O-hydroxy Schiff Bases Derived from 2-Hydroxy-4-methoxy Benzaldehyde: Synthesis, X-Ray Studies and Hydrogen Bonding Attributes

ABSTRACT

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.

KEYWORDS:

• Hydrogen bonding
• NMR
• o-hydroxy Schiff base
• X-ray

Acknowledgments

The authors are grateful to the Institution of Excellence, Vijnana Bhavana, University of Mysore, India, for providing the single-crystal X-ray diffractometer facility. The authors acknowledge Mr. Mukund for helping in acquisition of mass spectral data and Ms. Asha and Mr. Sanjay lal for IR data.