Acridine 0.75-hydrate

Abstract

The title compound, C13H9N·0.75H2O was obtained during a study of the polymorphic system of acridine, by slow evaporation from an ethanol–water solution. There are two acridine molecules (indicated by I and II, respectively) and one and a half water molecules in the asymmetric unit. The half-molecule of water is located on a crystallographic twofold axis. The crystal structure is built up from two threads of molecule II sewn together with water molecules through O—H...O and O—H...N hydrogen bonds from one side and with π–π interactions [centroid–centroid distance = 3.640 (3) and 3.7431 (3) Å] between overlapping molecules II on the other side. Molecule I is attached to this thread from both sides by C—H...O hydrogen bonds. The threads are connected to each other by π–π interactions [centroid–centroid distances = 3.582 (3) and 3.582 (3) Å] between the inner side of molecule I and stabilized by a C—H...π interaction on the other side of molecule I. This thread with rows of molecule I hanging on its sides is generated by translation perpendicular to the a axis.