Synthesis, Structure, and Properties of Tetrabenzo[7]circulene

Tetrabenzo­[7]­circulene,
a new member of aromatic saddles, was conveniently
synthesized from 2-(1-naphthoyl)­benzoic acid with the seven-membered
ring constructed at an early stage of the synthesis. This method,
upon minor modification, was also useful for synthesis of thiophene-annulated
[7]­circulenes. The structures of tetrabenzo[7]­circulene and [7]­circulene
were compared in terms of symmetry, flexibility, and curvature on
the basis of DFT calculations and X-ray crystallography. It was also
found that tetrabenzo[7]­circulene functioned as a p-type semiconductor
in thin-film transistors and cocrystallized with C60.