Synthesis, structure, and UV–VIS absorption spectra of azo dyes derived from (dialkylamino)thiazole dimers †

Abstract

published as an Advance Article on the web 16th February 2001(Dialkylamino)thiazole dimers act as very strong electron-donating coupling components in azo dyes, the first and second UV-VIS absorption bands of which were observed at λ = 568-737 (ε = 24000-88000) and 404-475 (ε = 9200-52000) nm in dichloromethane, respectively. The azo compounds derived from the (dialkylamino)thiazole dimers having very strong electron-withdrawing moieties such as 4-(perfluoroalkylsulfonyl)phenyls, 2,4-dinitrophenyl, and thiazol-2-yls exhibited a negative solvatochromism. This is the first example of a negative solvatochromism in neutral azo dyes.

An experimental study on relationship between hammett substituent constant and electronic absorption wavelength of some azo dyes

“…The lowest energy electronic transitions correspond to n-π* electronic transition gives rise to increasing the push-pull character of molecules (Kim et al 2000;Kim et al 2001). As seen from the all of the figures, we can say that this molecule is the highest non-linear optical molecule among the investigated azo dyes, since the optic intensity of third band (n-π* electronic transition) in Az14 is comparatively larger than those of the second band (π-π* electronic transition).…”

Synthesis of azo carbonate monomers and biocompatibility study of poly(azo-carbonate-urethane)s

“…The UV-Vis absorption bands of azo compounds depend on the combination of electron-donating and electron-withdrawing moieties in their structures. 37,38 If an electron-donating group is present, intense absorption bands arise, associated with the transfer of electron density from the donor group into the rest of the chromogen. The absorption wavelength can be increased by attaching electron-withdrawing groups to the second phenyl ring.…”

Solvatochromism and potentiometic studies of some active nitroso- and nitroso-azo- compounds

“…This dipolar aprotic solvent destabilizes the polarized electronic state leading to a hypsochromic shifting. For DNRC with an electron withdrawing group on the azo benzene nucleus, solvatochromism is observed in the (nπ*) absorption upon increasing the electron withdrawing character of the substituents [44]. The lowest transition absorption band is assigned to (nπ*) transition while the other absorption band corresponding to the higher energy is assigned as (πσ*) transition.…”