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Direct Imaging of Laser-driven Ultrafast Molecular Rotation
Published on: February 4, 2017
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Molecular Rotors as Reactivity Probes: Predicting Electrophilicity from the Speed of Rotation.
Hao Liu1, Xiaolong Huang1, Binzhou Lin1
1Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, 29205, USA.
Angewandte Chemie (International Ed. in English)
|July 30, 2025
Summary
A new reactivity parameter, E_RB, quantifies electrophilicity using molecular rotor rotational barriers. This method effectively predicts reactivity trends for diverse electrophiles and reaction types.
Area of Science:
- Organic Chemistry
- Physical Chemistry
- Computational Chemistry
Background:
- Electrophilicity is a key chemical property governing reactivity.
- Quantifying electrophilicity empirically across diverse reactions remains challenging.
- Existing methods often lack broad applicability or rely heavily on computational predictions.
Purpose of the Study:
- To develop a novel empirical parameter, E_RB, for quantifying electrophilicity.
- To establish a reliable method for predicting electrophilicity and reactivity trends.
- To validate the new parameter across a wide range of electrophilic reactions.
Main Methods:
- Synthesis of N-phenylimide molecular rotors with various electrophilic groups.
- Measurement of rotational barriers using dynamic Nuclear Magnetic Resonance (NMR) spectroscopy (EXSY).
- Computational analysis to understand transition state interactions.
Main Results:
- Rotational barriers were inversely correlated with electrophile strength.
- E_RB parameter was developed based on these rotational barriers.
- The parameter successfully predicted reactivity for Michael addition, S_N2, S_NAr, Pd-oxidative addition, and Sonogashira reactions.
Conclusions:
- E_RB provides an effective empirical measure of electrophilicity.
- The method captures crucial transition state interactions (electrostatic and steric).
- E_RB offers a versatile tool for predicting reactivity across diverse chemical transformations.
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