Dyes, organic structural classes

Organic dye materials represent the largest and best characterized class of probes used in all manner of fluorescent analysis. As an overall class, these dyes are used in almost all areas of biotechnology, including biosensing, cellular imaging, clinical immunofluorescence, and in DNA/protein microarrays (42-45). Several major structural classes of organic fluorophore span the UV-to-near-IR spectrum see Fig. 4. UV dyes are typically pyrene-based, naphthalene-based, and coumarin-based structures, whereas the Vis/near-IR dyes include a variety of... 

The chemistry of the three most important chemical classes of organic colorants, the azo, carbonyl and phthalocyanine classes, has been dealt with individually in Chapters 3-5 respectively. In this chapter, the chemistry of a further five chemical classes which are of some importance for specific applications is discussed. These classes are the polymethines, arylcarbonium ion colorants, dioxazines, sulfur dyes and nitro dyes. A section of this chapter is devoted to each of these, each individual section contains a description of the principal structural features which characterise the particular colorant type, together with an outline of the chemistry of the main synthetic routes. There are many other chemical types of dyes and pigments that do not fall into the categories previously mentioned, but which are neglected in this text either because they are commercially of little importance or because they have been less extensively investigated. 

The RP-TLC behaviour of some common food dyes was investigated in detail. The chemical structure of dyes are listed in Fig. 3.2. Measurements were carried out on RP-18 silica plates using aqueous ammonium sulphate (0.1 0.5 1.0 M), ethanol and acetone in various volume ratios. Developments were performed at room temperature (22 2°C) in chambers previously saturated with the vapours of the mobile phase. It was found that the presence of dissociable anorganic salt modifies markedly the RP retention behaviour of dyes. The retention of dyes generally decreases with increasing concentration of the organic modifier in the mobile phase. It was further concluded that RP-TLC can be successfully used for the separation of this class of synthetic food dyes [81]. 

Historically, most of the PS tested for their antimicrobial properties were already knovm to be effective for cancer treatment. They include the following classes of organic dyes porphyrin-related structures, phthalo-cyanines, phenothiazinium dyes, xanthylium dyes, and cationic fuller-enes (Dai et ah, 2009) (Table 3.3). 

The term phthalocyanine was first used by R. P. Linstead in 1933 [1] to describe a class of organic dyes, whose colors range from reddish blue to yellowish green. The name phthalocyanine originates from the Greek terms naphtha for mineral oil and cyanine for dark blue. In 1930-1940, Linstead et al. elucidated the structure of phthalocyanine (H2Pc) and its metal complexes [1-11]. The basic structure is represented by phthalocyanine (1) itself ... 

However, it is a truism in materials science that the pathway from vision to reality or from an idea to a marketable product is hardly ever as straightforward as it may seem. The field of organic materials for non-linear optics is no exception. Many problems are encountered when it comes to the translation of a molecular property into a bulk property. It has transpired that some of these problems are not easy to solve with classical NLO-phores that mostly belong chemically to the class of merocyanine dyes. New design strategies for organic molecules and their respective bulk structures, crystals or oriented composite materials like polymers, are needed. Only a more fundamental understanding of these issues will allow rational optimization of molecular and bulk properties. 

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