A Triply [5]Helicene-Bridged (1,3,5)Cyclophane

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Conjugated macrocycles are crucial in molecular electronics and materials science.
• Helicene derivatives offer unique chiroptical and electronic properties.
• Understanding electron delocalization in complex aromatic systems is key to designing novel functional molecules.

Purpose of the Study:

• To synthesize a novel propeller-shaped conjugated triple macrocycle.
• To investigate the electronic properties and aromaticity of this unique molecular architecture.
• To analyze the pi-electron delocalization pathways within the macrocycle.

Main Methods:

• Glyoxylic Perkin approach for macrocycle synthesis.
• Spectroscopic and crystallographic analyses for structural confirmation.
• Computational methods to study electron delocalization and aromaticity.

Main Results:

• Successful synthesis of a rigid, propeller-shaped triple macrocycle incorporating [5]helicene units.
• Demonstration of global aromaticity in the macrocyclic system.
• Identification of a dominant 78π-electron circuit along the macrocycle's edge.
• Reduced aromaticity in the internal stacked benzene rings due to delocalization into the macrocyclic circuit.

Conclusions:

• The synthesized macrocycle represents a new class of atypical aromatic molecules.
• The unique electronic structure facilitates extensive pi-electron delocalization, influencing the properties of constituent units.
• This work provides insights into the design principles for novel conjugated systems with tailored electronic properties.