Prussian blue (also known as Berlin blue, Brandenburg blue or, in
painting
Painting is the practice of applying paint, pigment, color or other medium to a solid surface (called the "matrix" or "support"). The medium is commonly applied to the base with a brush, but other implements, such as knives, sponges, and ...
, Parisian or Paris blue) is a dark
blue
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when obs ...
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 ...
produced by oxidation of ferrous
ferrocyanide
Ferrocyanide is the name of the anion CN)6">cyanide.html" ;"title="e(cyanide">CN)6sup>4−. Salts of this coordination complex give yellow solutions. It is usually available as the salt potassium ferrocyanide, which has the formula K4Fe(CN)6. e ...
salts. It has the
chemical formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
Fe
CN)">Cyanide.html" ;"title="e(Cyanide">CN) Turnbull's blue is chemically identical, but is made from different reagents, and its slightly different color stems from different impurities and particle sizes.
Prussian blue was the first modern synthetic pigment. It is prepared as a very fine colloidal dispersion, because the compound is not soluble in water. It contains variable amounts
[ of other ions and its appearance depends sensitively on the size of the colloidal particles. The pigment is used in ]paint
Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in many ...
s, and it is the traditional "blue" in blueprint
A blueprint is a reproduction of a technical drawing or engineering drawing using a contact print process on light-sensitive sheets. Introduced by Sir John Herschel in 1842, the process allowed rapid and accurate production of an unlimited number ...
s, and became prominent in 19th-century () Japanese woodblock print
Woodblock printing in Japan (, ''mokuhanga'') is a technique best known for its use in the ''ukiyo-e'' artistic genre of single sheets, but it was also used for printing books in the same period. Widely adopted in Japan during the Edo period (160 ...
s.
In medicine, orally administered Prussian blue is used as an antidote
An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon) antidoton'', "(medicine) given as a remedy". Antidotes for anticoagulants are s ...
for certain kinds of heavy metal poisoning
A toxic heavy metal is any relatively dense metal or metalloid that is noted for its potential toxicity, especially in environmental contexts. The term has particular application to cadmium, mercury and lead, all of which appear in the World He ...
, e.g., by thallium(I)
Thallium is a chemical element with the Symbol (chemistry), symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists W ...
and radioactive isotopes of caesium
Caesium (IUPAC spelling) (or cesium in American English) is a chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of , which makes it one of only five elemental metals that a ...
. The therapy exploits the compound's ion-exchange properties and high affinity for certain " soft" metal cations
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
.
It is on the World Health Organization's List of Essential Medicines
The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health ...
, the most important medications needed in a basic health system
Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organiza ...
. Prussian blue lent its name to prussic acid
Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an in ...
(hydrogen cyanide) derived from it. In German, hydrogen cyanide is called ('blue acid'). French chemist Joseph Louis Gay-Lussac
Joseph Louis Gay-Lussac (, , ; 6 December 1778 – 9 May 1850) was a French chemist and physicist. He is known mostly for his discovery that water is made of two parts hydrogen and one part oxygen (with Alexander von Humboldt), for two laws ...
gave cyanide
Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms.
In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...
its name, from the Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
word (, 'blue'/'cyan'), because of its Prussian blue color.
History
Prussian blue pigment is significant since it was the first stable and relatively lightfast
Lightfastness is a property of a colourant such as dye or pigment that describes its resistance to fading when exposed to light. Dyes and pigments are used for example for dyeing of fabrics, plastics or other materials and manufacturing paints or ...
blue pigment to be widely used since the loss of knowledge regarding the synthesis of Egyptian blue
Egyptian blue, also known as calcium copper silicate (CaCuSi4O10 or CaOCuO(SiO2)4 (calcium copper tetrasilicate)) or cuprorivaite, is a pigment that was used in ancient Egypt for thousands of years. It is considered to be the first synthetic pi ...
. European painters had previously used a number of pigments such as indigo dye
Indigo dye is an organic compound with a distinctive blue color. Historically, indigo was a natural dye extracted from the leaves of some plants of the ''Indigofera'' genus, in particular ''Indigofera tinctoria''; dye-bearing ''Indigofera'' pla ...
, smalt
Cobalt glass—known as "smalt" when ground as a pigment—is a deep blue coloured glass prepared by including a cobalt compound, typically cobalt oxide or cobalt carbonate, in a glass melt. Cobalt is a very intense colouring agent and very littl ...
, and Tyrian purple
Tyrian purple ( grc, πορφύρα ''porphúra''; la, purpura), also known as Phoenician red, Phoenician purple, royal purple, imperial purple, or imperial dye, is a reddish-purple natural dye. The name Tyrian refers to Tyre, Lebanon. It is ...
, and the extremely expensive ultramarine
Ultramarine is a deep blue color pigment which was originally made by grinding lapis lazuli into a powder. The name comes from the Latin ''ultramarinus'', literally 'beyond the sea', because the pigment was imported into Europe from mines in Afgh ...
made from lapis lazuli
Lapis lazuli (; ), or lapis for short, is a deep-blue metamorphic rock used as a semi-precious stone that has been prized since antiquity for its intense color.
As early as the 7th millennium BC, lapis lazuli was mined in the Sar-i Sang mines, ...
. Japanese painters
Japanese may refer to:
* Something from or related to Japan, an island country in East Asia
* Japanese language, spoken mainly in Japan
* Japanese people, the ethnic group that identifies with Japan through ancestry or culture
** Japanese diaspor ...
and woodblock print artists, likewise, did not have access to a long-lasting blue pigment until they began to import Prussian blue from Europe.
Prussian blue (also () · ''x'') was probably synthesized for the first time by the paint maker Johann Jacob Diesbach
Johann Jacob Diesbach () (born around 1670 – died in 1748), also written as Johann Jacob von Diesbach, was a Swiss pigment and dye producer known for first synthesizing a blue pigment known as Prussian blue (i.e. iron blue or Berlin blue).
Bio ...
in Berlin around 1706. The pigment is believed to have been accidentally created when Diesbach used potash
Potash () includes various mined and manufactured salts that contain potassium in water-soluble form. tainted with blood
Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...
to create some red cochineal
The cochineal ( , ; ''Dactylopius coccus'') is a scale insect in the suborder Sternorrhyncha, from which the natural dye carmine is derived. A primarily sessility (motility), sessile parasitism, parasite native to tropical and subtropical Sout ...
dye. The original dye required potash, ferric sulfate
Iron(III) sulfate (or ferric sulfate), is a family of inorganic compounds with the formula Fe2(SO4)3(H2O)n. A variety of hydrates are known, including the most commonly encountered form of "ferric sulfate". Solutions are used in dyeing as a morda ...
, and dried cochineal. Instead, the blood, potash, and iron sulfate reacted to create a compound known as iron ferrocyanide, which, unlike the desired red pigment, has a very distinct blue hue. It was named and in 1709 by its first trader.[Frisch, J. L. (1896) ''Briefwechsel mit Gottfried Wilhelm Leibniz'' L. H. Fischer (ed.), Berlin, Stankiewicz Buchdruck, reprint Hildesheim/New York: Georg Olms Verlag, 1976]
The pigment readily replaced the expensive lapis lazuli derived ultramarine and was an important topic in the letters exchanged between Johann Leonhard Frisch
Johann Leonhard Frisch (19 March 1666 – 21 March 1743) was a German linguist, entomologist and ornithologist
Ornithology is a branch of zoology that concerns the "methodological study and consequent knowledge of birds with all that relates t ...
and the president of the Prussian Academy of Sciences
The Royal Prussian Academy of Sciences (german: Königlich-Preußische Akademie der Wissenschaften) was an academy established in Berlin, Germany on 11 July 1700, four years after the Prussian Academy of Arts, or "Arts Academy," to which "Berlin ...
, Gottfried Wilhelm Leibniz
Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of mathema ...
, between 1708 and 1716.[ It is first mentioned in a letter written by Frisch to Leibniz, from March 31, 1708. Not later than 1708, Frisch began to promote and sell the pigment across Europe. By August 1709, the pigment had been termed ; by November 1709, the German name had been used for the first time by Frisch. Frisch himself is the author of the first known publication of Prussian blue in the paper in 1710, as can be deduced from his letters. Diesbach had been working for Frisch since about 1701.
To date, the ''Entombment of Christ'', dated 1709 by ]Pieter van der Werff
Pieter van der Werff (1665 – 26 September 1722) was a Dutch Golden Age painter. He assisted his older brother, Adriaen van der Werff.
Life
He learned to paint from his brother Adriaen and according to the RKD, he spent most of his life w ...
(Picture Gallery, Sanssouci
Sanssouci () is a historical building in Potsdam, near Berlin. Built by Prussian King Frederick the Great as his summer palace, it is often counted among the German rivals of Versailles. While Sanssouci is in the more intimate Rococo style and ...
, Potsdam) is the oldest known painting where Prussian blue was used. Around 1710, painters at the Prussian court
The Kingdom of Prussia (german: Königreich Preußen, ) was a German kingdom that constituted the state of Prussia between 1701 and 1918.Marriott, J. A. R., and Charles Grant Robertson. ''The Evolution of Prussia, the Making of an Empire''. Re ...
were already using the pigment. At around the same time, Prussian blue arrived in Paris, where Antoine Watteau
Jean-Antoine Watteau (, , ; baptised October 10, 1684died July 18, 1721) Alsavailablevia Oxford Art Online (subscription needed). was a French painter and draughtsman whose brief career spurred the revival of interest in colour and movement, a ...
and later his successors Nicolas Lancret
Nicolas Lancret (22 January 1690 – 14 September 1743) was a French painter. Born in Paris, he was a brilliant depicter of light comedy which reflected the tastes and manners of French society during the regency of the Duke of Orleans and, late ...
and Jean-Baptiste Pater
Jean-Baptiste Pater (December 29, 1695 – July 25, 1736) was a French rococo painter.
Born in Valenciennes, Pater was the son of sculptor Antoine Pater and studied under him before becoming a student of painter Jean-Baptiste Guide. Pater then m ...
used it in their paintings.[ ]François Boucher
François Boucher ( , ; ; 29 September 1703 – 30 May 1770) was a French painter, draughtsman and etcher, who worked in the Rococo style. Boucher is known for his idyllic and voluptuous paintings on classical themes, decorative allegories ...
used the pigment extensively for both blues and greens.
In 1731, Georg Ernst Stahl
Georg Ernst Stahl (22 October 1659 – 24 May 1734) was a German chemist, physician and philosopher. He was a supporter of vitalism, and until the late 18th century his works on phlogiston were accepted as an explanation for chemical processes.Ku ...
published an account of the first synthesis of Prussian blue. The story involves not only Diesbach, but also Johann Konrad Dippel
Johann Konrad Dippel, also spelled Johann Conrad Dippel (10 August 1673 – 25 April 1734), was a German Pietist theologian, physician, alchemist and occultist.
Life
Dippel was born at Castle Frankenstein near Mühltal and Darmstadt, and theref ...
. Diesbach was attempting to create a red lake pigment
A lake pigment is a pigment made by precipitating a dye with an inert binder, or mordant, usually a metallic salt. Unlike vermilion, ultramarine, and other pigments made from ground minerals, lake pigments are organic.K. Hunger. W. Herbst "Pigm ...
from cochineal, but obtained the blue instead as a result of the contaminated potash he was using. He borrowed the potash from Dippel, who had used it to produce his animal oil
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in w ...
. No other known historical source mentions Dippel in this context. It is, therefore, difficult to judge the reliability of this story today. In 1724, the recipe was finally published by John Woodward.
In 1752, French chemist Pierre J. Macquer made the important step of showing Prussian blue could be reduced to a salt of iron and a new acid, which could be used to reconstitute the dye. The new acid, hydrogen cyanide
Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ...
, first isolated from Prussian blue in pure form and characterized in 1782 by Swedish chemist Carl Wilhelm Scheele
Carl Wilhelm Scheele (, ; 9 December 1742 – 21 May 1786) was a Swedish German pharmaceutical chemist.
Scheele discovered oxygen (although Joseph Priestley published his findings first), and identified molybdenum, tungsten, barium, hydrog ...
, was eventually given the name (literally "blue acid") because of its derivation from Prussian blue, and in English became known popularly as Prussic acid. Cyanide
Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms.
In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...
, a colorless anion that forms in the process of making Prussian blue, derives its name from the Greek word for dark blue.
In the late 1800s, Rabbi
A rabbi () is a spiritual leader or religious teacher in Judaism. One becomes a rabbi by being ordained by another rabbi – known as ''semikha'' – following a course of study of Jewish history and texts such as the Talmud. The basic form of ...
Gershon Henoch Leiner
Grand Rabbi Gershon Chanoch Henech Leiner of Radzyn (1839 – December 15, 1890) was a rebbe of the Izhbitza – Radzin dynasty, and the first to be known as "the Radzyner Rebbe".
Biography
He was born in Izbica, Poland in 1839, where he studied ...
, the Hasidic
Hasidism, sometimes spelled Chassidism, and also known as Hasidic Judaism (Ashkenazi Hebrew: חסידות ''Ḥăsīdus'', ; originally, "piety"), is a Jewish religious group that arose as a spiritual revival movement in the territory of contem ...
Rebbe
A Rebbe ( yi, רבי, translit=rebe) or Admor ( he, אדמו״ר) is the spiritual leader in the Hasidic movement, and the personalities of its dynasties.Heilman, Samuel"The Rebbe and the Resurgence of Orthodox Judaism."''Religion and Spiritua ...
of Radzin, dyed
Dyeing is the application of dyes or pigments on textile materials such as fibers, yarns, and fabrics with the goal of achieving color with desired color fastness. Dyeing is normally done in a special solution containing dyes and particular ch ...
tzitziyot with Prussian blue made with sepia
Sepia may refer to:
Biology
* ''Sepia'' (genus), a genus of cuttlefish
Color
* Sepia (color), a reddish-brown color
* Sepia tone, a photography technique
Music
* ''Sepia'', a 2001 album by Coco Mbassi
* ''Sepia'' (album) by Yu Takahashi
* " ...
, believing that this was the true techeiles dye. Even though some have questioned its identity as techeiles because of its artificial production, and claimed that had Rabbi Leiner been aware of this he would have retracted his position that his dye was techeiles, others have disputed this and claimed that Rabbi Leiner would not have retracted.
From the beginning of the 18th century, Prussian blue was the predominant uniform coat color worn by the infantry and artillery regiments of the Prussian Army
The Royal Prussian Army (1701–1919, german: Königlich Preußische Armee) served as the army of the Kingdom of Prussia. It became vital to the development of Brandenburg-Prussia as a European power.
The Prussian Army had its roots in the co ...
. As (dark blue), this shade achieved a symbolic importance and continued to be worn by German soldiers for ceremonial
A ceremony (, ) is a unified ritualistic event with a purpose, usually consisting of a number of artistic components, performed on a special occasion.
The word may be of Etruscan language, Etruscan origin, via the Latin ''Glossary of ancient Rom ...
and off-duty occasions until the outbreak of World War I, when it was superseded by greenish-gray field gray ().
Production
Prussian blue is produced by oxidation of ferrous ferrocyanide salts. These white solids have the formula where = or . The iron in this material is all ferrous, hence the absence of deep color associated with the mixed valency. Oxidation of this white solid with hydrogen peroxide or sodium chlorate produces ferricyanide and affords Prussian blue.[
A "soluble" form, , which is really ]colloid
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend ...
al, can be made from potassium ferrocyanide
Potassium ferrocyanide is the inorganic compound with formula K4 e(CN)63H2O. It is the potassium salt of the coordination complex e(CN)6sup>4−. This salt forms lemon-yellow monoclinic crystals.
Synthesis
In 1752, the French chemist Pierr ...
and iron(III):
: + + →
The similar reaction of potassium ferricyanide
Potassium ferricyanide is the chemical compound with the formula K3 e(CN)6 This bright red salt contains the octahedrally coordinated 3−.html" ;"title="e(CN)6sup>3−">e(CN)6sup>3− ion. It is soluble in water and its solution shows some g ...
and iron(II) results in the same colloidal solution, because is converted into ferrocyanide.
"Insoluble" Prussian blue is produced if, in the reactions above, an excess of is added:
:4 + 3 →
Despite the fact that it is prepared from cyanide salts, Prussian blue is not toxic because the cyanide groups are tightly bound to iron. Both ferrocyanide ((FeII(CN)6)4−) and ferricyanide ((FeIII(CN)6)3−) are particularly stable and non-toxic polymeric cyanometalates due to the strong iron coordination to cyanide ions. Although cyanide bonds well with transition metals in general like chromium, these non-iron coordination compounds are not as stable as iron cyanides, therefore increasing the risk of releasing CN- ions, and subsequently comparative toxicity.
Turnbull's blue
In former times, the addition of iron(II) salts to a solution of ferricyanide
Ferricyanide is the anion e(CN)6sup>3−. It is also called hexacyanoferrate(III) and in rare, but systematic nomenclature, hexacyanidoferrate(III). The most common salt of this anion is potassium ferricyanide, a red crystalline material that i ...
was thought to afford a material different from Prussian blue. The product was traditionally named Turnbull's blue (TB). X-ray diffraction
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...
and electron diffraction
Electron diffraction refers to the bending of electron beams around atomic structures. This behaviour, typical for waves, is applicable to electrons due to the wave–particle duality stating that electrons behave as both particles and waves. Si ...
methods have shown, though, that the structures of PB and TB are identical. The differences in the colors for TB and PB reflect subtle differences in the methods of precipitation, which strongly affect particle size and impurity content.
Properties
Prussian blue is a microcrystalline
A microcrystalline material is a crystallized substance or rock that contains small crystals visible only through microscopic examination. There is little agreement on the range of crystal sizes that should be regarded as microcrystalline, but the ...
blue powder. It is insoluble, but the crystallite
A crystallite is a small or even microscopic crystal which forms, for example, during the cooling of many materials. Crystallites are also referred to as grains.
Bacillite is a type of crystallite. It is rodlike with parallel longulites.
Stru ...
s tend to form a colloid. Such colloids can pass through fine filters. Despite being one of the oldest known synthetic compounds, the composition of Prussian blue remained uncertain for many years. Its precise identification was complicated by three factors:
* Prussian blue is extremely insoluble, but also tends to form colloids
* Traditional syntheses tend to afford impure compositions
* Even pure Prussian blue is structurally complex, defying routine crystallographic analysis
Crystal structure
The chemical formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
of insoluble Prussian blue is · ''x'', where ''x'' = 14–16. The structure was determined by using IR spectroscopy
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functiona ...
, Mössbauer spectroscopy
Mössbauer spectroscopy is a spectroscopic technique based on the Mössbauer effect. This effect, discovered by Rudolf Mössbauer (sometimes written "Moessbauer", German: "Mößbauer") in 1958, consists of the nearly recoil-free emission and abso ...
, X-ray crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...
, and neutron crystallography
Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material. A sample to be examined is placed in a beam of thermal or cold neutrons to o ...
. Since X-ray diffraction cannot easily distinguish carbon from nitrogen in the presence of heavier elements such as iron, the location of these lighter elements is deduced by spectroscopic means, as well as by observing the distances from the iron atom centers.
PB has a face centered cubic
In crystallography, the cubic (or isometric) crystal system is a crystal system where the Crystal_structure#Unit_cell, unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.
There ...
lattice structure, with four iron III atoms per unit cell. "Soluble" PB crystals contain interstitial ions; insoluble PB has interstitial water, instead.
In ideal insoluble PB crystals, the cubic framework is built from Fe(II)–C–N–Fe(III) sequences, with Fe(II)–carbon distances of 1.92 Å and Fe(III)–nitrogen distances of 2.03 Å. One-fourth of the sites of subunits (supposedly at random) are vacant (empty), leaving three such groups on average per unit cell. The empty nitrogen sites are filled with water molecules instead, which are coordinated to Fe(III).
The Fe(II) centers, which are low spin Spin states when describing transition metal coordination complexes refers to the potential spin configurations of the central metal's d electrons. For several oxidation states, metals can adopt high-spin and low-spin configurations. The ambiguity o ...
, are surrounded by six carbon ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...
s in an octahedral
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at ea ...
configuration. The Fe(III) centers, which are high spin Spin states when describing transition metal coordination complexes refers to the potential spin configurations of the central metal's d electrons. For several oxidation states, metals can adopt high-spin and low-spin configurations. The ambiguity o ...
, are octahedrally surrounded on average by 4.5 nitrogen atoms and 1.5 oxygen atoms (the oxygen from the six coordinated water molecules). Around eight (interstitial) water molecules are present in the unit cell, either as isolated molecules or 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 a ...
ed to the coordinated water.
The composition is notoriously variable due to the presence of lattice defects, allowing it to be hydrated to various degrees as water molecules are incorporated into the structure to occupy cation
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
vacancies. The variability of Prussian blue's composition is attributable to its low solubility
In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution.
The extent of the solubil ...
, which leads to its rapid precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
without the time to achieve full equilibrium between solid and liquid.
Color
Prussian blue is strongly colored and tends towards black and dark blue when mixed into oil paint
Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. The viscosity of the paint may be modified by the addition of a solvent such as turpentine or white spirit, and varn ...
s. The exact hue depends on the method of preparation, which dictates the particle size. The intense blue color of Prussian blue is associated with the energy of the transfer of electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no kn ...
s from Fe(II) to Fe(III). Many such mixed-valence compound
Mixed valence complexes contain an element which is present in more than one oxidation state. Well-known mixed valence compounds include the Creutz–Taube complex, Prussian blue, and molybdenum blue. Many solids are mixed-valency including in ...
s absorb certain wavelengths of visible light resulting from intervalence charge transfer
192 px, The intense blue color of Prussian blue is a consequence of an intervalence charge transfer band.
In chemistry, intervalence charge transfer, often abbreviated IVCT or even IT, is a type of charge-transfer band that is associated with mix ...
. In this case, orange-red light around 680 nanometer
330px, Different lengths as in respect to the molecular scale.
The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re ...
s in wavelength is absorbed, and the reflected light appears blue as a result.
Like most high- chroma 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 ...
s, Prussian blue cannot be accurately displayed on a computer display. PB is electrochromic
Electrochromism is a phenomenon in which a material displays changes in color or opacity in response to an electrical stimulus.
In this way, a smart window made of an electrochromic material can block specific wavelengths of ultraviolet, visib ...
—changing from blue to colorless upon reduction. This change is caused by reduction of the Fe(III) to Fe(II), eliminating the intervalence charge transfer
192 px, The intense blue color of Prussian blue is a consequence of an intervalence charge transfer band.
In chemistry, intervalence charge transfer, often abbreviated IVCT or even IT, is a type of charge-transfer band that is associated with mix ...
that causes Prussian blue's color.
Use
Pigment
Because it is easily made, cheap, nontoxic, and intensely colored, Prussian blue has attracted many applications. It was adopted as a pigment very soon after its invention and was almost immediately widely used in oil paints, watercolor, and dyeing. The dominant uses are for pigments: about 12,000 tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s of Prussian blue are produced annually for use in black and bluish ink
Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thi ...
s. A variety of other pigments also contain the material.[Völz, Hans G. ''et al.'' (2006) "Pigments, Inorganic" in Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH, Weinheim. .] Engineer's blue
Engineer's blue (also known as scraping blue, Prussian blue, or simply bluing) is a highly pigmented paste used to assist in the mating of two or more components.
History
Joseph Whitworth popularized the first practical method of making accurat ...
and the pigment formed on cyanotype
The cyanotype (from Ancient Greek κυάνεος - ''kuáneos'', “dark blue” + τύπος - ''túpos'', “mark, impression, type”) is a slow-reacting, economical photographic printing formulation sensitive to a limited near ultraviolet ...
s—giving them their common name blueprint
A blueprint is a reproduction of a technical drawing or engineering drawing using a contact print process on light-sensitive sheets. Introduced by Sir John Herschel in 1842, the process allowed rapid and accurate production of an unlimited number ...
s. Certain crayon
A crayon (or wax pastel) is a stick of pigmented wax used for writing or drawing. Wax crayons differ from pastels, in which the pigment is mixed with a dry binder such as gum arabic, and from oil pastels, where the binder is a mixture of wax an ...
s were once colored with Prussian blue (later relabeled midnight blue
Midnight blue is a dark shade of blue named for its resemblance to the apparently blue color of a moonlit night sky around full moon. Midnight blue is identifiably blue to the eye in sunlight or full-spectrum light, but can appear black under ...
). Similarly, Prussian blue is the basis for laundry bluing
Bluing, laundry blue, dolly blue or washing blue is a household product used to improve the appearance of textiles, especially white fabrics. Used during laundering, it adds a trace of blue dye (often synthetic ultramarine, sometimes Prussian bl ...
.
Nanoparticles of Prussian blue are used as pigments in some cosmetics ingredients, according to the European Union Observatory for Nanomaterials.
Medicine
Prussian blue's ability to incorporate monovalent metallic cation
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
s (Me+) makes it useful as a sequestering agent
Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are ...
for certain toxic heavy metal
A toxic heavy metal is any relatively dense metal or metalloid that is noted for its potential toxicity, especially in environmental contexts. The term has particular application to cadmium, mercury and lead, all of which appear in the World He ...
s. Pharmaceutical-grade Prussian blue in particular is used for people who have ingested thallium
Thallium is a chemical element with the Symbol (chemistry), symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists W ...
(Tl+) or radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
caesium
Caesium (IUPAC spelling) (or cesium in American English) is a chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of , which makes it one of only five elemental metals that a ...
(134Cs+, 137Cs+) . According to the International Atomic Energy Agency
The International Atomic Energy Agency (IAEA) is an intergovernmental organization that seeks to promote the peaceful use of nuclear energy and to inhibit its use for any military purpose, including nuclear weapons. It was established in 1957 ...
(IAEA), an adult male can eat at least 10 g of Prussian blue per day without serious harm. The U.S. Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food s ...
(FDA) has determined the "500-mg Prussian blue capsules, when manufactured under the conditions of an approved New Drug Application, can be found safe and effective therapy" in certain poisoning cases. Radiogardase (Prussian blue in soluble capsules ) is a commercial product for the removal of caesium-137
Caesium-137 (), cesium-137 (US), or radiocaesium, is a radioactive isotope of caesium that is formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nucl ...
from the intestine
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...
, so indirectly from the bloodstream
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
by intervening in the enterohepatic circulation
Enterohepatic circulation refers to the circulation of biliary acids, bilirubin, drugs or other substances from the liver to the bile, followed by entry into the small intestine, absorption by the enterocyte and transport back to the liver. ...
of caesium-137, reducing the internal residency time (and exposure) by about two-thirds. In particular, it was used to adsorb
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a fl ...
and to remove from the organism of those poisoned in the Goiânia accident
The Goiânia accident was a radioactive contamination accident that occurred on September 13, 1987, in Goiânia, Goiás, Brazil, after a forgotten radiotherapy source was stolen from an abandoned hospital site in the city. It was subsequent ...
in Brazil.[
]
Stain for iron
Prussian blue is a common histopathology
Histopathology (compound of three Greek words: ''histos'' "tissue", πάθος ''pathos'' "suffering", and -λογία '' -logia'' "study of") refers to the microscopic examination of tissue in order to study the manifestations of disease. Spe ...
stain used by pathologist
Pathology is the study of the causal, causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when us ...
s to detect the presence of iron in biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
specimens, such as in bone marrow
Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic ce ...
samples. The original stain formula, known historically (1867) as "Perls Prussian blue
In histology, histopathology, and clinical pathology, Perls Prussian blue is a commonly used method to detect the presence of iron in tissue or cell samples. Perls Prussian Blue derives its name from the German pathologist Max Perls (1843–1881 ...
" after its inventor, German pathologist Max Perls (1843–1881), used separate solutions of potassium ferrocyanide
Potassium ferrocyanide is the inorganic compound with formula K4 e(CN)63H2O. It is the potassium salt of the coordination complex e(CN)6sup>4−. This salt forms lemon-yellow monoclinic crystals.
Synthesis
In 1752, the French chemist Pierr ...
and acid to stain tissue (these are now used combined, just before staining). Iron deposits in tissue then form the purple Prussian blue dye in place, and are visualized as blue or purple deposits.
File:Kupffer cell with hemosiderin and hepatocyte with lipofuscin.jpg, Histopathology
Histopathology (compound of three Greek words: ''histos'' "tissue", πάθος ''pathos'' "suffering", and -λογία '' -logia'' "study of") refers to the microscopic examination of tissue in order to study the manifestations of disease. Spe ...
of the liver, showing a Kupffer cell
Kupffer cells, also known as stellate macrophages and Kupffer–Browicz cells, are specialized cells localized in the liver within the lumen of the liver sinusoids and are adhesive to their endothelial cells which make up the blood vessel walls. Ku ...
s with significant hemosiderin
Hemosiderin image of a kidney viewed under a microscope. The brown areas represent hemosiderin
Hemosiderin or haemosiderin is an iron-storage complex that is composed of partially digested ferritin and lysosomes. The breakdown of heme gives rise ...
deposition next to a hepatocyte with lipofuscin
Lipofuscin is the name given to fine yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered to be one of the aging or "wear-and-tear" pigments, found in the liver, kidney, heart muscle, retin ...
pigment. H&E stain.
File:Kupffer cell with hemosiderin and hepatocyte with lipofuscin, iron stain.jpg, Prussian blue staining, highlighting the hemosiderin pigment as blue.
File:Intra-alveolar hemosiderin deposition - Prussian blue stain.jpg, Prussian blue stain
By machinists and toolmakers
Engineer's blue
Engineer's blue (also known as scraping blue, Prussian blue, or simply bluing) is a highly pigmented paste used to assist in the mating of two or more components.
History
Joseph Whitworth popularized the first practical method of making accurat ...
, Prussian blue in an oily base, is the traditional material used for spotting metal surfaces such as surface plate
A surface plate is a solid, flat plate used as the main horizontal reference plane for precision inspection, marking out (layout), and tooling setup. The surface plate is often used as the baseline for all measurements to a workpiece, therefore ...
s and bearings for hand scraping. A thin layer of nondrying paste is applied to a reference surface and transfers to the high spots of the workpiece. The toolmaker then scrapes, stones, or otherwise removes the marked high spots. Prussian blue is preferable because it will not abrade the extremely precise reference surfaces as many ground pigments may.
In analytical chemistry
Prussian blue is formed in the Prussian blue assay for total phenol
Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...
s. Samples and phenolic standards are given acidic ferric chloride and ferricyanide, which is reduced to ferrocyanide by the phenols. The ferric chloride and ferrocyanide react to form Prussian blue. Comparing the absorbance at 700 nm of the samples to the standards allows for the determination of total phenols or polyphenol
Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some of ...
s.
Household use
Prussian blue is present in some preparations of laundry bluing
Bluing, laundry blue, dolly blue or washing blue is a household product used to improve the appearance of textiles, especially white fabrics. Used during laundering, it adds a trace of blue dye (often synthetic ultramarine, sometimes Prussian bl ...
, such as Mrs. Stewart's Bluing
Mrs. Stewart's Bluing is a brand of liquid bluing agent used for whitening fabrics. It is primarily a colloid of the blue pigment "Prussian blue" and water.
History
Mrs. Stewart's was founded by Al Stewart, a traveling salesman who sold the fo ...
.
Battery materials
Prussian blue (PB) has been studied for its applications in electrochemical energy storage and conversion since 1978. It is possible to replace the Fe metal centers in PB with different metal ions such as Mn, Co, Ni, Zn, ''etc.'' to form electrochemically active Prussian blue analogues (PBAs). PB/PBAs and their derivatives can be used as electrode materials for reversible alkali-ion insertion and extraction in lithium-ion battery
A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also se ...
, sodium-ion battery
The sodium-ion battery (NIB or SIB) is a type of rechargeable battery that uses sodium ions (Na+) as its Electric charge, charge carriers. Its Lithium-ion battery#Electrochemistry, working principle and Lithium-ion battery#Design, cell constructio ...
, and potassium-ion battery
A potassium-ion battery or K-ion battery (abbreviated as KIB) is a type of battery and analogue to lithium-ion batteries, using potassium ions for charge transfer instead of lithium ions. It was invented by the Iranian/American chemist Ali Eftekhar ...
.
See also
*
* Blue pigments
Blue pigments are natural or synthetic materials, usually made from minerals and insoluble with water, used to make the blue colors in painting and other arts. The raw material of the earliest blue pigment, lapis lazuli, came from mines in Afgh ...
*
*
*
*
*
*
*
References
External links
The FDA's page on Prussian blue
The CDC's page on Prussian blue
* ttp://www.heyltex.com/ Heyltex Corporation distributors of Radiogardase (Prussian blue insoluble capsules)
Sarah Lowengard, "Prussian Blue" in ''The Creation of Color in Eighteenth Century Europe'' Columbia University Press, 2006
Prussian blue
ColourLex
*
{{DEFAULTSORT:Prussian Blue
Cyanides
Iron(II,III) compounds
Inorganic pigments
Iron complexes
Shades of blue
Photographic chemicals
World Health Organization essential medicines