Diffusion of nonionic azo dyes in nylon-6

Diffusion of 2,4-dinitroaniline and three nonionic azo dyes in Nylon-6 film was studied by analysis of the concentration-distance curves (profiles) of penetrants in the polymer. Actual diffusivities D_(c) of penetrants in polymer, diffusion coefficients as a function of the concentration C_f of penetrant in polymer, were calculated from the profile. It was found that D_(c) is almost constant or decreases gradually with decreasing C_f in the range of high-medium C_f but decreases appreciably with decreasing C_f at low C_f. The change in D_(c) with C_f was explained in terms of the dual-mode sorption-diffusion model. The penetrants diffuse in the polymer as two distinct species, i.e., a dissolved species and an adsorbed species. The former is the penetrant taken up by the polymer by a partition mechanism (dissolved species) and the latter is that taken up by Langmuir sorption (adsorbed species). The actual diffusivity D_P(c) of the dissolved species decreases with decreasing C_f. While the actual diffusivity D_L(c) of the adsorbed species normally increases gradually with decreasing C_f. D_P(c) is usually larger than D_L(c). © 1993 John Wiley & Sons, Inc.     

Photochromic properties of thienylpyrrole azo dyes in solution

The photochromic behaviour of thienylpyrrole azo dyes in THF solutions was studied for the first time. The photochromic properties are strongly dependent on the substitution pattern on the dyes. Nitro-substituted thienylpyrrole azo dyes are particularly interesting since they exhibit very fast colouration/decolouration processes. The activation energies of these compounds are among the lowest values reported for heterocyclic azo dyes. These compounds show aggregation phenomena in freshly prepared solutions of THF, which lead to variable photochromic behaviours. Only after 1-5 h the solutions reach equilibrium and then reproducible photochromic behaviour can be observed.     

Dual-mode sorption of nonionic azo dyes by Nylon 6

Sorption isotherms of 2,4-dinitroaniline and three 4-amino-azobenzene derivatives (nonionic dyes with adequate solubility in water) on Nylon 6 (film and fiber) from water were determined at various temperatures. The observed isotherms were curved, not linear. They were very well described in terms of the dual-mode sorption model, Nernst-type partitioning, plus Langmuir sorption. The contribution of the Langmuir sorption to the total dye sorption decreased with increasing temperature. The saturation value for the Langmuir sorption increased with the crystallinity of Nylon 6 film, suggesting that the Langmuir sorption is associated with the crystalline phase.     

Synthesis,characterization and antimicrobial activity of some new biquinoline derivatives containing a thiazole moiety

A series of new biquinoline derivatives containing a thiazole moiety were synthesized by a one-pot,base-catalyzed cyclocondensation reaction of 2-chloro-3-formyl quinoline,malononitrile and enaminone.All the synthesized compounds were characterized by elemental analysis,FT-IR,¹H NMR and ¹³C NMR data.All the synthesized compounds were screened against three bacterial pathogens,namely Bacillus cereus,B.substilis and Escherichia coli and for antifungal activity against three fungal pathogens,Aspergillus niger,Fusarium oxisporum and Rhizopus using the disc diffusion method.     

Keggin和Dawson结构多金属氧酸盐光催化脱色偶氮染料

The investigation photocatalytic degradation of three azo dyes solution(Acid Mordant Navy Blue RRN,Acid Mordant Black PV,Acid Mordant Brown RH) under UV light irradiation using the polyoxometalates as catalyst was reported in this article.The research results showed that the photocatalytic activity of Keggin catalyst is higher than that of Dawson,and the catalyst α-H4SiW12O40 had the best efficiency to the photocatalytic decoloration of RRN.In 350 mg·L-1(30 mL) RRN solution,the optimum reaction condition wa...     

Enhancement of the photochromic switching speed of bithiophene azo dyes

A series of heteroaryl substituted bithiophene azo dyes in solution were irradiated with visible light to promote the azo E-Z isomerization and then the kinetics of the thermal Z-E back reaction was studied. The speed of this process is strongly influenced by the nature of the aromatic ring linked to the NN function. While thiazole bithiophene azo dyes exhibit high switching speeds between the two isomers, but limited interconversion, for benzothiazole and substituted thiadiazole bithiophene azo dyes the switching between the two photoisomers can be performed in 3 s with a significant conversion of the trans-isomer to the thermal unstable cis-isomer (19-21%) and therefore a notable variation of the visible spectrum is observed.     

Synthesis of 6-chloro and 6-fluoro-4-hydroxyl-2-quinolone and their azo disperse dyes

<正>In this study,6-chloro-4-hydroxy-2-quinolone and 6-flouro-4-hydroxy-2-quinolone were synthesized from corresponding dianilides.These compounds were coupled with some diazotized aromatic amines to give the corresponding azo disperse dyes.The structures of the quinolone derivatives and new azo dyes were confirmed by UV-vis,FT-IR,~1H NMR and elemental analysis.     

Specific features of adsorption of azo dyes on fly ash

A possibility to utilize fly ash (FA) formed at coal-fired power plants as a cheap adsorbent for the purification of wastewater containing azo dyes methylene blue (MB) and methyl red (MR) was considered. The effect of an FA additive on the adsorption capacity of active carbon was studied. The efficiency of FA as an adsorbent for the purification of aqueous solutions from MB and MR was shown. The adsorption is also fairly efficient when active carbon is partially replaced by FA. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 545–548, March, 2007.     

The effects of solvation in the theoretical spectra of cationic dyes

We present a quantum-mechanical study on the solvent effects in the structure and electronic spectra of some cationic dyes: acridine orange, proflavine, safranine, neutral red, thionine and methylene blue. The geometry optimizations were carried out with the AM1 and DFT (with B3LYP functional) methods and the theoretical spectra of the dyes under study were obtained with Zindo time-dependent methods (TD–DFT and TD–HF). The solvation methodology adopted was the integral equation formulation (IEF) version of the polarizable continuum model (PCM).     

Thienylpyrrole azo dyes: synthesis, solvatochromic and electrochemical properties

The synthesis and the evaluation of solvatochromic and electrochemical properties of new donor-acceptor-substituted thienylpyrrole azo dyes 3 are described. These derivatives exhibit dramatic changes in both their electronic and redox properties in comparison with thienylpyrroles 1. In agreement with the solvatochromic and electrochemical studies of push-pull derivatives 3 the new compounds prepared, may find application in the manufacture of new materials with notable non-linear optical properties.     

Synthesis,characterization and corrosion inhibitive properties of new thiazole based polyamides containing diarylidenecyclohexanone moiety

The present work aimed to synthesize a new interesting series of thiazole based polyamides containing diarylidenecyclohexanone moiety 5a-5f using low temperature solution polycondensation technique. The new polymers were synthesized by the reaction of thiazole based monomer namely, bis(2-aminothiazol-4-ylbenzylidene)cyclohexanone 3 with different aliphatic and aromatic diacid chlorides using NMP, and in the presence of anhydrous Li Cl as catalyst. Adipoyl, sebacoyl, oxaloyl, terephthaloyl, isophthaloyl dichlorides and biphenyl dicarbonyl dichloride were used as diacid chlorides. The structure of the model compound 4 as well as the new polymers was confirmed by correct elemental and spectral analyses. The thermal properties of those polymers were evaluated by TGA and DTG measurements and correlated to their structural units, beside X-ray diffraction analysis, solubility and viscometry measurements. The inherent viscosities for the synthesized polymers were in the range 0.6–1.03 d L/g. On the other hand the corrosion inhibitive properties of monomer 3 as well as polyamides 5d and 5f as selected examples were carried out on carbon-steel in 0.5 mol/L H2SO4 at 40 °C. The calculated inhibition efficiency(IE%) for polymer 5d was in the range(82 ± 6)% in all selected concentrations. The best value of IE% was obtained at 1 mg/L to reach 98.24% for polymer 5d and at 0.5 mg/L to reach 87.75% for polymer 5f.     

镍铁类水滑石对偶氮阴离子染料的吸附脱色作用

采用镍铁类水滑石作为吸附剂,对偶氮阴离子染料酸性大红G、活性艳红X-3B和直接耐酸大红4BS废水进行脱色处理,研究了时间、镍与铁的物质的量之比、初始pH和无机电解质添加剂等因素对脱色率的影响,并结合红外光谱和X射线衍射分析结果讨论了其吸附脱色机理.结果表明,三种染料在镍铁类水滑石上的吸附均为层间的阴离子交换吸附和外表面的吸附.通过阴离子交换进入层间后,不同于直接耐酸大红4BS阴离子,酸性大红G和活性艳红X-3B两种阴离子与水滑石层间水分子之间产生氢键作用;在化学键合过程中,染料分子被镍铁类水滑石表面Fe3+氧化,同时偶氮键断裂导致脱色.     

基于QSAR对偶氮染料光响应性及降解路径研究

采用密度泛函理论方法计算偶氮染料类化合物的量子化学参数,研究该类化合物结构与光响应活性的定量构效关系(QSAR),应用多元回归方法建立的方程具有显著统计学意义,并结合紫外光谱结果进行降解过程预测.结果表明:光催化体系中会最先造成偶氮染料的N=N键与萘环的断开,然后再生成其他副产物,副产物再经过电子转移、开环等一系列反应...     

Effect of solvent on absorption and fluorescence spectra of a typical fluorinated azo dye for its acidic and basic structures

The effect of 15 polar solvents on absorption and fluorescence energies of a typical fluorinated azo dye, 4-(2,3,5,6-tetrafluoro-pyridin-4-yl azo)-phenol, was reported for its acidic, MH, and basic, M, structures.For MH, the absorption energy is described on the basis of multi-linear equation with Taft's π* (solvent polarity) and β (hydrogen bond acceptor) parameters while the fluorescence energy varies rectilinearly with free energy of transferring the proton to the surrounding solvent, ΔG_t°.For M, the hydrogen bonding donor ability of protic solvent, α, is a predominant factor which affects the absorption energy while in aprotic solvents, the absorption energy correlates linearly with Kirkwood function. As the ability of the solvent for hydrogen bonding increases, the absorption band width will increase in parallel with the transition energy.     

Supramolecular compounds of azo dyes derived from 1-phenylazo-2-naphthol and their nickel and copper complexes

In this study, experimental techniques including Raman, infrared and X-ray crystal diffraction, as well as quantum chemistry calculations, are used to investigate two new azo dyes supramolecular complexes: 1-phenylazo-2-naphthol (Sudan I) with nickel(II) ion and 1-(2,4-xylylazo)-2-naphthol (Sudan II) with copper(II) ion. The crystallographic structures have been solved for bis-1-(pheny-l-azo)-2-naphtholatenickel(II) and bis-1-(2,4-xylylazo)-2-naphtholatecopper(II) complexes, revealing the presence of supramolecular interactions, such as the centroid–centroid π-stacking interactions and CH…π hydrogen interactions. These weak intermolecular interactions appear to play an important role on the crystal structure stability for both compounds. Density functional theory calculations at B3LYP/6-311++G(d,p) level were performed in order to help understanding such molecular interactions and to assign the vibrational spectra. The experimental and theoretical data have allowed the analysis of the packing forces, revealing charge accumulation at key molecular regions.     

Enhancement of azo dyes removal efficiency by using LDH/Tris/Pd catalyst: Kinetic studies

LDH/Tris/Pd (CaAl‐layered double hydroxide/tris (hydroxymethyl)aminomethane/palladium) was synthesized and appraised for its catalytic activity towards the degradation of two selected azo dyes. The decolorization of azo dyes, acid red 18 (AR 18) and reactive yellow 15 (RY 15), requires considerably small amounts of synthesized catalyst. Kinetic studies show that the catalytic decolorization of these azo dyes follows the first order kinetic model. The reported method is simple and applicable; in addition, the stable catalyst can efficiently decolorize model azo dyes with good recyclability. Therefore, LDH/Tris/Pd can be accepted as the possible component for the utilization in wastewater treatment.     

Investigation of interactions between some anionic dyes and cationic surfactants by conductometric method

The interactions of cationic surfactants with anionic dyes were studied by conductometric method. Benzyltrimethylammonium chloride (BTMACl), benzyltriethylammonium chloride (BTEACl) and benzyltributylammonium chloride (BTBACl) were used as cationic surfactants and indigo carmine (IC) and amaranth (Amr) were chosen as anionic dyes. The specific conductance of dye–surfactant mixtures was measured at 25, 35 and 45 °C. A decrease in measured specific conductance values of dye–surfactant mixture was caused by the formation of non-conducting or less-conducting dye–surfactant complex. The equilibrium constants, K₁, the standard free energy changes, ΔG₁°$\mathrm{\Delta }{G}_1°$, the standard enthalpy changes, ΔH₁°$\mathrm{\Delta }{H}_1°$ and the standard entropy changes, ΔS₁°$\mathrm{\Delta }{S}_1°$ for the first association step of dye–surfactant complex formation were calculated by a theoretical model. The results showed that the equilibrium constants and the negative standard free energy change values for all systems decreased as temperature increased. Also these values decreased for all systems studied with increasing alkyl chains of surfactants due to the steric effect. When the equilibrium constant values, K₁, for the first association step of IC–surfactant and Amr–surfactant systems with the same surfactant were compared, the values of K₁ for IC–surfactant system were higher than that of Amr–surfactant system.     

Trichothiazole A,a dichlorinated polyketide containing an embedded thiazole isolated from Trichodesmium blooms

Mass spectrometry-guided isolation of the lipophilic extract of Trichodesmium bloom material led to the isolation and structure characterization of a new thiazole-containing di-chlorinated polyketide (1). The structure of 1 was deduced using 1D and 2D NMR analysis, high-resolution mass spectrometry analysis and complementary spectroscopic procedures. Trichothiazole A possesses interesting structural features, such as a terminal alkyne, two vinyl chlorides and a 2,4-disubstituted thiazole. Trichothiazole A showed moderate cytotoxicity to Neuro-2 A cells (EC₅₀: 13.3 ± 1.1 μM).     

Microwave-assisted synthesis and characterization of phthalocyanines substituted with azo compound containing eugenol moiety

The new metallophthalocyanines (Co, Ni, Cu, and Zn) substituted with azo compound containing eugenol moiety are described. Firstly, azo compound (I) containing eugenol moiety was synthesized by treating eugenol with p-hydroxyaniline. Then phthalonitrile compound (1) was synthesized by microwave-assisted synthesis method. The purification of phthalonitrile compound (1) was carried out by column chromatographic separation. Intramolecular hydrogen bonding in the azo compound (I) prevent base-catalyzed nucleophilic aromatic substitution of OH group belongs eugenol. At the last step, metallophthalocyanines (1a, 1b, 1c, and 1d) were synthesized by the microwave irradiation. The microwave-assisted synthesis method reduces reaction times and enhances the yield of the reactions. All phthalocyanine compounds are soluble in DMF and DMSO. The structures were confirmed by elemental analysis, ¹H NMR, ¹³C NMR, UV/Vis, IR and Mass spectra.