6,6′-Dibromoindigo is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula (BrC₆H₃C(O)CNH)₂. A deep purple solid, the compound is also known as

Tyrian purple Tyrian purple ( ''porphúra''; ), also known as royal purple, imperial purple, or imperial dye, is a reddish-purple natural dye. The name Tyrian refers to Tyre, Lebanon, once Phoenicia. It is secreted by several species of predatory sea snails ...

, a dye of historic significance. Presently, it is only a curiosity, although the related derivative

indigo InterGlobe Aviation Limited (d/b/a IndiGo), is an India, Indian airline headquartered in Gurgaon, Haryana, India. It is the largest List of airlines of India, airline in India by passengers carried and fleet size, with a 64.1% domestic market ...

is of industrial significance. It is produced by

snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...

s of the family

Muricidae Muricidae is a large and varied taxonomic family of small to large predatory sea snails, marine gastropod mollusks, commonly known as murex snails or rock snails. With over 1,700 living species, the Muricidae represent almost 10% of the Neog ...

. The pure compound has

semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...

properties in the thin film phase, which is potentially useful for wearable electronics, and has better performance than the parent indigo in this context.

Biosynthesis

Biosynthesis Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthe ...

of the molecule is intermediated by tyrindoxyl sulphate. The molecule consists of a pair of monobrominated indolin-3-one rings linked by a carbon–carbon double bond. Dibromoindigo can also be produced enzymatically in vitro from the

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromat ...

. The sequence begins with bromination of the benzo ring followed by conversion to 6-bromo

indole Indole is an organic compound with the formula . Indole is classified as an aromatic heterocycle. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indoles are derivatives of indole ...

. Flavin-containing monooxygenase then couples two of these indole units to give the dye.

Chemical synthesis

The main chemical constituent of the Tyrian dye was discovered by Paul Friedländer in 1909 to be 6,6′-dibromoindigo, derivative of

indigo dye Indigo dye is an organic compound with a distinctive indigo, blue color. Indigo is a natural dye obtained from the leaves of some plants of the Indigofera#Uses, ''Indigofera'' genus, in particular ''Indigofera tinctoria''. Dye-bearing ''Indigofer ...

, which had been synthesized in 1903. Although the first chemical synthesis was reported in 1914, unlike indigo, it has never been synthesized at commercial level. An efficient protocol for laboratory synthesis of dibromoindigo was developed in 2010.

References

{{DEFAULTSORT:Dibromoindigo, 6,6'- Indigo structure dyes Bromoarenes Organic semiconductors