Comprehensive Characterisation of the Ketoprofen-β-Cyclodextrin Inclusion Complex Using X-ray Techniques and NMR Spectroscopy

Racemic ketoprofen (KP) and β-cyclodextrin (β-CD) powder samples from co-precipitation (<b>1</b>), evaporation (<b>2</b>), and heating-under-reflux (<b>3</b>) were analysed using X-ray techniques and nuclear magnetic resonance (NMR) spectroscopy. On the basis of N...

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Bibliographic Details
Main Authors: Katarzyna Betlejewska-Kielak, Elżbieta Bednarek, Armand Budzianowski, Katarzyna Michalska, Jan K. Maurin
Format: Article
Language:English
Published: MDPI AG 2021-07-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/26/13/4089
Description
Summary:Racemic ketoprofen (KP) and β-cyclodextrin (β-CD) powder samples from co-precipitation (<b>1</b>), evaporation (<b>2</b>), and heating-under-reflux (<b>3</b>) were analysed using X-ray techniques and nuclear magnetic resonance (NMR) spectroscopy. On the basis of NMR studies carried out in an aqueous solution, it was found that in the samples obtained by methods <b>1</b> and <b>2,</b> there were large excesses of β-CD in relation to KP, 10 and 75 times, respectively, while the sample obtained by method <b>3</b> contained equimolar amounts of β-CD and KP. NMR results indicated that KP/β-CD inclusion complexes were formed and the estimated binding constants were approximately 2400 M<sup>−1</sup>, showing that KP is quite strongly associated with β-CD. On the other hand, the X-ray single-crystal technique in the solid state revealed that the (<i>S</i>)-KP/β-CD inclusion complex with a stoichiometry of 2:2 was obtained as a result of heating-under-reflux, for which the crystal and molecular structure were examined. Among the methods used for the preparation of the KP/β-CD complex, only method <b>3</b> is suitable.
ISSN:1420-3049