Photofading of Azo Pyridone Dyes in Solution

Abstract

The influence of various substituent groups on the absorption spectra and photostability of some azo pyridone dyes has been examined in N,N-dimethyl-formamide.On exposure to a spectrum of ultraviolet radiation, photoreduction is mostly caused by radiation of 254 nm. The primary photochemical reaction with azo pyridone dyes involves hydrogen abstraction from the amide solvent. Two electron-withdrawing substituents in the diazo component of azo pyridone dye exert a bathochromic effect and increase the fading rate, while introduction of an alkylol group to the coupling component results in hypsochromic shifts and a decrease in the fading rate.

Solvent and structural effects on the spectral shifts of 5-(substituted phenylazo)-3-cyano-6-hydroxy-1-(2-hydroxyethyl)-4-methyl-2-pyridones

“…13 C NMR shifts from two carbonyl groups (160.1-161.0 ppm) in the pyridone ring and 1 H NMR shifts in the region 14.28-14.84 ppm corresponding to the N H hydrazone proton strongly suggest the presence of the hydrazone form in DMSO-d 6 . UV-vis spectra of the investigated dyes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) in ethanol are given in Figure 2A. Intense bands appearing in the region 427.0-466.5 nm are ascribed to the intramolecular charge transfer (ICT) of the hydrazone tautomeric form.…”

“…The structure of arylazo pyridone dyes, along with their spectral properties and tautomerism have been reported previously [8][9][10][11]. Arylazo pyridone dyes exhibit azo-hydrazone tautomerism when hydroxy group is conjugated with the azo bridge.…”

Optimization of electrochemical decolorization of certain arylazo pyridone dyes

“…18 Dyes 3, 4, 6, 8, 11 and 12 are described in literature. [10][11][12][19][20][21][22] The physical, analytic _________________________________________________________________________________________________________________________ (CC) 2014 SCS. All rights reserved.…”

“…It was found that the simultaneous presence of two electron-withdrawing substituents in the diazo component of the dyes caused an increase in the fading rate, while the introduction of an hydroxyalkyl group to the coupling component resulted in a decrease in the fading rate. 10 In addition, the arylazo pyridone dyes were applied to polyester fabrics and the effects of substituents on the photofading on polyester substrates was studied. 11,12 Electron-withdrawing substituents on aniline inc-_________________________________________________________________________________________________________________________ (CC) 2014 SCS.…”

Substituent and solvent effects on the dipole moments and photophysical properties of two azo sulfonamide dyes

“…Their elongated molecular structures and large order parameter in liquid crystalline media, give them potential for application in non-linear optical (NLO) devices [3,4]. Many studies have been dedicated to investigate the relationship between the structure and the spectroscopic features of azo dyes [4][5][6][7][8][9]. Azo sulfonamide derivatives with heteroaromatic substituents are able to demonstrate NLO behavior in thin layers [10].…”