Push–pull bithiophene azo-chromophores bearing thiazole and benzothiazole acceptor moieties: Synthesis and evaluation of their redox and nonlinear optical properties

Abstract

Three series of bithiophene azo dyes functionalized with thiazol-2-yl or benzothiazol-2-yl-diazene acceptor moieties were synthesized through azo coupling reaction using 2,2´-bithiophene, 5-alkoxy-2,2´-bithiophenes, 5-N,N-dialkylamino-2,2´-bithiophenes and thiazolyl and benzothiazolyl diazonium salts as coupling components. The 5-alkoxy-2,2´bithiophene precursors yielded the 5-thiazolylazo-5´-alkoxy-2,2´-bithiophenes, while the azo coupling reaction of 5-N,N-dialkylamino-2,2´-bithiophenes with the thiazolyldiazonium salt gave 4-thiazolyl-azo-5-N,N-dialkylamino-2,2´-bithiophenes. A different reactivity behavior was observed for 2,2-bithiophene with thiazolyl diazonium salts which gave rise to the expected azo dyes together with several arylation products. The redox behavior, thermal stability, and the first hyperpolarizability of the novel chromophores were evaluated through cyclic voltammetry, thermogravimetric analysis (TGA) and hyper-Rayleight scattering (HRS) respectively. By varying the position of the thiazolyldiazene acceptor group on the bithiophene system, the electrochemical behavior as well as the optical (linear and nonlinear) properties of the donor-acceptor -conjugated systems can readily be tuned. Push-pull 5thiazolylazo-5´-alkoxy-2,2´-bithiophenes exhibit the most promising redox and the solvatochromic properties and second order nonlinear optical response. The redox and the optical properties also show notable variations for the different heterocyclic spacers and were also sensitive to the electronic acceptor strength of the (benzo)thiazolyldiazene moieties.

Novel push–pull heterocyclic azo disperse dyes containing piperazine moiety: Synthesis, spectral properties, antioxidant activity and dyeing performance on polyester fibers

“…Furthermore, push-pull azo dyes with heterocyclic components as disperse colorants have been intensively investigated to produce bright and strong color shades on synthetic textile fibers. These results led to the development of commercial products which replaced the conventional azo-benzene disperse dyes [11][12][13][14][15][16][17].…”

Synthesis of Novel Acid Dyes with Coumarin Moiety and Their Utilization for Dyeing Wool and Silk Fabrics

“…Thus, IR spectrum of 3indicated absorption bands at v max = 3370 cm −1 for hydroxyl group, 1653 cm −1 for carbonyl group and 1456, 1290 cm −1 for nitro group. 1 H NMR spectrum showed three singlet signals at δ = 8.05, 10.30 and 11.78 ppm corresponding to H 6 of hyroxyphenyl ring, hydroxyl and formyl protons, respectively, two doublet signals, each doublet for two protons at δ = 7.95 and 8.32 ppm for H 2,6 and H 3,5 of nitrophenyl ring, respectively, two doublet signals, each doublet for one proton at δ = 7.17 and 8.14 ppm due to H 3 and H 4 of hyroxyphenyl ring, respectively. IR spectrum of compound 4 showed absorption bands at v max = 3462 cm −1 for hydroxyl group, v max = 1658 cm −1 for carbonyl group and v max = 1386, 1150 cm −1 for sulphate group.…”

“…Pre-coated silica gel plates (silica gel 0.25 mm, 60 G F 254; Merck, Germany) were used for thin layer chromatography. The NMR spectra in (DMSO-d 6 ) were recorded at 400 MHz on a Varian Gemini NMR spectrometer (δ, ppm). Mass spectra were obtained on GC Ms-QP 1000 EX mass spectrometer at 70 ev.…”

“…Intensive efforts have been made in the investigation of monoazo dyes in which a heterocyclic system replaces one of the usual carboxylic systems. Many different heterocyclic diazo components have been studied, especially derivatives of thiazole, imidazole, benzimidazole owing to the marked bathochromic effect of such groups [6]- [12]. A majority of acid dyestuffs are sulphonic acid derivatives of azo dyes.…”

Synthesis, electrochemical, spectrophotometric and potentiometric studies of two azo-compounds derived from 4-amino-2-methylquinoline in ethanolic-aqueous buffered solutions

“…Azo-dyes are widely used in many practical applications such as photochromic materials, colorants, non-linear optics, sensors and indicators. [1][2][3][4][5][6][7][8][9][10][11][12] The synthesis and spectral properties of several azo-dyes as well as of their transition metal complexes have been reported in the literature. [13][14][15][16][17] The electrochemical behavior and electrode reaction pathways of numerous azo-dyes in various supporting electrolytes were studied and discussed.…”