Synthesis and structure of a square-planar copper–norflaxacin coordination complex

The title coordination complex, bis-[4-(3-carboxyl-ato-1-ethyl-6-fluoro-4-oxo-1,4-di-hydro-quinolin-7-yl)piperazin-1-ium-κ² <i>O</i> ³,<i>O</i> ⁴]copper(II) dinitrate, [Cu(C₁₆H₁₈FN₃O₃)₂](NO₃)₂, was synthesized from norfloxacin (NF) and Cu(NO₃)₂·3H₂O. The asymmetric unit contains half a mol-ecule of [Cu(NF)₂] and one nitrate anion, with the copper atom located at a special crystallographic position with 1 site symmetry. The NF ligands are zwitterionic and coordinate to the metal atom <i>via</i> two oxygen atoms and the nitrate ions remain uncoordinated as counter-ions. The supra-molecular features include π-π stacking inter-actions as well as N-H⋯O and C-H⋯F hydrogen bonds and short [2.718 (3) Å] F⋯F inter-actions, which facilitate the formation of a columnar assembly parallel to the <i>b</i>-axis. Hirshfeld surface and two-dimensional fingerprint plot analysis were used to qu-antify the supra-molecular inter-actions of the compound.