Perylene
Encyclopedia
Perylene or perilene is a polycyclic aromatic hydrocarbon
with the chemical formula
C20H12, occurring as a brown solid. It or its derivatives may be carcinogen
ic, and it is considered to be a hazardous pollutant
. In cell membrane
cytochemistry
, perylene is used as a fluorescent lipid probe. It is the parent compound of a class of rylene dye
s.
. It is used as a blue-emitting dopant material in OLEDs
, either pure or substituted. Perylene can be also used as an organic photoconductor. It has an absorption maximum at 434 nm, and as with all polycyclic aromatic compounds, low water solubility (1.2 x 10−5 mmol/L). Perylene has a molar absorptivity
of 38,500 M−1cm−1 at 435.7 nm (about 6.5 μg is sufficient for absorbence of 1).
consists of two naphthalene
molecules connected by a carbon-carbon bond at the 1 and 8 positions on both molecules. All of the carbon
atoms in perylene are sp2
hybridized. When drawing the structure of perylene, it is important not to represent the center ring as a fifth benzene ring. By doing so, this would depict two of the carbons as sp3 hybridized and fail to reflect the aromaticity of part of the molecule, and therefore its ability to fluoresce. The structure of perylene has been extensively studied by X-ray crystallography
.
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...
with the chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
C20H12, occurring as a brown solid. It or its derivatives may be carcinogen
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
ic, and it is considered to be a hazardous pollutant
Pollutant
A pollutant is a waste material that pollutes air, water or soil, and is the cause of pollution.Three factors determine the severity of a pollutant: its chemical nature, its concentration and its persistence. Some pollutants are biodegradable and therefore will not persist in the environment in the...
. In cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
cytochemistry
Cytochemistry
Cytochemistry is the biochemistry of cells, especially that of the macromolecules responsible for cell structure and function...
, perylene is used as a fluorescent lipid probe. It is the parent compound of a class of rylene dye
Rylene dye
A perylene dye is a dye based on the perylene framework. Perylene itself consists of two naphthalene units connected at the peri-position and in perylene homologues new naphthalene units are added, forming compounds - or polys - such as terrylene, quarterrylene....
s.
Emission
Perylene displays blue fluorescenceFluorescence
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...
. It is used as a blue-emitting dopant material in OLEDs
Organic light-emitting diode
An OLED is a light-emitting diode in which the emissive electroluminescent layer is a film of organic compounds which emit light in response to an electric current. This layer of organic semiconductor material is situated between two electrodes...
, either pure or substituted. Perylene can be also used as an organic photoconductor. It has an absorption maximum at 434 nm, and as with all polycyclic aromatic compounds, low water solubility (1.2 x 10−5 mmol/L). Perylene has a molar absorptivity
Molar absorptivity
The molar absorption coefficient, molar extinction coefficient, or molar absorptivity, is a measurement of how strongly a chemical species absorbs light at a given wavelength...
of 38,500 M−1cm−1 at 435.7 nm (about 6.5 μg is sufficient for absorbence of 1).
Structure
The perylene moleculeMolecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
consists of two naphthalene
Naphthalene
Naphthalene is an organic compound with formula . It is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings...
molecules connected by a carbon-carbon bond at the 1 and 8 positions on both molecules. All of the carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
atoms in perylene are sp2
Orbital hybridisation
In chemistry, hybridisation is the concept of mixing atomic orbitals to form new hybrid orbitals suitable for the qualitative description of atomic bonding properties. Hybridised orbitals are very useful in the explanation of the shape of molecular orbitals for molecules. It is an integral part...
hybridized. When drawing the structure of perylene, it is important not to represent the center ring as a fifth benzene ring. By doing so, this would depict two of the carbons as sp3 hybridized and fail to reflect the aromaticity of part of the molecule, and therefore its ability to fluoresce. The structure of perylene has been extensively studied by X-ray crystallography
X-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
.