Colour fastness properties of alkali-clearable azo disperse dyes containing a fluoro-sulphonyl group

The colour fastness properties of alkali-clearable azo disperse dyes containing a fluorosulphonyl group have been investigated. In particular, the colour fastness properties of alkali-cleared poly(ethyleneterephthalate) were compared with those of conventional reduction-cleared poly(ethyleneterephthalate). Specifically, 4-aminoazobenzene dyes containing a nitro group in place of the fluorosulphonyl group in the 4'-position were synthesised in order to compare their fastness properties on poly(ethyleneterephthalate) with those of the 4'-fluorosulphonyl analogues.     

Synthesis and properties of some novel pyrazolone-based heterocyclic azo disperse dyes containing a fluorosulfonyl group

A series of heteroarylazo disperse dyes derived from pyrazolones and fluorosulfonyl anilines were synthesized, and their thermal and spectral properties were investigated with respect to the effect of substituents on absorption spectra, halochromism, and solvatochromism. Heteroarylazo disperse dyes, which contain a nitro group instead of a fluorosulfonyl group para to the azo group in the diazo component, were also synthesized for comparative purpose. The fluorosulfonylarylazopyrazolone dyes had absorption maxima at shorter wavelength and showed lower extinction coefficients than the nitroarylazopyrazolone dyes. The synthesized dyes also exhibited positive halochromism and solvatochromism, so the absorption bands of the dyes moved toward longer wavelengths as the acidity or polarity of the solvent increased. 4-Fluorosulfonyl-substituted dyes generally showed lower thermal stability than their 4-nitro-substituted analogs, because the lower electron-withdrawing power in the diazo components tended to decrease the polarizability and dipole interactions.     

One-bath dyeing of poly(ethylene terephthalate)/cotton blends with alkali-clearable azo disperse dyes containing a fluorosulphonyl group

Monoazo disperse dyes containing a fluorosulphonyl group, based on 4-amino-4'-fluorosulphonylazobenzene derivatives, were dyed on poly(ethylene terephthalate)/cotton blends and their dyeing and fastness properties investigated. A one-bath dyeing method was used, as these dyes can be alkali cleared in the same bath. In particular, the cross-staining of cotton was studied in order to assess their suitability for the one-bath dyeing of poly(ethylene terephthalate)/cotton blends.     

Improvement of the dyeing and fastness properties of a naphthalimide fluorescent dye using poly(amidoamine) dendrimer

In this study, 4‐amino‐9‐methoxypropylnaphthalimide fluorescent dye (dye 1 ) was reacted with poly(amidoamine) dendrimer G = ?0.5 to prepare a naphthalimide–dendrimer hybrid dye (dye 2 ). The chemical structures of the synthesised dyes were confirmed by elemental analysis, Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy, and ultraviolet‐visible spectroscopy. The solvatochromism of the dyes was evaluated in various solvents with respect to visible absorption properties, and positive solvatochromism was observed by solvent polarity change from chloroform to ethanol. The dyeing ability of the synthesised dyes was investigated by their application onto nylon fabric, and nylon substrates dyed with dye 2 exhibited marked enhancement both in terms of colour strength and general fastness properties. The results of this study clearly demonstrated the high potential and performance of dye 2 as a novel promising fluorescent dye as compared with dye 1 . Overall, it was inferred that the modification of the naphthalimide fluorescent dye with poly(amidoamine) denderimer could markedly improve the dyeing and fastness properties of the naphthalimide fluorescent dye on nylon fabrics.     

Synthesis and properties of novel aziridinyl azo dyes from 2-aminothiophenes—Part 1: Synthesis and spectral properties

A series of yellow to greenish-blue aziridinyl azo dyes and their azo precursors containing a thienyl coupling moiety has been prepared from 2-aminothiophenes. The 2-aminothiophenes were readily obtained by using the Gewald reaction. It was found that cyclisation of the precursor dyes to the corresponding aziridinoazo dyes brought about bathochromic shifts in absorption maxima. Further spectral comparisons with N-phenylazo dyes derived from other terminal cyclic groups, such as four-, five-, six-, seven- and eight-membered rings, showed that the N-thienylaziridinoazo dyes are relatively bathochromic. From the viewpoint of solvatochromism, a clear contrast existed between λ_max values in different solvents; thus, a positive solvatochromism was observed in aprotic solvents, whereas a hypsochromic shift was brought about in polar protic solvents. PPP–MO calculations provided reliable predictions of absorption maxima for the various aziridinyl azo dyes and their precursor dyes.     

Synthesis, absorption characteristics and solvatochromism of some novel heterocyclic cyanine dyes

Novel heterocyclic monomethine, bis monomethine, trimethine and bis trimethine cyanine dyes incorporating benzo [2,3-b; , - ] bis furo [3,2-d] pyrazole nuclei were synthesised. The absorption characteristics of the prepared cyanines were studied and determined through measuring their electronic visible absorption spectra in 95% ethanol. The solvatochromism of some of the synthesised dyes was investigated.     

Solvatochromism,halochromism, and azo–hydrazone tautomerism in novel V‐shaped azo‐azine colorants – consolidated experimental and computational approach

The azo–hydrazone tautomerism, solvatochromism, and halochromism in four novel V‐shaped asymmetrical acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) compounds were examined. They contain 2,7,15,16‐functionalised benzophenazine cores connected to the anchoring electron‐deficient phenyl core via azo linkers and 2,7‐position fused with anthraquinone. These compounds derived from 2‐hydroxy‐1,4‐napthaquinone (lawsone) have been prepared in moderate to good yields. The synthesis involved the diazotisation of substituted aromatic amines, coupling onto 2‐hydroxy‐1,4‐napthaquinone, and further condensing the resulting azo compounds with 1,2‐diaminoanthraquinone in acetic acid. The absorption wavelengths of the dyes in different solvents were in the range 500–720 nm. The spectral changes of the synthesised azo‐azine compounds in different pH indicated the formation of hydrazone tautomer in acidic pH and of azo tautomer in alkaline pH. Density functional theory was used to assess the tautomers in terms of geometry and position of the tautomeric equilibrium. Time‐dependent density functional theory calculations allowed us to assign the electronic transitions (>90%) of the low‐energy bands.     

Tautomerism and fluorescent properties of aminovinylpyrazine dyes

We have reacted diaminomaleonitrile with pyruvic aldehyde or pyruvic acid to produce 2, 3-dicyano-5-methylpyrazine and 2, 3-dicyano-6-hydroxy-5-methylpyrazine. Although these compounds showed no fluorescence, condensation with arylaldehyde yielded red to violet coloured styryl-type dyes with strong orange to red fluorescence. We have investigated the tautomerism and fluorescent properties of these new pyrazine dyes by means of computer simulation, and have also investigated their spectral properties using molecular orbital and molecular mechanics calculation techniques. These studies revealed the dyes to have strong intramolecular charge-transfer chromophoric systems and high solvatochromism both in absorption and fluorescence spectra.     

Dyeing properties of novel electrolyte‐free reactive dyes on cotton fibre

A series of electrolyte‐free reactive dyes containing two quaternary ammonium salt groups as soluble moieties and one epoxy structure as the reactive group have been synthesised. The structures of the synthesised dyes were confirmed by Fourier Transform–infrared, proton nuclear magnetic resonance and elemental analysis, and their dyeing properties on cotton were studied using an electrolyte‐free dyeing process. The results indicate that electrolyte‐free reactive dyes with these structures give a high exhaustion rate, a high fixation rate and good build‐up properties on cotton. Fastness properties were, in general, also very good. The optimal dyeing process of these electrolyte‐free dyes for cotton fibre was 60 °C with 20 g/l sodium carbonate.     

Synthesis,absorption spectra studies,solvatochromism and halochromism of polymethine cyanine dyes

New polymethine cyanine dyes, including tetramethine and bis‐tetramethine cyanine dyes derived from benzo[2,3‐b;2′,3′‐b′]bis‐pyrazolo[4,5‐b]‐1,4‐(oxa‐, thia‐ and pyra‐)‐zine‐6,12‐dione, were synthesised. Absorption spectra for all the synthesised cyanine dyes were examined in 95% ethanol. The solvatochromism and halochromism for some selected dyes were investigated in pure solvents and in aqueous universal buffer solutions, respectively. Structural confirmations were carried out through elemental and spectroscopic analysis.     

Haloacetyl reactive dyes-synthesis and application to silk

A series of haloacetyl reactive dyes have been synthesised. The reactivity of haloacetyl groups and the dyeing properties of the dyes on silk fabric were studied. The results show that the bromoacetyl group is more reactive than the chloroacetyl group and molecules containing a bromoacetyl group would dye silk under relatively mild dyeing conditions. Both the exhaustion and fixation on silk fabric are increased if a second reactive group is present in the molecule     

Synthesis of temporarily solubilised azo disperse dyes containing a β‐sulphatoethylsulphonyl group and dispersant‐free dyeing of polyethylene terephthalate fabric

Disperse dyes containing a β‐sulphatoethylsulphonyl group have temporary solubility and can be applied for dispersant‐free dyeing of hydrophobic fibre. Six novel temporarily solubilised azo disperse dyes having a β‐sulphatoethylsulphonyl group in their structures were synthesised, and their dyeing properties on polyester were investigated. As a dye intermediate, a diazo component having dibromo groups was prepared, and 4‐diethylamino‐4′‐(2‐sulphatoethylsulphonyl‐4,6‐dibromo)azobenzene dyes were prepared by a diazo‐coupling reaction. Then, the dyes containing dicyano groups were prepared by cyanation of corresponding dyes with dibromo groups. The absorption maxima of the dyes were affected by the substituents in the diazo and coupling component rings and varied from 434 to 616 nm in dimethylformamide. Polyethylene terephthalate woven fabric could be dyed with the synthesised temporarily solubilised dyes without using any dispersants. Dyebath pH affected the K/S value at maximum absorption as well as percentage exhaustion on polyethylene terephthalate fabric, and the optimum pH was 5. The dyes gave brownish orange, red, purple, and greenish blue hues on polyethylene terephthalate fabrics, and colour build‐up was good. Wash fastness was good to excellent, rubbing fastness was moderate to excellent, and light fastness was poor to moderate.     

Synthesis and Properties of Monoazo Disperse Dyes Derived from 3-Amino-5-nitro[2,l]benzisothiazole

Disperse dyes based on 3-amino-5-nitro[2,1]benzisothiazole have been synthesised, using as coupling components derivatives of some alkyl esters of N-benzyl-N-phenyl-β-alanine and N-(β-phenylethyl)-N-phenyl-β-alanine. IR and visible spectra of the dyes were investigated and basic fastness properties were also determined. The lightfastness of the dyes was also studied in relation to mass spectral data.     

Chromophoric chain β-aryl-substituted styryl cyanines: effect of substituents on visible absorption spectra and photosensitisation properties

A number of chromophoric chain β-aryl-substituted (CCBAS) styryl cyanines (hemicyanines) have been synthesised by condensing substituted quaternised quinaldine bases with substituted benzophenones, with a view to studying the effect of the aryl substituents on their visible absorption and silver halide photosensitisation properties.The dyes absorb at longer wavelengths than the unsubstituted analogues, showing uniform bathochromic shifts and extra-photosensitisation properties, which corroborate the authors' previous findings.Irrespective of the nature of the substituent attached to the chromophoric β-phenyl group, electron withdrawing and donating groups result in a bathochromic shift of the visible absorption band and extension of the extra-photosensitisation in most cases.     

Structure—wet fastness relationships of some blue disperse dyes for polyester

A range of monoazo blue disperse dyes has been synthesised by coupling benzenoid and heterocyclic diazo components to aniline derivatives containing ester functions. The colour properties and wet fastness of the dyes on polyester at 1/1 standard depth have been examined and rationalised in terms of dye structure. Styryl dyes have also been prepared in order to compare their wet fastness properties to those of the azo dyes.     

Dyes derived from 1,4‐naphthoquinone as initiators for radical and cationic photopolymerisation

Several 2‐phenylamino‐1,4‐naphthoquinone‐based dyes and two related benzo[2,3‐b]–phenazines were synthesised and characterised by proton nuclear magnetic resonance spectroscopy and electron ionisation mass spectrometry. The electrochemical and spectral properties of these compounds were investigated. The synthesised dyes were found to be capable photosensitisers for radical (reducible/oxidisable) and cationic polymerisations, respectively. In radical polymerization, better results in the oxidisable process were achieved.     

Synthesis of azo benzo[b]thiophene derivatives and their application as disperse dyes

2-Amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitrile and ethyl-2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate were synthesised by reaction of cyclohexanone and sulphur with malononitrile and ethyl cyanoacetate respectively. These 2-aminothiophene derivatives were diazotised and coupled with a variety of coupling components to give azo dyes. The spectral properties of these dyes are reported. The dyes had generally good colouration and fastness properties on polyester.     

Dyes derived from aminothiophenes—Part 2. Spectroscepic properties of some disperse dyes derived from 2-aminothiophenes

The colour properties of a series of red to violet thienyl-2-azo disperse dyes in solution have been investigated. As expected, the attachment of increasingly electron-withdrawing groups to the thiophene ring resulted in bathochromic and hyperchromic shifts. The shifts in absorption maxima were predicted quantitatively by PPP-MO calculations with reasonable accuracy. The solvatochromism and halochromic behaviour of the dyes were also examined.     

A study of some monoazo dyes containing the 1H-benzotriazole nucleus

Dyes containing the benzotriazole nucleus with various groups imparting a chelating property to the dye molecules have been synthesised. The dyes showed interesting properties for application to cotton and polyester.     

Aggregation and photofading behaviour of unsymmetrical squarylium dyes containing a quinolylidene moiety

Representatives of a new class of unsymmetrical squarylium dyes containing a quinolylidene moiety have been synthesised and characterised. These dyes absorbed at a longer wavelength (11–50 nm) than the corresponding symmetrical squarylium dyes. The influence of the quinolylidene moiety on the absorption of these dyes was studied and compared with that calculated by the PPP-MO method. The photostability properties of the dyes were investigated in chloroform with a high-pressure mercury lamp. The aggregation of the unsymmetrical squarylium dyes were also studied in different DMSO/water solutions, including solutions with γ-cyclodextrin.