A macrocyclic oligofuran: synthesis, solid state structure and electronic properties

Area of Science:

• Organic electronics
• Macromolecular chemistry
• Materials science

Background:

• π-conjugated systems are crucial for organic electronic devices.
• Macrocyclic structures offer unique electronic and packing properties compared to linear polymers.
• Oligofurans are promising building blocks for conjugated materials.

Purpose of the Study:

• To synthesize and characterize the first π-conjugated macrocyclic system with an oligofuran backbone.
• To investigate the electronic properties, solid-state structure, and charge transport behavior.
• To compare its properties with linear oligofuran polymers and related macrocycles.

Main Methods:

• Synthesis of the oligofuran macrocycle.
• Computational calculations (HOMO-LUMO gap).
• X-ray crystallography.
• Solution and surface adsorption studies.
• Charge mobility measurements.

Main Results:

• The oligofuran macrocycle displays a small HOMO-LUMO gap, comparable to linear polymers, indicating significant electron delocalization.
• X-ray structure reveals a planar conformation and an exceptionally small intermolecular π-π stacking distance (3.17 Å).
• The macrocycle forms large π-aggregates in solution and ordered multilayers on surfaces, with molecules adopting a face-on orientation.
• Higher hole mobility was observed in the out-of-plane direction due to this orientation.

Conclusions:

• The synthesized oligofuran macrocycle is a promising material for organic electronics.
• Its planar structure and strong π-π stacking facilitate efficient charge transport.
• The findings open new avenues for designing advanced organic semiconductor materials.