Aromatic and Antiaromatic Dehydroannulenes.

Area of Science:

• Organic Chemistry
• Materials Science
• Physical Chemistry

Background:

• Cyclocarbons are an emerging class of carbon allotropes with unique properties.
• Their inherent instability hinders detailed physicochemical studies.
• Stable models are needed to investigate cyclocarbon precursors.

Purpose of the Study:

• To synthesize stable aromatic and antiaromatic models of cyclocarbon precursors.
• To investigate the electronic and structural properties of these novel compounds.
• To explore their potential applications in organic electronics.

Main Methods:

• Synthesis of cyclopentenone-annulated [18]- and [24]dehydroannulenes.
• Characterization using NMR spectroscopy, X-ray crystallography, optical spectroscopy, and electrochemistry.
• Computational analysis using density functional theory (DFT).

Main Results:

• Stable aromatic and antiaromatic annulene models were successfully synthesized.
• Cyclopenteno[24]dehydroannulenes showed two-electron reduction to form planar Hückel-aromatic dianions.
• Electron-withdrawing groups modulated redox potentials, enhancing electroactivity.
• NMR chemical shifts confirmed the aromatic and antiaromatic nature of the systems.

Conclusions:

• The synthesized annulenes serve as valuable models for studying cyclocarbons.
• These molecules exhibit tunable electronic properties and redox activity.
• The developed scaffolds show promise for applications in organic electronics and topochemical polymerization.