Issue 28, 2015

Structural insights into the hexamorphic system of an isoniazid derivative

Abstract

Crystal polymorphism is the capacity of a crystalline solid to exist in more than one structural arrangement. The variation in the crystalline forms often induces different mechanical, thermal, and chemical properties. These changes can markedly influence the bioavailability, hygroscopicity, stability and other performance characteristics of the active pharmaceutical ingredient. Isoniazid, a well-known pharmaceutical, is used as a first-line treatment against Mycobacterium tuberculosis (TB). Derivatives of isoniazid were developed in response to TB drug resistance. One such derivative synthesized, isonicotinic acid (E)-(1-phenylethylidene)hydrazide (IPH), was found to exhibit complex polymorphic behaviour. To date, only one crystal structure of IPH has been reported in the literature. We have discovered and isolated an additional five polymorphs of IPH from various crystallization techniques, namely slow cooling, rapid evaporation, sublimation, as well as from hot-stage experiments. All of the polymorphs display hydrogen bonding through the carbonyl acceptor and hydrazide donor. Structural information about the polymorphs was obtained by single crystal and powder diffraction, while characterisation included infrared spectroscopy and Raman spectroscopy. The thermal properties of these polymorphs were also investigated using differential scanning calorimetry and hot stage microscopy.

Graphical abstract: Structural insights into the hexamorphic system of an isoniazid derivative

  • This article is part of the themed collection: Polymorphism

Supplementary files

Article information

Article type
Paper
Submitted
05 feb 2015
Accepted
23 mar 2015
First published
14 apr 2015
This article is Open Access
Creative Commons BY-NC license

CrystEngComm, 2015,17, 5143-5153

Author version available

Structural insights into the hexamorphic system of an isoniazid derivative

D. Hean, T. Gelbrich, U. J. Griesser, J. P. Michael and A. Lemmerer, CrystEngComm, 2015, 17, 5143 DOI: 10.1039/C5CE00275C

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