This chapter is devoted to the structure and properties of dyes and pigments.Ĭolour provides a significant glimpse of our world. They are widely used in the textile, pharmaceutical, food, cosmetics, plastics, paint, ink, photographic and paper industries. Dyes and pigments are the most important colourants used to add colour or to change the colour of something. Pigments are organic and inorganic compounds which are practically insoluble in medium in which they are incorporated. The polar auxochrome makes the dye water-soluble and binds the dye to the fabric by interaction with the oppositely charged groups of the fabric structure. A Dye is a coloured compound due to the presence of chromophore and its fixed property to the acid or basic groups such as OH, SO3H, NH2, NR2, etc.
Dyes are coloured organic compounds that are used to impart colour to various substrates, including paper, leather, fur, hair, drugs, cosmetics, waxes, greases, plastics and textile materials.
These structures are said to be responsible for the absorption of electromagnetic radiation that has varying wavelengths, based upon the energy of the electron clouds. Their structures have Aryl rings that have delocalized electron systems. Both dyes and pigments are coloured as they absorb only some wavelength of visible light. These are the substances which are used as colourants i.e. In our daily life, we know about many substances which have specific colours.
Plants, animals, and minerals have been used as primary sources for colourants, dyes or pigments since ancient times. Colour is one of the elements of nature that makes human life more aesthetic and fascinating in the world.
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