Syntheses, structures, and supramolecular properties of giant π-expanded macrocyclic oligothiophenes

✍ Scribed by Masahiko Iyoda

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 257 KB
• Volume: 18
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.20337

✦ Synopsis

Abstract

Fully conjugated π‐expanded macrocyclic oligothiophenes with 60π‐, 90π‐, 120π‐, 150π‐, and 180π‐electron systems (1–5) were synthesized using modified McMurry coupling reaction as a key step. Compound 1 was converted into macrocyclic oligo(2,5‐thienylene‐ethynylene) 6 using bromination‐dehydrobromination procedure. X‐ray analysis of 1 revealed a unique molecular and packing structure, reflecting a round, planar shape with nanoscale inner cavity. Interestingly, 2 and 3 self‐aggregate in the solid state to form nanowires. The structure of fibrous aggregates was established by scanning electron microscopic and atomic force microscopic analyses. Compounds 1–6 exhibit multi‐step reversible redox behavior with fairly low first oxidation potentials, reflecting their cyclic conjugation. Doping of 1–3 with iodine gives semiconductors owing to their π‐donor properties and π–π stacking ability. © 2007 Wiley Periodicals, Inc. 18:460–466, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20337