Stabilizing the Hexacyanotrimethylenecyclopropane Electron Acceptor-Structural and Photophysical Characterization

Area of Science:

• Organic Chemistry
• Materials Science
• Physical Chemistry

Background:

• Hexacyanotrimethylenecyclopropane (CN6CP) is a potent organic electron acceptor used in molecular doping and electrochemical systems.
• Its fundamental molecular properties and structural characteristics remain largely uncharacterized.

Purpose of the Study:

• To perform a comprehensive structure-analytical characterization of neutral CN6CP.
• To elucidate the electronic structure and properties of CN6CP across its redox states.
• To establish the molecular basis for CN6CP's performance in organic electronics.

Main Methods:

• Improved low-temperature synthesis yielding crystalline and stable CN6CP.
• Solid-state structure determination.
• Combined IR/Raman, UV-Vis, and NMR spectroscopy.
• NICS calculations.
• Cyclic voltammetry.

Main Results:

• The first solid-state structure of neutral CN6CP was obtained.
• Oxidation-state-dependent electron density redistribution was observed.
• CN6CP exhibits a σ-aromatic cyclopropane core with tunable π-delocalization.
• An exceptionally low LUMO energy of -5.85 eV was measured, surpassing benchmarks like F4TCNQ.
• Two reversible one-electron processes were identified.

Conclusions:

• CN6CP is a structurally unique and extremely strong organic electron acceptor.
• Its electronic properties are tunable via redox state changes.
• This work provides critical molecular insights into CN6CP's utility in organic electronics and redox-active materials.