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The reluctant polymorph: investigation into the effect of self-association on the solvent mediated phase transformation and nucleation of theophylline

Bobrovs, R and Seton, L and Dempster, N (2015) The reluctant polymorph: investigation into the effect of self-association on the solvent mediated phase transformation and nucleation of theophylline. CrystEngComm, 17 (28). pp. 5237-5251. ISSN 1466-8033

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Abstract

Little is known concerning the pathway of the crystallization of the thermodynamically stable polymorph of
theophylline, form IV. Here we study the reasons why the thermodynamically stable theophylline form IV can be obtained only by slow, solvent mediated phase transformation (SMPT) in specific solvents, and whether the presence of prenucleation aggregates affect the polymorphic outcome. Solution concentration, polymorphic composition and morphology were monitored over time during the transformation from form II to form IV in several solvents. NMR and FTIR spectroscopy were used to detect prenucleation molecular aggregates present in the solutions. It was determined that theophylline self-associates in solvents which are good H-bond donors and the presence of these aggregates hinder the nucleation and phase transformation. SMPT from form II to form IV is a nucleation-growth controlled polymorphic transformation, nucleation is most likely homogenous, and form IV crystals grow along the
(001) plane, forming plate-like crystals.

Item Type: Article
Uncontrolled Keywords: 0306 Physical Chemistry (Incl. Structural), 0912 Materials Engineering, 0302 Inorganic Chemistry
Subjects: Q Science > QD Chemistry
Divisions: Pharmacy & Biomolecular Sciences
Publisher: Royal Society of Chemistry
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Date Deposited: 11 Sep 2015 11:18
Last Modified: 11 Sep 2015 11:18
DOI or Identification number: 10.1039/c4ce02484b
URI: http://researchonline.ljmu.ac.uk/id/eprint/1868

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