Xanthene dyes erythrosin

Quinophthalon dyes Quinoline yellow Xanthene dyes Erythrosine (see below)... 

The structure of the polymer produced from titanocene dichloride and the xanthene dye Erythrosine B is given as 2. 

Erythrosine (E 127, FD C Red No. 3, Cl Food Red 14) is a xanthene dye named disodium salt of 2-(2,4,5,7-tetraiodo-3-oxido-6-oxoxanthen-9-yl)benzoate monohydrate (or disodium salt of 9-(o-carboxyphenyl)-6-hydroxy-2,4,5,7-tetraiodo-... 

Nonchelating dyes include basic triphenylmethane dyes (e.g., Brilliant Green, Malachite Green, Crystal Violet), xanthene dyes (e.g., Rhodamine B, Rhodamine 6G), azine dyes (e.g., Methylene Blue), and acid dyes (e.g., Eosin, Erythrosin). These are intensely colored and when paired with an oppositely charged analyte ion lead to high sensitivities. 

With rose bengal and erythrosin as xanthene dye sensitizers, the... 

Automated HPLC methods were developed for the determination of subsidiary dyes, intermediates, and side reaction products of erythrosine. Peeples and Heitz (154) described a reverse-phase HPLC method to monitor the purity of erythrosine and a series of xanthene dyes involving a yuBondapak Cl 8 column and mixtures of methanol and ammonium acetate buffer. 

Macrae and Wright (96) demonstrated that visible light irradiation of xanthene dyes (eosin, erythrosin, rhodamine B, or RB) in ethanolic solutions of 4-(N,N-diethylamino)benzene-diazonium chloride (as the zinc chloride double salt) resulted in decomposition of the diazonium salt. Electron transfer from the dye excited state(s) to the diazonium salt was postulated and dye-diazonium salt ion pair formation in the ground state was shown to be important. Similar dyes and diazonium salts were claimed by Cerwonka (97) in a photopolymerization process in which vinyl monomers (vinylpyrrolidone, bis(acrylamide)) were crosslinked by visible light. Initiation occurs by the sequence of reactions in eqs. 40-42 ... 

The acid xanthene dyes comprise Eosin (tetrabromofluorescein, formula 4.34) [79,80], Erythrosin (tetraiodofluorescein) and Rose Bengal B (formula 4.35) [79]. All these reagents are available as sodium salts. 

Use has been made of ion-pairs formed by the cationic complex of zinc with 1,10-phenanthroline or 2,2 -dipyridyl and acid dyes, such as eosin, Erythrosin, Rose Bengal, dibromofluorescein (xanthene dyes) [72-74], Bromophenol Blue, Bromophenol Red (triphenylmethane dyes) [75,76]. In some of these methods, molar absorptivities are -10. Chloroform is the usual extraction solvent. 

The second family of xanthene dyes is fluorescein and its derivatives. Fluorescein itself is only slightly fluorescent in alcohol solution. In contrast, the alkali salt obtained by addition of alkali exhibits the well-known yellow-green fluorescence characteristic of the fluorescein dianion (uranin). Fluorescein and its derivatives, e.g. eosin Yand erythrosin Y, are known to be very sensitive to pH and can thus be used as pH fluorescent probes (see Chapter 10). 

Electron transfer to the xanthenes, particularly reduction with amines, has been used for a number of years to initiate acrylate polymerization. A typical system is that reported to form volume holograms—lithium or zinc acrylate, triethanolamine and Eosin, Erythrosin, or Rose Bengal [290], Similar mixtures are used to form printing plates photoreducible dye, phenylac-ridine, and acrylate monomer [292], A recent patent application discloses aryl iodonium salts, Rose Bengal, and oxidizable triazines such as 2-methyl-4,6-bis(trichloromethyl)-s-triazine to polymerize acrylates [292],... 

Fig. 4 Chemical structures of triarylmethane (food green S and brilliant blue FCF), xanthene (erythrosine), and quinoline (quinoline yellow) dyes.

Rate constants for quenching of triplet erythrosin (an acidic dye of the xanthene series) by a series of anilines were found to correlate with the aniline ionization potential (32). 

REE ions with 1,10-phenanthroline form cationic complexes such as [La(phen)3 which give ion-associates with xanthene acid dyes, eosin or Erythrosin [117,118]. Molar absorptivities are of the order of 1-10. Europium(II) has been determined by an indirect method, after reduction of Fe(III) and reaction of the resulting Fe(II) with 1,10-phenanthroline [119]. 

Some of the early studies of spectral sensitization of semiconductors have been on ZnO and CdS. The first report was published by Putzeiko and Terenin in 1949 when they reported sensitization of pressed ZnO powder by adsorbed Rhodamine B, Eosin, Erythrosin and by Cyanine dyes [12]. Hauffe and Gerischer coworkers made some pioneering studies in the seventies and these have been extended by many others [13-18]. Most of these early studies focussed on organic dyes of interest to photographic industry (e.g. Xanthenes such as Rhodamine B or Eosin or Cyanines). 

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