The Green Box: An Electronically Versatile Perylene Diimide Macrocyclic Host for Fullerenes

Area of Science:

• Supramolecular Chemistry
• Organic Electronics
• Photochemistry

Background:

• Fullerenes are key electron acceptors in biomimetic systems, modeling natural photosynthesis.
• Perylene diimides (PDIs) are typically electron-deficient, hindering their use in fullerene recognition systems.
• Designing electron-rich PDIs is crucial for creating favorable donor-acceptor dyads.

Purpose of the Study:

• To synthesize a novel macrocyclic host using electron-rich PDI units for fullerene recognition.
• To investigate the electronic interactions and electron transfer dynamics between the host and fullerene guests.
• To explore solvent-tunable electronic communication in fullerene-based supramolecular systems.

Main Methods:

• Synthesis of a large, macrocyclic receptor (
• Green Box
• ) composed of electron-rich bis-pyrrolidine PDI panels.
• Spectroscopic characterization including electronic absorption, fluorescence emission, NMR, time-resolved EPR, and mass spectrometry.
• Electrochemical analysis via cyclic voltammetry and computational studies using DFT.

Main Results:

• The Green Box effectively recognizes fullerenes (C_60/70) through noncovalent interactions.
• Partial charge transfer occurs in low polarity solvents, while full electron transfer to form a radical ion pair is achieved in high polarity solvents.
• The charge-separated state exhibits thermodynamic reversibility and kinetic stability.
• Demonstrated unprecedented intermolecular, solvent-tunable ground-state electronic communication with fullerenes.

Conclusions:

• The Green Box is a pioneering host utilizing electron-rich PDIs for fullerene recognition.
• This system enables control over electron transfer, bridging the gap between host-guest chemistry and organic electronics.
• The ability to tune charge transfer states offers new avenues for designing advanced functional materials.