Supra-molecular inter-actions in a 1:1 co-crystal of acridine and 3-chloro-thio-phene-2-carb-oxy-lic acid

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.

Supra-molecular inter-actions in the 1:2 co-crystal of 4,4'-bipyridine and 3-chloro-thio-phene-2-carb-oxy-lic acid

The asymmetric unit of the title compound, 2C5H3ClO2S·C10H8N2, is comprised of a mol-ecule of 3-chloro-thio-phene-2-carb-oxy-lic acid (3TPC) and half of a mol-ecule of 4,4'-bi-pyridine (BPY). A distinctive O-H⋯N-based synthon is present. Cl⋯Cl and π-π stacking inter-actions further stabilize the crystal structure, forming a two-dimensional network parallel to the bc plane.