Light-Fueled Transformations of a Dynamic Cage-Based Molecular System.

Area of Science:

• Chemical Equilibrium
• Photochemistry
• Supramolecular Chemistry

Background:

• Chemical equilibrium typically favors low-energy states, making high-energy species formation inefficient in closed systems due to microscopic reversibility.
• Azobenzene imine cages offer a unique platform for dynamic control over chemical reactions.

Purpose of the Study:

• To circumvent the limitations of microscopic reversibility in chemical equilibria.
• To demonstrate a light-induced method for shifting equilibria energetically uphill in a closed system.
• To achieve light-controlled cage-to-cage transformations.

Main Methods:

• Coupling a dynamic imine exchange equilibrium to light-induced E/Z isomerization of an azobenzene imine cage.
• Utilizing the stable E-cage's resistance to imine exchange and the strained Z-cage's spontaneous opening.
• Employing subsequent isomerization to kinetically trap high-energy E-open species.

Main Results:

• Demonstrated the ability to circumvent microscopic reversibility using light-induced azobenzene imine isomerization.
• Achieved an energetically uphill shift in imine equilibrium within a closed system.
• Successfully performed a light-induced cage-to-cage transformation by adding a ditopic aldehyde.

Conclusions:

• Light-induced isomerization of azobenzene imine cages provides a powerful strategy to control chemical equilibria.
• This method allows for the efficient generation of high-energy, kinetically trapped species.
• The developed principle enables novel light-driven molecular transformations and supramolecular assembly.