Reversible redox switching between local and global aromaticity for core-modified expanded carbaisophlorinoids

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Theoretical Chemistry

Background:

• Dithienothiophene units are key building blocks in organic electronics.
• Antiaromatic macrocycles present unique electronic properties due to their (4n+2)π electron systems.
• Understanding local and global aromaticity is crucial for designing novel materials.

Purpose of the Study:

• To synthesize and characterize novel dithienothiophene-based 28π antiaromatic macrocycles.
• To investigate the influence of benzene and azulene units on macrocyclic (anti)aromaticity.
• To elucidate the ring current effects in neutral and dicationic states.

Main Methods:

• Synthesis of dithienothiophene-based macrocycles.
• Experimental characterization (e.g., NMR spectroscopy, X-ray crystallography).
• Computational studies (e.g., DFT calculations) to analyze electronic structure and ring currents.

Main Results:

• Successful synthesis of two 28π antiaromatic macrocycles incorporating benzene and azulene units.
• Experimental and computational evidence for weak paratropic ring current effects in the neutral state.
• Observation of strong diatropic ring current effects in the dicationic state.

Conclusions:

• The designed macrocycles exhibit tunable antiaromatic character.
• Benzene and azulene units significantly influence the electronic properties and aromaticity.
• These findings contribute to the understanding of antiaromaticity in complex π-systems.