Cyclophanes

chemical compound

thumbnail|230px|Crystal structure of a catenane with a cyclobis(paraquat-p-phenylene)|cyclobis(paraquat-p-phenylene) [[macrocycle reported by Stoddart and coworkers. ]]

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.

[[Image:CyclophaneTypes.svg|thumb|440px|right|Structures of some fundamental cyclophanes: [n]-paracyclophanes (left), [n]-metacyclophanes, and [n.n]paracyclophanes (right).]]

Dibenzo-18-crown-6 is the organic compound with the formula [OC6H4OCH2CH2OCH2CH2]2. It is a white solid that is soluble in organic solvents. As one of the most popular crown ethers, it facilitates the dissolution of many salts in organic solvents. It is related to the non-benzannulated 18-crown-6.

chemical compound

Cavicularin is a natural phenolic secondary metabolite isolated from the liverwort Cavicularia densa. This macrocycle is unusual because it was the first compound isolated from nature displaying optical activity solely due to the presence of planar chirality and axial chirality. The specific rotation for (+)-cavicularin is +168.2°. It is also a very strained molecule. The para-substituted phenol ring is bent about 15° out of planarity, adopting a somewhat boat-like geometry. This type of angle strain in aromatic compounds is normally reserved for synthetic cyclophanes.

[2.2]Paracyclophane is a cyclophane that is applied in bio- and materials science. It was first synthesized by Brown and Farthing in 1949 by pyrolyzing para-xylene in the gas phase under low pressure.