Synthesis of Indigo-Dyes from Indole Derivatives by Unspecific Peroxygenases and Their Application for In-Situ Dyeing

Tyrian purple (also known as royal or imperial purple) is the oldest known commercial pigment and still one of the most expensive dyes, often associated with the wardrobes of clergy and royalty. It is a brominated derivative of indigo, a natural dye that has been used since 4000 BC. Moreover, just recently, the therapeutic value of indigoids for the treatment of several disorders was discovered. The manufacturing of indigo derivatives by the existing chemical routes has become increasingly uninteresting due to the use of aggressive reagents, expensive starting materials and high-energy costs. Thus, both dyestuff manufacturers and the pharmaceutical industry are interested in the development of gentle preparation methods of indigoids from simple precursors. Here, we describe a simple enzymatic method for the one-step synthesis of Tyrian purple and other indigo derivatives with fungal peroxygenases (UPO, EC 1.11.2.1). The reaction does not require complex co-substrates and works well in phosphate buffers with H2O2 (<0.1 wt%) and less than 5% (v/v) acetonitrile as co-solvent. We demonstrate the scaling up of the reaction to 10 Liters and established thereupon an environmentally friendly combined synthesis and in-situ dyeing process, further simplifying the manufacturing of vat-dyed fabrics. Eventually, we screened a number of halogen-substituted indoles in the search for novel indigo derivatives, which may be of interest for pharmaceutical and/or dyeing purposes.

Pigments—the palette of organic colourants in wall paintings

The present contribution deals with the use of organic colourants in wall paintings, polychrome pottery and painted stone artworks, i.e. painted artworks on inorganic supports. The term organic colourants is referred to the chemical nature of these compounds but not to the way of application; therefore, organic colourants can be dyes, lakes or pigments. The use of organic colourants in wall paintings has been given little attention in the past, perhaps on the assumption that they were rarely used by ancient artists. Recent diagnostic studies, however, brought evidence that their use was not fragmentary; on the contrary, there seems to be continuity in the centuries, at least with regard to the most widely used such as madder, Tyrian purple and indigo. Sources, alteration phenomena, identification methods and analytical evidence is given for the main organic colourants with concern to red, yellow, green, purple and blue hues. Drawbacks and issues are discussed with concern to the identification techniques.

Dioxazine pigments

This chapter provides an overview of the structural and synthetic chemistry, and the industrial applications, of dioxazine pigments, a small group of high performance organic pigments. The color violet (or purple) has frequently assumed a prominent position in history, on account of its rarity and cost. The natural colorant Tyrian purple and the first synthetic textile dye, Mauveine, are prime examples of this unique historical feature. CI Pigment Violet 23, also referred to as Dioxazine Violet or Carbazole Violet, is one of the most universally used organic pigments, by far the most important industrial pigment in the violet shade area. Dioxazine Violet is also unique as the dominant industrial violet pigment providing a brilliant, intense violet color and an excellent all-round set of fastness properties. The pigment has a polycyclic molecular structure, originally described wrongly as a linear arrangement, and later shown to adopt an S-shaped arrangement on the basis of X-ray structural analysis. Two other dioxazine pigments are of rather lesser importance. The synthesis and manufacturing route to CI Pigment Violet 23 is described in the review. Finally, a survey of the principal current applications of the individual dioxazine pigments is presented.

Tyrian purple: an ancient natural dye for cross-conjugated n-type charge transport

N-type charge transport from cross-conjugated polymers derived from an ancient dye.

AENEAS THE FLAMEN: DOUBLE TOGAS AND TABOOS IN VIRGIL'S CARTHAGE

This is an investigation of an aspect of Virgil's Aeneid—ultimately, of the ways in which the poet guides his reader's response to Aeneas’ stay in Carthage—and, while it touches on Roman religious practice, clothing codes, late antique Virgilian commentary and Augustan ideology, it hinges on a single word in Aeneid Book 4 and its implications for Virgil's depiction of his hero in this book. That word is laena, and it features in one of the most celebrated scenes of the poem, when Mercury descends to earth to find Aeneas busily engaged in founding Carthage (Aen. 4.259–64):ut primum alatis tetigit magalia plantis,Aenean fundantem arces ac tecta nouantemconspicit. atque illi stellatus iaspide fuluaensis erat Tyrioque ardebat murice laenademissa ex umeris, diues quae munera Didofecerat, et tenui telas discreuerat auro.As soon as Mercury with winged feet touched the Carthaginian huts, he caught sight of Aeneas founding the citadel and raising new buildings: his sword was studded with stars of yellow jasper, and a laena, hanging from/let down from his shoulders, blazed with Tyrian purple, a gift that Dido with her wealth had made, interweaving in the web a subtle cross-thread of gold.Line 4.262 is the only place in the Aeneid where this word is used, and I shall be suggesting that laena represents an unusually evocative piece of clothing to put on Aeneas, even aside from the particular character, its decoration and origin, that Virgil attributes to the example Aeneas is wearing at lines 4.262–4. What I offer is a cumulative argument, as a whole (I believe) persuasive but also necessarily speculative given the limited state of our knowledge in various areas from religion to clothing. My essential claim is that Virgil is encouraging his reader at this point in the poem to associate Aeneas with, and judge his behaviour in comparison to, one of the most important members of the Roman priesthood.

The Origin of the Porphyry Deposit Name: From Shellfish, Tyrian Purple Dye, and Imperial Rome to the World’s Largest Copper Deposits

The porphyry deposit name has a long and fascinating etymological history of over 3,000 years. “Porphyry” is derived from the ancient Greek word porphyra (πoρϕύρα), or purple. It was originally applied to a rare purple dye, Tyrian purple, extracted by the Phoenicians from murex shells. It was later applied to a prized purple porphyritic rock, Imperial Porphyry or Porfido rosso attico, quarried by the Romans from Mons Porphyrites in the Eastern Red Sea hills of Egypt from the first to fifth centuries A.D., and used as a monumental stone in Imperial Rome and Byzantium (Istanbul). The name evolved in the field of igneous petrology to include all rocks with a porphyritic texture, regardless of their color. Mining of the first porphyry copper deposits, which were originally called disseminated or low-grade copper deposits, started in 1905. As a result of the close spatial and genetic relationship to porphyry stocks, they became known as porphyry copper deposits. The term was first used by W. H. Emmons in his 1918 textbook The Principles of Economic Geology, but it was originally used more as an engineering and economic description, as in Parsons’ 1933 book The Porphyry Coppers. It was slow to catch on in the geological literature. It was first used in the title of a paper in Economic Geology in 1947 but did not gain widespread use until the 1970s, following the publication of seminal papers on porphyry models and genesis by Lowell and Guilbert (1970) and Sillitoe (1972, 1973).