Structural Expression of Exo-Anomeric Effect

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• 作者：Elena R. Alonso ; Isabel Peña ; Carlos Cabezas ; José L. Alonso
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：March 3, 2016
• 年：2016
• 卷：7
• 期：5
• 页码：845-850
• 全文大小：385K
• ISSN：1948-7185

文摘

Structural signatures for exo-anomeric effect have been extracted from the archetypal methyl-β-d-xyloside using broadband Fourier transform microwave spectroscopy combined with laser ablation. Spectrum analysis allows the determination of a set of rotational constants, which has been unequivocally attributed to conformer cc-β-⁴C₁ g–, corresponding to the global minimum of the potential energy surface, where the aglycon residue (CH₃) orientation contributes to maximization of the exo-anomeric effect. Further analysis allowed the determination of the r_s structure, based on the detection of 11 isotopologues—derived from the presence of six ¹³C and five ¹⁸O atoms—observed in their natural abundances. The observed glycosidic C₁–O₁ bond length decrease (1.38 Å) can be interpreted in terms of the exo-anomeric effect. As such, the exo-anomeric effect presents itself as one of the main driving forces controlling the shape of many biologically important oligosaccharides.