Etude experimentale de L′auto-association des molécules modèles dipeptidiques. III. Influence de la dimerisation stéréosélective sur les spectres de résonance magnétique protonique |
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Authors: | Manh Th ng Cung,Michel Marraud,Jean Neel |
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Affiliation: | Manh Thông Cung,Michel Marraud,Jean Neel |
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Abstract: | Proton magnetic resonance spectra of model dipeptide molecules R1–C′1O1–N2H2–CHR2–C′2O2–N3H3–R3 in CCl4 solutions exhibit splited signals when investigating on mixtures of L and D enantiomers differing from the racemic composition. The major effect is observed on amide proton signals which are the ones most sensitive to the ratio of aggregation. The stereoselective dimerization of enantiomeric molecules in the so-called C5 conformational state is shown to be responsible for such a phenomenon, the intensity of which depends on the bulkiness of the side chain R2. A theoretical approach is proposed which gives predictions in close agreement with our own experimental findings. |
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