The title compound, C(28)H(28)N(2)O(4), crystallizes in a zwitterionic form with deprotonated naphthol hy-droxy groups and protonated imine N atoms. The asymmetric unit contains one half-mol-ecule located on a twofold rotation axis. Intra-molecular N-H⋯O hydrogen bonds occur and the two bicyclic ring systems form a dihedral angle of 64.2 (1)°. In the crystal, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into layers parallel to the bc plane.