Natural dyes are widely used in the coloring of food, leather and wood [1]. Traditionally they were the only colorants for textile fibers like wool, silk, cotton and flax. Their use in textiles declined drastically with the introduction of synthetic dyes in 1856 [2-6]. Presently the use of synthetic dyes is estimated at around 10,000,000 tons per annum [7-11]. The manufacture and use of this la...

Azo dyes are one of the oldest industrially synthesized organic compounds characterized by presence of Azo bond (-N=N-) and are widely utilized as coloring agents in textile, leather, cosmetic, paint, plastic, paper, and food industries During textile processing, inefficiencies in dyeing result in large amounts of the dyestuff (varying from 2% loss when using basic dyes to a 50% loss when certa...

A simple and easy solubility enhancement of basic dyes was performed with bulky and symmetric weakly coordinating anions (WCAs). The WCAs decreased the ionic character of the dyes by broadening the partial charge distribution and causing a screening effect on the ionic bonding. This new modification with WCAs has advantages in that it has no influence on the optical properties of the dyes. The ...

Dyes derived from natural materials such as plant leaves, roots, bark, insect secretions, and minerals were the only dyes available to mankind for the coloring of textiles until the discovery of the first synthetic dye in 1856. Rapid research strides in synthetic chemistry supported by the industrialization of textile production not only led to the development of synthetic alternatives to popul...

Dyes are synthetic organic compounds widely used in various industries such as, textile, leather, plastic, food, pharmaceutical, and paints manufacturing industries. Coloured effluents are highly toxic to the aquatic life and mutagenic to humans. Wastewater containing dyes has become an important issue demanding serious attention. Among the synthetic dyes, azo dyes are the largest and most wide...

Heptamethine cyanine dyes are attractive compounds for imaging purposes in biomedical applications because of their chemical and photophysical properties exhibited in the nearinfrared region. A series of meso amino-substituted heptamethine cyanine dyes with indolenine, benz[e]indolenine and benz[c,d]indolenine heterocyclic moieties were synthesized and their spectral properties including fluore...

A new preparation method of polymer dyes was developed to improve both the grafting degree of the azo dyes onto O-carboxymethyl chitosan (OMCS) and the water solubility of prepared polymer dyes. Firstly, the coupling compound of two azo edible colorants, sunset yellow (SY) and allura red (AR), was grafted onto OMCS, and then coupled with their diazonium salt. The chemical structure of prepared ...

Caterpillars of Manduca sexta use two distinct transport mechanisms for the excretion of dyes. One pump (Type A) has a high affinity for acid (anionic) dyes and occurs in the midgut and medial Malpighian tubules. Acid dyes accumulate rapidly in the lumen of the midgut while the Malpighian tubules appear to play only a minor role in the excretion of these dyes. The other pump (Type B) excretes b...