Crystal structure of the 1:1 co-crystal 4-(dimethylamino)pyridin-1-ium 8-hydroxyquinoline-5-sulfonate–N,N-dimethylpyridin-4-amine

Abstract

The asymmetric unit of the title compound is composed of two independent ion pairs of 4-(dimethylamino)pyridin-1-ium 8-hydroxyquinoline-5-sulfonate (HDMAP+·HqSA−, C7H11N2 +·C9H6NO4S−) and neutral N,N-dimethylpyridin-4-amine molecules (DMAP, C7H10N2), co-crystallized as a 1:1:1 HDMAP+:HqSA−:DMAP adduct in the monoclinic system, space group Pc. The compound has a layered structure, including cation layers of HDMAP+ with DMAP and anion layers of HqSA− in the crystal. In the cation layer, there are intermolecular N—H...N hydrogen bonds between the protonated HDMAP+ molecule and the neutral DMAP molecule. In the anion layer, each HqSA− is surrounded by other six HqSA−, where the planar network structure is formed by intermolecular O—H...O and C—H...O hydrogen bonds. The cation and anion layers are linked by intermolecular C—H...O hydrogen bonds and C—H...π interactions.