Triazine-linked dyes

The marked differences in substantivity between the various forms of monofunctional vinylsulphone dyes (section 7.3.8) recur to a moderated extent in the Sumifix Supra dyes because of the influence of the substantive triazine ring. The scarlet chromogen (7.77) linked via a chlorotriazine unit to the three variants of the vinylsulphone grouping showed similar trends (Table 7.4) to those already seen for those of Cl Reactive Red 22 tested under the same conditions (Table 7.3). The rate of secondary exhaustion will be easier to control in this instance because of the lower difference in substantivity between the precursor and the vinylsulphone form [37]. 

Rate constants and the products formed in the hydrolysis of Cl Reactive Red 194 (7.76) at 50 °C and pH values in the 10-12 region were determined by high-pressure liquid chromatography. In addition to the normal hydrolysis of the two reactive systems, the imino link between the triazine and benzene nuclei was also hydrolysed [67]. The heterobifunctional copper formazan dye Cl Reactive Blue 221 and two blue anthraquinone monofunctional reactive dyes of the bromamine acid type, namely the aminochlorotriazine Blue 5 and the sulphatoethylsulphone Blue 19, were compared in terms of their sensitivity to... 

Triazinyl Dyes. The principle of linking two or three azo dyes by means of a tria-zine ring was established by Ciba patents [7], The triazine bridge increases the substantivity of the dyes, in a similar manner to the -NH-CO- NH- group (for synthesis see Section 3.3.4). 

The blue component (H acid — cresidine—>H acid) is linked with the triazine ring by means of the amino group of the H acid after reduction of the nitro group, the yellow component (j9-nitroaniline —> salicylic acid) replaces the second chlorine atom of cyanuric chloride, and aniline the third chlorine atom. The dye constitutes a very pure, clear, bluish green with very good fastness properties. 

Cibacron Blue is a blue, polyaromatic, sulfonated dye (Fig. 6). It can be attached, as an affinity li nd, to solid matrix supjmrts (e.g. dextran, agarose) by the reaction of the triazine ring with free hydroxyl groups of the supports. The conditions of this triazine coupling method have been described by Bohme Such a dye affinity sorbent is also produced commercially, e.g. under trade name Blue Sepharose CL-6B (Cibacron Blue F3G-A covalently bound to the cross-linked agarose gel Sepharose CL-6B ) by Pharmacia, Sweden. 

Among the newest of the dyes are the fiber reactive compounds, which form a covalent link to the hydroxyl groups of cellulose. The reaction involves an amazing and little understood nucleophilic displacement of a chloride ion from the triazine part of the molecule by the hydroxyl groups of cellulose yet the reaction occurs in aqueous solution. 

Photosensitizer-Linked Photoinitiator or Coinitiator-Based Systems Attempts have been made to incorporate the dye and the energy or the electron donor in the same molecule. An old example was apolymeric system where a morpholinoketone and a thioxanthone derivative were grafted [215]. A first recent example corresponds to a dye linked to a triazine derivative (10.61) where an intramolecular electron transfer yields a radical anion on the triazine moiety that results in the production of a radical [216,217],... 

Other examples can be found in xanthene-thiol [219], carbazole-triazine [220], photosensitizer-ketones [221 ]. In both last cases, the reactivity of the dye-donor linked photoinitiator is higher than that of a physical mixture of the dye and donor moieties. 

The structure of Blue Dextran 2000, a water-soluble commercial derivative, involves a triazine type of dye covalently linked to dextran, and, in a way analogous to that used for other dyed polysaccharides, has been employed for the assay of dextranase. The ability of Blue Dextran 2000 to bind proteins cannot be attributed to formation of a covalent link, because no chloro groups remain on the triazinyl rings. The binding must involve an ionic bond between the protein and the sulfonic groups of the dye residue, and, in one case, the association could be reversed by using 0-(2-diethylaminoethyl) cellulose to abstract the dyed polysaccharide. Other chlorotriazinyl dyes have been used in the preparation of dyed derivatives of amylopectin, laminaran, dextrans, pectin, pelvetian, zosterine, and cellulose. As already mentioned, triazine-dyed polysaccharides are useful in enzyme insolubilization. 

Unspecific inhibition of ribonucleotide reduction is produced by compounds like pyridoxal phosphate, or the sulfonated anthraquinone-triazine dye, Cibacron blue. They interact, like in many enzymes, with nucleotide binding domains where pyridoxal phosphate becomes covalently linked to lysine, or in that the dye occupies the whole nucleotide fold. The latter interaction permits its use in affinity chromatography of ribonucleotide reductases Likewise, EDTA is not a specific, nor a potent inhibitor, it may, for example, act by complexation of the structure-stabilizing Mg " ions in native holoenzymes. However the iron-promoted radical regeneration process appears far more susceptible to interference from EDTA ... 

Linking together two reactive moieties instead of having two separate reactants (e g. in Eosin-oxime ester [BUR 99] or dye-triazine [KAW 13]) facilitates efficient intramolecular interactions (generally through electron... 

One approach of utilizing fully synthetic (and cheaper) nicotinamide analogs was suggested by Lowe and coworkers (Scheme 8.19) [85]. Here, nicotinamides covalently linked to triazine dyes were evaluated. However, catalytic performance of these artificial NAD analogs was rather poor. The same is true for N-benzyl nicotinamide derivatives for ADH-catalyzed reductions (Scheme 8.19) [86]. Unfortunately, again, the catalytic performance of these synthetic mimics (mNADs) fell back by orders of magnitude behind the natural nicotinamide cofactors. 

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