A Boat-Shaped Tetracationic Macrocycle with a Semiconducting Organic Framework

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Electronics

Background:

• Cyclobis(paraquat-p-phenylene) (CBPQT4+) is a well-known tetracationic macrocycle.
• Naphthalenediimide (NDI) units are electroactive and have been explored in organic electronics.

Purpose of the Study:

• To synthesize a novel tetracationic macrocycle by incorporating NDI units into CBPQT4+.
• To investigate the supramolecular, electrochemical, and electronic properties of the new macrocycle.
• To explore its potential applications in organic electronic materials.

Main Methods:

• Chemical synthesis of the tetracationic macrocycle.
• Single-crystal X-ray diffraction for structural analysis.
• Electrochemical studies (cyclic voltammetry, conductivity measurements).
• Electron Paramagnetic Resonance (EPR) and Electron Nuclear Double Resonance (ENDOR) spectroscopies.

Main Results:

• A novel tetracationic macrocycle containing two NDI units within a CBPQT4+ framework was successfully synthesized.
• The solid-state structure revealed a 3D supramolecular framework with 1D hexagonal channels (2.8 nm diameter).
• Solid-state thin films exhibited semiconducting properties with redox-conductivity up to 7.6×10-4 S/m.
• Charge was found to be equally shared between NDI units in the one-electron reduced state.

Conclusions:

• The incorporation of NDI units significantly alters the supramolecular and electronic properties of CBPQT4+.
• The synthesized macrocycle demonstrates promising semiconducting behavior for organic electronics.
• The study highlights the potential of tailored macrocyclic structures for advanced materials applications.