A circulene is a

macrocyclic Macrocycles are often described as molecules and ions containing a ring of twelve or more atoms. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry. ...

arene Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past groupin ...

in which a central

polygon In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed ''polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two to ...

is surrounded and fused by benzenoids. 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 been synthesized include irculene (

corannulene Corannulene is a polycyclic aromatic hydrocarbon with chemical formula C20 H10. The molecule consists of a cyclopentane ring fused with 5 benzene rings, so another name for it is irculene. It is of scientific interest because it is a geodesi ...

), irculene (

coronene Coronene (also known as superbenzene and cyclobenzene) is a polycyclic aromatic hydrocarbon (PAH) comprising seven peri-fused benzene rings. Its chemical formula is . It is a yellow material that dissolves in common solvents including benzene, tol ...

), irculene, and 2irculene ( kekulene) These compounds belong to a larger class of geodesic polyarenes. Whereas irculene is bowl-shaped and irculene is planar, irculene has a unique

saddle The saddle is a supportive structure for a rider of an animal, fastened to an animal's back by a girth. The most common type is equestrian. However, specialized saddles have been created for oxen, camels and other animals. It is not k ...

-shaped structure (compare to cones and partial cones in

calixarene A calixarene is a macrocycle or cyclic oligomer based on a methylene-linked phenols. With hydrophobic cavities that can hold smaller molecules or ions, calixarenes belong to the class of cavitands known in host–guest chemistry. Nomenclature Cal ...

s). The

helicene In organic chemistry, helicenes are ortho-condensed polycyclic aromatic compounds in which benzene rings or other aromatics are angularly annulated to give helically-shaped chiral molecules. The chemistry of helicenes has attracted continuin ...

s are a conceptually related class of structures in which the array of benzene rings form an open

helix A helix () is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helic ...

rather than a closed ring.

Quadrannulene ( irculene)

The simple irculene compound itself has not been synthesized, but a derivative, tetrabenzo irculene, also called quadrannulene, has.

irculenes

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

Heterocyclic circulenes

heterocyclic A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...

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 on

thiophene Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a planar five-membered ring, it is aromatic as indicated by its extensive substitution reactions. It is a colorless liquid with a benzene-like odor. In most of its react ...

Gallery

Image:Corannulene.svg,

Corannulene Corannulene is a polycyclic aromatic hydrocarbon with chemical formula C20 H10. The molecule consists of a cyclopentane ring fused with 5 benzene rings, so another name for it is irculene. It is of scientific interest because it is a geodesi ...

( irculene) Image:Coronene 200.svg,

Coronene Coronene (also known as superbenzene and cyclobenzene) is a polycyclic aromatic hydrocarbon (PAH) comprising seven peri-fused benzene rings. Its chemical formula is . It is a yellow material that dissolves in common solvents including benzene, tol ...

( irculene) Image:-7-circulene.svg, irculene Image:Kekulene.svg, Kekulene ( 2irculene)

References

{{PAHs Polycyclic aromatic hydrocarbons Geodesic polyarenes