Zwitterionic 1-{(1E)-[(4-hy-droxy-phen-yl)iminio]meth-yl}naphthalen-2-olate: crystal structure and Hirshfeld surface analysis.

The title zwitterion, C17H13NO2 (systematic name: 1-{(1E)-[(4-hy-droxy-phen-yl)iminium-yl]meth-yl}naphthalen-2-olate), features an intra-molecular charge-assisted N+-H⋯O- hydrogen bond. A twist in the mol-ecule is evident around the N-C(hy-droxy-benzene) bond [C-N-C-C torsion angle = 39.42 (8)°] and is reflected in the dihedral angle of 39.42 (8)° formed between the aromatic regions of the mol-ecule. In the crystal, zigzag supra-molecular chains along the a axis are formed by charge-assisted hy-droxy-O-H⋯O(phenoxide) hydrogen bonding. These are connected into a layer in the ab plane by charge-assisted hy-droxy-benzene-C-H⋯O(phenoxide) inter-actions and π-π contacts [inter-centroid distance between naphthyl-C6 rings = 3.4905 (12) Å]. Layers stack along the c axis with no specific inter-actions between them. The Hirshfeld surface analysis points to the significance C⋯H contacts between layers.

Crystal structure of 2-{(E)-[(2-hy-droxy-phen-yl)iminium-yl]meth-yl}-4-methyl-phenolate.

The title compound, C14H13NO2, exists as a zwitterion in the solid state, with the H atom of the phenol group transferred to the imine N atom. The dihedral angle between the planes of the benzene rings is 10.13 (9)°. Intra-molecular N-H⋯O hydrogen bond generate S(6) and S(5) loops. In the crystal, mol-ecules are connected by O-H⋯O hydrogen bonds, generating C(9) chains propagating in the [010] direction.