Acirculene is amacrocyclicarene in which a centralpolygon is surrounded andfused bybenzenoids.^[1] Nomenclature within this class of molecules is based on the number of benzene rings surrounding the core, which is equivalent to the size of the central polygon. Examples which have beensynthesized include [5]circulene (corannulene), [6]circulene (coronene), [7]circulene,^[2][3][4][5] and [12]circulene (kekulene) These compounds belong to a larger class ofgeodesic polyarenes. Whereas [5]circulene is bowl-shaped and [6]circulene is planar, [7]circulene has a uniquesaddle-shaped structure (compare to cones and partial cones incalixarenes). Thehelicenes are a conceptually related class of structures in which the array of benzene rings form an openhelix rather than a closed ring.

The simple [4]circulene compound itself has not been synthesized, but a derivative, tetrabenzo[4]circulene, also calledquadrannulene, has.^[6]

The isolation of the[8]circulene derivative 2,5,6,9,10,13,14-octamethyl-3,4,7,8,11,12,15,16-octa(4-tolyl)[8]circulene has been reported.^[7]Tetrabenzo[8]circulene (TB8C), a functionally stable form of the parent molecule [8]circulene has also been reported.^[8][9][10]

Aheterocyclic circulene is one in which the fused rings around the periphery are not simple hydrocarbons, but instead contain at least one other element.Sulflower is a stable heterocyclic octacirculene based onthiophene.

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  Corannulene ([5]circulene)
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  Coronene ([6]circulene)
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  [7]circulene
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  Kekulene ([12]circulene)

• Polycyclic aromatic hydrocarbons
• Geodesic polyarenes

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