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Updated: Jun 24, 2026

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Polymer-induced heteronucleation of tolfenamic acid: structural investigation of a pentamorph
Vilmalí López-Mejías1, Jeff W Kampf, Adam J Matzger
1Department of Chemistry and the Macromolecular Science and Engineering Program, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA.
Abstract:
The nonsteroidal anti-inflammatory drug (NSAID) tolfenamic acid (TA), previously thought to be dimorphic, is demonstrated to have at least five polymorphs. The new forms were uncovered through the emerging screening technique of polymer-induced heteronucleation (PIHn). The presence of conformational changes among forms, whole molecule disorder, space group diversity, and varying number of molecules in the asymmetric unit occurring within a very narrow free energy window (approximately 0.3 kcal/mol) make the solid-state chemistry of this molecule uniquely complex among pharmaceuticals. These aspects make it a particularly suitable benchmark compound for crystal structure prediction methods.
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