Geodesic polyarene

A geodesic polyarene in organic chemistry is a polycyclic aromatic hydrocarbon with curved convex or concave surfaces. 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.

One member of this group of organic compounds, pentaindenocorannulene (depicted below), can be considered a large fullerene fragment. The experimentally obtained curvature and degree of pyramidalizion (12.6° ) are both actually larger then 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.