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Updated: Dec 23, 2025

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Enhanced reactivity of twisted amides inside a molecular cage
Hiroki Takezawa1, Kosuke Shitozawa2, Makoto Fujita3,4
1Department of Applied Chemistry, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, Japan. takezawa@appchem.t.u-tokyo.ac.jp.
Abstract:
When an amide group is distorted from its planar conformation, the conjugation between the nitrogen lone pair and the π* orbital of the carbonyl is disrupted and the reactivity towards nucleophiles is enhanced. Although there are several reports on the synthesis of activated twisted amides, amide activation through mechanical twisting is much less common. Here, we report twisted amides that are stabilized through their inclusion in a self-assembled coordination cage. When secondary aromatic amides are included in a Td-symmetric cage, the cis-twisted conformation is favoured over the trans-planar one-as evidenced by single-crystal X-ray diffraction analysis-revealing that the amide can twist by up to 34°. As a consequence of this distortion, the hydrolysis of amides is significantly accelerated upon inclusion.
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