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

Autor: Stephan K. Pedersen, Pernille S. Bols, Glib V. Baryshnikov, Ole Hammerich, Kasper H. Hansen, Michael Pittelkow, Sergey V. Bondarchuk, Boris F. Minaev, Michelle R. Pedersen, Bodil Lousen, Hans Ågren
Rok vydání: 2020
Předmět:
Zdroj: Chemistry – A European Journal. 26:4935-4940
ISSN: 1521-3765
0947-6539
Popis: 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).
Databáze: OpenAIRE
Externí odkaz:
Nepřihlášeným uživatelům se plný text nezobrazuje