indigo-carmine and 6-6--dibromoindigo

Topics: Color; Coloring Agents; Indigo Carmine; Indoles

Tyrian purple, mainly composed of 6,6'-dibromoindigo (6BrIG), is an ancient dye extracted from sea snails and was recently demonstrated as a biocompatible semiconductor material. However, its synthesis remains limited due to uncharacterized biosynthetic pathways and the difficulty of regiospecific bromination. Here, we introduce an effective 6BrIG production strategy in Escherichia coli using tryptophan 6-halogenase SttH, tryptophanase TnaA and flavin-containing monooxygenase MaFMO. Since tryptophan halogenases are expressed in highly insoluble forms in E. coli, a flavin reductase (Fre) that regenerates FADH

Topics: Biocompatible Materials; Cloning, Molecular; Coloring Agents; Escherichia coli; Escherichia coli Proteins; Flavin-Adenine Dinucleotide; FMN Reductase; Gene Expression; Gene Expression Regulation, Bacterial; Genetic Vectors; Halogenation; Indigo Carmine; Indoles; Metabolic Engineering; Oxidoreductases; Oxygenases; Recombinant Proteins; Semiconductors; Stereoisomerism; Tryptophan; Tryptophanase

A new series of symmetrical organic dyes containing an indigo central core decorated with different electron donor groups have been prepared, starting from Tyrian Purple and using the Pd-catalyzed Stille-Migita coupling process. The effect of substituents on the spectroscopic properties of the dyes has been investigated theoretically and experimentally. In general, all dyes presented intense light absorption bands, both in the blue and red regions of the visible spectrum, conferring them a bright green color in solution. Using the same approach, an asymmetrically substituted D-A-π-A green dye, bearing a triarylamine electron donor and the cyanoacrylate acceptor/anchoring group, has been synthesized for the first time and fully characterized, confirming that spectroscopic and electrochemical properties are consistent with a possible application in dye-sensitized solar cells (DSSC).

Topics: Amines; Color; Coloring Agents; Electric Power Supplies; Indigo Carmine; Indoles; Models, Molecular; Solar Energy; Spectrum Analysis

Attempts at identification of mollusc species producing Tyrian purple from archaeological material are usually done with high performance liquid chromatography in the reversed-phase system, but the peaks obtained are often wide and asymmetric. This is due to the low solubility of the indigoids and their brominated derivatives in the mobile phase, especially 6,6'-dibromoindigotin, which is soluble in only few, particular solvents. Our study focused on improving both symmetry and peak height for more precise quantification. The influence of various factors was evaluated: stationary phase characteristics, mobile phase composition, elution gradient parameters and temperature on the peak shape of the main components of Tyrian purple. The best results were obtained using highly retentive, but moderately bonded ODS stationary phases (about 2.8 μmol m(-2)), percolated with gradient of acetonitrile with acidified aqueous mobile phases (0.1% strong acid) at elevated temperatures (70°C). The upper quantification limit for 6,6'-dibromoindigotin was improved by over 350%, between standard and optimised systems. Using them, the detection and quantification of trace Tyrian purple components (less than 0.15%) aside from major indigoids becomes possible. Consequently, for the first time, the new analogues of brominated and unbrominated indirubins were found in the shellfish purple from Hexaplex trunculus.

Topics: Acetonitriles; Bromine; Chromatography, High Pressure Liquid; Indigo Carmine; Indoles; Solubility; Spectrophotometry, Ultraviolet; Temperature

Over the past century, various synthetic approaches have been suggested to the most famous dye of antiquity, Tyrian purple (6,6'-dibromoindigo). These synthetic routes have been exhaustively surveyed and critically evaluated from the perspective of convenience, cost, safety and yield.

Topics: Benzaldehydes; Benzoic Acid; Chemistry, Organic; Indigo Carmine; Indoles

6,6'-Dibromoindigo is a major component of the historic pigment Tyrian purple, arguably the most famous dye of antiquity. Over the last century, chemists have been interested in developing practical syntheses of the compound We describe herein a new, reasonably simple and efficient synthesis of Tyrian purple which opens the way to the production of large quantities of the dye with minimal hazards and at low cost.

Topics: Benzaldehydes; Benzoic Acid; Chemistry, Organic; Halogenation; Indigo Carmine; Indoles