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A Nonalternant Aromatic Belt: Methylene-Bridged [6]Cycloparaphenylene Synthesized from Pillar[6]arene.

A Nonalternant Aromatic Belt: Methylene-Bridged [6]Cycloparaphenylene Synthesized from Pillar[6]arene.

Authors :
Li Y
Segawa Y
Yagi A
Itami K
Source :
Journal of the American Chemical Society [J Am Chem Soc] 2020 Jul 22; Vol. 142 (29), pp. 12850-12856. Date of Electronic Publication: 2020 Jul 09.
Publication Year :
2020

Abstract

The synthesis, structure, and properties of methylene-bridged [6]cycloparaphenylene ([6]CPP), a nonalternant aromatic belt, are described. This belt-shaped methylene-bridged [6]CPP, in which each phenylene unit is tethered to its neighbors by methylene bridges, was constructed through 6-fold intramolecular nickel-mediated aryl-aryl coupling of triflate-functionalized pillar[6]arene in 18% isolated yield. As compared to the analogous [6]CPP, the methylene bridges coplanarize neighboring paraphenylene units and enhance the degree of π-conjugation, which results in a significant decrease in energy gap. Moreover, the incorporation of small molecules in the defined pocket of methylene-bridged [6]CPP makes it an attractive supramolecular architecture. Methylene-bridged [6]CPP is characterized by high internal strain energy reaching 110.2 kcal mol <superscript>-1</superscript> , attributed to its restricted structure. This work not only exhibits an efficient strategy to construct a new family of aromatic belt, but also showcases their properties, which combine the merits of CPPs and pillararenes.

Details

Language :
English
ISSN :
1520-5126
Volume :
142
Issue :
29
Database :
MEDLINE
Journal :
Journal of the American Chemical Society
Publication Type :
Academic Journal
Accession number :
32603101
Full Text :
https://doi.org/10.1021/jacs.0c06007