Automated derivation of structural class symbols and extended Z′ descriptors for molecular crystal structures in the Cambridge Structural Database

The determination of crystal structures of active pharmaceutical ingredients from X-ray powder diffraction data: a brief, practical introduction, with fexofenadine hydrochloride as example

“…Because of the considerable overlap of reflections in a powder pattern, the determination of the extinction conditions is less reliable than for single‐crystal data. It is therefore advised to consider the statistical frequency of space groups, crystal symmetries and molecular site symmetries for organic compounds [12–15]…”

“…It is therefore advised to consider the statistical frequency of space groups, crystal symmetries and molecular site symmetries for organic compounds. [12][13][14][15] Indexing easily fails if the sample contains a mixture of phases, if the crystallinity is insufficient (less than 30 sharp reflections), if the XRPD measurement is not well per-formed or if the user makes wrong assumptions, for example, on the accuracy of the reflection positions, on the maximum values for cell lengths or cell volume or if the correct lattice parameters are not considered, because they are regarded as unlikely.…”

Solid-State Studies of the Triclinic (Z′ = 2) Antiprotozoal Drug Ternidazole

“…[12][13][14][15][16][17][18] Statistically, the frequency of Z values in molecular crystal structures is 1 or less in about 89% of the cases and 10% exhibits Z = 2. 19 A study, focusing on imidazole derivatives, reports that Z = 1 is found in more than 75% and Z = 2 in 13% of the structures. 20 In this paper, a solid-state study of ternidazole (R = CH 2 CH 2 CH 2 OH), a 2-methyl-5-nitroimidazole derivative is presented together with its crystal structure, which has been pending ever since the molecule was patented in 1964.…”

A New Software Framework for Implementing Crystal Growth Models to Materials of Any Crystallographic Complexity

“…Complex compounds may have more than one molecule within the asymmetric unit; solid forms such as hydrates, solvates, cocrystals, and organic salts must also have multiple molecules or chemical entities within the asymmetric unit. Such complex solid forms where Z ′ (the number of molecules in the asymmetric unit) does not equal unity are being more commonly introduced as techniques to optimize material properties and crystal shape. − However, model compounds studied from the perspective of mechanistic morphology predictions have typically been limited to a single molecule in the asymmetric unit …”