Stereoselective Syntheses, Structures and Properties of Extremely Distorted Chiral Nanographenes Embedding Hextuple Helicenes - Aix-Marseille Université Access content directly
Journal Articles Angewandte Chemie International Edition Year : 2020

Stereoselective Syntheses, Structures and Properties of Extremely Distorted Chiral Nanographenes Embedding Hextuple Helicenes

Salomé Poyer
Laurence Charles
Jean Rodriguez
  • Function : Author
  • PersonId : 921781
  • IdRef : 260692638

Abstract

We report a molecular design and concept using p-system elongation and steric effects from helicenes surrounding a triphenylene core toward stable chiral polycyclic aromatic hydrocarbons (PAHs) with a maximal p-distortion to tackle their aromaticity, supramolecular and molecular properties. The selective syntheses, and the structural, conformational and chiroptical properties of two diastereomeric large multi-helicenes of formula C90H48 having a triphenylene core and embedding three [5]helicene units on their inner edges and three [7]helicene units at their periphery are reported based on diastereoselective and, when applicable, enantiospecific (!) Yamamoto-type cyclotrimerizations of racemic or enantiopure 9,10-dibromo[7]helicene. Both molecules have an extremely distorted triphenylene core, and one of them exhibits the largest torsion angle recorded so far for a benzene ring (twist = 36.9º). The analysis of aromaticity distribution in these model molecules using magnetic criteria revealed a non-aromatic character of their triphenylene cores and provides a new look at aromaticity in threedimensional PAHs. One diastereomer can complex up to three silver(I) ions in the bay region (cavities) of its peripheral [7]helicene units, opening the door to chiral cationic metal-nanographene hybrids.
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Dates and versions

hal-03064338 , version 1 (14-12-2020)

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Cite

Myriam Roy, Veronika Berezhnaia, Marco Villa, Nicolas Vanthuyne, Michel Giorgi, et al.. Stereoselective Syntheses, Structures and Properties of Extremely Distorted Chiral Nanographenes Embedding Hextuple Helicenes. Angewandte Chemie International Edition, 2020, 59 (8), pp.3264-3271. ⟨10.1002/anie.201913200⟩. ⟨hal-03064338⟩

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