Azo-dye molecules

Azo dye molecules have color due to their azo bond, auxochromes, and system of conjugated double bonds. The azo bond, while resistant to aerobic degradation, can be cleaved under anaerobic or anoxic condition, resulting in decolorization and the production of aromatic amines. Anaerobic reduction of the azo dyes is relatively easy to achieve, but the products have been found to be biorecalcitrant... 

Incorporation of the thiazole and thiophene rings into the donor portion of the azo dye molecule as in (108) and (109) also results in a bathochromic shift, the former dye being green and the latter violet, absorbing at 554 nm (emax 50 000dm3moF1 cm-1), a bathochromic shift of 75 nm when compared with the iso-7r-electronic p-dimethylaminophenyl systems, which has been explained in terms of the easier ionizability of the thienyl residue (78C323). 

James and coworkers [38] have synthesized an azo dye molecule with boronic acid, receptor 40, which can act as a colorimetric sensor for detection... 

The photo-induced trans-cis isomerization reaction of certain azo-dye molecules such as Dispersed Red 1 (DRl),... 

Pseudo-stilbenes may emit fluorescence that is, contrary to true stilbenes, generally weak at room temperature and often weak even at low temperatures. Protonated azobenzene-type molecules and many protonated azo dye molecules emit strong fluorescence in sulfuric acid at 77 K with quantum yields of about 0.1. Inclusion of azobenzene in the channels of AIPO4-5 crystals provides complexation of the n-electrons and space confinement. This leads to emission by protonated azobenzene at room temperature. For their cyclopalladated azobenzenes, Ghedini et al. " report quantum yields of ca. 1T0 and lifetimes of ca. 1 ns. In contrast, donor/acceptor pseudo-stilbenes, if emitting at low temperatures or when adsorbed to surfaces, are weak emitters. In textile chemistry, it has long been known that azo dyes adsorbed to fibers may show fluorescence. ... 

Fig. 37a,b. Schematic view of the orientation mechanism in all optical poling with azo dye molecules (a) and electron transition diagram between fundamental and excited singlet states (b). In the case of azo dyes, the trans-cis isomerization is achieved through both one- and two-photon excitations [144]... 

Borchardt and Still have developed an assay for the evaluation of the binding of a 5 x 10 -member (peptide) substrate library [95]. Azo dye molecules were attached to the tetracyclic peptide receptor shown in Figure 70, Intense coloration of a polystyrene bead containing a substrate signaled strong... 

Pseudo-stilbenes may emit fluorescence that is, contrary to true stilbenes, generally weak at room temperature and often weak even at low temperatures. Protonated azobenzene-type molecules and many protonated azo dye molecules emit strong fluorescence in sulfuric acid at 77 with quantum... 

Advincula RC, Baba A, Kaneko F. 1999. Polymer ultrathin films via alternate self assembly adsorption of polyelectrolyte and azo dye molecules photo induced alignment and LC display properties. MRS Proc Spring Symp D Liquid Crystal Materials and Devices, San Francisco, 559. 

Hoshino and Saji [7] first reported the preparation of azo-dye thin films using FTMA. These films were prepared by controlled-potential electrolysis of the FTMA micelle aqueous solution solubilizing the azo dye at 4-0.3 V versus SCE. The azo-dye molecules exist as sol-ubilizate in the micelles, and are then released from the micelles and deposited... 

Lakowicz has also prepared boronic acid azo dye molecules 41 and 42 in which direct conjugation with the boron center is possible. In particular, the azo dye 42 produces a visible color change from yellow to orange at pH 7. 

Ono, H., Kowatari, N. and Kawatsuki, N. (2001) Holographic grating generation in thick polymer films containing azo dye molecules . Opt. Mater, 17,387-394. 

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