Cyclophane

Phanes as chemical compounds are referred to, consisting of an aromatic compound, which is bridged by a generally aliphatic chain. They are therefore largely the ansa compounds (Latin ansa = handle ), so the planar, aromatic compounds, which are bridged by a handle, which consists of a chain. In the IUPAC nomenclature, the suffix (a kind of shorthand or representation of chemical compounds so ) is - phan in which rings are regarded as super atoms.

Classification

Is the aromatic benzene ring so the compound is referred to as cyclophane ( composition cyclo, phenyl and alkane ), which term is generally used for molecules in which two benzene rings has at least two aliphatic chains (also known as the Henkel compounds ) bridged to each other on opposite carbon atoms are. The latter therefore belong to the group of polycyclic aromatic hydrocarbons. The most important compounds are the Metacyclophanes (I) Paracyclophanes (II) and [n, n ' ] cyclophanes (III). In addition, also exist Orthocyclophane. Include Inductees heteroatoms in the aromatic ring are they called Heterophane. Are the heteroatoms in the bridge located, it is called Heteraphanen. Shows one of the atoms of the compound ( for example, a hydrogen atom) to the inside, this is referred to in - cyclophanes.

If the maximum possible bridging achieved, then one speaks of a superphane. As Metallacyclophane finally Cyclophankomplexverbindunden are denoted by transition metals.

For the nomenclature of the IUPAC Inductees has developed a simple method which consists in outline on a replacement nomenclature to be used in which the individual subunits of the cyclic compounds construed as super atoms and equal footing with other ring atoms and numbered consecutively.

History

In 1937, Arthur described Lüttringhaus ( 1902-1992 ) the first ansa compounds. The cyclophanes were synthesized in 1949 by Brown and Farthing and studied in detail by Donald J. Cram and H. Steinberg in the early 1950s. The first ferrocenophanes were synthesized by Lüttringhaus and Kullik in the late 1950s.

Properties and Uses

Inductees are distinguished by unusual chemical and physical properties, such as high reactivity, high ring strain, chirality and deviating from the norm molecular parameters from. Because of their special geometric structure Cyclophanes are excellent building blocks of supramolecular chemistry. The simplest representative of a cyclophane would be a benzene ring with an alkane as a bridge. The best known cyclophane is the [ 2.2] paracyclophane, which was the beginning of the 1970s by Brown and Farthing extracted from polymers. May Hofmann elimination or Wurtz coupling are shown on the pyrolysis of p- xylene ( Swarc pyrolysis ). Other methods for the preparation of cyclophanes, such as flash vacuum pyrolysis for the production of [ 3.3] cyclophane are possible. Since macrocyclic cyclophanes can form tube-like structures, they can absorb smaller molecules and thus serve as a transporter. The similar can also cryptophanes caused by covalent linkage of two Cyclotriveratryleneinheiten that serve as containers for other molecules. They belong to the inclusion or cage compounds. In nature, some Cyclophanes come in actinomycetes ( eg in the form of rifampicin and rifabutin ) and blue-green algae problem (eg Nostocyclophane ).