Zwitterionic (E)-1-[(4-nitro-phen-yl)iminio-meth-yl]naphthalen-2-olate

3-{[(E)-(2-Hydroxynaphthalen-1-yl)methylidene]amino}pyridinium per-chlorate

In the title Schiff base salt, C₁₆H₁₃N₂O⁺·ClO₄⁻, the pyridine ring and the naphthalene ring system are approximately co-planar [making a dihedral angle of 6.05 (12)°] and an intra­molecular O—H⋯N hydrogen bond occurs between the hydroxyl and imino groups. In the crystal, the cations and anions are linked by N—H⋯O and weak C—H⋯O hydrogen bonds, forming the supra­molecular layers parallel to (100). The crystal studied was an inversion twin refined with minor component = 0.43 (13).

2-Bromo-4-chloro-6-(cyclo-hexyl-imino-meth-yl)phenol

The title compound, C(13)H(15)BrClNO, was prepared by the condensation of equimolar quanti-ties of 3-bromo-5-chloro-salicyl-aldehyde with cyclo-hexyl-amine in methanol. There is an intra-molecular O-H⋯N hydrogen bond in the mol-ecule. The cyclo-hexyl ring adopts a chair conformation.