Studies on the crystal structure and arrangement of water in sitagliptin l-tartrate hydrates

Eszter Tieger, Violetta Kiss, György Pokol, Zoltán Finta, Michal Dušek, Jan Rohlíček, Eliška Skořepová, Petr Brázda

Research output: Article

13 Citations (Scopus)

Abstract

The hydration/dehydration behavior of four distinct channel hydrates of sitagliptin l-tartrate (SLT) was investigated by thermoanalytical methods, dynamic vapour sorption analysis and variable humidity X-ray powder diffraction. The crystal structures were determined from single crystal and powder X-ray diffraction data. A survey of the forms revealed that SLT hydrates exhibit both stoichiometric and non-stoichiometric features demonstrating that the characterization of channel hydrates can be challenging as their behavior is not inevitably unambiguous. Upon dehydration, the parent hydrates retain their structures, and the lattices do not collapse; isostructural dehydrates are formed. The solved crystal structures of the packing polymorphs SLT phase 1 and phase 2 provide an effective basis to rationalize the observed hydration/dehydration pathways. The structures are dominated by infinite sheets formed by hydrogen tartrate anions, linked by hydrogen bonds. These layers separate the parallel, infinite chains of water molecules. The water molecules stabilize the structures by providing additional hydrogen bonds between the cation and the anion. This interaction substantiates the high affinity of water molecules to the API framework and explains the stoichiometric characteristics observed by solid state analytical methods. On the other hand, their non-stoichiometric character is evidenced by the non-destructive dehydration processes.

Original languageEnglish
Pages (from-to)3819-3831
Number of pages13
JournalCrystEngComm
Volume18
Issue number21
DOIs
Publication statusPublished - 2016

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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    Tieger, E., Kiss, V., Pokol, G., Finta, Z., Dušek, M., Rohlíček, J., Skořepová, E., & Brázda, P. (2016). Studies on the crystal structure and arrangement of water in sitagliptin l-tartrate hydrates. CrystEngComm, 18(21), 3819-3831. https://doi.org/10.1039/c6ce00322b