Crystal structure of 1,1'-{(pentane-1,5-di-yl)bis[(aza-niumylyl-idene)methanylyl-idene]}bis(naphthalen-2-olate).

The whole mol-ecule of the title compound, C27H26N2O2, is generated by twofold rotational symmetry, with the central C atom of the pentyl chain located on the twofold rotation axis. The compound crystallizes as a bis-zwitterion, and there are two intra-molecular N-H⋯O hydrogen bonds generating S(6) ring motifs. In the crystal, mol-ecules are linked by pairs of C-H⋯O hydrogen bonds, forming ribbons propagating along [001], and enclosing R 2 (2)(22) ring motifs.

Crystal structure of 1,1'-{(dodecane-1,12-di-yl)bis-[(aza-niumylyl-idene)methanylyl-idene]}bis-(naphthalen-2-olate).

The title compound, C34H40N2O2, exists in an extended conformation and has crystallographically imposed centrosymmetry. The crystal packing can be described as being composed of parallel layers stacked along [010]. The zwitterionic structure is stabilized by an intra-molecular N-H⋯O hydrogen-bond inter-action.

1,1'-{(Hexane-1,6-di-yl)bis-[(aza-niumylyl-idene)methanylyl-idene]}bis-(naphthalen-2-olate).

The whole molecule of the title Schiff base compound, C28H28N2O2, is generated by inversion symmetry. It is formed from two units of ortho-hy-droxy-naphthaldehyde bridged with 1,6-di-amino-hexane. The N atoms are protonated and, thus, the structure is a bis-zwitterionic compound in the solid state.