Bis(8-hy-droxy-quinolinium) naphthalene-1,5-di-sulfonate tetra-hydrate

The inter-action between 8-hy-droxy-quinoline (8HQ, C₉H₇NO) and naphthalene-1,5-di-sulfonic acid (H₂NDS, C₁₀H₈O₆S₂) in aqueous media results in the formation of the salt hydrate bis-(8-hy-droxy-quinolinium) naphthalene-1,5-di-sulfonate tetra-hydrate, 2C₉H₈NO⁺·C₁₀H₆O₆S₂ ^2-·4H₂O. The asymmetric unit comprises one protonated 8HQ⁺ cation, half of an NDS^2- dianion symmetrically disposed around a center of inversion, and two water mol-ecules. Within the crystal structure, these components are organized into chains along the [010] and [10] directions through O-H⋯O and N-H⋯O hydrogen-bonding inter-actions, forming a di-periodic network parallel to (101). Additional stabilizing inter-actions such as C-H⋯O, C-H⋯π, and π-π inter-actions extend this arrangement into a tri-periodic network structure.