Tautomeric polymorphism of 4-hydroxynicotinic acid

Sihui Long, Mingtao Zhang, Panpan Zhou, Faquan Yu, Sean Parkin, Tonglei Li

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


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.

Original languageEnglish
Pages (from-to)2573-2580
Number of pages8
JournalCrystal Growth and Design
Issue number5
StatePublished - May 4 2016

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics


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