X-Ray crystal structure analysis and determination of azo-enamine and hydrazone-imine tautomers of two hetarylazo indole dyes

Two hetarylazo indole dyes were analyzed by single crystal X-ray diffraction. Dye 1 , C₁₈H₁₄N₄O, crystallises in the monoclinic system, space group P2₁/c, with two independent molecules in the asymmetric unit. Dye 2 , C₂₀H₁₆N₄, also crystallises in the monoclinic system, space group P2₁/n, Z  = 4. In both compounds, there are two intramolecular C–H...N hydrogen bonds which influenced the molecular conformation between the azo group and the indole ring system and its phenyl substituent. Each of the independent molecules of dye 1 interact through the N–H...N hydrogen bond, whereas no classical intermolecular hydrogen bond was observed in dye 2 . The molecules of dye 1 and dye 2 are packed differently in both structures.     

Laser Raman studies of α–bromoacrylamide reactive dyes and wool

The use of laser Raman spectroscopy in the investigation of interactions in α–bromoacrylamide reactive dye–wool fibre systems has been established. The spectra obtained (in particular using C. I. Reactive Red 84) provide some evidence to support the proposal that the dye reacts via addition at the double bond of the reactive group, followed by ring closure through nucleophilic substitution. Furthermore, preliminary studies of the effect of the commercial levelling assistant Albegal B on the aqueous dye environment have been made using C. I. Reactive Yellow 39. The results show that, whilst the primary interaction between the dye and auxiliary may be via the water–solubilising sulphonate groups of the dye, hydrophobic interactions are also important.     

氧化石墨烯-壳聚糖纤维制备及其对染料吸附性能

选取壳聚糖和聚乙烯醇与氧化石墨烯共混复合,通过湿法纺丝工艺技术,制备不同氧化石墨烯含量的氧化石墨烯-壳聚糖复合纤维。利用扫描电镜和红外光谱表征了复合纤维的微观结构和化学组成,结果表明:复合纤维成形较好,氧化石墨烯与壳聚糖之间形成了稳定的氢键。通过染料吸附试验可知:氧化石墨烯可明显提高复合纤维对染料的吸附能力,当氧化石墨烯质量分数为1%时,吸附效果最理想,吸附量可达407 mg/g,有望用于印染废水的综合处理。     

复合胺改性尼龙6纤维染色性能的研究 I.染色工艺及其染色机理

在己内酰胺水解聚合时加入一定量的可反应型复合胺类改性剂(HAS),合成出含有胺类改性剂的尼龙6树脂,经纺丝后得到尼龙6纤维。研究了该改性剂及pH值、染色温度、时间等染色条件对尼龙6纤维染色性能的影响。结果表明:尼龙6纤维采用酸性蓝AGL上染时,其染色性能与染色条件有关;在相同的染色条件下,HAS改性尼龙6纤维的染料上染量均大于未改性样的上染量。由于酸性染料分子除了以范德华力和氢键的形式与纤维结合外,还会与纤维生成盐键结合,因此上染量的增加是由于改性后尼龙6纤维的端氨基增加的缘故。     

Ethanol and water capacities of alcohols: A molecular dynamics study

The extended hydrogen bond networks formed by alcohols are good indicators of their capacities to hold water. Results from molecular dynamics simulations on 24 linear alcohol isomers containing 6-12 carbon atoms show the effects of hydroxyl location on bulk hydrogen-bonded structures. Calculated oxygen-oxygen radial distributions obtained from simulations were correlated to experimental liquid-liquid solvent extraction studies involving ternary water/ethanol/alcohol systems. It was found that hydroxyl group location determines the primary structure of the bulk alcohol's hydrogen bond network and that an alcohol's capacity for water correlates directly to the size of this network.     

Synthesis of stilbene-based azo dyes and application for dichroic materials in poly(vinyl alcohol) polarizing films

Stilbene-based azo dyes were synthesized and poly(vinyl alcohol) polarizing films were prepared using these dyes. Spectral properties of synthesized dyes were affected by amino group and intramolecular hydrogen bond in the coupling component ring. Adsorption of dye molecules onto the film was mainly influenced by hydrogen bonding interaction. Sodium sulfate added in the dyeing solution reduced the repulsion between dye anions and the film resulting in high degree of polarization. The increase in draw ratio improved the optical properties of the polarizing films.     

Dyes based on a 1,4‐naphthoquinone skeleton as new type II photoinitiators for radical polymerisation

Photoredox pairs consisting of 1,4‐naphthoquinone dyes and commercially available hydrogen donors (2‐mercaptobenzoxazole, 2‐mercaptobenzothiazole, 2‐mercaptobenzimidazole and 2,5‐dimercapto‐1,3,4‐thiadiazole) are found to be effective initiator systems for the radical polymerisation of trimethylolpropane triacrylate under visible light. The efficiency of these initiator systems is discussed in terms of the free energy change for the electron transfer process from the dye to the hydrogen donor. The results show that the photoinitiation ability of tested photoredox pairs depends on the structure of both the dye and the hydrogen donor.     

Theoretical study on the nature of the hydrogen bonds in an α-helical polymer and its model systems

The semi-empirical CNDO/2 SCF (self-consistent field) MO (molecular orbital) method using the tight-binding approximation for polymers was applied to polyglycine. The CNDO/2 calculations were also performed on model systems of this polymer. From the calculated results, the characteristics of the hydrogen bond in the α-helix were derived by comparison with those in the model systems. It was found that the hydrogen bond in the α-helix is very stable against proton transfer whereas the hydrogen bond in the model system is not so stable; this characteristic difference between the two systems is due to the coupling of two π-electron systems through hydrogen bonding in the α-helix.     

Applicability of hemicyanine phenyltrialkylborate salts as free‐radical photoinitiators in the visible‐light polymerization of acrylate

The photoinitiation ability of photoredox pairs composed of a hemicyanine dye cation and different borate anions for the radical polymerization of 2‐ethyl‐2‐(hydroxymethyl)‐1,3‐propanediol triacrylate was investigated. In such a system, the excited dye chromophore is reduced by different tetraorganylborate anions. Upon irradiation at 488 nm, reductive carbon–boron bond cleavage occurs, producing reactive radicals, which start the chain reaction. The efficiency of bond‐breaking processes was found to be dependent on the nature of both the acceptors and the donors. The experimental results show that the photoinitiating ability of the tested photoredox pairs were controlled by both the driving force of the electron‐transfer process between the electron donor and the electron acceptor and the reactivity of the free radical that resulted from the secondary reactions occurring after the photoinduced electron‐transfer process. Using the nanosecond flash photolysis method, we studied the spectral and kinetic characteristics of the triplet state of cyanine dye and determined the rate constants of the triplet quenching by phenyltrialkylborate salts. The results obtained show that the tetramethylammonium phenyl‐tri‐n‐butylborate (TB7) has a faster electron‐transfer rate than the tetramethylammonium n‐butyltriphenylborate (TB2) salt, which bore only one butyl group attached to the boron. The relative initiator efficiency of the triphenylbutylborate salts, as compared to the corresponding phenyltrialkylborate salts with a common chromophore, was determined. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dynamics of water interacting with interfaces, molecules, and ions

Water is a critical component of many chemical processes, in fields as diverse as biology and geology. Water in chemical, biological, and other systems frequently occurs in very crowded situations: the confined water must interact with a variety of interfaces and molecular groups, often on a characteristic length scale of nanometers. Water's behavior in diverse environments is an important contributor to the functioning of chemical systems. In biology, water is found in cells, where it hydrates membranes and large biomolecules. In geology, interfacial water molecules can control ion adsorption and mineral dissolution. Embedded water molecules can change the structure of zeolites. In chemistry, water is an important polar solvent that is often in contact with interfaces, for example, in ion-exchange resin systems. Water is a very small molecule; its unusual properties for its size are attributable to the formation of extended hydrogen bond networks. A water molecule is similar in mass and volume to methane, but methane is a gas at room temperature, with melting and boiling points of 91 and 112 K, respectively. This is in contrast to water, with melting and boiling points of 273 and 373 K, respectively. The difference is that water forms up to four hydrogen bonds with approximately tetrahedral geometry. Water's hydrogen bond network is not static. Hydrogen bonds are constantly forming and breaking. In bulk water, the time scale for hydrogen bond randomization through concerted formation and dissociation of hydrogen bonds is approximately 2 ps. Water's rapid hydrogen bond rearrangement makes possible many of the processes that occur in water, such as protein folding and ion solvation. However, many processes involving water do not take place in pure bulk water, and water's hydrogen bond structural dynamics can be substantially influenced by the presence of, for example, interfaces, ions, and large molecules. In this Account, spectroscopic studies that have been used to explore the details of these influences are discussed. Because rearrangements of water molecules occur so quickly, ultrafast infrared experiments that probe water's hydroxyl stretching mode are useful in providing direct information about water dynamics on the appropriate time scales. Infrared polarization-selective pump-probe experiments and two-dimensional infrared (2D IR) vibrational echo experiments have been used to study the hydrogen bond dynamics of water. Water orientational relaxation, which requires hydrogen bond rearrangements, has been studied at spherical interfaces of ionic reverse micelles and compared with planar interfaces of lamellar structures composed of the same surfactants. Water orientational relaxation slows considerably at interfaces. It is found that the geometry of the interface is less important than the presence of the interface. The influence of ions is shown to slow hydrogen bond rearrangements. However, comparing an ionic interface to a neutral interface demonstrates that the chemical nature of the interface is less important than the presence of the interface. Finally, it is found that the dynamics of water at an organic interface is very similar to water molecules interacting with a large polyether.     

Dye–fiber interactions in PET fibers: Hydrogen bonding studied by IR‐spectroscopy

Dye–fiber interactions are studied in poly (ethylene terephthalate) fibers by FT‐IR spectroscopy. It is shown for the first time that DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) serves as an easy applicable and accurate technique for the study of fibrous structures. This article focuses on the possible hydrogen bond interactions in the dye–fiber system, where the PET fibers are dyed with anthraquinone‐based disperse dyes. The dyes and related anthraquinone structures are studied in both the dilute solution state, the solid state, and as present in the PET fibers. It is proven that 1‐amino anthraquinones show strong “chelate‐type” intramolecular hydrogen bonding in all three states. In the fibers an important supplementary intermolecular hydrogen bonding with the C?O groups in the PET fiber is observed. The extend of hydrogen bonding seems to be prone to dye concentration variations. Further analysis by modulated differential scanning calorimetry links the hydrogen bonding to an intrinsic plasticizing effect of the dyes affecting the dye diffusion process. This thus offers a tool for the fundamental understanding of the dyeing process and possible observed differences in dyeing behavior in dye–fiber systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

X-ray crystal structure of disperse red 167

X-ray diffractometer data have been used to determine the crystal structure of CI Disperse Red 167, an important automotive disperse dye. The structure was solved by direct methods and refined by least squares to R = 0.0442 for 1115 independent reflections. This monoazo dye possesses a planar azobenzene skeleton, as the dihedral angle between the planes made by the two aromatic rings is 1.5°. The non-bonding distance between the hydrogen atom of the acetamido group and azo nitrogen N(1) is well within the expected distance for intramolecular hydrogen bonding. Interestingly, the chloro and acetamido groups lie on the same side of the azo bond, and each unit cell of this dye contains 8 molecules.     

水溶型聚酯表面活性剂的合成及性能研究

采用溶剂法制得马来酸双聚乙二醇酯。与邻苯二甲酸酐缩聚。用亚硫酸氢钠加成缩聚物中马来酸酐上的双键。用红外光谱，核磁共振，对聚合物进行了结构确认，具有良好的降低表面张力的能力。抗硬水性，对苯及同系物具有一定的增溶及分散作用，通过紫外光谱，初步确认其增溶方式。     

A computational investigation on the molecular structure,electronic properties and intramolecular hydrogen bonding interaction of 1,1,1-trifluoro-4-mercaptobut-3-ene-2-thione in ground and electronic excited state

The hydrogen bond (HB) strength, geometry optimization, vibrational frequencies and several well-established indices of aromaticity in 1,1,1-trifluoro-4-mercaptobut-3-ene-2-thione and its 15 derivatives in two positions, R1 and R2, have been investigated by means of the density functional theory (DFT) method with 6-311++G** basis set in the gas phase. The obtained results show that the HB strength is mainly governed by resonance variations inside the chelate ring induced by the substituent groups. The following substituents have been taken into consideration: NO₂, SCF₃, Ph, PhOCH₃, SCOCH₃, CH₂OCH₃ and CH₂OH. The strongest S–H···S HBs belong to PhOCH₃-substituted system in both positions, whereas NO₂ and H substitutions in R1 and R2 positions, respectively, produce the weakest S–H···S hydrogen bridges. The excited-state properties of intramolecular hydrogen bonding in substituted systems have been investigated theoretically using the time-dependent DFT method. Natural bond orbital analysis is also performed for a better understanding of the nature of intramolecular interactions. The electron density and Laplacian (?²ρ) properties, estimated by atoms in molecule calculations, indicate that the H···S bond possesses low ρ, positive ?² ρ and H_C<0, which are in agreement with the partially covalent character of HBs.     

Novel N‐ethyl‐2‐styrylquinolinum iodides as sensitizers in photoinitiated free radical polymerization of trimethylolopropane triacrylate (TMPTA), part 3

Three‐component systems, which contain a light‐absorbing species (dye), an electron donor (n‐butyltriphenylborate salt), and a third component (N‐alkoxypyridinum salt or 1,3,5‐triazine derivative), have emerged as efficient, visible‐light sensitive photoinitiators of free radical polymerization. It was found that three‐component systems are more efficient than their two‐component counterparts. Kinetic studies based on microcalorimetry revealed a significant increase in polymerization rate with increasing concentration of N‐alkoxypyridinum salt. Such results were not obtained for photoinitiating systems possessing 1,3,5‐triazine derivative as a second coinitiator. Based on the experimental results we concluded that the primary photochemical reaction involves electron transfer from the borate anion to the excited dye followed by the reaction of resulting dye‐based radical with second coinitiator that regenerates the original dye and simultaneously produces the alkoxy radical or triazynyl radical which could start the polymerization chain reaction. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis,properties, and application of new benzothiazole‐based sensitisers in polymer chemistry

New photoinitiating systems composed of benzothiazolestyrylium dyes as chromophores and n‐butyltriphenylborate anion as electron donor were prepared and characterised. Photoredox pairs consisting of hemicyanine dyes and organoborate salts may act as visible‐light photoinitiators for the radical polymerisation of multifunctional acrylates. The efficiences of these photoinitiator systems are based on the free energy changes of an electron transfer from borate salt to the dye. Experimental results show that the photoinitiating ability of the photoredox pair tested strongly depends upon the reduction potential of hemicyanine dye, the oxidation potential of borate salt, and the structure of the dicationic dye.     

Acriflavine–cobaloxime–triethanolamine homogeneous photocatalytic system for water splitting and the multiple effects of cobaloxime and triethanolamine

Acriflavine dye, with a long-lived triplet excited state, has a strong sensitizing ability for photodriven water splitting when [Co^III(dmgH)₂(py)Cl] complex is used as a catalyst and triethanolamine as electron donor. This catalytic system is an example of a noble-metal-free homogeneous system for hydrogen generation from water. Moreover, the mechanistic details of the overall reaction pathway, as well as Acriflavine fading, is presented to offer significant guidance to developing more robust photocatalytic systems.     

方酸菁染料/二芳基碘鑑盐体系引发丙烯酸酯光交联反应

近年来随着高新技术的迅猛发展,激光技术和光化学也随之大量应用到先进材料中,为适应这种发展需要,开发感可见光和近红外光的光敏反应体系已成为十分迫切的研究课题［１,２］．方酸类染料是一类重要的功能性染料,广泛地应用于静电复印、太阳能电池和光记录材料［３］...     

过氧化氢处理含染料废水研究新进展

简要介绍近来利用过氧化氢处理含染料废水的各种方法研究进展,染料包括直接染料、酸性染料、活性染料、媒介染料等,其中多含偶氮键。处理方法包括Fenton法、UV／Fenton法、UV／H2O2法、超声波／H2O2法、O3／H2O2法等。大多均以脱色率和TOC去除率来评价处理效果。实验结果表明,各种方法的处理效果均较显著,但均是以模拟染料废水进行的实验室研究,有待生产应用和检验。有些研究涉及染料降解脱色反应动力学方面,均确定过程为一级或假一级反应,有些研究给出动力学方程式和反应速率常数。     

Semiconductor-mediated photocatalytic degradation of anazo dye, chrysoidine Y in aqueous suspensions

The photocatalytic degradation of an azo dye derivative, chrysoidine Y (1), was investigated in aqueous suspensions of titanium dioxide and zinc oxide by monitoring the change in substrate concentration employing UV spectroscopic analysis and decrease in total organic carbon content as a function of irradiation time under a variety of conditions. The degradation of the dye was studied under different conditions such as pH, catalyst concentration, substrate concentration and in the presence of electron acceptors such as hydrogen peroxide (H₂O₂) and potassium bromate (KBrO₃) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with zinc oxide