Synthesis and Structure of a Longitudinally Twisted Hexacene

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are crucial in organic electronics.
• Achieving high degrees of twisting in PAHs is challenging but offers unique electronic properties.
• Tetrabenzohexacene derivatives provide a scaffold for exploring complex PAH architectures.

Purpose of the Study:

• To synthesize and characterize a novel, highly twisted hexacene derivative.
• To investigate the structural and conformational properties of the synthesized compound.
• To compare experimental findings with computational predictions.

Main Methods:

• Addition of phenyllithium to a polycyclic quinone precursor.
• Tin(II) chloride-mediated reduction of a diol intermediate.
• X-ray crystallography for structural determination.
• AM1 computational calculations for conformational analysis.

Main Results:

• Successfully synthesized octaphenyltetrabenzohexacene (4).
• Crystallographic analysis revealed a significant longitudinal twist of 184°.
• The experimental twist angle closely matched AM1 computational predictions.
• Compound 4 represents the most twisted acene synthesized to date.
• Its substructure contains the most twisted naphthalene, anthracene, tetracene, and pentacene moieties.

Conclusions:

• A new, highly twisted hexacene derivative was synthesized and characterized.
• The study demonstrates the feasibility of creating PAHs with extreme twists.
• The findings provide insights into structure-property relationships in twisted aromatic systems.