纤维上染料的老化紫外光谱分析

本文通过模拟纤维使用过程中所经历的光照、氧化和还原等环境作用因素，用紫外光谱的方法研究了几种染料的化学结构的变化，其中光化学变化、氧化还原烟气(NO2、H2S等)作用是影响染料老化的几个重要因素之一，光化学作用是使染料发生化学变化(如偶氮键断裂)的主要因素。     

Photochemical Tendering Activity of Sulphur Dyes

The photochemical tendering activity of a series of sulphur dyes on cotton cloth has been assessed in terms of (I) the changes in the physical and chemical properties of the fibre and (2) the extent of fading of the dyes and the formation of hydrogen peroxide during exposure.     

The effect of perspiration on photo-induced chemical reaction of azo dyes and the determination of aromatic amine products

In order to investigate the impact of perspiration on photo-induced chemical reaction of azo dyes and the carcinogenic aromatic amine products produced from the reaction, we have carried out experimental studies on the photochemical reaction of C.I. Reactive Red 2 mixed with American Association of Textile Chemists and Colorists（AATCC）standard artificial perspiration. UV-vis spectroscopic technique was employed to monitor the reaction processes, and the reaction products were analyzed by hollow fiber protected liquid-liquid-liquid phase micro-extraction with capillary electrophoresis（HF-LLLME-CE). The results showed that perspiration had remarkable influence on the photochemical reaction of azo dyes. Aromtic amines formed during the photochemical process as a result of reduction of azo dyes by organic components in perspiration. The HF-LLLME-CE methodology was validated in analyzing aromatic amines produced from the photochemical degradation of azo dye C.I. Reactive Red 2 and C.I. Acid Red 35 mixed with artificial perspiration.     

Studies on Aminoanthraquinone Compounds IV–Photochemistry of some Simple Derivatives in Solution and on Polymer Films

An attempt has been made to determine the validity of the concept of the dye–ethanolsystem as a model for the photochemical degradation of textile materials sensitised by anthraquinone vat dyes. The action of (a) near–ultraviolet and visible radiation and (b) short–wave ultraviolet radiation (mainly 253–7 mμ) on anaerobic solutions of 1–aminoanthraquinone in ethanol, n–hexane, ethyl acetate, and carbon tetrachloride has been studied. Extensive fading of the dye occurs in these solvents with both typesof radiation. In the hydrogen–containing solvents characteristic spectra of reduction products of 1–aminoanthraquinone are produced, whereas in carbon tetrachloride there is extensive general destruction of the absorbing systems. The spectral changes occurring on the irradiation under anaerobic conditions of 1, 5–diaminoanthraquinone and 2–aminoanthraquinone in solution in ethanol and dyedon polymer films of N–methoxymethyl nylon, nylon 6. 6, and secondary cellulose acetate are compared. Only with 1, 5–diaminoanthraquinone and 1–aminoanthraquinone on N–methoxymethylnylon film are the changes on irradiation in dry nitrogen similar to those in ethanol. It is concluded that the photochemical behaviour ofanthraquinone dyes in organic solvents and in polymer systems can show considerable differences.     

Screening Xanthene Dyes for Visible Light‐Driven Nicotinamide Adenine Dinucleotide Regeneration and Photoenzymatic Synthesis

Regeneration of the nicotinamide cofactor is a critical issue in biocatalysis. Herein we have screened xanthene dyes for a highly efficient, visible light‐driven photochemical regeneration of cofactors and enzymatic synthesis. Superior catalytic performance was observed with several xanthene dyes such as phloxine B, erythrosine B, eosin Y, and rose bengal. We found that the photo‐ and electrochemical properties of the xanthene dyes were affected by the halogen atom substitution, which is a key factor in the efficient light‐induced electron transfer from the donor molecule to the catalytic mediator.     

Structure and hydrophilicity of azo‐dye‐derived rotaxane: density functional theory approach

We investigated the most probable molecular structure, energy, and corresponding properties, including the solvation energy and binding free energy in solution, for non‐encapsulated azo dyes using quantum mechanical density functional theory (DFT). The structures of non‐encapsulated azo dyes with six conformations were optimised to find the most stable conformation with the lowest energy, but the energy differences among the conformations were within ~2.2 kcal mol^?1. The LUMO–HOMO gaps were also similar, meaning that their interaction with light would be similar. The energies of alpha‐cyclodextrin (α‐CD) encircling the phenyl ring fragments were significantly higher than other conformations, because α‐CD tends preferably to encircle azo fragments to create a thermodynamically stable form. From solvation free energy calculations, the hydrophobic non‐encapsulated azo dye and hydrophilic α‐CD showed reasonable values for solvation free energy with respect to dimethyl sulphoxide (DMSO) and water: the former has more solvation in DMSO, while the latter has more solvation in water. Rotaxane formation is thermodynamically feasible in water (?3.06 kcal mol^?1) but not in DMSO (25.56 kcal mol^?1) according to calculation of binding free energy in solution state.     

还原橄榄T的间接电还原法

本工作采用循环伏安法和正交电解实验法研究了还原橄榄T在Fe-TEA媒质中的电化学行为。Fe(III)-TEA络合物在碱性环境下表现出良好的电化学活性,能够还原橄榄T而不会引起过度还原。此外,通过L9(34)正交实验分析了电流密度、温度、媒质浓度和NaOH浓度四因素对电流效率的影响。结果表明在本实验所设条件范围内,最高电流效率可达59.03%,对电流效率影响最大的因素为电流密度。     

Comparison of oxidation efficiency of disperse dyes by chemical and photoelectrocatalytic chlorination and removal of mutagenic activity

Degradation of Disperse Orange 1, Disperse Red 1 and Disperse Red 13 dyes has been performed using electrochemical oxidation on Pt electrode, chemical chlorination and photoelectrochemical oxidation on Ti/TiO₂ thin film electrodes in NaCl or Na₂SO₄ medium. 100% discoloration was obtained for all tested methods after 1 h of treatment. Faster color removal was obtained by photoelectrocatalytic oxidation in 0.1 mol L⁻¹ NaCl pH 4.0 under UV light and an applied potential of +1.0 V (vs SCE reference electrode), which indicates also values around 60% of TOC removal. The conventional chlorination method and electrochemical oxidation on Pt electrode resulted in negligible reduction of TOC removal. All dyes showed positive mutagenic activity in the Salmonella/microsome assay with the strain TA98 in the absence and presence of S9 (exogenous metabolic activation). Nevertheless, there is complete reduction of the mutagenic activity after 1 h of photoelectrocatalytic oxidation, suggesting that this process would be good option to remove disperse azo dyes from aqueous media.     

The adsorption of basic dyes by poly(styrene sulphonate)

The adsorption of basic dyes (Safranine, Neutral Red, Acridine Orange and Proflavine) on poly(styrene sulphonate) has been studied by measuring the amount of free dye in solution using a photochemical method. Adsorption free energies are in the range 7.1–5.3 kcal/mol. Comparing the values of these energies as a function of the structure of the dyes, three different types of interactions can be postulated to contribute to the binding of the dyes to the polymer, viz., electrostatic (c. 4 kcal/mol), hydrophobic and charge-transfer.     

Direct electrochemical reduction of indigo: process optimization and scale-up in a flow cell

Reducing agents required in the dyeing process for vat and sulfur dyes cannot be recycled, and lead to problematic waste products. Therefore, modern economical and ecological requirements are not fulfilled. The industrial feasibility of the direct electrochemical reduction of indigo as a novel method has been determined and a preliminary optimization of electrolytic conditions was performed using a laboratory-scale flow-cell system. The role of current density, pH, temperature and the rate of mass transport are discussed. The influence of particle size reduction by the application of ultrasound is critically considered.     

Some Aspects of the Light Fastness of Reactive Azo-dyes on Cellulose under Wet Conditions

The photochemical behaviour of four reactive-azo dyes, (two dyes with poor wet light fastness and two dyes with normal wet light fastness) was examined to elucidate the mechanisms by which some reactive azo dyes, applied to cellulose, fade more rapidly when wet. In one case it was found that the major primary photochemical reaction is photoejection of electrons, which is enhanced in the aqueous environment, while in the second case, a back reaction between hydroxyl radicals and dye molecules is facilitated by the aqueous environment.     

New 2,2-difluoro-1,3,2(2H)oxazaborines and merocyanines derived from them

Synthetic methods have been developed to prepare oxazaborines, the azaanalogues of 2,2-difluoro-1,3,2(2H)dioxaborines, which can form merocyanine dyes. The first oxazaborine merocyanines with the isomeric position of the coordinating nitrogen atom have also been obtained. Comparing the spectral properties of donor-acceptor dioxa- and oxazaborine dyes, it is seen that substitution of the 3-O atom by the NH group in the chelate ring has a slight effect on absorption and fluorescence band positions but causes the intensity redistribution between the 0-0 and 0-1 vibronic absorption peaks and thus induces a change in the absorption band shape due to the enhanced solvation of oxazaborines. Substitution of the 1-O ring atom by the NPh group leads to a bathochromic shift and a manifold increase in the fluorescence quantum yield for the corresponding boron chelate dyes.     

Electrochemical reduction of indigo in fixed and fluidized beds of graphite granules

Reducing agents required in the dyeing process for vat and sulfur dyes cannot be recycled and lead to problematic waste products. The electrochemical reduction of indigo on a fixed bed cathode consisting of graphite granules has been investigated by spectrophotometric experiments in laboratory cells. Experiments yield information about the kinetics and show the possibility of this process for production of water soluble leuco indigo, which offers environmental benefits. The influence of noble metals deposited on the granules and of different pretreatment methods of the graphite is demonstrated. In addition, the immobilization of quinoid molecules on the graphite surface has been investigated.     

Electrochemical reduction off 4-aminopyrimidine in aqueous media

The redox and associated chemical behavior of 4-aminopyrimidine (4-AP) and its reduction products in buffered aqueous media have been examined by a variety of electrochemical techniques. In acidic medium (pH 0–2), 4-AP undergoes a two-step reduction: pH-dependent wave I corresponds to a three-electron (3e) process; wave II, which corresponds to a 1e transfer, is accompanied by catalytic hydrogen discharge. Between pH 2 and 7.5, only wave I is visible; its height diminishes above pH 4, becoming zero by pH 8. Macroscale electroreduction at potentials on the crests of waves I and II has been followed electrochemically and by ultraviolet spectrophotometry with isolation and identification of the wave I reduction products. The photochemical transformation of the reduction products on ultraviolet irradiation has been examined. The reduction of 4-AP is accompanied by isomerization, ring opening and/or deamination of the primary reduction products and of the resulting secondary chemical products.     

6‐Pyridinium benzo[a]phenazine‐5‐oxide derivatives as visible photosensitisers for polymerisation

Several 6‐pyridinium benzo[a]phenazine‐5‐oxide derivatives have been synthesised and characterised by proton nuclear magnetic resonance spectroscopy and mass spectrometry. The spectroscopic and electrochemical properties of these dyes were examined. The dyes were used as reducible sensitisers for selected electron donors (phenylthioacetic acid, phenoxyacetic acid, N‐phenylglycine, and ethyl 4‐N,N‐dimethylaminobenzoate) and as oxidisable sensitisers for electron acceptors (onium and N‐alkoxypyridinium salts). These photoredox pairs were found to be effective visible‐wavelength photoinitiators for the free radical polymerisation of trimethylolpropane triacrylate under visible light. The cationic photopolymerisation of cyclohexene oxide by the studied dyes and the onium salt photoredox pairs was ineffective. The obtained results are discussed on the basis of both free energy change for electron transfer to or from the benzo[a]phenazine dyes and the photochemical properties of the dyes, particularly their photobleaching. The proposed mechanism of dye fading is supported by density functional theory calculations and spectroscopic characterisation of the radical cation of the dye.     

纳米银粒子制备及应用研究进展

综述了制备纳米银粒子的方法,主要包括液相化学还原法,电化学还原法、光化学还原法和分子自组装等,分析比较了这些方法的基本原理、制备过程及优缺点,阐述了纳米银粒子在化学反应,光学领域及抗菌等领域的应用.     

Photodecomposition of Aminoanthraquinone Disperse Dyes on Poly(ethylene terephthalate)

The rapid fading on polyester fibres of certain blue anthraquinone disperse dyes under normal conditions of exposure is due to the ease of photochemical de-alkylation of their substituted-amino groups. The products of the photoelimination reaction for a series of dyes have been identified, and a mechanism for the reaction is proposed. The higher photochemical stability of these dyes on cellulose acetate and nylon is perhaps due to hydrogen bonding of the alkylamino groups to the polymer. The influence of wavelength of irradiation, oxygen, moisture and the physical structure of the polymer is discussed.     

II—Evidence for the Formation of Singlet Oxygen by Phototendering Vat Dyes

The reaction of tetraphenylcyclopentadienone (TPC) with singlet oxygen has been used as a probe for the photochemical formation of singlet oxygen by phototendering vat dyes. The dyes C.I. Vat Yellow 1, 2 and 26 and C.I. Vat Orange 9 sensitised the oxidation of TPC in phenol-methylene chloride solution by the action of visible light. In each case the sole photo-oxidation product was cis-dibenzoylstilbene, indicating the intermediacy of singlet oxygen. Similar results were obtained when the dyes were applied to cotton fabric, although the relative efficiencies of the dyes as sensitisers differed from those observed in solution. The singlet-oxygen-sensitising efficiencies of the dyes on cotton parralleled their relative phototendering activities towards cellulose, providing evidence in favour of the singlet-oxygen theory of phototendering. Quenching studies of the dye-sensitised oxidation of TPC confirmed that the reaction proceeded by a singlet-oxygen mechanism rather than a radical process.     

还原染料电化学还原染色方法研究进展

还原染料的电化学还原染色方法是环境友好的新型染色方法,具有还原剂使用量少或不使用还原剂、排放的废水少,染色过程易于控制等特点。介绍了还原染料的间接电化学还原、直接电还原和电催化氢化方法的原理、特点和工艺过程,探讨了三种方法各自的优点和需要解决的问题。     

New diaminomaleonitrile-based azo-azomethine dyes; synthesis, characterization and spectral properties

New diaminomaleonitrile-based azo-azomethine dyes were synthesized via a condensation between 2,6-bis(N-(2-amino-1,2-dicyanoetheneimino))-4-methylphenol and 5-(4-substituted-phenyl)-azo-salicyladehyde. FT-IR and ¹H NMR spectroscopy and mass spectrometry studies as well as elemental analysis data revealed the symmetrical bis-iminated structures of the dyes. The electrochemical behavior of the dyes has been investigated by cyclic voltammetry. The effect of various solvents with different polarities on the UV-Vis spectra of the dyes was also studied. The thermal analysis data indicated that the framework of the dyes was stable up to 285 °C.