Classical Organic Dyes

Until the middle of the 19th century, when William Perkin (1856) discovered serendipitously mauveine, the first synthetic dyestuff, all dyestuffs had been obtained from natural sources. Perkin s discovery sparked a major revolution in the dyeing industry and, over the ensuing few decades, a whole raft of new chromophores were discovered, laying the foundation for the first major industry based on the manufacture of complicated organic chemicals, the European dyestuff industry.  

Natural dyestuffs have not gone away, in fact there has been an upturn in then-fortunes as consumer demand has risen for natural materials to be used in the coloration of their food and drinks, in cosmetics and in the dyeing of fashion garments 

The main differentiating performance characteristic between dyestuffs and pigments is solubility. During their application, dyestuffs are solubilised, either in the medium or the hbre and hence lose any particular aspect of their crystal structure or physical form. Pigments, on the other hand, remain practically insoluble during their application processes, thus retaining aspects of their morphology, which are of importance to both their colour and performance. 

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Although the results of the last two approaches below previously reported results, this new extension of organo-photoredox catalysis to classic organic dyes would find broadly utility across many applications. 

Statistics for the production of basic dyes include those products hsted as cationic dyes, eg, cyanines, for dyeing polyacrylonitrile fibers and the classical triaryhnethane dyes, eg, malachite green, for coloring paper and other office apphcations (2,53). Moreover, statistics for triaryhnethane dyes are also hidden in the production figures for acid, solvent, mordant, and food dyes, and also organic pigments. Between 1975 and 1984, the aimual production of basic dyes in the United States varied from 5000—7700 t. However, from 1985—1990, aimual production of basic dyes varied from 5000—5700 t, and the annual sales value increased from 56 to 73 million per year. 

The aim of this Chapter is to review a method by which fluorescence properties of organic dyes can, in general, be predicted and understood at a microscopic (nm scale) by interfacing quantum methods with classical molecular dynamics (MD) methods. Some review of our extensive applications [1] of this method to the widely exploited intrinsic fluorescence probe in proteins, the amino acid tryptophan (Trp) will be followed by a discussion of electrochromic membrane voltagesensing dyes. 

The development of the synthetic dye industry led to the emergence of classical organic chemistry. Its application in industry was rapid. From the end of the nineteenth century the intermediates employed in the manufacture of synthetic dyes were used to make pharmaceutical products such as aspirin. Some synthetic dyes exhibited bactericidal properties they were called medicinal dyes. Sulfonamides, drugs introduced in the 1930s, are based on research into dyestuffs and their intermediates. Less fast dyes have... 

There must be a variety of reasons. One of them is certainly the overwhelming success of classical organic chemistry in studying low-molecular-weight natural products. Success tends to make people conservative. Alkaloids, natural dyes, carbohydrates, terpenes, steroids, and vitamins were all chemically exceedingly interesting, and many of them were biologically important as well as medically. 

Fluorescent semiconductor nanocrystals (CdSe, CdTe, PbSe, and others), otherwise included in the term quantum dots (QDs), have attracted much attention in various research fields for more than 20 yeais owing to their chemical and physical properties, which differ markedly fi om those of the bulk solid (quantum size effect). Quantum dots have size-tuneable light emission (usually with a narrow emission band), bright luminescence (high quantum yield), long stability (photobleaching resistance), and broad absorption spectra for simultaneous excitation of multiple fluorescence colors compared with classical organic fluorescent dyes. 

These classes of colorants are organized primarily according to classic textile dyeing terminology and are part of the classification scheme used by the Colour Index. 

In the first chapter, devoted to thiazole itself, specific emphasis has been given to the structure and mechanistic aspects of the reactivity of the molecule most of the theoretical methods and physical techniques available to date have been applied in the study of thiazole and its derivatives, and the results are discussed in detail The chapter devoted to methods of synthesis is especially detailed and traces the way for the preparation of any monocyclic thiazole derivative. Three chapters concern the non-tautomeric functional derivatives, and two are devoted to amino-, hydroxy- and mercaptothiazoles these chapters constitute the core of the book. All discussion of chemical properties is complemented by tables in which all the known derivatives are inventoried and characterized by their usual physical properties. This information should be of particular value to organic chemists in identifying natural or Synthetic thiazoles. Two brief chapters concern mesoionic thiazoles and selenazoles. Finally, an important chapter is devoted to cyanine dyes derived from thiazolium salts, completing some classical reviews on the subject and discussing recent developments in the studies of the reaction mechanisms involved in their synthesis. 

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