An automated parallel crystallisation search for predicted crystal structures and packing motifs of carbamazepine

Alastair J. Florence, Andrea Johnston, Sarah L. Price, Harriott Nowell, Alan R. Kennedy, Norman Shankland

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An automated parallel crystallisation search for physical forms of carbamazepine, covering 66 solvents and five crystallisation protocols, identified three anhydrous polymorphs (forms I-III), one hydrate and eight organic solvates, including the single-crystal structures of three previously unreported solvates (N,N-dimethylformamide (1:1); hemi-furfural; hemi-1,4-dioxane). Correlation of physical form outcome with the crystallisation conditions demonstrated that the solvent adopts a relatively nonspecific role in determining which polymorph is obtained, and that the previously reported effect of a polymer template facilitating the formation of form IV could not be reproduced by solvent crystallisation alone. In the accompanying computational search, approximately half of the energetically feasible predicted crystal structures exhibit the C=(OH)-H-...-N R-2(2)(8)dimer motif that is observed in the known polymorphs, with the most stable correctly corresponding to form III. Most of the other energetically feasible structures, including the global minimum, have a C=(OH)-H-...-N C(4) chain hydrogen bond motif. No such chain structures were observed in this or any other previously published work, suggesting that kinetic, rather than thermodynamic, factors determine which of the energetically feasible crystal structures are observed experimentally, with the kinetics apparently favouring nucleation of crystal structures based on the CBZ-CBZ R-2(2)(8) motif. (c) 2006 Wiley-Liss, Inc.

Original languageEnglish
Pages (from-to)1918-1930
Number of pages13
JournalJournal of Pharmaceutical Sciences
Issue number9
Publication statusPublished - Sep 2006


  • crystal structure prediction
  • solid state
  • polymorphism
  • crystallisation
  • hydrates/solvates
  • X-ray powder diffractometry
  • crystal structure
  • multivariate analysis
  • distributed multipole
  • polymorph selection
  • solvent
  • blind test
  • nucleation


x-ray diffractometer

Alan Kennedy (Manager)

Pure And Applied Chemistry

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