Crystal structure determination of thymoquinone by high-resolution X-ray powder diffraction

Abstract

The crystal structure of 2-isopropyl-5-methyl-1,4-benzoquinone (thymoquinone) and its thermal behavior--as necessary physical and chemical properties--were determined in order to enhance the current understanding of thymoquinone chemical action by using high resolution x-ray powder diffraction, Fourier transform infrared spectroscopy (FTIR), and 3 thermo-analytical techniques thermogravimetric analysis (TGA), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). The findings obtained with high-resolution x-ray powder diffraction and molecular location methods based on a simulated annealing algorithm after Rietveld refinement showed that the triclinic unit cell was a = 6.73728(8) A, b = 6.91560(8) A, c = 10.4988(2) A, alpha = 88.864(2) degrees, beta = 82.449(1) degrees, gamma = 77.0299(9) degrees; cell volume = 472.52(1) A3, Z = 2, and space group P1. In addition, FTIR spectrum revealed absorption bands corresponding to the carbonyl and C-H stretching of aliphatic and vinylic groups characteristically observed in such p-benzoquinones. Also, a chemical decomposition process starting at 65 degrees C and ending at 213 degrees C was noted when TGA was used. DSC allowed for the determination of onset at 43.55 degrees C and a melting enthalpy value of DeltaH(m) = 110.6 J/g. The low value obtained for the fusion point displayed a van der Waals pattern for molecular binding, and the thermograms performed evidence that thymoquinone can only be found in crystalline triclinic form, as determined by DRX methods.

Fabrication of Thymoquinone‐Loaded Albumin Nanoparticles by Microfluidic Particle Synthesis and Their Effect on Planarian Regeneration

“…The Fourier‐transform infrared (FTIR) spectrum of free TQ presented the characteristic peaks of CH stretching at 2966 cm −1 , CO bond at 1637 cm −1 , and CH bending at 1245, 1131, and 1022 cm −1 ( Figure 2 A). The obtained spectrum was similar to the standard TQ spectrum reported in the literature …”

“…The obtained spectrum was similar to the standard TQ spectrum reported in the literature. [6,33,34] Various characteristic peaks of albumin were present in the FTIR spectrum at different wavelengths such as 3282 (OH or NH stretching), 2924 (CH 2  symmetric vibration), 2854 (CH 2  asymmetric vibration), 1648 (amide I), 1535 (amide II), and 1390 and 1260 cm −1 (CN stretching/NH bending vibrations) ( Figure 2B).…”

A Practical Synthesis and X-ray Crystallographic Analysis of Dithymoquinone, a Photodimer of Thymoquinone

“…4. The crystal structure of 3 belongs to the triclinic, space group P-1, and shows similarity to the previously determined crystal structure of 1 [21]. The crystal structure confirms that the methyl groups on carbons C7 and C7′ are oriented about the cyclobutane ring in the trans-anti configuration, and also supports earlier findings on the dithymoquinone-epoxide derivative [16].…”

Thymoquinone

“…Thymoquinone Bhanushree Gupta, Kallol K. Ghosh and Ramesh C. Gupta that TQ exists only in crystalline triclinic form (Pagola et al, 2003). Quantification of TQ can be performed by several other methods like gas chromatography, highperformance liquid chromatography, and differential pulse polarography (Houghton et al, 1995).…”