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Updated: Apr 23, 2026

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
Determination of preferred conformations of ibuprofen in chloroform by 2D NOE spectroscopy
I A Khodov1, S V Efimov2, V V Klochkov2
1Institute of Physics, Kazan Federal University, Kremlevskaya St. 18, Kazan 420008, Russia; G.A. Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Akademicheskaya St. 1, Ivanovo 153045, Russia.
Abstract:
Solution of an anti-inflammatory drug ibuprofen ((RS)-2-(4-isobutylphenyl) propionic acid) in chloroform was studied by nuclear magnetic resonance spectroscopy. A set of 2D NOESY spectra was analyzed in order to obtain atom-atom distances. Since ibuprofen is known to exist as an ensemble of different conformations, these distances are averaged over the ensemble. To compare experimental and calculated distances, three models of averaging were concerned. Our data allowed to determine the dominant conformers of ibuprofen dissolved in chloroform. The population of conformers in the saturated solution leads to a certain crystal morphology formed within the nucleation process. Observed and calculated (13)C chemical shifts (at the DFT/B3LYP/6-311+G(2d,p) level) were in good agreement.
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