These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
4 files

A Non-alternant Aromatic Belt: Methylene-bridged [6]Cycloparaphenylene Synthesized from Pillar[6]arene

submitted on 03.06.2020, 05:11 and posted on 04.06.2020, 05:14 by Yuanming Li, Yasutomo Segawa, Akiko Yagi, Kenichiro Itami
The synthesis, structure, and properties of methylene-bridged [6]cycloparaphenylene ([6]CPP), a non-alternant 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 six-fold intramolecular nickel-mediated aryl-aryl coupling of triflate-functionalized pillar[6]arene in 15% isolated yield. Compared with the analogous [6]CPP, the methylene bridges co-planarize neighboring paraphenylene units and enhance the degree of p-conjugation, resulting 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–1, 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.


Email Address of Submitting Author


Nagoya University



ORCID For Submitting Author


Declaration of Conflict of Interest

no conflict of interest