Spectroscopic studies of a near-infrared absorbing pH sensitive aminodienone-carbocyanine dye system

Synthetic red and near-infrared absorbing dyes may be used as probe molecules in a large number of applications. Dyes exhibiting spectral changes with hydrogen ion concentration are useful as pH probes. Those dyes which have their absorption and fluorescence maxima in the long wavelength region of the visible spectral region are specially valuable because of decreased interference and semiconductor laser applications. In this paper we have evaluated an aminodienone dyes 1 which demostrates pH dependent absorption and fluorescence spectra as well as solvent polarity dependence. In organic solvents the long wavelength absorption band of the dye is in the reduced interference region. The absorption maximum is at 535 nm in neutral or alkaline solutions in methanol. The absorption spectra undergo a strong bathochromic shift in the presence of acids (lambda(max) = 709 nm) with a concomitant change in the fluorescence spectra. This pH sensitive dye was found to be specially especially useful for organic solvents. The analytical utility of this and similar near-infrared absorbing dyes is discussed.     

有机染料及其在染料敏化太阳电池中的应用

在染料敏化太阳电池中,染料敏化剂分成无机染料与有机染料两大类。无机染料受稀有金属钌的制约而成本较高,开发有机染料是降低染料敏化太阳电池成本的有效手段,成为目前研究的热点。本文从有机染料敏化剂的分子设计入手,简述了染料敏化太阳电池中有机染料敏化剂的基本结构,将有机染料敏化剂分为吲哚啉类染料、香豆素类染料、三苯胺类染料、菁...     

蓝光有机存储染料研究进展

近年来,蓝光有机存储染料作为超高密度存储技术的核心已经日益受到人们的广泛关注,出现了与之相关的大量专利文献报道.本文介绍了卟啉染料、偶氮染料、菁染料、芪类染料和香豆素衍生物染料等蓝光染料的合成及应用,并对蓝光有机存储染料的发展趋势作了展望.     

有机染料共振光散射法测定蛋白质的研究进展

对用有机染料作试剂的共振光散射光谱法测定蛋白质研究的进展情况(主要包括1990年至2004年间)作了评述。对测定蛋白质的反应体系中有机染料作用的基本原理作了简要论述。文中涉及的有机染料主要有:三苯甲烷类、偶氮类、酞菁类及羟基蒽醌类等(引用文献58篇)。     

The preparation of new palladium (II) complexes with Schiff base type ligands and its impregnated Al2O3 materials: As the catalysts for degradation/reduction of organic dyes

The removal of organic dyes used in many sectors such as textile, paper, leather, and packaging from water sources is very important in terms of preventing the spread of industrial pollutants to the environment. Transition metal complexes supported to an inorganic solid material are frequently used for the degradation/reduction of organic dyes causing this pollution. In this study, new Pd (II) complexes with Schiff base ligands were synthesized and structurally characterized by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), mass spectrometry (MS), and single-crystal X-ray diffraction (sc-XRD) spectroscopic methods. Then, the Al₂O₃-impregnated materials of these Pd (II) complexes were prepared and characterized by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), FT-IR, and thermogravimetry (TG) techniques. The catalytic activities of the synthesized Pd (II) complexes and their Al₂O₃-impregnated materials were comparatively analyzed to investigate the degradation/reduction of organic dyes (2-nitroaniline, 4-nitroaniline, 4-nitrophenol, eosin yellow, and methylene blue). The catalytic results indicate that Al₂O₃-impregnated materials are very active catalysts for the degradation/reduction of organic dyes under those circumstances. Conversions of up to 98% for all substrates were obtained after 5 min at ambient temperature.     

铝硅酸盐活性中间体对有机染料脱色的实验研究

采用粉煤灰与NaOH煅烧、水解合成铝硅酸盐中间体对不同有机阳离子和阴离子染料通过改变实验条件进行脱色研究 .样品用FT -IR和XRD表征 ,实验采用Uv -vis光谱分析方法 .实验结果表明 ,通过改变脱色条件 ,中间体不仅对阳离子染料而且对阴离子染料也有十分显著的脱色效果     

Electroanalytical sensing of dyes and colorants

Color is an important element of the final product of many industries, including the textile, leather, food, cosmetic, pharmaceutical, plastic, and fuel-marking industries. Dyes are complex organic substances with chromophore and auxochromic groups, which can be electrochemically oxidized and/or reduced; this constitutes the basis of their electroanalytical determination. Despite some controversies, dyes pose risks to living organisms, especially after biotransformation, as the metabolites can be more toxic, mutagenic, or carcinogenic than the original dyes. The present work provides a brief overview of the recent progress in electrochemical sensors used for dye detection in diversified matrices. Sensors developed over the recent years are characterized by high sensitivity and selectivity, besides being economically advantageous once they allow the use of little or no clean-up samples in portable and miniaturized systems.     

Mechanisms and advancement of antifading agents for fluorescence microscopy and single-molecule spectroscopy

Modern fluorescence microscopy applications go along with increasing demands for the employed fluorescent dyes. In this work, we compared antifading formulae utilizing a recently developed reducing and oxidizing system (ROXS) with commercial antifading agents. To systematically test fluorophore performance in fluorescence imaging of biological samples, we carried out photobleaching experiments using fixed cells labeled with various commonly used organic dyes, such as Alexa 488, Alexa 594, Alexa 647, Cy3B, ATTO 550, and ATTO 647N. Quantitative evaluation of (i) photostability, (ii) brightness, and (iii) storage stability of fluorophores in samples mounted in different antifades (AFs) reveal optimal combinations of dyes and AFs. Based on these results we provide guidance on which AF should preferably be used with a specific dye. Finally, we studied the antifading mechanisms of the commercial AFs using single-molecule spectroscopy and reveal that these empirically selected AFs exhibit similar properties to ROXS AFs.     

Counterion-induced transformations of cationic surfactant micelles studied by using the displacing effect of solvatochromic pyridinium N-phenolate betaine dyes

In this paper, we demonstrate that the behavior of a set of eight large-sized negatively solvatochromic pyridinium N-phenolate betaine dyes reflects the principle transformations, occurring in aqueous micellar solutions of three cationic surfactants. As surfactants, cetyltrimethylammonium bromide (CTAB), n-octadecyltrimethylammonium chloride (OTAC), and N-cetylpyridinium bromide (CPB) were used. Normally, for such probes coupled with micelles, a red shift of the vis absorption band is expected as a result of a hydrophobization ("drying") of the micellar interface. However, under addition of electrolytes with anions such as tosylate, salicylate, and some n-alkanesulfonates or n-alkanecarboxylates to the micellar solutions, an unexpected effect was observed. Instead of a red shift, a blue shift of the vis absorption band of some of the dissolved betaine dyes was registered, as compared with the spectrum measured in pure aqueous micellar solutions of CTAB, OTAC, or CPB (Deltalambda(max) up to ca. 80 nm). This blue shift, indicating an increase in the polarity of the dye microenvironment, is explained by displacing the large dye dipoles from the thinned micelles toward the aqueous phase. The effect is well expressed at concentrations of C(betaine dye) approximately 10(-5) M, C(cationic surfactant) approximately 0.001 M, and C(organic anion) approximately 0.01 M. Transmission electron microscopy of dried samples confirms the distinct changes occurring in the studied micellar systems upon the addition of organic anions. The excess of inorganic salts [C(NaBr, KBr, or KCl) = 0.5-4.0 M] restored the position of the vis absorption band or even shifted it toward the red. Moreover, some of the betaine dyes studied (i.e., the more hydrophobic ones) stay in the micellar pseudophase or precipitate under the aforementioned concentration conditions. The peculiarities of the behavior of these betaine dyes are in agreement with their molecular structure.     

A comparison of H+-restacked nanosheets and nano-scrolls derived from K4Nb6O17for visible-light degra-dation of dyes

H＋-restacked nanosheets and nanoscrolls peeled from K4Nb6O17 display different structures and surface characters. The two restacked samples with increased surface areas have an amazing visible-light response for the photodegradation of dyes, which is superior to commercial TiO2 （P25） and Nb205. By comparison, H＋/nanosheets have a relatively faster photodegradation rate originated from large and smooth basal plane. The work reveals that dye adsorbed on the unfolded nanosheets can effectively harvest sunlight. Due to facile preparation, low-cost and high photocatalytic efficiency, H＋/nanosheets and H＋/nanoscrolls might be used for the visible light-driven degradation of organic dyes as a substitute for TiO2 in industry.     

Fabrication of flexible graphene oxide paper-like adsorbent doped with magnetite nanoparticles for removal of dyes

Organic dyes are used in many industries, e.g., textile, cosmetics and food. Hence, contamination of organic dyes to water sources is a critical issue. To reduce water pollution by organic dyes, we propose a paper-like adsorbent with a practical and economical production procedure. Subsequently, a flexible adsorbent was produced using a one-step approach by vacuum filtration of graphene oxide (GO) and iron oxide nanoparticles (Fe₃O₄-NPs) containing dispersion through a membrane and quoted as GO/Fe₃O₄ paper. For comparison, GO paper was also prepared using the same procedure. Both papers were characterized using UV–VIS absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, electron diffraction X-ray analysis, X-ray photoelectron spectroscopy, and powder X-ray diffraction techniques. At the steady-state conditions, GO/Fe₃O₄ and GO papers were performed as adsorbent for cationic dyes of methylene blue, neutral red, and anionic dyes of methyl orange and fluorescein. In general, the removal efficiency of GO/Fe₃O₄ paper was higher than that of GO paper for adsorption of all dyes and this adsorbent revealed satisfactory adsorption properties for cationic dyes when compared to anionic dyes.

     

Preparative chromatography in hollow cylinders made from stacked discs

Summary A tube-shaped layer made with perforated cylindrical discs of adsorbent material has been used in this work, in order to simplify the application of samples in a narrow band as well as their separation after development during preparative layer chromatography. The preparation of discs of several adsorbents, several development techniques and their application to the purification of organic dyes have also been studied.     

Matrix effect in second-order data: determination of dyes in a tanning process using vegetable tanning agents

The aim of this paper is to determine the concentration of three dyes throughout the tanning process of leather using vegetable tanning agents with a sequential injection analyser with second-order data treatment. As the vegetable tanning agents used are highly absorbent species, we focus on three aspects: (i) difficulties with the resolution (ii) the reduction in the working concentration range; and (iii) matrix effects. Ideally, second-order instruments provide “second-order advantage”; i.e. calibration is possible in the presence of uncalibrated interfering species. However, if the interfering species change the instrumental response of the analyte (in scale or shape), standard additions must be used to ensure the accuracy of the estimated analyte concentration. Here we study the presence of matrix effects for three dyes in several samples in order to significantly improve the accuracy of predictions in the presence of such effects. We found that there were matrix effects in at least 80% of the samples with an alpha risk of 5%. We used this method to study the exhaustion of dyes in the dyeing process.     

Excited-State Intramolecular Proton Transfer Dyes with Dual-State Emission Properties: Concept,Examples and Applications

Dual-state emissive (DSE) fluorophores are organic dyes displaying fluorescence emission both in dilute and concentrated solution and in the solid-state, as amorphous, single crystal, polycrystalline samples or thin films. This comes in contrast to the vast majority of organic fluorescent dyes which typically show intense fluorescence in solution but are quenched in concentrated media and in the solid-state owing to π-stacking interactions; a well-known phenomenon called aggregation-caused quenching (ACQ). On the contrary, molecular rotors with a significant number of free rotations have been engineered to show quenched emission in solution but strong fluorescence in the aggregated-state thanks to restriction of the intramolecular motions. This is the concept of aggregation-induced emission (AIE). DSE fluorophores have been far less explored despite the fact that they are at the crossroad of ACQ and AIE phenomena and allow targeting applications both in solution (bio-conjugation, sensing, imaging) and solid-state (organic electronics, data encryption, lasing, luminescent displays). Excited-State Intramolecular Proton Transfer (ESIPT) fluorescence is particularly suitable to engineer DSE dyes. Indeed, ESIPT fluorescence, which relies on a phototautomerism between normal and tautomeric species, is characterized by a strong emission in the solid-state along with a large Stokes’ shift, an enhanced photostability and a strong sensitivity to the close environment, a feature prone to be used in bio-sensing. A drawback that needs to be overcome is their weak emission intensity in solution, owing to detrimental molecular motions in the excited-state. Several strategies have been proposed in that regard. In the past few years, a growing number of examples of DSE-ESIPT dyes have indeed emerged in the literature, enriching the database of such attractive dyes. This review aims at a brief but concise overview on the exploitation of ESIPT luminescence for the optimization of DSE dyes properties. In that perspective, a synergistic approach between organic synthesis, fluorescence spectroscopy and ab initio calculations has proven to be an efficient tool for the construction and optimization of DSE-ESIPT fluorophores.     

Staining and quantification of proteins separated by polyacrylamide gel electrophoresis.

The present review concentrates on techniques for the staining and quantification of proteins separated by polyacrylamide gel electrophoresis. Staining with organic dyes has been used for approximately thirty years; the silver staining technique was introduced in 1979. The problems of silver staining are presented separately because the mechanism of this staining is in principle different from staining with organic dyes. Less attention has been devoted to quantification of two-dimensional gels, because this autoradiography is preferred because of its high sensitivity and fewer problems with accurate quantification in contrast to silver staining.     

Investigation of the colourants used in icons of the Cretan School of iconography

The red shades of 13 icons (15th-17th century) of the Cretan School of iconography are investigated in detail to identify the inorganic and organic colouring materials comprising the paint layers. Examination of sample cross-sections is performed with optical microscopy. Micro-Raman spectroscopy and high performance liquid chromatography (HPLC) coupled to a photodiode array detector are employed for the identification of the inorganic and organic colouring materials, respectively. The results reveal the extensive use of coccid dyes by the Cretan painters: kermes (Kermes vermilio Planchon) is found in icons dated before the middle 16th century and cochineal in icons created several decades after the discovery of the New World. Other dyestuffs detected in the historical samples are madder (possibly Rubia tinctorum L., according to HPLC profiles), soluble redwood and indigoid dyes. Organic dyes were used by the painters as exclusive colouring matters (or glazes) or in mixtures with inorganic pigments, such as red ochre, cinnabar, minium, azurite lead white and carbon black.Liquid chromatography with mass spectrometry (LC-MS) coupled to a negative electrospray ionization mode is employed to provide information on the identity of some unknown colouring components, of the aforementioned dyes, detected in the historical samples. The results suggest that (i) the type B compound (also known as Bra′) is a dehydro-brazilein product and (ii) the deprotonated molecular ion of the type C compound corresponds to m/z = 243. Both compounds are commonly used as markers for the identification of soluble redwood in historical samples. LC-MS analysis of cochineal shows that the dcIV and dcVII components are isomeric with carminic acid, as it has been recently suggested. Finally, LC-MS is employed to identify and record kermesic and flavokermesic acid in kermes and rubiadin in wild madder.     

Analyses of trace amounts of dyes with a new enhanced sensitivity FTIR spectroscopic technique: MU-ATR (metal underlayer ATR spectroscopy)

The identification of organic dyes is a challenging task in all the fields such as the forensic and conservation sciences, especially in cases where the amount of sample is extremely small. In this paper we propose a new enhanced FTIR method (MU-ATR metal underlayer ATR spectroscopy), which we believe is the first of its kind, for the analysis of a few ng of dyes. With this method, dyed fiber micro-extracts can be analyzed using a commercial FTIR microscope with a fixed incident angle, obtaining the same separation between the different classes of dyes investigated as we obtained analyzing pure dyes in transmission mode.     

有机染料敏化纳米晶太阳能电池

本文综述了有机染料敏化纳米晶太阳能电池的研究现状,简要介绍了有机染料敏化纳米晶太阳能电池的结构和工作原理以及氧化物电极、对电极和电解质的设计思路和制备情况。重点介绍了有机染料的研究现状,包括香豆素类染料、多烯类染料、噻吩类染料、天然染料、半花菁类染料、卟啉类染料、三苯胺类染料、苝类染料等。同时讨论了若干影响有机染料敏化太阳能电池性能的因素,提出了提高光电转换效率的设想与对策,对未来的发展进行了展望。     

Time-dependent density functional theory investigations on structural modification in carbazole-based organic photosensitizers to improve electron injection in dye-sensitized solar cell

The time-dependent density functional theory approach, implemented at hybrid-B3LYP, GGA-PBE, and density functional-based tight binding levels of theory, was used to model photoinjection in organic dye/TiO₂ quantum dot to explore the prospects of improvement of dye-sensitized solar cell (DSSC). The photosensitizer used in this study consisted of six carbazole-based organic dyes, a cyanoacrylic acid group as an acceptor and an oligothiophene π-bridge spacer. The modifications were made in the dyes by increasing the length of the spacer by adding thiophene and oxadiazole rings at different positions of the donor-acceptor bridge. The structural variations appeared to alter the electronic and optical properties of dyes studied via energy levels and excitation spectra. The UV-Vis spectra calculated for all the dyes in solvents exhibited a red shift in spectral peaks with an increase in the polarity of the solvents. The findings of the study pointed toward the indirect photoinjection of the dye-(TiO₂)₉₆ complex for six different dyes. The substitution of the oxadiazole ring at the center and addition of a thiophene ring at the edge of the spacer produced two dyes that exhibited the lowest injection energies of 0.11 and 0.17 eV, along with the regeneration energies of 1.18 and 1.12 eV, respectively. The dyes reported here may have promising applications in photoanode for enhancing the performance of DSSC.