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Updated: May 22, 2026
09:45
Modification and Functionalization of the Guanidine Group by Tailor-made Precursors
Published on: April 27, 2017
Controlling the Guanidinium Cation Rotation by Cation-π Interactions
Hannah Busch1,2, Lennart Günzel3, Ettore Bartalucci1,2,4
1Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Aachen, Germany.
Angewandte Chemie (International Ed. in English)
|May 21, 2026
Summary
Researchers trapped guanidinium cations in a π-container, restricting their rotation. This work brings chemists closer to controlling molecular motion using host-guest interactions.
Area of Science:
- Supramolecular Chemistry
- Solid-State Chemistry
- Molecular Dynamics
Background:
- Guanidinium is crucial in biology and chemistry, participating in molecular recognition via noncovalent interactions.
- Guanidinium cations in solids typically exhibit rapid rotation (picoseconds) around symmetry axes.
Purpose of the Study:
- To investigate host-guest interactions and control guanidinium cation rotation.
- To utilize a π-container to trap guanidinium cations via cation-π interactions.
Main Methods:
- Employing a π-container (calixarene framework) to encapsulate guanidinium.
- Utilizing X-ray crystallography and solid-state nuclear magnetic resonance (NMR) spectroscopy.
- Conducting temperature-dependent NMR experiments, quantum-chemical calculations, and molecular dynamics (MD) simulations.
Main Results:
- Successfully trapped guanidinium cations within the π-container.
- Characterized host-guest interactions and restricted guanidinium cation rotation.
- Observed ns-order correlation times for rotation about the C3-axis, a significant slowdown from ps-scale.
Conclusions:
- The calixarene framework acts as a bearing, effectively trapping and controlling guanidinium cation rotation.
- This study demonstrates a method for achieving controlled molecular motion, a long-sought goal in chemistry.
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