Prussian blue pigment

Turchino was considered by Merrifield (1849) to be a carbonate of copper said to have been imported into Italy by the Turks. It was also mentioned as turquin in the so-called Bmssels MS translated by Merrifield where it is described as a blue frit. Turchino is also refered to in Sir Joshua Reynolds manuscript notes, where it clearly refers to a Prussian blue pigment (. v. Kirby Talley, 1986). 

Prussian Blue. Reaction of [Fe(CN)3] with an excess of aqueous h on(Ill) produces the finely divided, intensely blue precipitate Pmssian Blue [1403843-8] (tetrairon(Ill) tris(hexakiscyanoferrate)), Fe4[Fe(CN)3]. Pmssian Blue is identical to Turnbull s Blue, the name which originally was given to the material produced by reaction of [Fe(CN)3] with excess aqueous h on(Il). The soHd contains or has absorbed on its surface a large and variable number of water molecules, potassium ions (if present in the reaction), and h on(Ill) oxide. The h on(Il) centers are low spin and diamagnetic h on(Ill) centers are high spin. Variations of composition and properties result from variations in reaction conditions. Rapid precipitation in the presence of potassium ion affords a colloidal suspension of Pmssian Blue [25869-98-1] which has the approximate composition KFe[Fe(CN)3]. Pmssian Blue compounds are used as pigments in inks and paints and its formation on sensitized paper is utilized in the production of blueprints. 

Prussian blue (PB ferric ferrocyanide, or iron(III) hexacyanoferrate(II)) was first made by Diesbach in Berlin in 1704.88 It is extensively used as a pigment in the formulation of paints, lacquers, and printing inks.89,90 Since the first report91 in 1978 of the electrochemistry of PB films, numerous studies concerning the electrochemistry of PB and related analogs have been made,92 with proposed applications in electrochromism1 and electrochemical sensing and catalysis 93... 

Prussian blue (inorgchem) Fe4 Fe(CN)6 3 Ferric ferrocyanide, used as a blue pigment and in the removal of hydrogen sulfide from gases. prash an blu j prussic acid See hydrocyanic acid. pras ik as ad ... 

Prussian Blue (PB) has been known for many decades, originally because of its wide use as a pigment and later because of its interesting redox properties [91]. PB is comprised of Fe(II) and Fe(III) centers, CN ligands and K counterions. It has a... 

Prussian blue or ferric ferrocyanide or iron(lll) hexakis(cyanoferrate(3—)) has the formula Fe4[Fe(CN)6]3. There are several commercial applications. It is used as pigment for paints, inks, typewriter ribbons, alkyd resins, enamels. 

A GCE coated with a film of Prussian Blue (Fe4[Fe(CN)6]3) mimics HRP as catalyst for selective electrochemical reduction of H2O2 in the presence of O2. A careful deposition method has to be followed to prevent leakage of the oxidized form of the pigment from the coating into the solution. Amperometric determinations in phosphate buffer at pH 6.0, with an apphed potential of —50 mV vs. SCSE, shows Unearity in the 0.1 to 100 p,M range. ... 

Figure 16 shows the spectra obtained for two other pigments— green earth and Prussian blue. In the former case there are actually two spectra, one of which consists of a widely split doublet typical of iron (II) compounds. Heating this pigment changes it to a brownish-red and removes the ferrous doublet. 

The term iron blue pigments as defined in ISO 2495 has largely replaced a great number of older names (e.g., Paris blue, Prussian blue, Berlin blue, Milori blue, Turnbull s blue, toning blue, and nonbronze blue). These names usually stood for insoluble pigments based on microcrystalline Fe(II)Fe(III) cyano complexes many were associated with specific hues. A standardized naming system has been demanded by users and welcomed by manufacturers, and has led to a reduction in the number of varieties [3.177],... 

Another candidate for the first coordination compound is Prussian Blue, potassium iron(III) hexacyanoferrate(II), a complex of empirical formula KCN-Fe(CN)2- Fe(CN)3. It was first obtained accidentally in 1704 by Diesbach, a manufacturer of artist s colors from Berlin. Initially it was described9 as a nontoxic pigment suitable for oil colors, but its method of preparation was kept secret, probably because Diesbach wished to benefit monetarily from his discovery. 

Some coordination compounds have been used as dyes and pigments, but it must be admitted that these applications developed without reference to the fact that the compounds are complexes. Examples of paint pigments are Prussian blue and the phthalocyanines metallized azo dyes are common in the textile industry. 

Cyanide Iron Blues. Cyanide iron blue, also known as Prussian blue, is one of the oldest industrially produced, inoiganic pigments. Chemically, cyanide iron blues are based on the [Fe2+ [Fe3+ (CN)6] " anion. The charge is balanced by sodium, potassium, or ammonium cations. Modem... 

Inorganic Color Pigments. Iron blue is made in several shades, such as Milori blue and Prussian blue. It is economical, but has poor alkali resistance. It is also used as a toner in some black inks. 

Alkali or alkaline-earth salts of both complexes are soluble in water (except for Ba2[Fe(CN)6]) but are insoluble in alcohol. The salts of hexakiscyanoferrate(4—) are yellow and those of hexakiscyanoferrate(3—) are mby red. A large variety of complexes arise when one or more cations of the alkali or alkaline-earth salts is replaced by a complex cation, a representative metal, or a transition metal. Many salts have commercial applications, although the majority of industrial production of iron cyanide complexes is of iron blues such as Prussian Blue, used as pigments (see PIGMENTS, inorganic). Many transition-metal salts of [Fe(CN) J4"" have characteristic colors. Addition of [Fe(CN)6]4 to an unknown metal salt solution has been used as a qualitative test for those transition metals. 

The intense blue color of Prussian Blue is attributed to electron transfer between the [Fe(CN) ]4 and Fe(III) ions. A related pigment called Berlin Green is obtained by oxidation of Prussian Blue. It is thought that the intense color of this other compound results only if oxidation of the fFe(CN)6] units is incomplete and some remain as hexakiscyanoferrate(4—). The compound in which only iron(III) is present, Fe[Fe(CN)6] [14433-93-3], is brown and is subject to autoreduction processes. 

After extraction with ether as described above, the pigment should be thoroughly mixed in a mortar before examining it, since with mixtures the heavier components are deposited in the ether before the lighter ones, so that strata of different compositions are formed. In some cases this is recognised by the appearance of the deposit and useful indications on the nature of the mixture may be thus obtained e.g., when a coloured and a white substance are mixed, or two coloured ones (for instance, chrome yellow and Prussian blue). 

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