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Issue 15, 2014

Structure determination of the theophylline–nicotinamide cocrystal: a combined powder XRD, 1D solid-state NMR, and theoretical calculation study

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Abstract

The crystal structure of a powder pharmaceutical cocrystal, theophylline–nicotinamide (1 : 1) crystal complex, is determined for the first time by using a combination of X-ray powder diffraction (XRPD), 1D solid state NMR, as well as density functional theory (DFT) calculations. With the aid of solid state NMR spectroscopy, a candidate structure can be determined from XRPD data by Rietveld refinement with acceptable residual variances. The structure was subjected to periodic geometry optimization, followed by NMR parameter calculations. The agreement between experimental and computed 13C and 15N NMR chemical shift values validates the refined structure as an accurate representation of the actual cocrystal structure. Intermolecular interactions existing in the cocrystal are further confirmed by the commonly used vibrational spectra. This study confirms that the straightforward synergistic approach offers a simple and credible way to solve the crystal structure of powder cocrystal samples.

Graphical abstract: Structure determination of the theophylline–nicotinamide cocrystal: a combined powder XRD, 1D solid-state NMR, and theoretical calculation study

Supplementary files

Article information


Submitted
04 Jan 2014
Accepted
30 Jan 2014
First published
30 Jan 2014

CrystEngComm, 2014,16, 3141-3147
Article type
Paper
Author version available

Structure determination of the theophylline–nicotinamide cocrystal: a combined powder XRD, 1D solid-state NMR, and theoretical calculation study

P. Li, Y. Chu, L. Wang, R. M. Wenslow, K. Yu, H. Zhang and Z. Deng, CrystEngComm, 2014, 16, 3141 DOI: 10.1039/C4CE00012A

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