Formation and structure of a complex of sucrose with cobaltIIIbisphenanthrolineReportar como inadecuado

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Sucrose forms a dicationic complex with cobaltIIIbisphenanthroline which can be isolated as the sparingly water-soluble triiodide salt or the water-soluble chloride. The circular dichroism CD spectrum demonstrates the Delta configuration at CoIII and the presence of two phenanthroline and one sucrose residues in the complex. The 0-2g-O-1f distance in crystalline sucrose permits strain-free coordination of these centers with CoIII and in the complex the H-1,1 - f singlet of sucrose separates into a pair of doublets. The H-1 NMR spectrum in DMSO-d6 shows that OH-2g is deprotonated and the signal of OH-1f is shifted strongly downfield by complexation with CoIII. Coordination involving glucose and fructose residues is consistent with neither a-methyl glucoside nor fructofuranose forming mixed complexes with phenanthroline. Structure simulation with the semi-empirical PM3tm basis set indicates that complexation by O-2g and OH-1f can give a Delta -complex with little structural distortion, whereas in hypothetical Delta -complexes there is distortion of the sucrose residue. Observation of an NOE involving the sucrose and phenanthroline residues supports the postulated structure of the Delta -complex.Nota general

Artículo de publicación ISI

Autor: Bunel Torrealba, Sergio; - Ibarra, Carmen; - Moraga, Exequiel; - Larrazábal Rojas, Guillermo; - Gillitt, N. D.; - Parada Aliste,



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