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Chiral Distorted Hexa‐ peri ‐hexabenzocoronenes Bearing a Nonagon‐Embedded Carbohelicene
Author(s) -
Medel Miguel A.,
Cruz Carlos M.,
Miguel Delia,
Blanco Victor,
Morcillo Sara P.,
Campaña Araceli G.
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202109310
Subject(s) - helicene , moiety , planarity testing , hexa , chemistry , ring (chemistry) , stereochemistry , crystallography , circular dichroism , helix (gastropod) , molecule , organic chemistry , ecology , snail , biology
A new family of chiral saddle‐helix hybrid nanographenes is reported. The first hexa‐ peri ‐hexabenzocoronene (HBC) analogues bearing a nine‐membered carbocycle are presented. Furthermore, for the first time, π‐extended carbo[ n ]helicenes containing a nine‐membered ring as part of the helical moiety have been synthesized. The combination of a [5]helicene moiety and a nonagon ring in a single chiral motif induces a tremendous distortion from planarity into the nanographenic structures compared to other saddle‐helix hybrids such as heptagon‐ and octagon‐containing π‐extended carbo[5]helicenes. In fact, the interplanar angle of the two terminal rings reaches the largest angle (134.8°) of a carbohelicene reported to date, thus being by far the most twisted helicene yet prepared. Photophysical properties evaluation showed improved absorption dissymmetry factors (| g abs |=4.2×10 −3 ) in the new family of nonagon‐containing π‐extended carbo[5]helicenes.