1. INTRODUCTION
Dexamethasone is a glucocorticoid commonly used for treatment of many inflammatory and autoimmune conditions, such as rheumatoid arthritis and bronchospasm (Hossain, et al., Reference Hossain, Rashid, Babu, Saha and Banik2018; Formica, et al., Reference Formica, Barreto and Zenobi-Wong2019). The title compound (Figure 1) is an intermediate in the synthesis of dexamethasone.
Molecular diagram of the title compound.
In order to better study the effect of the minor difference in the structure on the steroids binding to human serum albumin, Lin et al. (Reference Lin, Wang, Peng and Li2017) analyzed the single-crystal structures of some novel steroids. The single crystallographic data of the title compound [a = 8.26215(13) Å, b = 12.27870(19) Å, c = 18.4797(3) Å, α = 90°, β = 90°, γ = 90°, unit-cell volume V = 1874.73(5) Å3, Z = 4, ρ cal = 1.256 g cm−3 and space group P212121] were deposited with the Cambridge Crystallographic Data Center (CCDC) with a supplementary publication number of CCDC-1471422. To date, the detailed X-ray powder diffraction (PXRD) data for the title compound have not been reported.
II. EXPERIMENTAL
A. Sample preparation
The sample was purchased from J&K Scientific (Beijing, People's Republic of China). The melting point and measured density of the title compound are 244–245 °C and 1.253 g cm−3, respectively. Crystallization of the title compound at room temperature was successful using methanol as solvent. The crystals have a prismatic and transparent crystal structure. Then, part of crystals was dried, smashed, and screened through 75 µm mesh size.
B. Diffraction data collection and reduction
PXRD measurement was performed at room temperature using an X'Pert PRO diffractometer (PANalytical Co., Ltd., Netherlands) with a PIXcel 1D detector and Cu Kα radiation (generator setting: 40 kV and 40 mA). The diffraction data were collected over the angular range from 4° to 50° 2θ with a step size of 0.01313° 2θ and a counting time of 30 ms step−1 (Figure 2).
(colour online) X-ray powder diffraction pattern of the title compound using CuKα radiation (black line) and the simulated pattern of the crystal structure (red line).
The software package Material Studio 8.0 (Accelrys Co., Ltd., CA, USA) was used to process the data in the Analytical & Testing Center (Sichuan University, Chengdu, China). The XRD pattern was pre-treated by subtracting the background, smoothing, and stripping off the Kα 2 component. Automatic indexing results were obtained by DICVOL91 method (Boultif and Louër, Reference Boultif and Louër1991). The indexing results were then refined using Pawley (R wp = 9.63%) (Pawley, Reference Pawley1981), which involves assigning the Miller indices (h, k, l) to each observed peak in the experimental PXRD pattern.
III. RESULTS
Pawley refinement results confirmed that the title compound is orthorhombic with space group P212121 and unit-cell parameters: a = 18.435(1) Å, b = 12.269(3) Å, c = 8.251(5) Å, α = 90°, β = 90°, γ = 90°, unit-cell volume V = 1866.43 Å3, Z = 4, ρ cal = 1.261 g cm−3. The values of 2θ obs, d obs, I obs, h, k, l, 2θ cal, d cal, Δ2θ are listed in Table I. The results are in good agreement with the single-crystal data and the deviations of the unit-cell parameters and unit-cell volume were between 0.07% and 0.44%. The comparison of PXRD pattern (Supplementary Material) with the simulated pattern is shown in Figure 2.
Indexed X-ray powder diffraction data for the title compound. The d-values were calculated using CuKα 1 radiation (λ = 1.54056 Å).
SUPPLEMENTARY MATERIAL
The supplementary material for this article can be found at https://doi.org/10.1017/S088571561900054X.
Acknowledgements
This work was supported by the Scientific Research Staring Foundation of Yangzhou University (grant number 5010/137011392) and Yangzhou Green Yang Gold Phoenix plans.
