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Geodesic polyarene

A geodesic polyarene in organic chemistry is a polycyclic aromatic hydrocarbon with curved convex or concave surfaces ^[1]. Examples are fullerenes, nanotubes, corannulenes, helicenes and sumanene. The carbon atoms in these systems are to some extent pyramidalized resulting a different pi electron density on either side of the molecule with consequences for reactivity.

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One member of this group of organic compounds, pentaindenocorannulene (depicted below) ^[2] ^[3], can be considered a large fullerene fragment. The experimentally obtained curvature and degree of pyramidalizion (12.6° ^[4]) are both actually larger than that of fullerene but according to its discoverers the compound is relatively easy to synthesize starting from corannulene and a way is opened to produce larger such fragments by stitching.

References

^ Geodesic polyarenes with exposed concave surfaces Lawrence T. Scott,† Hindy E. Bronstein, Dorin V. Preda, Ronald B. M. Ansems, Matthew S. Bratcher and Stefan Hagen Pure & Appl. Chem., Vol. 71, No. 2, pp. 209–219, 1999 Link
^ Pentaindenocorannulene and Tetraindenocorannulene: New Aromatic Hydrocarbon Systems with Curvatures Surpassing That of C60Edward A. Jackson, Brian D. Steinberg, Mihail Bancu, Atsushi Wakamiya, and Lawrence T. Scott J. Am. Chem. Soc.; 2007; 129(3) pp 484 - 485; (Communication) doi:10.1021/ja067487h
^ The two steps in this sequence are a Suzuki-Miyaura coupling with an ionic liquid and Tris(dibenzylideneacetone)dipalladium(0) and a Heck reaction with another palladioum catalyst, DBU and DMAC
^ by a so-called p-orbital axis vector (POAV). The value for fullerene is 11.6° and benzene 0°