INT UNION CRYSTALLOGRAPHY Acta Medica Okayama 2056-9890 75 10 2019 Crystal structures of 3-chloro-2-nitrobenzoic acid with quinoline derivatives: 3-chloro-2-nitrobenzoic acid-5-mtroqumohne (1/1), 3-chioro-2-nitrobenzoic acid-6-mtroquinoline (1/1) and 8-hydroxyquinolinium 3-chioro-2-nitrobenzoate 1552 1557 EN Kazuma Gotoh Department of Chemistry, Faculty of Science, Okayama University Hiroyuki Ishida Department of Chemistry, Faculty of Science, Okayama University The structures of three compounds of 3-chloro-2-nitrobenzoic acid with 5-nitroquinoline, (I), 6-nitroquinoline, (II), and 8-hydroxyquinoline, (III), have been determined at 190 K. In each of the two isomeric compounds, (I) and (II), C7H4ClNO4 center dot C9H6N2O2, the acid and base molecules are held together by O - H center dot center dot center dot N and C - H center dot center dot center dot O hydrogen bonds. In compound (III), C9H8NO+center dot-C7H3ClNO4-, an acid-base interaction involving H-atom transfer occurs and the H atom is located at the N site of the base molecule. In the crystal of (I), the hydrogen-bonded acid-base units are linked by C -H center dot center dot center dot O hydrogen bonds, forming a tape structure along the b-axis direction. Adjacent tapes, which are related by a twofold rotation axis, are linked by a third C - H center dot center dot center dot O hydrogen bond, forming wide ribbons parallel to the ((1) over bar 03) plane. These ribbons are stacked via pi-pi interactions between the quinoline ring systems [centroid-centroid distances = 3.4935 (5)-3.7721 (6) angstrom], forming layers parallel to the ab plane. In the crystal of (II), the hydrogen-bonded acid-base units are also linked into a tape structure along the b-axis direction via C -H center dot center dot center dot O hydrogen bonds. Inversion-related tapes are linked by further C-H center dot center dot center dot O hydrogen bonds to form wide ribbons parallel to the ((3) over bar 08) plane. The ribbons are linked by weak pi-pi interactions [centroid-centroid distances = 3.8016 (8)-3.9247 (9) angstrom], forming a three-dimensional structure. In the crystal of (III), the cations and the anions are alternately linked via N - H center dot center dot center dot O and O - H center dot center dot center dot-O hydrogen bonds, forming a 2(1) helix running along the b-axis direction. The cations and the anions are further stacked alternately in columns along the a-axis direction via pi-pi interactions [centroid-centroid distances = 3.8016 (8)-3.9247 (9) angstrom], and the molecular chains are linked into layers parallel to the ab plane through these interactions. No potential conflict of interest relevant to this article was reported.