LAUSR

Fluconazole (CAS Registry number 86386-73-4) is used to treat a number of fungal infections, particularly candidiasis, and has many polymorphs. There are five low-precision experimental patterns of fluconazole in the Powder Diffraction File (00-057-1444, 00-058-1926, 00-059-1308, 00-062-1568, and 00-062-1569); one of them, 00-059-1308, corresponds to polymorph V, but does not contain all of the peaks observed here. In this study a commercial sample of fluconazole crystallized in the orthorhombic space group Pbca (#61) with a = 12.97949(12), b = 6.13624(7), c = 35.1757(5) Å, V = 2801.57(8) Å, and Z = 8 at 295 K. A reduced cell search in the Cambridge Structural Database (Groom et al., 2016) yielded a previously reported crystal structure of polymorph V (Karanam et al., 2012; Refcode IVUQOF02) collected at 100 K. In this work, the sample was ordered from SigmaAldrich (Product # F8929-100 mg) and analyzed as received. Other commercial samples evaluated as part of this study were found to have consisted of mixtures of polymorphs. The room-temperature crystal structure was refined using synchrotron (λ = 0.412708 Å) powder diffraction data, density functional theory, and Rietveld refinement techniques. The diffraction data were collected on beamline 11-BM at the Advanced Photon Source, Argonne National Laboratory (see crystallographic details in the supplementary material). Figure 1 shows the powder X-ray diffraction pattern of the compound. The thermal expansion between 100 and 295 K is anisotropic; the expansion is 0.40, 1.86, and 0.98% along a, b, and c, respectively. The cell volume is 3.27% larger at room temperature. The hydroxyl group forms a strong hydrogen bond to a ring nitrogen atom along the a-axis, but the crystal packing is dominated by ring–ring interactions. The pattern and room-temperature crystal structure have been submitted to ICDD for inclusion in the Powder Diffraction File.