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Updated: Apr 24, 2026

Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants
Published on: October 19, 2017
Solid-state NMR studies of theophylline co-crystals with dicarboxylic acids
Edyta Pindelska1, Agnieszka Sokal1, Lukasz Szeleszczuk2
1Faculty of Pharmacy, Medical University of Warsaw, Department of Inorganic and Analytical Chemistry, Banacha 1, 02-093 Warsaw, Poland.
Abstract:
In this work, three polycrystalline materials containing co-crystals of theophylline with malonic, maleic, and glutaric acids were studied using (13)C, (15)N and (1)H solid-state NMR and FT-IR spectroscopy. The NMR assignments were supported by gauge including projector augmented waves (GIPAW) calculations of chemical shielding, performed using X-ray determined geometry. The experimental (13)C cross polarization/magic angle spinning (CP/MAS) NMR results and the calculated isotropic chemical shifts were in excellent agreement. A rapid and convenient method for theophylline co-crystals crystal structure analysis has been proposed for co-crystals, which are potentially new APIs.
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