Intramolecular Amide Stacking and Its Competition with Hydrogen Bonding in a Small Foldamer

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• 作者：William H. James III ; Christian W. Mller ; Evan G. Buchanan ; Michael G. D. Nix ; Li Guo ; Luke Roskop ; Mark S. Gordon ; Lyudmila V. Slipchenko ; Samuel H. Gellman ; Timothy S. Zwier
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：October 14, 2009
• 年：2009
• 卷：131
• 期：40
• 页码：14243-14245
• 全文大小：174K
• 年卷期：v.131,no.40(October 14, 2009)
• ISSN：1520-5126

文摘

Attractive interactions between two carboxamide groups in a “stacked” geometry are explored under isolated molecule conditions. Infrared spectra of single conformations of a small γ-peptide, Ac-γ²-hPhe-NHMe, reveal the presence of a conformation in which the two amide planes are approximately parallel with the amide dipoles in an antialigned orientation. This stacked conformation is energetically comparable to conformations that contain an intramolecular amide−amide H-bond. Amide stacking interactions can compete with H-bonding in circumstances where the amide groups can be brought into a stacking configuration with minimal strain, opening the way for its use in the design of future foldamer structures.