Synthesis and properties of novel aziridinyl azo dyes from 2-aminothiophenes—Part 2: Application of some disperse dyes to polyester fibres

A series of yellow to greenish-blue aziridinyl azo dyes and their azo precursors containing a thienyl coupling moiety has been applied to conventional polyester fibre as well as microdenier polyester by high temperature exhaust dyeing. Heat transferability of these dyes onto polyester fibre has also been examined, using conventional heat-transfer printing techniques. The relevant dyeing characteristics, heat transferability, build-up, dyeability on microfibre polyester, washfastness and lightfastness are given. These aziridinyl dyes are reactive to polyester fibres under HT dyeing conditions. Fabrics dyed with aziridinyl dyes are more resistant to solvent extraction than those dyed with conventional dyes. Residual liquors showed only a pale colour when fabric dyed with aziridinyl dyes was dissolved and then precipitated, whereas a coloured polyester precipitate was obtained.     

Studies of novel monomeric and polymeric azo disperse dyes

A series of polymeric dyes were synthesized by free‐radical addition polymerization of monomeric dyes that were derived from diazotized 2‐amino‐3,5‐bis‐(ethoxycarbonyl)‐4‐methylthiophene by coupling with various N‐arylmaleimides. All the polymeric dyes were characterized by elemental analysis, IR and visible spectroscopy, viscometry, and TGA. Color and dyeability of the polymeric dyes are discussed by comparing them with those of the corresponding monomeric dyes. All the dyes have been found to give various color shades with good to very good depth and levelness on the fiber. The dyeing of the monomeric dyes shows good fastness to light and very good to excellent fastness to washing, perspiration, sublimation, and solvents. The corresponding polymeric dyes show excellent fastness properties. The percentage dyebath exhaustion and fixation on the fiber have been found to be good to very good (60–90%). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1380–1389, 2002; DOI 10.1002/app.10276     

Spectrophotometric investigations and computational calculations of prototropic tautomerism and acid-base properties of some new azo dyes

The prototropic tautomerism in four novel azo compounds derived from pyrazolo[1,5-a]pyrimidin-7(4H)-one was intensively examined. Tautomeric structures which result from annular and azo-hydrazone tautomerism were exposed to semiempirical and density functional theory (DFT) calculations, allowing the recording of structural parameters, physicochemical properties and equilibrium constants to be recorded. The values of the equilibrium constants determined among the most stable forms clearly showed that compounds 1 and 2 co-exist in the NH and hydrazone forms. However, NH tautomers were strongly preferred to other forms in compounds 3 and 4. The observed electronic absorption bands were assigned and compared with the predicted transitions using a time-dependent DFT method (TDDFT). In all solvents employed, except for DMF and acetonitrile, compounds 1 and 2 exhibited azo-hydrazone tautomerism. However, the ionized species were predominant in highly polar solvents for compounds 3 and 4. In DMF, all the investigated dyes exist either in acid-base equilibrium or in the ionized form depending on the molecular structure. Hence, the values of the ionization constant (K_ion) and Gibbs free energy (ΔG) of the equilibrium existing in solution were calculated. In addition, the pK_a values of the investigated dyes were determined spectrophotometrically.     

The synthesis and structural study of two benzothiazolyl azo dyes: X-ray crystallographic and computational study of azo–hydrazone tautomerism

The synthesis, FT-IR, ¹H and ¹³C NMR characterisation, as well as crystal and molecular structure determined by single-crystal X-ray diffraction data, of two azo dyes derived from 6-aminobenzothiazole: 6-[(4-N,N-dimethylaminophenyl)diazenyl]benzothiazole and 6-[(2-hydroxy-1-naphthyl)diazenyl]benzothiazole are reported. Both dyes are essentially planar with the exclusion of methyl groups in 6-[(4-N,N-dimethylaminophenyl)diazenyl]benzothiazole, which exibits 100% E-configuration in terms of orientation of the substituents about the central azo linkage. Single-crystal X-ray study of 6-[(2-hydroxy-1-naphthyl)diazenyl]benzothiazole was undertaken to established whether the hydrazone or azo tautomer was present in the solid state as well as any potential shift in tautomeric equilibrium imparted by temperature variation (296 and 100 K). Density functional theory calculations revealed that the hydrazone tautomer was more stable than the azo tautomer and that the tautomeric equilibrium was shifted towards the hydrazone form at lower temperature.     

Synthesis and dyeing properties of novel disperse dyes. Part 2: Pyrazole disperse dye derivatives

Several new disperse dyes derived from thiosemicarbazides and acetoacetanilide have been synthesised. The dye structures were ascertained by chemical analysis and infrared measurements. Prepared dyes were used for dyeing nylon fabric by the exhaustion method. The colour strengths and dye fixation on the fabric were also determined. The results suggest a practical significance.     

Switching azonaphthols containing a side chain with limited flexibility. Part 1. Synthesis and tautomeric properties

A series of azo dyes, possessing amide fragments with restricted flexibility tethered to 4-(phenyldiazenyl)naphthalen-1-ol, was obtained from 1-hydroxy-2-naphthoic acid by subsequent conversion to amides and diazo coupling. It was shown that the position of the tautomeric equilibrium in solution strongly depends on the solvent in both UV and NMR concentration scale. The compounds exist as pure enol forms in chloroform and hydrocarbons, while in polar solvents (acetone, acetonitrile, alcohols) a tautomeric mixture is observed. According to the quantum-chemical calculations the aggregation of the keto tautomer is the possible reason for this shift in the position of the tautomeric equilibrium. To support the theoretical predictions, it was found that from acetone the keto form crystallizes as a dimer with hydrogen bonding between N₁-H in the one molecule and amide CO in the other forming a three-dimensional structure. The importance of the side-chain nitrogen atom on the dimer formation was confirmed by solution and solid state study of 4-(phenyldiazenyl)-2-acetylnaphthalen-1-ol. The results indicate that the new azo-dyes obtained could be suitable candidates for switching and sensing applications in non-polar solvents.     

Synthesis of 6-(4-diethylamino)phenyl-2-oxo-2H-pyran-3-carbonitorile derivatives and their fluorescence in solid state and in solutions

One-pot synthesis of a new 2-pyrone dye (3a) by the reaction of 4-diethylamino-acetophenone (1) with methyl 2-cyano-3,3-bis(methylsulfanyl)acrylate (2) in the presence of sodium hydroxide as the base was carried out in DMSO. Compound 4a was synthesized by the replacement of methylsulfanyl group of 3a with dimethylamine at 4-position of pyrone ring. Similarly, compound 5a was prepared via the reaction of 3a with diethyl malonate. Compounds 3a-5a exhibited the following fluorescence in the solid state: red (3a), green (4a), and orange (5a). In addition, it was revealed that 2-pyrone dyes exhibit fluorescence in various solvents and show positive solvatochromism. Compounds 3a and 5a exhibited intense fluorescence in chloroform and dichloromethane (fluorescence quantum yield Φ: 0.94-0.95). In contrast, compound 4a exhibited intense fluorescence in polar solvents (methanol: Φ = 0.92). These 2-pyrone dyes have the potential for applications in various fields.     

Heterocyclic hansa yellow analogues: Synthesis of novel azodisperse dyes from 3-oxo-N-(pyrazol-4-yl) butanamide as possible dyes for polyester fibres

Different heterocyclic Hansa Yellow analogues were synthesized from 3-oxo-N-(pyrazol-4-yl)butanamide for possible use as azodisperse dyes for dyeing polyester fibres. The free energy relationship between the position of absorption of these dyes-λ-and substituent Hammett sigma constants was investigated.     

The synthesis, characterization, thermal and optical properties of copper, nickel, and vanadyl complexes derived from azo dyes

Two, novel, tetradentate Schiff-base ligands, namely bis-5-phenylazosalicylaldehyde diethylenetriimine and bis-5-[(4-methoxyphenyl)azo]salicylaldehyde diethylenetriimine, as well as their Cu²⁺, Ni²⁺, and VO²⁺ complexes, were synthesized and characterized using elemental analysis, infrared and also UV–Visible spectroscopy, ¹HNMR and mass spectra. The thermal stability of the free ligands and the related metal complexes, as determined using differential scanning calorimetry and thermal gravimetric analysis, were found to be thermally stable upto 240–275 °C depending on the type of ligand and the central metal atom. The λ_max of the ligands and their transition metal complexes in the region 300–800 nm are discussed. The novel metal complexes offer potential for application as recording media owing to both their absorption spectra in the blue-violet light region and high thermal stability.     

1-Amino-4-hydroxyanthraquinone-β-ethers and thioethers: Red dyes for synthetic-polymer fibres

Condensation of 1-amino-2-bromo-4-hydroxyanthraquinone and of 1-amino-3-bromo-4-hydroxyanthraquinone with alcohols, phenols and thiols yields the corresponding β-ethers and thioethers. These compounds colour polyester in deep rose-red to violet-red hues of excellent build-up and good fastness to light and sublimation. The colour of the dyes is discussed with respect to the nature and orientation of the β-substituents.     

Cationic azomethine disperse dyes: Synthesis,antifungal activity and tinctorial properties of N-arylideneamino p-substituted pyridinium salts as possible dyes for synthetic fibres

In a four-step synthesis, a series of N-arylideneamino p-substituted pyridinium salt derivatives were prepared for use as cationic azomethine disperse dyes for polyester and polyacrylonitrile fibres. The effect of different substituents, in both of homo- and heterocyclic ring systems, on position of maximum absorbance in UV-vis spectra was used to explain the different hues of the prepared dyes. Besides, showing promising tinctorial properties, the synthesised dyes revealed fungicidal activity against Aspergillus niger. The structure of the hitherto prepared dyes was inferred by elemental and spectral data.     

Alkyl and substituted alkyl 2-cyanoacrylates. Part 1. Synthesis and properties

Twenty-six alkyl, alkenyl, cycloalkyl, and substituted alkyl 2-cyanoacrylates were synthesized in the pure state. The purity was determined by gas-liquid chromatography, and a correlation between the log retention time and the number of carbons in the compounds within the homologous series was deduced. Their physical properties such as parachor and molar refraction were determined and the data were fitted to a linear relation to the number of carbons present in the ester within a homologous series of cyanoacrylates. The tensile strengths of the 2-cyanoacrylate bonds between various metal surfaces are also presented. The tensile strength of the adhesive bonds gradually decreased with an increase in the alkyl chain length, beginning from ethyl cyanoacrylate.     

Attempts to reduce water and chemical usage in the removal of reactive dyes: Part 1 bis(aminochlorotriazine) dyes

Dyeings on cotton obtained using three commercial reactive dyes were subjected to three wash-off processes namely, a standard, five-stage method which used a proprietary wash-off agent, a five-stage process in which Na₂CO₃ was used in place of the commercial wash-off agent and a three-stage, chemical-free method. Dyeings that were generally of the same hue and colour strength and which also displayed similar levels of fastness to repeated washing, were obtained using each of the three wash-off processes. The replacement of the commercial wash-off agent in the five-stage, standard wash-off process with Na₂CO₃ reduced, considerably, both the COD and BOD₅ loads of the residual wastewater; the corresponding COD/BOD₅ ratios showed an improvement in the biodegradability of the residual wastewater. Although reducing the number of wash-off stages from five to three and replacing Na₂CO₃ with 98 °C water rinses increased both COD and BOD₅ loads, the ensuing biodegradability of the residual wastewater was improved. Thus, by using a three-bath, water-only wash-off process, not only was the amount of water used for reactive dye wash-off reduced but also the wastewater generated was of higher biodegradability.     

Synthesis and physico-chemical properties of highly conjugated azo-aromatic systems. 4-(azulen-1-yl)-pyridines with mono- and bis azo-aromatic moieties at C3-position of azulene

Highly conjugated azo-aromatic systems have been prepared in high to moderate yields by linking mono- and bis-azo aromatic fragments to 4-(Rn-azulen-1-yl)-2,6-dimethyl-pyridine. The synthesized π-extended systems have been studied by NMR spectroscopy, UV-Vis and electrochemistry. Systematic increase of the conjugation along the azobenzene skeleton has affected the spectral properties of the azophenyl substituted 4-(azulen-1-yl)-pyridine. The synthesized compounds exhibit a bathochromic shift of the visible absorption maxima with the increase of the conjugating skeleton and introduction of an electron-withdrawing group. The electrochemical behavior revealed a high stability toward oxidation owing to the higher polarization induced by the azulenylpyridine moiety.     

Heterocyclic alternatives for benzidine-based mono- and disarylazo pigments: Synthesis and characterization of a novel class of pyrazolo (1,5-a)pyrimidine azo pigments

In a sequence of reactions, three different series of novel mono- and disarylazo pyrazolo(1,5-a)pyrimidine pigments were prepared to determine whether these products might successfully act as possible alternatives for benzidine-based dyestuffs, which are known to be associated with toxicological hazard and carcinogenic effects. The structure of the named compounds was inferred from elemental and spectral analysis and, in some cases, by alternative synthetic routes.     

Al, N, C and H NMR spectra and negative-ion electrospray mass spectra of the 2:1 aluminium(III) complexes of azo dyes derived from anthranilic acid

The ²⁷Al, ¹⁵N, ¹³C and ¹H NMR spectra in DMSO and mass spectra of 2:1 aluminium(III) complexes (1b–4b) derived from anthranilic acid azo coupling products with 4-tert.butylphenol (1a), 2-naphthol (2a) acetoacetanilide (3a) 3-methyl-1-phenylpyrazol-5-one (4a) were measured and analysed. It was found that the aluminium atom was six-coordinated, being bound to two oxygens and the nitrogen originating from anthranilic acid.     

Photoresponsive peptide and polypeptide systems: Part 9. Synthesis and reversible photochromism of azo aromatic poly(L-α,ω-diaminobutyric acid)

Poly(L-α,ω-diaminobutyric acid) having azo aromatic side chains was synthesized by the water-soluble carbodiimide procedure. The photoresponsive properties of the polypeptide poly[N⁷-p-(phenylazo)benzoyl-L -α,ω-diaminobutyric acid] (PPABLDBA) due to the trans (about 71%, under visible light) cis (under ultraviolet light) photoisomerization of the azo aromatic moieties in the side chains were investigated by absorption and circular dichroism spectroscopy in hexafluoro-2-propanol (HFIP). The starting slightly turbid solution of trans-PPABLDBA becomes clear on irradiation at 360 nm, accompanied by photoconversion of the conformer of the azo moieties to cis. The backbone conformation of PPABLDBA in HFIP is right-handed helical (helical content, about 60%) when the azo moieties are trans (71%), while the conformation is random coil when cis. The backbone conformational transition of PPABLDBA from helical to coil is mostly reversible under the influence of light.     

新显色剂7-(苯并噻唑-2-偶氮)-8-羟基喹啉-5-磺酸的分析性能及其与锌显色反应的研究

报道了新显色剂７－（苯并噻唑－２－偶氮）－８－羟基喹啉－５－磺酸（简称ＢＴＨＱＳＡ）的离解常数的测定，同时研究了该显色剂对锌离子光度分析的条件，摩尔吸光系数ε＝５．１×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，锌离子浓度在０～６．５μｇ／２５ｍＬ符合比尔定律，并对人发中的微量锌进行测定。     

Development of novel fluorescent offset ink based on coumarin dyes: Synthesis and properties

Novel fluorescent inks based on coumarin dyes used in offset printing techniques were developed, and their considered chemical and physical properties were investigated. First, the influences of very long alkyd resin, maleic varnish, and phenolic varnish substrates and dye concentrations on the fluorescence properties of these dyes, and secondly, the effects of the presence of fluorescent dyes on the physical properties of inks were examined. Accordingly, two offset inks were prepared: one with an obtained optimum formulation possessing the strongest fluorescence emission in alkyd resin and maleic varnish with a weight ratio of 60:40, and one without fluorescent dyes. Their physical properties, such as rheological behavior, tack, and ink-in-water emulsification, were studied. Both inks showed Newtonian behavior, and the dye induced small increases in the viscosity, thixotropy, and tack values of the fluorescent ink.     

Click‐coupling of anthraquinone dyes with β‐cyclodextrin: formation of polymeric superstructures

Two novel cyclodextrin‐modified anthraquinone dyes were synthesized and investigated for their complexation behaviour and formation of superstructures. Therefore, 1‐fluoro‐4‐N‐(propargylamino)anthraquinone and 1,4‐bis(propargyloxy)anthraquinone were prepared via nucleophilic aromatic displacement and subsequently covalently ‘click‐coupled’ in a copper(I)‐catalysed azide–alkyne cycloaddition with β‐cyclodextrin monoazide. Both the propargyl‐modified precursor and the click‐coupled anthraquinone dyes were evaluated as hosts and guests, respectively, in β‐cyclodextrin interactions. The anthraquinone dye bearing two cyclodextrins, 1,4‐bis((1‐β‐cyclodextrin‐1H‐1,2,3‐triazol‐5‐yl)methoxy)anthraquinone, enables the reversible formation of supramolecular crosslinked poly[(N,N‐dimethyl acrylamide)‐co‐(N‐(ferrocenoylmethyl)acrylamide)] ( 11 ), whereas the monofunctionalized compound 1‐fluoro‐4‐(((1‐β‐cyclodextrin‐1H‐1,2,3‐triazol‐5‐yl)methyl)amino)anthraquinone can be supramolecularly linked to 11 resulting in coloured polymers. These features of β‐cyclodextrin‐linked anthraquinone dyes can be verified with either ¹H ¹H NMR rotating frame nuclear Overhauser effect spectroscopy or the naked eye. © 2016 Society of Chemical Industry