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The present work deals with the preparation of WO 3 and WO 3 -ZnO nanocomposites in presence of ultrasonic irradiation, and its use in the sonocatalytic degradation of brilliant blue dye. WO 3 -ZnO nanocomposite is prepared using one step in-situ ultrasound assisted method. The successfully prepared WO 3 and WO 3 -ZnO nanocomposites were characterized using different characterization techniques such as XRD, Raman, BET, FE-SEM and EDS. The XRD pattern reveals that the formation of monoclinic and hexagonal crystal structures of WO 3 and ZnO respectively. BET study shows that WO 3 -ZnO nanocomposite have maximum surface area than that of the WO 3 . EDS study confirms the formation of WO 3 -ZnO nanocomposites. Further the use of the prepared WO 3 and WO 3 -ZnO nanocomposites as a sonocatalyst for the degradation of brilliant blue dye. The rate constant (k) was evaluated as a function of the initial concentration of brilliant blue dye. It is found that WO 3 -ZnO nanocomposites exhibits maximum sonocatalytic activity as compared to WO 3 photocatalyst. [ABSTRACT FROM AUTHOR]

The phenomenon of metachromasia, which is related to molecular aggregation, leads to significant changes in the photophysical properties of dyes. This review summarizes existing knowledge about molecular aggregation in hybrid systems containing inorganic nanoparticles and metachromatic dyes. The history of metachromasia, physical principles of molecular aggregation, and spectral properties of dye aggregates of various structures are briefly presented. The structure, surface properties, and several types of layered nanomaterials are also described. The main part of the review covers the fundamental properties of nanoparticles, metachromatic dyes, and their hybrid systems, that influence the aggregation of dye molecules. The focus is on the colloidal properties and the surface charge effect of nanoparticles. The importance of the surface charge of layered particles is demonstrated by detailed analysis of current research. The relevance of the phenomenon of molecular aggregation for research and application in the context of layered nanoparticles is then summarized. [ABSTRACT FROM AUTHOR]

Using a model developed by Professor Kucherenko M.G. a mathematical description of the effect of metal nanoparticles on the absorbing capacity of organic dye molecules in Graetzel cells was carried out. The enhanced absorption spectra of the dyenanoparticle system and the current-voltage characteristics of the investigated solar cells are calculated. [ABSTRACT FROM AUTHOR]

A “naked-eye” detection of health hazardous bisulfite (HSO 3 − ) and hypochlorite (ClO − ) using an indicator dye (Quinaldine Red, QR) in a wide range of pH is demonstrated. The molecule contains a quinoline moiety linked to an N , N -dimethylaniline moiety with a conjugated double bond. Treatment of QR with HSO 3 − and ClO − , in aqueous solution at near-neutral pH, resulted in a colorless product with high selectivity and sensitivity. The detection limit was 47.8 μM and 0.2 μM for HSO 3 − and ClO − respectively. However, ClO − was 50 times more sensitive and with 2 times faster response compared to HSO 3 − . The detail characterization and related analysis demonstrate the potential of QR for a rapid, robust and highly efficient colorimetric sensor for the practical applications to detect hypochlorite in water samples. [ABSTRACT FROM AUTHOR]

Historical objects in exhibitions can be subject to light induced damages resulting in a shift of color and brightness. Besides certain ambient influences the main factor governing these effects is the spectral irradiance applied to the surface. As the photochemical efficiency of electromagnetic radiation depends on its wavelength it is desirable to know the effect of individual spectral components in order to estimate the damage potential of a certain light source. In this work the modifications of the reflectance spectra of 40 dyes and pigments relevant in historical book illumination resulting from irradiation by eight narrow band LED light sources are presented. The LED wavelengths cover the visible part of the electromagnetic spectrum. Based on the measured reflectance spectra, color values are calculated and their evolution is studied as a function of the amount of radiation applied. [ABSTRACT FROM AUTHOR]

Fe3O4@carbon nanocomposite (Fe3O4@C) was continuously prepared by combining microreactor with pyrolysis reactor. The Fe3O4 nanoparticles homogeneously disperse in the carbon matrix with an average size of about 9.2 nm and narrow size distribution. The Fe3O4@C nanocomposite has a Brunauer–Emmett–Teller specific surface area of 71.9 m2/g and total pore volume of 0.37 cm3/g. This nanocomposite has a saturation magnetisation value of 16 emu/g and could be easily separated from water by an external magnet. With the increase of pH value or temperature, the Rhodamine B absorbing capacity of the Fe3O4@C nanocomposite first increases and then decreases after a certain value. The absorbing capacity at pH value 9 is about 169 mg/g when the temperature is 20°C. The above said value also exceeds 150 mg/g at pH value 3. The capacity is still higher than 120 mg/g after four regenerations. The absorbing capacity even reaches to 184 mg/g at 60°C of the absorbing temperature. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) detection and measurement in materials with near infrared spectroscopy (NIRS) have been an unresolved constraint till date. This paper focused on the use of NIRS for rapid detection and quantification of pure VOCs (ethanol, ethyl acetate and acetic acid) in mixed VOCs via employing sensitive intermediary chemo-responsive dyes as capture probes, whose NIRS spectra were scanned, preprocessed and used to build partial least squares (PLS) prediction models. Average predicted rates based on the PLS-built prediction models for the pure VOCs in the mixed VOCs yielded 98.60 ± 17.41%. 78.26% of the pure VOCs prediction rates ranged between 85 and 114% and normally distributed. The high prediction rates achieved imply the technique may be deployed as a panacea to widen the usage scope of NIRS and e-nose based colorimetric sensors for rapid detection and quantification of VOCs content in materials which hitherto had been a constraint for both systems. [ABSTRACT FROM AUTHOR]

In this article, an extensive work is presented concerning the characterization with both chromatographic (high-performance liquid chromatography) and spectroscopic (surface-enhanced Raman spectroscopy and visible reflectance spectroscopy) techniques of historical Chinese dyestuffs in several carpets, mostly coming from the Ningxia region in Northern China and dating to the seventeenth-nineteenth centuries. Notably, the color of the background of these fine artifacts has been an object of debate since, while being depicted as bright red in the ancient iconography, nowadays it appears as orange/yellow. Therefore, in addition to the identification of all the colorants used in the carpets, the present study investigated the reasons of this apparent inconsistency, pointing out an explanation based on the joined use of the yellow dye obtained from the pagoda tree and a 'fugitive' dye obtained from brazilwood. [ABSTRACT FROM AUTHOR]

Spectral properties of dyes change upon attachment to surfaces which need to be understood. While the effects of surface properties affecting the changes such as Brønsted acidity is well-covered, that of surface energy components is not well studied. In this work, two dyes with different number of carboxylic groups were attached on three surfaces (PET, PDMS, and silicon). It was observed the "surface energy components" rather than "total surface free energy" were more pertinent in explaining changes in the spectral properties of the immobilized dyes. An increase in the basic component of surface energy favored monomer formation, while a decrease favored agglomeration. Thus, tuning the spectra of a dye by using surfaces with different surface energy components enables use of the dye for different applications. As an application, dye attached on PET substrate showed promise as optical pH sensor in the range of pH 7-10. [ABSTRACT FROM AUTHOR]

A novel hybrid bisphotochromic system involving a chromene residue and a styryl dye fragment is described. Initially, the compound shows almost no photochromism due to intramolecular energy and electron transfer between the chromophores. Protonation of the hybrid system blocks the transfer processes and unlocks a dual photochromic activity that includes ring opening of the chromene fragment and E-Z-isomerization of the styryl dye residue. Deprotonation of any photoinduced form resets the system to the initial photoinactive form. [ABSTRACT FROM AUTHOR]

The decolorization and detoxification of Acid Orange 7 (AO7), a commonly used azo dye, by zero-valent iron (Fe0) and UV light was investigated. The influence of important reaction parameters, such as initial pH and the Fe0 dosage, on the color removal and effluent toxicity, was elucidated. Results indicated that the decolorization of AO7 was enhanced in the UV/Fe0 system, as compared to that with only UV or Fe0, in which the decolorization efficiency in 60 min increased with increasing Fe0 dosage and decreasing solution pH. The kinetics of the AO7 removal conformed to the Langmuir-Hinshelwood model with high correlation coefficient (R² = 0.9962). Under the optimum conditions, AO7 was decolorized rapidly within 60 min (over 97% decolorization efficiency), with 34.8% of TOC reduction. Fe0 could be used for repeated cycles to decolorize AO7 effectively. Furthermore, nearly no Daphnia magna immobilization was found after the treatment, suggesting that the method was effective to reduce the AO7 toxicity. [ABSTRACT FROM AUTHOR]

Upconversion nanocrystals (UCNCs) hold promise for bioimaging, solar cells, photocatalysis and volumetric displays. However, their upconversion luminescence intensities are usually low due to the weak and narrowband near-infrared absorption of lanthanide ions. Herein, we introduce and validate a strategy to hugely enhance upconversion luminescence intensity by using an organic near-infrared dye as an antenna to sensitize core/shell UCNCs. The dye can increase absorptivity and broaden the absorption spectrum of the UCNCs. Such dye sensitization, in combination with a core/shell structure, can tremendously enhance the upconversion luminescence (UCL) intensity of the UCNCs. The UCL intensity of dye-sensitized UCNCs excited at 820 nm is 800-folds higher than that of pure UCNCs excited at 980 nm. Further enhancement can be obtained by optimization of the dye emission and UCNC absorption spectral overlap. Moreover, the proposed approach can be extended to cover any part of the solar spectrum by using a set of dyes. This work provides new insights into the efficient enhancement of upconversion luminescence of the UCNCs and facilitates their applications. [ABSTRACT FROM AUTHOR]

The present work describes the photophysical properties of two newly synthesized compounds, namely ( E )-10-butyl-3-(2-(thiazolo[4,5- b ]quinoxalin-2-yl)vinyl)-10H-phenothiazine (PTQ) and ( E )-10-butyl-3-(2-(1,1-dimethyl-1H-benzo[ e ]indol-2-yl)vinyl)-10H-phenothiazine (PBI). A strong intramolecular charge transfer (ICT) is observed in both dyes as indicated from absorption and emission studies on varying the solvent polarity. This can be concluded from the large Stokes shifts among these dyes as PTQ exhibits large Stokes shift with > 270 nm and PBI around 200 nm. The effect of increasing polarity caused drastic increase in the charge transfer process leading to twisted intramolecular charge transfer (TICT) process in both the dyes PTQ and PBI. Time-resolved emission studies and non-radiative decay rate constant indicates that the excited states of both dyes behave differently with respect to solvent polarity. The non-radiative decay constant increases dramatically with the solvent polarity specifying change of ICT emissive states in non-polar solvent while TICT emitting states in highly polar solvent. On the other hand, PBI follows a general trend initially exhibiting higher non-radiative decay constant in non-polar solvent like cyclohexane, lowest in moderate polarity owing to the ICT emissive state but with increase in the polarity, the non-radiative decay constant again increases indicating TICT states. [ABSTRACT FROM AUTHOR]

Third - order nonlinear optical (NLO) properties of aqueous solutions of an anthraquinone dye (Acid green 25 dye, color index: 61570) have been studied by Z ─ scan method with a 5 mW continuous wave (CW) diode laser operating at 635 nm. The nonlinear refractive index (n 2 ) and the absorption coefficient (β) have been evaluated respectively from the closed and open aperture Z─scan data and the values of these parameters are found to increase with increase in concentration of the dye solution. The negative sign of the observed nonlinear refractive index (n 2) indicates that the aqueous solution of acid green 25 dye exhibits self-defocusing type optical nonlinearity. The mechanism of the observed nonlinear absorption (NLA) and nonlinear refraction (NLR) is attributed respectively to reverse saturable absorption (RSA) and thermal nonlinear effects. The magnitudes of n 2 and β are found to be of the order of 10 −7 cm 2 /W and 10 − 3 cm/W respectively. With these experimental results, the authors suggest that acid green 25 dye may have potential applications in nonlinear optics. [ABSTRACT FROM AUTHOR]

We describe herein the first synthesis of silyl- and disilanyl-BODIPYs through transition-metal-catalyzed dehalosilylation of iodo-BODIPYs using a Pd(P( tBu)3)2/Et3N/toluene system. Various mono- and bis-silyl-BODIPYs, mono- and bis-disilanyl-BODIPYs and bis-BODIPYs linked by silylene and SiOSi groups were synthesized by using this straightforward method. Silyl- and disilanyl-substitution significantly modifies the spectroscopic properties of the BODIPY, in which the fluorescence quantum yields of the silyl-BODIPYs are remarkably increased, whereas the emission spectra of disilanyl-BODIPYs are red-shifted due to effective σ(SiSi)-π(BODIPY) conjugation. [ABSTRACT FROM AUTHOR]

The spectroscopic characteristics of a series of ten aminosquaraine dyes that differ in the type of chemical substituent at the p -position of the phenyl ring were investigated. The effect of solvent on the properties of the dyes in their ground and excited state is described. The absorption and emission properties, fluorescence lifetime and rate constants for radiative and non-radiative deactivation processes are also presented. The dyes displayed very short fluorescence lifetimes (about 3 ns) and dependence of the radiative deactivation process on the solvent viscosity. [ABSTRACT FROM AUTHOR]

Magnetic Prussian blue (PB) nanocomposites were synthesized by binding PB to a core of magnetite (Fe3O4) nanoparticles for highly efficient and rapid separation of cesium (Cs+) from aqueous solution. The average particle size of the magnetic PB nanocomposites was 13.6 nm, and they had a high surface area (322.19 m²/g), leading to efficient Cs+ adsorption capability. The nanocomposites showed a maximum sorption capacity of 280.82 mg/g at an initial Cs+ concentration of 50 mM, pH 7, and 10 °C, which is much higher than those of previously reported PB-based adsorbents for removing Cs+. The adsorption behavior followed pseudo-second-order kinetics and obeyed the Tempkin isotherm. The adsorption capacity of Cs+ on magnetic PB nanocomposites remained consistent even at high ionic competition in the simulated seawater. The obtained magnetic PB nanocomposite is a cost-effective adsorbent and can be easily retrieved from an aqueous solution by a magnet after decontamination of cesium. These results showed that the magnetic PB nanocomposite has extensive applicability for the removal of cesium from aqueous solution. [ABSTRACT FROM AUTHOR]

A small fluorescence ratiometric probe consisting of a single dye species, N-methyl-6-hydroxyquinolinium (MHQ), and coupled enzymatic substrates, exhibits a dramatic colour change (deep blue to red) and possesses a huge response ratio (over 2000 fold) upon specific recognition of target enzymes. Such dramatic responses are attributed to the excited-state proton transfer processes of MHQ molecules in water. Here the detection of β-galactosidase and porcine pancreatic lipase is successfully demonstrated and this class of molecules has the potential to be developed as a “naked-eye” probe in vitro. [ABSTRACT FROM AUTHOR]

We have synthesized a new family of directly-fused bisBODIPY BBP 1 through a key FeCl3-mediated intramolecular oxidative cyclodehydrogenation reaction and its derivatives 2 and 3 from the Knoevenagel reaction. These dyes display effective expansion of π-conjugation over the two BODIPYs due to their locked coplanar conformation, showing intriguing electrochemical and spectroscopic properties, such as intensive absorption/emission bands ranging from 676 to 877 nm and high photostability. [ABSTRACT FROM AUTHOR]

Inverse analysis of transmission spectra for triarylamine dye in acetone is presented. This analysis employed a parametric model of transmission through a sample of finite thickness, where the permittivity function was represented parametrically by a linear combination of Lorentzian functions. The results of this analysis provided estimates of the permittivity function for triarylamine dye, which can be adopted as input data to other types of models, such as those for prediction of transmission and reflectivity spectra for composites containing mixtures of dyes and other materials. In addition, this analysis demonstrated that the absorption coefficients for a dye, which were obtained by inverse analysis of transmission spectra for that dye in solution, can be validated as reasonable estimates of the absorption coefficients for that dye in fabric. [ABSTRACT FROM AUTHOR]

Broadening the absorption spectra of dyes is an effective way to increase the energy conversion efficiency in dye-sensitized solar cells. Here POSS-based hybrids with broad-band absorbing properties were successfully prepared by using octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) and three organic molecules with their absorption band in the range of UV, Vis and NIR via Heck reaction. The structure and property of the hybrids were well characterized by FTIR, 1 H NMR, UV-Vis-NIR and fluorescence spectra. It was found that the hybrids not only combined the absorbing bands of different dyes, but also prevented the aggregation of dye chromophores, resulting in an improvement in optical stability. [ABSTRACT FROM AUTHOR]

Indigoid dyes are well known as vat dyes. In their oxidized dichetonic form they are stable and insoluble in water, whereas in their reduced form, commonly known as leuco, they are soluble in water and able to be attached to fabric for dyeing purposes. These blue dyes are usually easily detectable in art objects by means of Raman spectroscopy by adopting for analyses a laser line at a high wavelength, such as a 785 nm diode laser. Unfortunately, in ancient artworks, that are often highly degraded, it is not always possible to collect high quality Raman spectra, which makes the analysis and identification of these compounds particularly challenging. In this work, we present a tailor-made methodology for the extraction and the recognition of indigoid dyes in works of art, which exploits the solubility of these compounds in their reduced form. Excellent Raman and surface enhanced Raman spectroscopy (SERS) spectra of indigo were acquired after micro-extraction on ancient and reference textiles, confirming the reliability of the presented procedure. Moreover, the methodology has been applied also for the extraction of the indigoid dye Tyrian purple on a reference textile, showing excellent results. This analytical method has been found to be extremely safe both for the reference textiles and the investigated ancient textiles, thus being a promising procedure for the selective analysis and detection of indigoid compounds in objects of artistic relevance. [ABSTRACT FROM AUTHOR]

The results of adsorption and spectral studies on the interaction of organic anions and cations with Organo-substituted layered silicates are generalized; schemes of adsorption mechanisms are proposed. It is proved that the adsorption of organic anions is carried out due to formation of ionic associates with modifiers. Thus, the unknown fact is found - in case of the silicates substituted with long chain cationic surfactants, a desorption of the modifier and its secondary adsorption as a part of ionic associates to organic anions takes place. It has been found that large organic cations are physically adsorbed on the surface of cationic surfactant-substituted silicates and on the polycation-substituted ones - by ion exchange mechanism. [ABSTRACT FROM AUTHOR]

A simple and facile approach was developed for monitoring EcoRI endonuclease activity and inhibition, in which a hairpin-like DNA containing restriction cutting site for EcoRI endonuclease acts as the sensing element and Hoechst dyes as the signal indicator in a label-free format. [ABSTRACT FROM AUTHOR]

Low molecular weight chitosan, prepared as chitosan beads was used for the adsoption of Tartrazine (TAR), Congo Red (CR) and Methyl Orange (MO). The efficiency of dyes removal from aqueous solution was investigated, therefore samples containing various concentrations of TAR, CR, and MO were mixed with chitosan beads and the adsorption was estimated using a validated chromatographic method. The results provided by the UPLC method were fitted to Freundlich, Temkin and Dubinin-Radushkevich adsorption models. [ABSTRACT FROM AUTHOR]

A series of data from voltammetric, spectral, and UPLC-MS and Py-GC-MS analyses of extracts from synthetic Maya Blue-type specimens provides evidence on the presence of a significant amount of dehydroindigo, identified on the basis of its MS, FTIR, and UV-Vis signatures, accompanying indigo and other minority compounds, supporting the view of this material as a complex polyfunctional organic-inorganic hybrid material. Estimates of dehydroindigo/indigo in-depth distribution and thermochemical data for the dye association to the clay from chromatographic and voltammetric data are provided. [ABSTRACT FROM AUTHOR]

Elucidating how molecules bind to HSA is fundamental for predicting drug incompatibilities. Through combinatorial screening, we identified a novel fluorescent dye (BD140) with turn-on fluorescence emission and specific binding at HSA drug site 2. We further combined it with dansylamide to develop a fluorescent dye cocktail for high-throughput mapping of the interaction between therapeutics at HSA drug-binding sites. [ABSTRACT FROM AUTHOR]

Properties of both amorphous and polycrystal films of azodye AD-1 have been investigated. The films' structure depends on conditions of thermal treatment, light polarization and intensity. High dichroic ratio (>20) has been obtained. Film structure control allows fabrication of good photoaligning coatings. [ABSTRACT FROM AUTHOR]

A novel column reactor was constructed and successfully applied to dye-sensitized photooxygenation reactions in aqueous alcohol solutions. The air flow pattern within the narrow glass column could be controlled via the size of the air inlet capillary. Using a 500 μm capillary, a slug flow pattern was realized which allowed for superior mass transfer and light transparency within a thin solvent layer. These features subsequently gave higher conversion rates and isolated yields. [ABSTRACT FROM AUTHOR]

Lignin is a source for obtaining natural phenols with high commercial value that can act as redox mediators enhancing effects in dye decolorization. In this study Trametes hirsuta Bm-2 was grown on wheat bran to produce laccases and phenol extracts (PE). Ultrafiltered phenols obtained at different times were evaluated in their potential as redox mediators of laccase activity and indigo carmin decolorization. Laccase activity (L) on ABTS increased up to 12.4 times with L/PE72 compared with laccase alone and L/PE48 showed the highest level of dye decolorization (97%) compared with laccase (12%). The chromatographic analysis by HPLC showed variation in the profile and concentration of phenols at different times of culture. Stability of the laccase mediator system (LMs) in dye decolorization was maintained over 3 months. Our results suggest the use of natural mediators as a strategy for improving efficiency in dye biodegradation by laccase-producing fungi. [ABSTRACT FROM AUTHOR]

Review: 48 refs. [ABSTRACT FROM AUTHOR]