and bac , phez , and dpy , one-dimensional (1D) structures were formed through the hydrogen bonding between the acid and the base. For each combination of the acid and the bases, several kinds of polymorphic co-crystals with a similar structure were obtained. Among them, a combination of 1 and dabco gave three kinds of co-crystals which had a layered structure. In one of the co-crystals, a phenomenon where layers of the crystals could be exfoliated by dropping water was observed. The two-dimensional (2D) fingerprinting plot of the co-crystals showed that the major interaction to form the 1D structure was O-H N hydrogen bonding and that to form the layered structure was the CH-π interaction, and the influence of the latter interaction on the robustness of the crystal was stronger than the former in the co-crystals. Co-crystals of the title compound with bases formed 1D and layer structures and the layer structure was separated by water.