Control of pyramidal inversion rates by redox switching

Area of Science:

• Organic Chemistry
• Molecular Dynamics
• Supramolecular Chemistry

Background:

• Pyramidal nitrogen inversion is a fundamental molecular motion.
• Controlling molecular dynamics is crucial for designing novel chemical processes.
• Aziridines are strained three-membered heterocycles with unique reactivity.

Purpose of the Study:

• To investigate the control of pyramidal nitrogen inversion dynamics.
• To explore the role of redox switching in modulating molecular motion.
• To synthesize and characterize novel trans-2,3-diphenylaziridines with redox-active substituents.

Main Methods:

• Synthesis of trans-2,3-diphenylaziridines with 1,4-naphthaquinone substituents.
• Redox manipulation of the naphthaquinone moiety.
• Variable temperature Nuclear Magnetic Resonance (NMR) spectroscopy to study inversion dynamics.
• Density Functional Theory (DFT) calculations to support experimental observations.

Main Results:

• Reversible redox switching effectively controlled nitrogen inversion dynamics.
• Reduction of the 1,4-naphthaquinone substituent induced an intramolecular hydrogen bond.
• This hydrogen bond significantly increased the nitrogen inversion barrier by over 50-fold.
• DFT calculations corroborated the experimental findings regarding the hydrogen bond's influence.

Conclusions:

• Nitrogen inversion dynamics in diphenylaziridines can be precisely controlled via external redox stimuli.
• Intramolecular hydrogen bonding is a powerful strategy for modulating high-energy molecular motions.
• This work provides a new platform for designing switchable molecular systems.