Crystal structure of minocycline hydrochloride dihydrate form A, C23H28N3O7Cl (H2O)2. Issue 1 (21st November 2018)

• Record Type: Journal Article
• Authors: Wheatley, Austin M.; Kaduk, James A.; Gindhart, Amy M.; Blanton, Thomas N.
• Is Part Of: Powder diffraction. Volume 34:Issue 1(2019)
• Page Start: 59
• Page End: 65
• Publication Date: 2018-11-21
• Subjects: minocycline hydrochloride dihydrate, -- Minocin®, -- powder diffraction, -- Rietveld refinement, -- density functional theory; Powder metallurgy -- Periodicals; Materials -- Analysis -- Periodicals; 620.1127
• DOI: 10.1017/S0885715618000787
• Languages: English
• ISSNs: 0885-7156

Abstract

Abstract : The crystal structure of minocycline hydrochloride dihydrate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Minocycline hydrochloride dihydrate crystallizes in space group P 21 21 21 (#19) with a = 7.40772(1), b = 14.44924(3), c = 22.33329(4) Å, V = 2390.465(12) Å 3, and Z = 4. The minocycline cation is a zwitterion: both dimethylamino groups are protonated and one hydroxyl group is ionized. A potential ambiguity in the orientation of the amide group was resolved by considering Rietveld refinement residuals and displacement coefficients, as well as DFT energies. The crystal structure is dominated by hydrogen bonds. Both water molecules and a hydroxyl group act as donors to the chloride anion. Both protonated dimethyl amine groups act as donors to the ionized hydroxyl group. Several intramolecular O–H···O hydrogen groups help determine the conformation of the cation. The powder pattern is included in the Powder Diffraction File™ as entry 00-066-1606.