2‐Chloro‐4‐nitrobenzoic acid as a coformer with pharmaceutical cocrystals and molecular salts

A series of five binary complexes, i.e. three cocrystals and two molecular salts, using 2‐chloro‐4‐nitrobenzoic acid as a coformer have been produced with five commonly available compounds, some of pharmaceutical relevance, namely, 2‐chloro‐4‐nitrobenzoic acid–isonicotinamide (1/1), C 7 H 4 ClNO 4 ·C 6 H 6 N 2 O, 2‐chloro‐4‐nitrobenzoic acid–3,3‐diethylpyridine‐2,4(1 H ,3 H )‐dione (2/1), 2C 7 H 4 ClNO 4 ·C 9 H 13 NO 2 , 2‐chloro‐4‐nitrobenzoic acid–pyrrolidin‐2‐one (1/1), C 7 H 4 ClNO 4 ·C 4 H 7 NO, 2‐carboxypiperidinium 2‐chloro‐4‐nitrobenzoate, C 6 H 12 NO 2 − ·C 7 H 3 ClNO 4 − , and (2‐hydroxyethyl)ammonium 2‐chloro‐4‐nitrobenzoate, C 2 H 8 NO + ·C 7 H 3 ClNO 4 − . The coformer falls under the classification of a `generally regarded as safe' compound. All five complexes make use of a number of different heteromeric hydrogen‐bonded interactions. Intermolecular potentials were evaluated using the CSD‐Materials module.