Flyby reaction trajectories: Chemical dynamics under extrinsic force

Area of Science:

• Chemical dynamics
• Mechanochemistry
• Organic chemistry

Background:

• Dynamic effects significantly influence chemical reactivity and selectivity.
• Manipulating atomic motions during chemical reactions is challenging.
• Understanding force-induced effects is crucial for controlling chemical transformations.

Purpose of the Study:

• To demonstrate the influence of extrinsic force on chemical product selectivity.
• To investigate force-imparted nonstatistical dynamic effects in a stepwise ring-opening reaction.
• To establish a mechanistic model for mechanochemical stereoselectivity.

Main Methods:

• Applying extrinsic mechanical force to cyclobutanes via pendant polymer chains.
• Quantifying product stereoselectivity using carbon-13 labeling.
• Employing computational modeling and simulations to analyze reaction dynamics.

Main Results:

• External force significantly influences product stereoselectivity.
• Mechanical force activates intramolecular motions nonstatistically, creating direct "flyby trajectories".
• Force alters energy barriers and promotes direct product formation without isomerization.

Conclusions:

• Extrinsic force can deliberately manipulate atomic motions to control chemical reactivity.
• Nonstatistical dynamic effects are key to achieving high mechanochemical stereoselectivity.
• A mechanistic model incorporating these effects explains isomer-dependent outcomes.