In Situ Quantification of Directional Rotation by a Catalysis-Driven Azaindole-N-Oxide-Phenoic Acid Molecular Motor

Area of Science:

• Molecular Engineering
• Supramolecular Chemistry
• Nanotechnology

Background:

• Artificial molecular motors are crucial for nanoscale applications.
• Previous methods for assessing motor directionality relied on indirect models.
• Quantifying motor performance metrics like speed and efficiency is essential for development.

Purpose of the Study:

• To report the in situ quantification of directional rotation for a novel catalysis-driven rotary motor.
• To establish a straightforward method for assessing motor behavior directly.
• To validate a new approach by comparing it with restricted rotation models.

Main Methods:

• Utilized a phenyl carboxylic acid rotor and a 7-azaindole-N-oxide stator.
• Employed carbodiimide hydration catalyzed by a chiral pyrrolidinylpyridine-N-oxide.
• Analyzed transient concentrations of diastereomeric intermediates for directionality determination.

Main Results:

• Achieved continuous, directional 360° rotation of the molecular motor.
• Demonstrated in situ quantification of motor directionality, speed, and efficiency.
• Found excellent agreement between in situ determined directionality and restricted rotation models.

Conclusions:

• The developed method provides direct access to key performance indicators of molecular motors.
• This approach simplifies the assessment of motor directionality, avoiding reliance on indirect models.
• The findings facilitate the design and optimization of advanced artificial molecular motors.