Tuning rotational barriers through substituent modification in catechol-diyl molecular gyrotops
Hyu Kishii1, Yusuke Inagaki1, Kazuaki Ohara2
1Division of Applied Chemistry, Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan. wsetaka@tmu.ac.jp.
Organic & Biomolecular Chemistry
|October 17, 2025
Summary
Researchers designed novel molecular gyrotops with a bridged π-electron system. Tuning substituents modulated internal rotor dynamics, offering a strategy for controllable molecular machines.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
- Materials Science
Background:
- Macrocage molecules with bridged π-electron systems offer unique platforms for molecular rotors.
- Molecular gyrotops utilize internal rotors confined within a cage structure.
Purpose of the Study:
- To design and synthesize novel molecular gyrotops incorporating a bridged catechol-3,6-diyl unit.
- To investigate the rotational dynamics and energy barriers of these novel molecular gyrotops.
- To explore the modulation of internal motion through systematic substituent tuning.
Main Methods:
- Organic synthesis for the design and preparation of macrocage molecules 1a, 1b, and 1c.
- Structural characterization using spectroscopic techniques.
- Variable-temperature nuclear magnetic resonance (VT-NMR) spectroscopy to study rotational dynamics.
Main Results:
- Successful synthesis of novel molecular gyrotops 1a (catechol-3,6-diyl), 1b (dimethoxy), and 1c (diethoxy).
- Variable-temperature NMR spectroscopy confirmed the active rotational dynamics of the phenylene rotor within the macrocage.
- Systematic variation of alkoxy substituents demonstrated control over the rotational energy barriers.
Conclusions:
- A new class of molecular gyrotops has been developed.
- Tuning substituents on the bridged π-electron system allows for modulation of internal rotational dynamics.
- These findings provide design principles for engineering controllable internal motion in functional molecular machines.
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