Alternately Twisted, Electron-Rich Rylenes and Their Stable Cations

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Solution-phase synthesis of long rylenes is difficult due to aggregation.
• Backbone twisting can mitigate aggregation and introduce chirality.

Purpose of the Study:

• To synthesize novel, long rylene molecules with reduced aggregation.
• To investigate the impact of backbone twisting and substituents on molecular properties.

Main Methods:

• Stepwise cross-coupling reactions.
• Controlled oxidative dehydrogenation.
• X-ray crystallography, 1H NMR, and ACID analyses.

Main Results:

• Successfully synthesized rylene molecules up to octarylene with twisted backbones and n-butoxy substituents.
• Observed alternating P/M helicity in rylenes with multiple tetra(n-butoxy) motifs.
• Demonstrated length-dependent optical properties (visible to NIR) and facile formation of radical cations/dications.
• Revealed evolution from local to global aromaticity in dications.

Conclusions:

• The developed synthetic strategy effectively overcomes aggregation challenges in long rylene synthesis.
• Twisted rylene structures exhibit unique helical conformations and tunable optoelectronic properties.
• The electron-rich nature and stability of their oxidized forms are promising for electronic applications.