Azo dye complexes

Metallized Azo Dyes. The three metals of importance in azo dyes are copper, chromium, and cobalt. The most important copper dyes are the 1 1 copper(II) azo dye complexes of formula (21) they have a planar stmcture. 

For textile ink jet printing, conventional 2 1 Cr3+/Co3+ azo dye complex blacks are used, such as Cl Reactive Black 8 (S8).46... 

The CCAs which impart a negative charge to the toner are invariably metal complexes, particularly 2 1 Cr111 azo dye complexes such as (6), and colorless complexes such as (7), both of which have a delocalized negative charge [2,3],... 

Unfortunately, many of the observations of Cotton effects in proteins must, in the absence of spectrophotometric details, be viewed with some skepticism. This caution arises from the ease with which rotatory artifacts may be produced in regions of high absorbance. Winkler and Markus (1959) found that the unusual rotatory dispersions observed in azo-dye complexes of human serum albumin between 550 and 750 m/i (Markus and Karush, 1958) were attributable to stray light polarized by reflection within the cell housing and which the opacity of dye solutions allowed to predominate. It has more recently been found (Urnes et al., 1961b) that stray light in the optical path can give rise to artifacts at absorption bands that simulate... 

Complexation of the optically active model ligands to form Co(III)(EDDA)(azo dye) complexes would not necessarily be expected to generate a CD spectrum unless some diastereomeric preference was obtained. Indeed, a CD spectrum is observed for the azotyrosine (NA-MAT) complex, Figure 6. The spectrum is substantially more intense than that obtained for the free ligand, but... 

Isomerization has been studied in polymers containing aromatic azo-groups. For example, Eisenbach has investigated isomerization of azo-groups in poly(ethyl acrylate) and found the process to be very dependent on the cross-linking density. Photoinduced reversible pH changes in poly(carboxylic acid)-azo dye complexes were found to be very dependent upon the composition of the copolymer. Cis-trans isomerization of azobenzene has been used as a tool to... 

---