Structural, optical, and electrochemical properties of three-dimensional push-pull corannulenes

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Corannulene derivatives are explored for their unique optoelectronic properties.
• Tuning substituent groups influences molecular behavior and potential applications.
• Understanding structure-property relationships is crucial for designing new materials.

Purpose of the Study:

• To synthesize and characterize novel electrochemically active corannulene derivatives.
• To investigate the impact of electron-donating and electron-withdrawing substituents on optoelectronic and conformational properties.
• To explore the potential for intramolecular charge-transfer (ICT) and fluorescence in these systems.

Main Methods:

• Synthesis of corannulene derivatives with 4-(N,N-dimethylamino)phenylethynyl or cyanobutadienyl substituents.
• Variable-temperature Nuclear Magnetic Resonance (NMR) and X-ray diffraction for conformational analysis.
• Electronic absorption/emission spectroscopy and electrochemical measurements for optoelectronic characterization.
• Dispersion-corrected density functional calculations (B97-D/def2-TZVPP) for theoretical validation.

Main Results:

• Electron-donating derivatives (1-4) exhibit strong ICT absorptions (350-550 nm) and high-yield green/orange fluorescence.
• These derivatives show enhanced reducibility compared to unsubstituted corannulene.
• Electron-withdrawing cyanobutadienyl derivatives (5-8) display red-shifted ICT absorptions extending to 800 nm.
• Intersubstituent interactions in 5-8 cause core distortions, reduced symmetry, and suggest intermolecular dimer formation.
• Bowl-inversion barriers were determined for specific cyanobutadienyl derivatives.

Conclusions:

• The synthesized corannulene derivatives possess tunable optoelectronic properties based on substituent type.
• The study provides insights into structure-property correlations, including ICT, fluorescence, and conformational dynamics.
• These findings contribute to the development of advanced functional organic materials.