Salt formation, hydrogen-bonding patterns and supramolecular architectures of acridine with salicylic and hippuric acid molecules.

The intermolecular interactions and salt formation of acridine with 4-aminosalicylic acid, 5-chlorosalicylic acid and hippuric acid were investigated. The salts obtained were acridin-1-ium 4-aminosalicylate (4-amino-2-hydroxybenzoate), C13H10N+·C7H6NO3- (I), acridin-1-ium 5-chlorosalicylate (5-chloro-2-hydroxybenzoate), C13H10N+·C7H4ClO3- (II), and acridin-1-ium hippurate (2-benzamidoacetate) monohydrate, C13H10N+·C9H8NO3-·H2O (III). Acridine is involved in strong intermolecular interactions with the hydroxy group of the three acids, enabling it to form supramolecular assemblies. Hirshfeld surfaces, fingerprint plots and enrichment ratios were generated and investigated, and the intermolecular interactions were analyzed, revealing their quantitative contributions in the crystal packing of salts I, II and III. A quantum theory of atoms in molecules (QTAIM) analysis shows the charge-density distribution of the intermolecular interactions. The isosurfaces of the noncovalent interactions were studied, which allows visualization of where the hydrogen-bonding and dispersion interactions contribute within the crystal.