1,1′-{(1E,1′E)-[Octane-1,8-diylbis(azanylylidene)]bis(methanylylidene)}bis(naphthalen-2-ol) in the zwitterionic form

The title compound, C30H32O2N2, is formed from two units of ortho-hy­droxy­naphthaldehyde bridged with 1,8-di­amino­octane. In the solid state, it exists as a double zwitterion. The N atoms are protonated and the C—O− bonds lengths are 1.265 (2) A, with intra­molecular N—H⋯O hydrogen bonds forming S(6) ring motifs. The mol­ecule has twofold rotational symmetry, with the twofold axis bis­ecting the central –CH2—CH2– bond of the bridging octane chain. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, forming chains propagating along the [-201] direction. The chains are linked via C—H⋯O hydrogen bonds, forming a supra­molecular three-dimensional framework structure.