13C, 15N CP-MAS as well as FT-IR studies of gossypol derivatives with aromatic substituents in solid

Two hydrazones and one Schiff base of racemic gossypol have been studied by FT-IR, 13C and 15N CP-MAS spectroscopy. The spectroscopic methods have provided evidence that the hydrazones exist in the N-imine–N-imine tautomeric forms, whereas the Schiff base exists in the solid state as enamine–enamine tautomer. The spectral features characteristic of both tautomers and the hydrogen bonds within these structures are discussed.