Photoswitchable Norbornadiene-Quadricyclane Interconversion Mediated by Covalently Linked C₆₀

Area of Science:

• Organic Chemistry
• Materials Science
• Photochemistry

Background:

• Norbornadiene/quadricyclane (NBD/QC) systems are known energy storage molecules.
• Fullerenes are versatile carbon allotropes with unique electronic properties.
• Hybrid molecules combining NBD/QC scaffolds with fullerenes offer novel functionalities.

Purpose of the Study:

• To synthesize and characterize novel norbornadiene/quadricyclane fullerene hybrids.
• To investigate the photoisomerization behavior of these hybrid systems.
• To develop a light-driven molecular switch based on NBD/QC fullerene interconversion.

Main Methods:

• Cyclopropanation of C60 using malonates with NBD scaffolds to form monoadducts and hexakisadducts.
• Photoisomerization studies under varying UV-Vis irradiation wavelengths.
• Redox potential measurements to study the fullerene core's influence.

Main Results:

• Successful synthesis of a library of NBD-fullerene monoadducts and hexakisadducts.
• Demonstration of direct photoisomerization from NBD-fullerene to QC-fullerene derivatives.
• Achieved reversible switching between NBD and QC forms using light (310-400 nm).
• The fullerene core's electron affinity impacts QC derivative properties.

Conclusions:

• NBD-fullerene hybrids can be controllably switched between isomers using light, functioning as pure photoswitches.
• The developed system simplifies the study of NBD-QC interconversion.
• These hybrids show potential for applications in molecular switches and light-responsive materials.