The Crystal Structure and Intermolecular Interactions in Fenamic Acids–Acridine Complexes

In order to improve pharmaceutical properties of drugs, complexes are synthesized as combinations with other chemical substances. The complexes of fenamic acid and its derivatives, such as mefenamic-, tolfenamic- and flufenamic acid, with acridine were obtained and the X-ray structures were discussed. Formation of the crystals is determined by the presence of the intermolecular O–H…N hydrogen bond that occur between fenamic acids and acridine. Intermolecular interactions stabilizing the crystals such as π…π stacking, C–H…X (X = O, Cl) intermolecular hydrogen bonds as well as C–H…π and other dispersive interactions were analyzed by theoretical methods: the quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) approaches.