Compressing a Non-Planar Aromatic Heterocyclic [7]Helicene to a Planar Hetero[8]Circulene

Pittelkow, M. and Lousen, B. and Pedersen, S. K. and Bols, P. S. and Pedersen, M. R. and Hansen, K. H. and Hammerich, O. and Bondarchuk, S. and Minaev, B. and Baryshnikov, G. V. and Agren H, H. (2020) Compressing a Non-Planar Aromatic Heterocyclic [7]Helicene to a Planar Hetero[8]Circulene. Chem.-Eur. J, Vol.26 (N 22). pp. 4935-4940.

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This work describes a synthetic approach where a non-planar aromatic heterocyclic [7]helicene is compressed to yield a hetero[8]circulene containing an inner antiaromatic cyclooctatetraene (COT) core. This [8]circulene consists of four benzene rings and four heterocyclic rings, and it is the first heterocyclic [8]circulene containing three different heteroatoms. The synthetic pathway proceeds via a the flattened dehydro-hetero[7]helicene, which is partially a helicene and partially a circulene: it is non-planar and helically chiral as helicenes, and contains a COT motif like [8]circulenes. The antiaromaticity of the??COT core is confirmed by nucleus independent chemical shift (NICS) calculations. The planarization from a helically p-conjugated [7]helicene to a fully planar heterocyclic [8]circulene significantly alters the spectroscopic properties of the molecules. Post-functionalization of the [7]helicenes and the [8]circulenes by oxygenation of the thiophene rings to the corresponding thiophene-sulfones allows an almost complete fluorescence emission coverage of the visible region of the optical spectrum (400–700 nm).

Item Type: Article
Subjects: Хімічні науки
Divisions: Навчально-науковий інститут природничих та аграрних наук
Depositing User: Наукова Бібліотека
Date Deposited: 05 Mar 2021 09:01
Last Modified: 05 May 2021 07:17

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