4-Hydroxynicotinic acid (4-HNA) was discovered to exist in the solid state as either 4-HNA or its tautomer 4-oxo-1,4-dihydropyridine-3-carboxylic acid (4-ODHPCA) in three polymorphs and two hydrates. Packing motifs differ as each of the three oxygen atoms acts as the hydrogen-bond acceptor, respectively, in the anhydrate forms, while in the hydrate forms, water molecules participate in hydrogen bonding with 4-HNA. Phase behaviors of the forms were characterized by differential scanning calorimetry (DSC), hot-stage microscopy (HSM), and thermogravimetric analysis (TGA). It was found that anhydrates I and II converted into III during heating; the two hydrate forms dehydrated at different temperatures and eventually transformed into anhydrate III, and sublimation of all five forms led to form III when the crystals were heated. Quantum mechanical calculations were performed providing further insight into the polymorphism.
|Number of pages||8|
|Journal||Crystal Growth and Design|
|State||Published - May 4 2016|
Bibliographical noteFunding Information:
S.L. thanks the Natural Science Foundation of Hubei Province for financial support (Grant No. 2014CFB787). P.Z. acknowledges the financial support by the National Natural Science Foundation of China (Grant No. 21403097) and the Fundamental Research Funds for the Central Universities (Grant No. lzujbky-2014-182). T.L. is grateful to NSF for supporting the work (Grant No. DMR1006364) and to the Allen Chao Endowment.
© 2016 American Chemical Society.
ASJC Scopus subject areas
- Chemistry (all)
- Materials Science (all)
- Condensed Matter Physics