Quinacridone is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

used as a

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

. Numerous derivatives constitute the quinacridone pigment family, which finds extensive use in industrial

colorant A colourant/colour additive (British spelling) or colorant/color additive (American spelling) is a substance that is added or applied in order to change the colour of a material or surface. Colourants can be used for many purposes including printing ...

applications such as robust outdoor paints,

inkjet Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpensi ...

printer ink An ink cartridge or inkjet cartridge is a component of an inkjet printer that contains the ink that is deposited onto paper during printing. Each ink cartridge contains one or more ink reservoirs; certain producers also add electronic contacts ...

tattoo ink Tattoo inks consist of pigments combined with a carrier, used in the process of tattooing to create a tattoo in the skin. These inks are also used for permanent makeup, a form of tattoo. Professional tattoo inks are available in many colors and ...

s, artists'

watercolor paint Watercolor (American English) or watercolour (British English; see spelling differences), also ''aquarelle'' (; from Italian diminutive of Latin ''aqua'' "water"), is a painting method”Watercolor may be as old as art itself, going back to t ...

s, and

color laser printer Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively-charged cylinder called a "drum" to d ...

toner Toner is a powder mixture used in laser printers and photocopiers to form the printed text and images on paper, in general through a toner cartridge. Mostly granulated plastic, early mixtures only added carbon powder and iron oxide, however, ...

. As pigments, the quinacridones are insoluble. The development of this family of pigments supplanted the

alizarin Alizarin (also known as 1,2-dihydroxyanthraquinone, Mordant Red 11, C.I. 58000, and Turkey Red) is an organic compound with formula that has been used throughout history as a prominent red dye, principally for dyeing textile fabrics. Histori ...

dyes.

Synthesis

The name indicates that the compounds are a fusion of

acridone Acridone is an organic compound based on the acridine skeleton, with a carbonyl group at the ''9'' position. It is a yellow solid. Synthesis and structure The molecule is planar. Optical spectra reveal that the keto tautomer predominates in the ga ...

and

quinoline Quinoline is a heterocyclic aromatic organic compound with the chemical formula C9H7N. It is a colorless hygroscopic liquid with a strong odor. Aged samples, especially if exposed to light, become yellow and later brown. Quinoline is only sli ...

, although they are not made that way. Classically the parent is prepared from the 2,5-dianilide of

terephthalic acid Terephthalic acid is an organic compound with formula C6H4(CO2H)2. This white solid is a commodity chemical, used principally as a precursor to the polyester PET, used to make clothing and plastic bottles. Several million tonnes are produced annua ...

(C₆H₂(NHPh)₂(CO₂H)₂). Condensation of succinosuccinate esters with

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine In organic chemistry, an aromatic amine is an organic compound consisting of an aroma ...

followed by

cyclization A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where al ...

affords dihydroquinacridone, which are readily

dehydrogenated In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...

. The latter is oxidized to quinacridone. Derivatives of quinacridone can be readily obtained by employing substituted anilines. Linear ''cis''-Quinacridones can be prepared from

isophthalic acid Isophthalic acid is an organic compound with the formula C6H4(CO2H)2. This colorless solid is an isomer of phthalic acid and terephthalic acid. The main industrial uses of purified isophthalic acid (PIA) are for the production of polyethylene t ...

Derivatives

Quinacridone-based

s are used to make high performance paints. Quinacridones were first sold as pigments by

Du Pont DuPont de Nemours, Inc., commonly shortened to DuPont, is an American multinational chemical company first formed in 1802 by French-American chemist and industrialist Éleuthère Irénée du Pont de Nemours. The company played a major role in ...

in 1958. Quinacridones are considered "high performance" pigments because they have exceptional color and weather fastness. Major uses for quinacridones include automobile and industrial coatings.

Nanocrystalline A nanocrystalline (NC) material is a polycrystalline material with a crystallite size of only a few nanometers. These materials fill the gap between amorphous materials without any long range order and conventional coarse-grained materials. De ...

dispersions of quinacridone pigments functionalized with

solubilizing Micellar solubilization (solubilization) is the process of incorporating the solubilizate (the component that undergoes solublization) into or onto micelles. Solublization may occur in a system consisting of a solvent, an association colloid (a c ...

surfactant Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming ...

s are the most common magenta printing ink. Typically deep red to violet in color, the hue of quinacridone is affected not only by the R-groups on the molecule but by the crystal form of the solid. For example, the γ crystal modification of unsubstituted quinacridone provides a strong red shade that has excellent color fastness and resistance to solvation. Another important modification is the β phase which provides a maroon shade that is also more weather resistant and light-fast. Both crystal modifications are more

thermodynamically stable In chemistry, chemical stability is the thermodynamic stability of a chemical system. Thermodynamic stability occurs when a system is in its lowest energy state, or in chemical equilibrium with its environment. This may be a dynamic equilibriu ...

than the α crystal phase. The γ crystal modification is characterized by a criss-cross lattice where each quinacridone molecule

hydrogen-bond In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing ...

s to four neighbors via single H-bonds. The β phase, meanwhile, consists of linear chains of molecules with double H-bonds between each quinacridone molecule and two neighbors. Basic modifications to the chemical structure of quinacridones include the addition of CH₃ and Cl substituents. Some magenta shades of quinacridone are labeled under the proprietary name "Thio Violet" and "Acra Violet".

Semiconductor properties

Quinacridone derivatives exhibit intense

fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

in the dispersed state, and high

carrier mobility In solid-state physics, the electron mobility characterises how quickly an electron can move through a metal or semiconductor when pulled by an electric field. There is an analogous quantity for holes, called hole mobility. The term carrier mobi ...

. These properties complement good photo-, thermal, and electrochemical stability. These properties are desired for

optoelectronic Optoelectronics (or optronics) is the study and application of electronic devices and systems that find, detect and control light, usually considered a sub-field of photonics. In this context, ''light'' often includes invisible forms of radiatio ...

applications including

organic light-emitting diode An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light i ...

s (OLEDs),

organic solar cell An organic solar cell (OSC) or plastic solar cell is a type of photovoltaic that uses organic electronics, a branch of electronics that deals with conductive organic polymers or small organic molecules, for light absorption and charge transport t ...

s (OSCs), and

organic field-effect transistor An organic field-effect transistor (OFET) is a field-effect transistor using an organic semiconductor in its channel. OFETs can be prepared either by vacuum evaporation of small molecules, by solution-casting of polymers or small molecules, or ...

s (OFETs). Due to interplay of intermolecular H-bonding and pi-pi stacking, quinacridone can form a self-assembling,

supramolecular Supramolecular chemistry refers to the branch of chemistry concerning chemical systems composed of a discrete number of molecules. The strength of the forces responsible for spatial organization of the system range from weak intermolecular forces, ...

organic semiconductor Organic semiconductors are solids whose building blocks are pi-bonded molecules or polymers made up by carbon and hydrogen atoms and – at times – heteroatoms such as nitrogen, sulfur and oxygen. They exist in the form of molecular crystals or ...

. :

References

Additional reading

* *{{cite journal , doi = 10.1002/adma.201204039 , title = Hydrogen-Bonded Semiconducting Pigments for Air-Stable Field-Effect Transistors , year = 2013 , last1 = Głowacki , first1 = Eric Daniel , last2 = Irimia-Vladu , first2 = Mihai , last3 = Kaltenbrunner , first3 = Martin , last4 = Gsiorowski , first4 = Jacek , last5 = White , first5 = Matthew S. , last6 = Monkowius , first6 = Uwe , last7 = Romanazzi , first7 = Giuseppe , last8 = Suranna , first8 = Gian Paolo , last9 = Mastrorilli , first9 = Piero , last10 = Sekitani , first10 = Tsuyoshi , last11 = Bauer , first11 = Siegfried , last12 = Someya , first12 = Takao , last13 = Torsi , first13 = Luisa , author-link13=Luisa Torsi, last14 = Sarıçiftçi , first14 = Niyazi Serdar , author-link14=Niyazi Serdar Sarıçiftçi , journal = Advanced Materials , volume = 25 , issue = 11 , pages = 1563–9 , pmid = 23239229 Organic semiconductors Organic pigments Diketones Heterocyclic compounds with 5 rings Nitrogen heterocycles