Structural Characterization of Industrially Relevant Polymorphic Materials from Powder Diffraction Data

Abstract

To fully characterize a polymorphic system, it is necessary to know the structural properties of all polymorphs formed by the molecule of interest. Traditionally, single-crystal X-ray diffraction techniques have been used for this purpose, although different polymorphic forms of a given molecule can differ significantly in crystal quality and in many cases only one or a few of the polymorphs yield single crystals that are suitable for investigation by single-crystal X-ray diffraction. Structural characterization of the other polymorphs must be carried out using powder X-ray diffraction. Fortunately, recent years have seen significant developments in techniques for determining crystal structures of molecular solids directly from powder diffraction data. This article highlights the current scope of these techniques and highlights some examples involving studies of polymorphic materials of industrial relevance.

Crystallization and Crystallinity of Fluticasone Propionate

“…In the Form I polymorph molecules are H-bonded in zigzag chains where adjacent chains are stacked parallel, while in Form II, these chains are stacked in an antiparallel geometry. 6,41 Representative diffractograms of FP crystals and microparticles are presented in Figure 7. The positions of the peaks are identical in each diffractogram, demonstrating that the same polymorph of FP was produced irrespective of the solvent system employed.…”

“…The monotropic polymorphism arises due to a different packing of the monomers in the crystal lattice. In the Form I polymorph molecules are H-bonded in zigzag chains where adjacent chains are stacked parallel, while in Form II, these chains are stacked in an antiparallel geometry. , …”

Solving molecular crystal structures from laboratory X-ray powder diffraction data withDASH: the state of the art and challenges

“…Global optimization methods for crystal structure determination from powder diffraction data (SDPD) have become widely available in recent years and have successfully been applied to solve the structures of organic (Harris & Cheung, 2003;Johnston et al, 2004;Rukiah et al, 2004;Zaske et al, 2004), inorganic (Deem & Newsam, 1989;Edgar et al, 2002;Reinaudi et al, 2000) and organometallic (Ivashevskaja et al, 2002;Dinnebier et al, 2000) materials, to cite but a few examples. The basis of global optimization strategies has been fully described elsewhere and software implementing global optimization methods is now widely available [e.g.…”

WinPSSP: a revamp of the computer program PSSP and its performance solving the crystal structures of small organic compounds and solids of biological and pharmaceutical interest

“…Crystal structure determination from powders has been reviewed in various articles (Louë r & Langford, 1996;Harris & Tremayne, 1996;Č erný & Favre-Nicolin, 2007;Harris, 2012). For organic solids in particular, the applications to the economically important pharmaceutical solids (and their salts, hydrates, solvates, polymorphs and co-crystals) have occupied a prominent position, leading to further development of this research field (Harris & Cheung, 2003;Datta & Grant, 2004;Stephenson, 2005;Shankland et al, 2013). However, crystal structure determination from powders still remains a rather timeconsuming and not well automated task in comparison with its single-crystal diffraction counterpart (Le Bail et al, 2009).…”