Crystal structure of the 1:1 co-crystal 4-(di-methylamino)-pyridin-1-ium 8-hy-droxy-quinoline-5-sulfonate-,-di-methyl-pyridin-4-amine.

The asymmetric unit of the title compound is composed of two independent ion pairs of 4-(di-methyl-amino)-pyridin-1-ium 8-hy-droxy-quinoline-5-sulfonate (HDMAP·HqSA, CHN ·CHNOS) and neutral ,-di-methyl-pyridin-4-amine mol-ecules (DMAP, CHN), co-crystallized as a 1:1:1 HDMAP:HqSA:DMAP adduct in the monoclinic system, space group . 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 inter-molecular N-H⋯N hydrogen bonds between the protonated HDMAP mol-ecule and the neutral DMAP mol-ecule. In the anion layer, each HqSA is surrounded by other six HqSA, where the planar network structure is formed by inter-molecular O-H⋯O and C-H⋯O hydrogen bonds. The cation and anion layers are linked by inter-molecular C-H⋯O hydrogen bonds and C-H⋯ inter-actions.