O-hydroxy Schiff bases derived from -hydroxy--methoxy benzaldehyde: Synthesis, x-ray studies and hydrogen bonding attributes

The o-hydroxy Schiff bases consisting of N’-[(Z)-(2-hydroxy-4-
methoxyphenyl)methylidene]pyridine-4-carbohydrazide and N’-[(Z)-
(2-hydroxy-4-methoxyphenyl)methylidene]pyridine-3-carbohydrazide
were prepared by reaction of isonicotinic acid hydrazide and nicotinic
acid hydrazide by employing 2-hydroxy-4-methoxy benzaldehyde.
The spectroscopic techniques, X-ray crystal structure determination
as well as DFT calculations have been carried out to shed light on the
nature of hydrogen bonding. The both experimental and theoretical
investigations demonstrate the presence of intramolecular neutral
hydrogen bonding (enol-imine type) in these molecules.