Introduction The ortho-hydroxy Schiff bases and the azo- analogues are interesting families of organic compounds.
Fabian and co-workers illustrated that DFT/B3LYP can calculate energy parameters that are in good agreement with the experimental tautomerism energies [44] for anils and azo- analogues derived from hydroxynaphthalenes.
On the other hand the three (H OMe and CN) azo-derivatives have similar keto-tautomer relative stabilities which imply that this azo- molecular system exhibits the maximum possible relative stabilization for the keto-tautomer.