Norfloxacinium nitrate.

In the title salt [systematic name: 4-(3-carb-oxy-1-ethyl-6-fluoro-4-oxo-1,4-di-hydro-quin-olin-7-yl)piperazin-1-ium nitrate], C 16 H 19 FN 3 O 3 + ·NO 3 - , proton transfer from nitric acid to the N atom of the piperazine ring of norfloxacin has occurred to form a mol-ecular salt. In the extended structure, N-H⋯O hydrogen bonds link alternating cations and anions into [100] chains, which are reinforced by aromatic π-π stacking inter-actions between the quinoline moieties of the norfloxacinium cations.