Some properties of dual fluorescence of methine dyes

Studies of the dependence of methine dye absorption and fluorescence properties on the molecular composition of the dyes, on solvent polarity and on the temperature of the sample were made. The results have confirmed our recent suggestion that the emission band of methine dyes in polar solvents is composed of molecular and excimer fluorescence. The spectral properties of different types of molecular composition of methine dyes indicated the centre in the dye molecule involved in excimer formation. On the basis of a liquid nitrogen temperature spectrum and the lifetimes of fluorescence it is suggested that this type of methine dye which can form the excimers has a strong tendency to aggregate in the ground states. These aggregates are able to quench the molecular fluorescence. An increase of solvent polarity causes disaggregation of dye molecules giving an increase of molecular fluorescence and an increased probability of excimer formation. Thus, in polar solvents the long-wavelength emission band arises.     

Pad-Batch Dyeing of Wool Fabric—Development of an Industrial Process*

This paper describes an industrial procedure developed for the application of dyes of good fastness properties, especially reactive dyes, to wool fabric by a pad-batch technique, following the initial observations (7) that by dyeing from concentrated solutions of urea the rates of diffusion and of reaction of reactive dyes with wool are greatly increased. The chemical and mechanical developments necessary to apply this initial observation under practical dyeing conditions are described.     

Relationship between the absorption spectra and spatial hindrance in starch graft copolymers

The photochemical trans–cis isomerization of graft copolymers of azo dyes onto starch was studied in liquids spectrophotometrically. The relationship between the absorption spectra and spatial hindrance was investigated. The experimental results showed that the structure of the graft copolymers had a marked influence on photoisomerization. The smaller the spatial hindrance was, the easier the photoisomerization was. The copolymers showed better photoisomerization than their corresponding monomers, and this showed that the backbone of starch in the main chain influenced not the maximum‐wavelength position of the copolymers but the retroactive structure of the copolymers and favored their photoisomerization. In addition, the thermal cis–trans isomerization rate of the graft copolymers was studied in various polar solvents. The results suggested that the solvent polarity had a large effect on the thermal back‐isomerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2123–2126, 2006     

The use of ultraviolet radiation in an adsorbable organohalogen-free print preparation for wool and in wool dyeing: the Siroflash process

German legislation controlling the discharge of adsorbable organohalogens (AOX) in process effluents has focused attention on the need for environmentally acceptable alternatives to chlorination as a prepare-for-print (PFP) treatment for wool. The Siroflash process is a novel AOX-free approach which involves continuous UV irradiation of dry wool fabric, followed by conventional wet oxidation using hydrogen peroxide or permonosulphuric acid. Although permonosulphuric acid or peroxide treatments alone are ineffective as a PFP, the colour yields of prints on Siroflash-treated fabric are similar to those on chlorinated wool. The synergistic interaction between UV exposure and wet oxidation results in high levels of cystine oxidation, cuticle damage and loss of soluble protein, all of which are highly specific to irradiated surface fibres. UV irradiation of wool can significantly increase dyeing colour yields. The use of 1:1 metal-complex dyes is particularly effective, and a 3% o. w. f. dyeing on UV-treated fabric can produce a better depth of shade than a 5% dyeing on untreated fabric.     

Dyeing of wool with temporarily solubilised disperse dyes

Temporarily solubilised disperse dyes derived from aminophenyl-4-(β-sulphatoethylsulphone) have been applied to wool fabric without the use of a levelling agent. By virtue of their characteristic dye structure, excellent levelling properties were observed on wool fabric. Good exhaustion, fixation and fastness test values were also obtained.     

Surface modification of wool fabric for printing with acid and reactive dyes

The present study investigates environmentally safe pretreatments for wool fabric to improve its printing with acid and reactive dyes. Wool fabric was pretreated either with activated hydrogen peroxide using tetraacetylethylenediamine or with lipase enzyme under specified conditions. Some acid and reactive dyes were applied for wool printing using normal techniques. These treatments were found to improve the colour intensity of the printed fabrics to a level comparable with those of prechlorinated wool fabrics.     

Synthesis and spectroscopic investigation of cationic donor‐(π‐bridge)‐acceptor dye, 4‐[N‐(5,6,7,8‐tetrahydroisoquinolinium‐5‐ylidene)methyl]‐N,N‐dialkylaniline iodide

The synthesis and fundamental spectroscopic properties of eight hemicyanine (HC) dyes are presented. The dyes were prepared by the condensation of N‐methyl‐5,6,7,8‐tetrahydroisoquinolinium iodide with p‐(N,N‐dialkylamino)benzaldehydes. The compounds were characterised by nuclear magnetic resonance spectroscopy and their purity was checked with the use of thin‐layer chromatography. The spectroscopic properties of the dyes were determined in three organic solvents. The electronic absorption spectra of the dyes demonstrate moderate sensitivity to the nature of the substituent present in the aromatic ring and low solvent polarity dependence. In contrast to this, the positions of fluorescence bands are affected by the structure of an electron donor and solvent polarity. The 4‐[N‐(5,6,7,8‐tetrahydroisoquinolinium‐5‐ylidene)methyl]‐N,N‐dialkylaniline iodides were applied as fluorescent probes for the monitoring of the progress of free radical polymerisation. The study on the changes in the fluorescence intensity and spectroscopic shifts of the dyes was carried out during thermally initiated polymeriszation of methyl methacrylate. The purpose of these studies was to find a relationship between the changes in the shape and intensity of probe fluorescence and the degree of monomer conversion into polymer.     

新型溴代长波长BODIPY类荧光染料的合成及表征

通过吡咯和乙酰氯经一步法合成了含吡咯取代基的长波长BODIPY染料,溴化后得到一溴和二溴染料,染料通过质谱、二维核磁等手段进行了结构表征.测试了这些染料的吸收光谱和发射光谱,研究了不同极性的溶剂对染料光谱性能的溶剂化效应以及Br原子对染料光谱的重原子效应.结果表明:随着溶剂极性的增大所合成的染料吸收波长均发生了蓝移,发射波长变化不大,摩尔消光系数逐渐增大,荧光量子产率逐渐减小,表现出明显的溶剂化效应;在同一溶剂中,随着染料结构中Br原子取代基数目的增加,发射波长发生红移,吸收波长变化不大,摩尔消光系数逐渐增大,荧光量子产率逐渐减小,表现出明显的重原子效应.     

Investigation into the dyeing of wool with Lanasol and Remazol reactive dyes in seawater

Freshwater is an increasingly scarce resource that is extensively used in textile wet‐processing. In seeking to identify alternative low freshwater‐usage coloration technology, this study examined the potential use of seawater (SEAW) as the dyeing medium for wool coloration using a range of reactive dyes. Initially, the dyeing behaviour of the wool fabric in simulated seawater (SSW) was compared with conventional dyeing from distilled water (DW) using α‐bromoacrylamide‐based Lanasol dyes and sulphatoethyl sulphone‐based Remazol dyes. These preliminary studies demonstrated that comparable coloration could be achieved in the SSW medium based on an assessment of the dye exhaustion, dye fixation, colour yield and levelness. Subsequent dyeing studies of wool using Mauritian seawater with both the Lanasol and Remazol reactive dyes confirmed that, based on the dye exhaustion, dye fixation, colour yield and levelness, comparable coloration could be achieved, highlighting the possibility of substituting freshwater with seawater as the dyeing medium.     

Sublimation Transfer Printing of Wool with Metallizable Dyes

The transfer printing of pretreated wool using sublimable dyes that form metal complexes on the fibre during printing is described. The most successful pretreatment involved padding a mixture of chromic chloride, an an ionic surfactant, urea and lactic acid and then drying. Low molecular-weight monoazo dyes containing salicylic acid residues, or hydroxyl or amino groups on carbon atoms in two ortho positions relative to the azo group, were screen printed onto transfer papers. Optimum heating conditions for transferring dye from paper to fabric were 200d?C for 30 s. After separation of the transfer paper, the fabric was steamed at 100d?C for 30 min. Prints with good fastness properties were obtained in a wide range of colours. The method offers promise for commercial transfer printing of pure wool fabric.     

Use of lipoprotein lipase in the improvement of some properties of wool fabrics

Wool fabrics were pretreated with hydrogen peroxide in the presence of different stabilisers; namely, sodium silicate, magnesium sulphate and imino disuccinic acid sodium salt. The effect of stabiliser type and concentration on the properties of the treated wool were studied. Imino disuccinic acid sodium salt was found to be the most effective stabiliser for hydrogen peroxide when added to the bleaching bath of wool fabric. The effect of after‐treatment of the pre‐oxidised wool fabric with commercially produced lipoprotein lipase enzyme on its dyeability with acid and reactive dyes, as well as on some of its physico‐mechanical properties, was assessed. Chemical and microscopic analyses were conducted to assess changes in the chemical composition of wool treated with this system. Wool fabrics treated with hydrogen peroxide/imino disuccinic acid sodium salt/lipoprotein lipase enzyme exhibit improved wettability and, hence, dyeability with both acid and reactive dyes, as well as enhanced resistance to felting shrinkage and pilling, without severe deterioration in the fabric’s inherent properties.     

Evaluation of Some Reactive Disperse Dyes for Sublimation Transfer Printing of Wool

The transfer printing of wool by the sublimation method using a number of low–molecular–weight dyes containing chloro– and bromo–acetyl, chloroacetamido, chloro– and bromo–propionamido, 2–bromoacryloyl, 2–chloroethylamino and epoxy groups has been examined. To achieve build–up of the dyes to heavy depths, it was necessary to pretreat the wool with a polymer or surfactant and to steam the prints after transfer of the designs. Several dyes exhibited good fastness properties on pure wool and on a wool–polyester blend fabric.     

Reactive dyeing systems for wool fibres based on hetero-bifunctional reactive dyes. Part 2: Investigation of dyeing properties during the dyeing cycle

The dyeing behaviour during the dyeing cycle of a Sumifix Supra dye and some other commercial reactive dyes under various dyebath pH conditions was investigated. Studies of the dyeing of wool serge fabric indicated that the diffusion properties of hetero-bifunctional Sumifix Supra dyes generally lie between those of b-sulphatoethylsulphone (Remazol dyes) and monochlorotriazine (Procion H dyes).     

Reactive dyeing systems for wool fibres based on hetero-bifunctional reactive dyes. Part 1: Application of commercial reactive dyes

The wool dyeing properties, such as exhaustion and fixation parameters, of selected hetero-bifunctional Sumifix Supra dyes and some other commercial reactive dyes were quantified under various dyebath pH conditions. Studies of the dyeing of wool serge fabric indicated that Sumifix Supra dyes could produce reasonably high fixation values. However, remarkably improved fixation values were obtained when these dyes were pre-activated to the vinylsulphone form and dyed in this form, especially at low pH values (pH 4 or lower).     

Wet and Dry Boundaries and Unlevel Dyeing of Wool Fabric

The problem of ‘weathering’ faults in the dyeing of wool fabric has been studied. It was possible to reproduce these faults under laboratory conditions, and attempts were made to determine their nature and to devise correction or prevention techniques. Hydrolysis of the wool fibre is probably less important in the formation of ‘weathering’ faults than oxidation effects. With equalising acid dyes, re-treatment of the faulty dyeing in a boiling dyebath corrects the fault. However, with dyes of poor migration properties no technique is available that will ensure the correction of ‘weathering’ faults. Consequently, fabric left lying in carts should be covered, and fabric likely to be stored for a long period should be wrapped.     

A microscopical study of the pathway for diffusion of rhodamine B and octadecylrhodamine B into wool fibres*

The pathways for the diffusion of the basic dyes rhodamine B and octadecylrhodamine B into wool under aqueous and non–aqueous dyeing conditions have been investigated. The distribution of each dye within the fibre at various stages of the dyeing process was monitored by fluorescence microscopy. By judicious choice of solvent system and treatment time, the dyes could be directed into different histological components of the fibre. Intercellular diffusion, involving passage of the dye through the cell membrane complex between the cortical cells, was generally the preferred route for penetration of the fibre. The distribution patterns of the two dyes differed markedly and were strongly dependent upon the solvent composition. Whilst selective staining of the cell membrane complex occurred in an anhydrous solvent system, preferential staining of that region of the cell membrane complex associated with the orthocortex resulted when the dyes were applied from aqueous alcohol systems.     

五元杂环取代BODIPY染料的合成及光谱性能研究

以吡咯和2-呋喃甲醛、2-噻吩甲醛为原料,经缩合、氧化、环化反应合成了含新型五元杂环的BODIPY荧光染料,进一步溴化分别得到两种一溴代染料,所有合成的染料分子均通过质谱、核磁等手段进行了结构表征,并测试了这些染料的吸收光谱和发射光谱.结果表明:所有染料随着溶剂极性的增大表现出一定的溶剂化效应,吸收和发射波长变化不大(...     

Protection against phototendering of wool by metal salts and mordanted dyes

Samples of treated and dyed wool have been irradiated with an artificial UV radiation source with a spectral distribution that matched the summer solar UV spectrum. The extent of phototendering was determined by measuring the loss of tensile strength of strips of wool fabric. Many of the dyes studied accelerated phototendering, although some metal-complex dyes prolonged the lifetime. Significant protection of wool against phototendering could be obtained by treatment with aluminium salts, or related salts, followed by dyeing with classical mordant dyes.     

Research in the cold pad–batch dyeing process for wool pretreated by hydrogen peroxide

The cold pad–batch dyeing process of wool pretreated by hydrogen peroxide was carried out with Lanasol reactive dyes and Realan reactive dyes. The influences of various conditions of the dyeing process, including urea dosage, sodium bisulphite dosage, pH value, batching time and the liquor pickup on colour yield, were analysed. Fixation, levelness of dyeing, dye penetration, colour fastness, breaking strength and elongation were compared between untreated and treated wool fabrics. The study showed that cold pad–batch dyeing of wool fabric is a good prospect for future use because of the resulting advantages, such as higher fixation yield, less energy usage and lower sewage discharge.     

Differential dyeing of wool fabric with metal‐complex dyes after ultraviolet irradiation

Experiments were conducted to investigate the ultraviolet irradiation of wool fabric as a pretreatment for differential dyeing. Wool fabric was irradiated using a medium‐pressure mercury lamp in order to obtain, on the irradiated area, increased dye uptake under the same dyeing conditions as untreated wool. The chemical modification of the fibre surface as a result of ultraviolet irradiation was confirmed by an increase in metal ion absorption and hydrophilicity, in agreement with Fourier Transform‐infrared–attenuated total reflectance spectra, although scanning electron microscopy showed that the fibre morphology was unaffected. A selection of 1:1 metal‐complex dyes was used to show the maximum colour difference between irradiated and untreated areas of the fabric. The experiments focused on two effects: a double face with the same shade but different depths (greater depth on the treated side), and a double face with different shades. The latter effect was achieved by dyeing the irradiated fabrics with mixtures of acid and metal‐complex dyes. Rubbing and washing fastness evaluations at 50 °C confirmed that the dyeings after irradiation with the selected 1:1 metal‐complex dyes scored identically to conventional dyeings.