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Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate
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Tautomerism and microsolvation in 2-hydroxypyridine/2-pyridone
Santiago Mata1, Vanessa Cortijo, W Caminati
1Grupo de Espectroscopía Molecular Edificio Quifima, Area de Química Física, Campus Miguel Delibes, Universidad de Valladolid, 47011 Valladolid, Spain.
The Journal of Physical Chemistry. A
|October 8, 2010
Summary
Water molecules influence the tautomeric equilibrium of 2-pyridinone/2-hydroxypyridine (2PO/2HP). Hydration shifts the balance towards the keto tautomer, contrary to the enol preference of the bare molecules.
Area of Science:
- Physical Chemistry
- Molecular Spectroscopy
- Supramolecular Chemistry
Background:
- Tautomerism is a fundamental chemical phenomenon involving the interconversion of isomers.
- Understanding molecular hydration is crucial for various chemical and biological processes.
- The 2-pyridinone/2-hydroxypyridine (2PO/2HP) system exhibits interesting tautomeric behavior.
Purpose of the Study:
- To investigate the effect of water on the tautomeric equilibrium of 2-pyridinone/2-hydroxypyridine.
- To identify and characterize hydrated species of 2PO/2HP using rotational spectroscopy.
- To elucidate the structural and electronic changes induced by hydration.
Main Methods:
- Fourier transform microwave spectroscopy was employed to study molecular complexes.
- Supersonic expansion was used to generate and cool the molecular species.
- Analysis of rotational transitions and ¹⁴N quadrupole hyperfine structure confirmed molecular identities.
Main Results:
- Three hydrated species were identified: 2PO-H₂O, 2HP-H₂O, and 2PO-(H₂O)₂.
- The presence of water molecules significantly alters the tautomeric equilibrium.
- Hydration favors the keto tautomer (-NH-C(═O)-) over the enol form (-N═C(OH)-).
Conclusions:
- Water acts as a structure-directing agent, influencing the preferred tautomeric form.
- The study provides detailed insights into the intermolecular interactions in hydrated systems.
- Microwave spectroscopy is a powerful tool for characterizing weakly bound molecular complexes and their properties.
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