Triphenylene
Encyclopedia
In chemistry
, the organic compound
triphenylene is a flat polycyclic aromatic hydrocarbon
(PAH) consisting of four fused benzene
rings. Triphenylene can be isolated from coal tar
, but it is also made synthetically using benzyn chemistry. One molecule of triphenylene has delocalized 18-π-electron systems based on a planar structure. It has the molecular formula .
Triphenylene is a fully benzenoid PAH, meaning its structure is composed only of full benzene rings interconnected by carbon-carbon single bonds. The three benzene rings can be drawn as the three outer rings, with the central ring formed by one face of each and the three carbon-carbon single bonds.
Being a fully bezenoid PAH means that triphenylene is much more resonance
stable than its isomers chrysene
, benz[a]anthracene, benzo[c]phenanthrene
, and tetracene
. This makes it much more difficult to hydrogenate to the saturated hydrocarbon.
In light of these characteristics, triphenylene may have uses in optics
and electronics
. Triphenylene is a disc-shaped molecule with a planar structure and three-fold rotation axes. Consisting of colorless needle-like crystals, it emits bluish purple fluorescence
by UV
irradiation.
In terms of its crystallographic point group
, the symmetry of triphenylene is classified as D3h in Schoenflies notation
. Because of these characteristics, six-fold (in the 2, 3, 6, 7, 10, and 11 positions) alkyloxy- or alkylthiol-substituted triphenylenes can be used as a discotic mesogen
in liquid crystal
line materials.
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, the organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
triphenylene is a flat polycyclic aromatic hydrocarbon
Polycyclic aromatic hydrocarbon
Polycyclic aromatic hydrocarbons , also known as poly-aromatic hydrocarbons or polynuclear aromatic hydrocarbons, are potent atmospheric pollutants that consist of fused aromatic rings and do not contain heteroatoms or carry substituents. Naphthalene is the simplest example of a PAH...
(PAH) consisting of four fused benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
rings. Triphenylene can be isolated from coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...
, but it is also made synthetically using benzyn chemistry. One molecule of triphenylene has delocalized 18-π-electron systems based on a planar structure. It has the molecular formula .
Triphenylene is a fully benzenoid PAH, meaning its structure is composed only of full benzene rings interconnected by carbon-carbon single bonds. The three benzene rings can be drawn as the three outer rings, with the central ring formed by one face of each and the three carbon-carbon single bonds.
Being a fully bezenoid PAH means that triphenylene is much more resonance
Resonance (chemistry)
In chemistry, resonance or mesomerism is a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by one single Lewis formula...
stable than its isomers chrysene
Chrysene
Chrysene is a polycyclic aromatic hydrocarbon with the molecular formula that consists of four fused benzene rings. It is a natural constituent of coal tar, from which it was first isolated and characterized...
, benz[a]anthracene, benzo[c]phenanthrene
Benzo(c)phenanthrene
Benzo[c]phenanthrene is a polycyclic aromatic hydrocarbon with the chemical formula C18H12....
, and tetracene
Tetracene
Tetracene, also called naphthacene, is a polycyclic aromatic hydrocarbon. It has the appearance of a pale orange powder. Tetracene is the four-ringed member of the series of acenes, the previous one being anthracene and the next one being pentacene.Tetracene is a molecular organic semiconductor,...
. This makes it much more difficult to hydrogenate to the saturated hydrocarbon.
In light of these characteristics, triphenylene may have uses in optics
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...
and electronics
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
. Triphenylene is a disc-shaped molecule with a planar structure and three-fold rotation axes. Consisting of colorless needle-like crystals, it emits bluish purple fluorescence
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
by UV
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
irradiation.
In terms of its crystallographic point group
Crystallographic point group
In crystallography, a crystallographic point group is a set of symmetry operations, like rotations or reflections, that leave a central point fixed while moving other directions and faces of the crystal to the positions of features of the same kind...
, the symmetry of triphenylene is classified as D3h in Schoenflies notation
Crystallographic point group
In crystallography, a crystallographic point group is a set of symmetry operations, like rotations or reflections, that leave a central point fixed while moving other directions and faces of the crystal to the positions of features of the same kind...
. Because of these characteristics, six-fold (in the 2, 3, 6, 7, 10, and 11 positions) alkyloxy- or alkylthiol-substituted triphenylenes can be used as a discotic mesogen
Mesogen
Mesogen is the fundamental unit of a liquid crystal that induces structural order in the crystals.Typically, a liquid-crystalline molecule consists of a rigid moiety and one or more flexible parts. The rigid part aligns molecules in one direction, whereas the flexible parts induce fluidity in the...
in liquid crystal
Liquid crystal
Liquid crystals are a state of matter that have properties between those of a conventional liquid and those of a solid crystal. For instance, an LC may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of LC phases, which can be...
line materials.