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Dye Molecules (dye + molecule)
Selected AbstractsControlling Light Emission in Luminescent Solar Concentrators Through Use of Dye Molecules Aligned in a Planar Manner by Liquid CrystalsADVANCED FUNCTIONAL MATERIALS, Issue 17 2009Paul P. C. Verbunt Abstract A luminescent solar concentrator (LSC) is a potential low-cost enhancement of the standard large-area silicon photovoltaic panels for the generation of electricity from sunlight. In this work, guest,host systems are investigated using anisotropic fluorescent dyes and liquid crystal mesogens to control the direction of emitted light in the LSC. It is determined that up to 30% more light is emitted from the edge of an LSC waveguide with planar dye alignment parallel to the alignment direction than from any edge of an LSC with no alignment (isotropic). The aligned samples continue to show dichroic performance after additions of both edge mirrors and rear scattering layer. [source] In Situ Coacervated Microcapsules with Filled Polyelectrolytes and Charge-Controlled Permeation for Dye MoleculesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2008Feng Wang Abstract Microcapsules with charge-controlled permeation for electrolytes were fabricated by an in situ coacervation method in the presence of polyelectrolyte during core removal. A layer of PAH was adsorbed onto PSS-doped CaCO3 microparticles, followed by crosslinking of the PAH layer with GA and core removal in a solution of EDTA with or without PAH. In the presence of PAH, microcapsules with a larger size, weight and PSS content than with PAH were obtained. Microcapsules produces without PAH showed a unique feature of charge-controlled permeation for electrolytes: negatively charged probes were completely rejected, but positively charged ones were attracted. [source] Electron Transport in the Long-Range Charge-Recombination Dynamics of Single Encapsulated Dye Molecules on TiO2 Nanoparticle Films,ANGEWANDTE CHEMIE, Issue 40 2009Xiangyang Wu Auf langsamer Fahrt: Langlebige dunkle ladungsgetrennte Zustände resultieren aus dem Transport des injizierten Elektrons auf TiO2 -Nanopartikeln nach seiner Übertragung aus einem einzelnen Atto647N-Farbstoffmolekül, das in Cucurbit[7]uril (CB7) eingeschlossen ist. Diese Zustände lassen sich direkt mithilfe der Periodizität der Trajektorien der Emissionsintensität untersuchen (siehe Spektren). [source] Analysis of proteins stained by Alexa dyesELECTROPHORESIS, Issue 6 2004Shijun Huang Abstract Alexa dye staining of proteins is used for the fluorescence microscopy of single particles that are sometimes multimolecular protein complexes. To characterize the staining, post-staining determination must be made of which protein(s) in a complex have been Alexa-stained. The present communication describes the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for performing this determination. The Alexa-stained proteins are observed directly in gels by illumination with an ultraviolet transilluminator. The test multimolecular particle is bacteriophage T7. The protein capsid of T7 is a multimolecular complex that has both external and internal proteins. SDS-PAGE of Alexa-stained bacteriophage T7 produces fluorescent capsid proteins each of which usually comigrates with an unstained protein. However, one Alexa-induced modification of protein migration was observed by SDS-PAGE. Mass spectrometry shows that the protein with modified migration is the major protein of the outer shell of the T7 capsid. The procedures used are generally applicable. The distribution of Alexa staining among T7 capsid proteins depends on the size of the dye molecule used. The larger the dye molecule is, the greater the preference for external proteins. [source] Two-Step Energy Transfer: Energy Transfer in Fluorescent Nanofibers Embedding Dye-Loaded Zeolite L Crystals (Adv. Mater.ADVANCED MATERIALS, Issue 10-11 200911/2009) The inside cover displays a confocal image of electroluminescent polymeric nanofibers embedding dye-loaded zeolite L crystals obtained by electrospinning. Varun Vohra and co-workers show on p. 1146 that such nanofibers exhibit a two-step energy transfer (FRET) from the polymer to the dye molecule inside the zeolites. The stopcock molecule present at the channel entrances is the key to this two-step energy transfer. [source] Possibilities of polymer-aided dyeing of cotton fabric with reactive dyes at neutral pHJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010B. J. Agarwal Abstract Water-soluble polymers have versatile application, viz., water-soluble polyacrylates have been widely used in the reactive dyeing of cellulosic fibers and the related soaping as an important component of the leveling and washing agent. In this article, one such water-soluble polymer, polyacrylic acid has been synthesized, characterized, and applied in conjunction with various types of reactive dyes, namely triazinyl, vinyl sulfone, high exhaustion, and bifunctional reactive dyes, along with crosslinking agents, namely glycerol 1,3-dichlorohydrin and hexamethylene tetramine-hydroquinone, respectively. One of the crosslinking agents (the former one) has been synthesized in the laboratory. Crosslinking agent is necessary to adhere the dye molecule onto the cellulose macromolecule. Different process sequences have been formulated and explored for dyeing purpose. All such dyeings were carried out at neutral pH. The dyed samples were assessed through color strength in terms of K/S values and their fastness properties were assessed by standard methods. All such dyeings were compared with conventional dyed samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Evaluation of the reduction of imidazophenazine dye derivatives under fast-atom-bombardment mass-spectrometric conditions,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2006Marina V. Kosevich Abstract Satellite [M + 2]+, and [M + 3]+ peaks accompanying the common peak of the protonated molecule [M + H]+ that are known to indicate the occurrence of a reduction process were observed in the fast atom bombardment (FAB) mass spectra of imidazophenazine dye derivatives in glycerol matrix. The distribution of the abundances in the [M + nH]+ peak group varied noticeably for different derivatives. This indicated different levels of the reduction depending on the different structure variations of the studied molecules. In the search for correlations between the mass spectral pattern and the structural features of the dyes, ab initio HF/6-31++G** quantum chemical calculations were performed. They revealed that the abundances of the [M + 2]+, and [M + 3]+ ions show growth proportional to the decrease of the energy of the lowest unoccupied molecular orbital, i.e. proportional to the increase of the electron affinity of the dye molecule. A method for rapid screening of reductive properties of sets of dye derivatives on the basis of the FAB mass spectral data is discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Supramolecular order following binding of the dichroic birefringent sulfonic dye Ponceau SS to collagen fibersBIOPOLYMERS, Issue 3 2005B. C. Vidal Abstract The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggregates of the sulfonic azo-dye Ponceau SS and of dye complexed with chicken tendon collagen fibers were investigated in order to assess their polarizing properties and similarity to liquid crystals. In some experiments, the staining was preceded by treatment with picric acid. Crystalline fibrous aggregates of the dye had a negative LD, and their electronic transitions were oriented perpendicular to the filamentary structures. The binding of Ponceau SS molecules to the collagen fibers altered the LD signal, with variations in the fiber orientation affecting the resulting dichroic ratios. The long axis of the rod-like dye molecule was assumed to be bound in register, parallel to the collagen fiber. Picric acid did not affect the oriented binding of the azo dye to collagen fibers. There were differences in the optical anisotropy of Ponceau SS-stained tendons from 21-day-old and 41-day-old chickens, indicating that Ponceau SS was able to distinguish between different ordered states of macromolecular aggregation in chicken tendon collagen fibers. In the presence of dichroic rod-like azo-dye molecules such as Ponceau SS, collagen also formed structures with a much higher degree of orientation. The presence of LD in the Ponceau SS-collagen complex even in unpolarized light indicated that this complex can act as a polarizer. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 121,128, 2005 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Interaction of cyanine dyes with nucleic acids.BIOPOLYMERS, Issue 4 2001Abstract The spectral luminescent properties of two groups of monomethine cyanine dyes were studied in the presence of DNA. The first group included five dyes with 5,6-methylenedioxy-[d]-benzo-1,3-thiazole heterocycle and their unsubstituted analogs. Five monomethine pyrylium cyanines and their N -methyl-pyridine analogs were included in the second group. In each pair the pyrylium and pyridine dyes had similar geometry but differed in charge density distribution. The results presented some evidence in favor of the half-intercalation interaction mode between the studied dyes and DNA. When the benzothiazole residue had the lowest electron donor ability between the two heterocycles in the dye molecule, its substitution with the bulky methylenedioxy group led to a significant decrease in fluorescence enhancement of the dye,DNA complex. On the contrary, when the substituents that create steric hindrance (e.g., methylenedioxy and methyl groups) were introduced into the heterocycle with the higher electron donor ability, the fluorescence enhancement value of the dye,DNA complex was virtually unchanged. The changes in the Stock's shift values upon the formation of the dye,DNA complexes were in agreement with the proposed half-intercalation model. Interestingly, in the dye,DNA complexes the pyrylium dyes probably resided in a place similar to the pyridine ones. It is possible that the benzothiazole (or benzooxazole) ring intercalated between the DNA bases and the pyrylium (or pyridine) residue was located in the DNA groove closer to the phosphate backbone. © 2001 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 219,227, 2001 [source] Electronic and Vibrational Properties of Fluorenone in the Channels of Zeolite LCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2004André Devaux Dr. Abstract Fluorenone (C13H8O) was inserted into the channels of zeolite L by using gas-phase adsorption. The size, structure, and stability of fluorenone are well suited for studying host,guest interactions. The Fourier transform IR, Raman, luminescence, and excitation spectra, in addition to thermal analysis data, of fluorenone in solution and fluorenone/zeolite L are reported. Normal coordinate analysis of fluorenone was performed, based on which IR and Raman bands were assigned, and an experimental force field was determined. The vibrational spectra can be used for nondestructive quantitative analysis by comparing a characteristic dye band with a zeolite band that has been chosen as the internal standard. Molecular orbital calculations were performed to gain a better understanding of the electronic structure of the system and to support the interpretation of the electronic absorption and luminescence spectra. Fluorenone shows unusual luminescence behavior in that it emits from two states. The relative intensity of these two bands depends strongly on the environment and changes unexpectedly in response to temperature. In fluorenone/zeolite L, the intensity of the 300 nm band (lifetime 9 ,s) increases with decreasing temperature, while the opposite is true for the 400 nm band (lifetime 115 ,s). A model of the host,guest interaction is derived from the experimental results and calculations: the dye molecule sits close to the channel walls with the carbonyl group pointing to an Al3+ site of the zeolite framework. A secondary interaction was observed between the fluorenone's aromatic ring and the zeolite's charge-compensating cations. [source] Silver Coated Platinum Core,Shell Nanostructures on Etched Si Nanowires: Atomic Layer Deposition (ALD) Processing and Application in SERSCHEMPHYSCHEM, Issue 9 2010Vladimir A. Sivakov Dr. Abstract A new method to prepare plasmonically active noble metal nanostructures on large surface area silicon nanowires (SiNWs) mediated by atomic layer deposition (ALD) technology has successfully been demonstrated for applications of surface-enhanced Raman spectroscopy (SERS)-based sensing. As host material for the plasmonically active nanostructures we use dense single-crystalline SiNWs with diameters of less than 100 nm as obtained by a wet chemical etching method based on silver nitrate and hydrofluoric acid solutions. The SERS active metal nanoparticles/islands are made from silver (Ag) shells as deposited by autometallography on the core nanoislands made from platinum (Pt) that can easily be deposited by ALD in the form of nanoislands covering the SiNW surfaces in a controlled way. The density of the plasmonically inactive Pt islands as well as the thickness of noble metal Ag shell are two key factors determining the magnitude of the SERS signal enhancement and sensitivity of detection. The optimized Ag coated Pt islands on SiNWs exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability and reproducibility. The plasmonic activity of the core-shell Pt//Ag system that will be experimentally realized in this paper as an example was demonstrated in numerical finite element simulations as well as experimentally in Raman measurements of SERS activity of a highly diluted model dye molecule. The morphology and structure of the core-shell Pt//Ag nanoparticles on SiNW surfaces were investigated by scanning- and transmission electron microscopy. Optimized core,shell nanoparticle geometries for maximum Raman signal enhancement is discussed essentially based on the finite element modeling. [source] Selectively Deposited Silver Coatings on Gold-Capped Silicon Nanowires for Surface-Enhanced Raman SpectroscopyCHEMPHYSCHEM, Issue 8 2009M. Becker Dr. Abstract Gold caps on silicon nanowires are selectively coated with silver by autometallography (electroless deposition). Changing the conditions of silver deposition, a variety of different coating morphologies can be produced (see figure). The different silver coating morphologies are investigated in terms of their capabilities for surface enhanced Raman scattering (SERS) experiments. Gold caps on silicon nanowires are hemispherical and only a few tens of nanometers in diameter when grown from metal catalysts by the vapor-liquid-solid growth mechanism using chemical vapor deposition. These gold caps are capable of enhancing Raman signals based on the surface-enhanced Raman scattering effect. The Raman signal can be enhanced even further (by at least one order of magnitude) when silver is selectively deposited onto these gold caps by autometallography (electroless deposition). By changing the silver deposition conditions, different coating morphologies can be realized on the gold caps that range from very thin, smooth layers to uneven and extremely rough coatings. The SERS signal enhancement and the spatial homogeneity of the achievable enhancement are compared for the different silver coatings using a model dye molecule. [source] Donor,Acceptor Systems: Energy Transfer from CdS Quantum Dots/Rods to Nile Red DyeCHEMPHYSCHEM, Issue 14 2008Suparna Sadhu Abstract We demonstrate strong evidence of shape-dependent efficient resonance energy transfer between CdS quantum dots (QDs) and quantum rods (QRs) (donor) to Nile Red dye (acceptor). We also report a simple solution-based method for the preparation of high quality CdS QDs and CdS QRs at relatively low temperature. The observed quenching of PL intensities are 78.8,% and 63.8,% for CdS QDs and QRs, respectively in the presence of Nile Red dye. The calculated energy-transfer efficiencies are 45,% and 19,% from QDs and QRs to dyes, respectively. The energy transfer varies with changing the shape of the nanoparticles. The estimated Förster distances (R0) are 37.8 and 33.8 Å for CdS QDs and QRs, respectively. In the present study, the estimated distances (r) between one donor and one acceptor are 39.1 and 43.1 Å for QDs and QRs, respectively, using the efficiency of Förster resonance energy transfer (FRET) which depends on the inverse sixth power of the distance of separations between one nanocrystal and one dye molecule. Considering single donor and multiple acceptors interactions, the calculated average distances (rn) between the donor and acceptor are 47.7 and 53.9 Å for QD's and QR's, respectively. The steady-state and time-resolved spectroscopic analysis of nanoassemblies confirm the formation of one donor and multiple acceptors. [source] Molecular modelling of inclusion compounds from hydrophobic dyes and ,-cyclodextrinCOLORATION TECHNOLOGY, Issue 4 2009Ahmed El-Shafei This paper arises from studies aimed at developing new approaches to combining the fabric formation and coloration steps of fabric processing. A key aspect of these studies involved the evaluation of cyclodextrin (CD)-based compounds as hosts for dye molecules that could be released onto a fabric surface following fabric formation. In this study, experimental data from wide-angle X-ray diffraction and differential scanning calorimetry experiments were used in tandem with molecular modelling studies to confirm the formation of ,-CD,dye complex inclusion compounds and to demonstrate the utility of parameterised model number 3 (PM3) semi-empirical molecular modelling methods for predicting the nature of the preferred ,-CD,dye inclusion compounds. Calculations revealed that the inclusion compounds containing two dye molecules was preferred over the inclusion compound containing one dye molecule. Further, molecular modelling of the inclusion compound obtained using ,-CD linked to an epichlorohydrin-based oligomer and commercial disperse dyes showed inclusion compound formation to be an energetically favourable process. [source] Electrocatalysis and Amperometric Detection of the Reduced Form of Nicotinamide Adenine Dinucleotide at Toluidine Blue/Zinc Oxide Coated ElectrodesELECTROANALYSIS, Issue 18 2007Ashok Kumar Abstract Thin toluidine blue (TBO) and zinc oxide (ZnO) hybrid films have been grown on glassy carbon electrode (GCE) and indium tin oxide coated (SnO2) glass electrodes by using cyclic voltammetry (CV). Scanning electron microscopy (SEM) images revealed spherical and beads-like shape of highly oriented TBO/ZnO hybrid films. Energy dispersive spectrometry (EDS) results declared that the films composed mainly of Zn and O. Moreover, TBO/ZnO hybrid films modified electrode is electrochemically active, dye molecules were not easily leached out from the ZnO matrix and the hybrid films can be considered for potential applications as sensor for amperometric determination of reduced nicotinamide adenine dinucleotide (NADH) at 0.0,V. A linear correlation between electrocatalytic current and NADH concentration was found to be in the range between 25,,M and 100,,M in phosphate buffer. In addition, we observed that dopamine, ascorbic acid and uric acid are not interference in amperometric detection of NADH in this proposed method. In addition, TBO/ZnO hybrid film modified electrode was highly stable and its response to the NADH also remained relentless. [source] Background-free, fast protein staining in sodium dodecyl sulfate polyacrylamide gel using counterion dyes, zincon and ethyl violetELECTROPHORESIS, Issue 24 2002Jung-Kap Choi Abstract A background-free, fast protein staining method in polyacrylamide gel electrophoresis using an acidic dye, zincon (ZC) and a basic dye, ethyl violet (EV) is described. It is based on the counterion dye staining technique that employs two oppositely charged dyes to form an ion-pair complex in staining solution. The selective binding of free dye molecules to proteins in acidic solution produces bluish violet-colored bands. It is a rapid and end-point staining procedure, involving only fixing and staining steps that are completed in 1,1.5 h. The detection limit of this method is 8,15 ng of protein that is comparable to the sensitivity of the colloidal Coomassie Brilliant Blue G (CBBG) stain. Due to its sensitivity and speed, this stain may be more practical than any other dye-based stains for routine laboratory purposes. [source] Design, Synthesis, and Spectral Luminescent Properties of a Novel Polycarbocyanine Series Based on the 2,2-Difluoro-1,3,2-dioxaborine NucleusEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2008Konstantin Zyabrev Abstract The natures of the chromophores in symmetric polymethine dyes derived from 2,2-difluoro-1,3,2-dioxaborine have been investigated. Ab initio quantum chemical calculations demonstrated that the presence of dioxaborine end residues stabilizes the frontier levels of the corresponding polymethine dye and makes electron-density distribution over the oxygen atoms in the chelate ring more even than in the analogous dye structure with boron-free acyclic end groups. A series of novel symmetric polycarbocyanines and a tricarbocyanine series with variously bridged polymethine chromophores have been synthesized from hitherto unknown pyrimidino-annelated dioxaborines. The absorption, fluorescence and 13C NMR spectroscopic data point to the polymethinic type of electron-density distribution in the 2,2-difluoro-1,3,2-dioxaborine polymethine dye molecules. The fundamental options for controlling the spectral properties of these dyes by modification of their polymethine chains have been evaluated. One of the new compounds synthesized is remarkable among the known open-chain polymethine dyes for its record high fluorescence quantum yield. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Preparation of Uniform, Water-Soluble, and Multifunctional Nanocomposites with Tunable SizesADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Dechao Niu Abstract Novel, thiol-functionalized, and superparamagnetic, silica composite nanospheres (SH-SSCNs) with diameters smaller than 100,nm are successfully fabricated through the self-assembly of Fe3O4 nanoparticles and polystyrene100 - block -poly(acrylic acid)16 and a subsequent sol-gel process. The size and magnetic properties of the SH-SSCNs can be easily tuned by simply varying the initial concentrations of the magnetite nanoparticles in the oil phase. By incorporating fluorescent dye molecules into the silica network, the composite nanospheres can be further fluorescent-functionalized. The toxicity of the SH-SSCNs is evaluated by choosing three typical cell lines (HUVEC, RAW264.7, and A549) as model cells, and no toxic effects are observed. It is also demonstrated that SH-SSCNs can be used as a new class of magnetic resonance imaging (MRI) probes, having a remarkably high spin,spin (T2) relaxivity (r2*,=,176.1,mM,1 S,1). The combination of the sub-100-nm particle size, monodispersity in aqueous solution, superparamagnetism, and fluorescent properties of the SH-SSCNs, as well as the non-cytotoxicity in vitro, provides a novel and potential candidate for an earlier MRI diagnostic method of cancer. [source] Photovoltaics Based on Hybridization of Effective Dye-Sensitized Titanium Oxide and Hole-Conductive Polymer P3HTADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Ke-Jian Jiang Abstract Here, the fabrication of quasi-solid-state TiO2/dye/poly(3-hexylthiophene) (P3HT) solar cells is reported, in which the dyes with oleophilic thienyl groups were employed and ionic liquid (IL), 1-ethyl-3-methylimidazolium (EMIm) containing lithium bis(trifluromethanesulfone)amide (Li-TFSI) and 4- tert -butylpyridine (t -BP) are assembled with dyed TiO2 surfaces. One of the devices gave a high conversion efficiency of up to 2.70% under 1 sun illumination. The excellent performance is ascribed to successful molecular self-organization at interface of the dye molecules and P3HT, and to the efficient charge separation and diffusion acquired by introduction of the IL coupled with Li-TFSI and t-BP. [source] Tuning the Thermal Relaxation of a Photochromic Dye in Functionalized Mesoporous SilicaADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Lea A. Mühlstein Abstract In this study, it is shown that the kinetics of the back-switching reaction of a photochromic spirooxazine dye encapsulated in mesoporous silica materials can be significantly influenced both by the space available to the dye molecules and by the functionalization of the silica wall. Steric hindrance of the ring-closing process due to high dye content or small pore size leads to a slow fading speed of the irradiated dye species. Further, the density of surface silanol-groups present at the silica walls has an effect on the switching behavior of the dye because of their ability to stabilize the zwitterionic merocyanine isomers, thereby slowing the fading process from the open to the closed form. This stabilization effect is further enhanced in the presence of acidic functional groups, while, in contrast, basic functional groups reduce the stabilization of the open-from dye isomers, and thus a faster decay of the irradiated species is observed. Control over the fading speed of photochromic dyes is interesting for applications requiring a particularly fast or slow fading speed. [source] Hexagonal Network Organization of Dye-Loaded Zeolite,L Crystals by Surface-Tension Driven Autoassembly,ADVANCED FUNCTIONAL MATERIALS, Issue 17 2006S. Yunus Abstract Highly fluorescent dye-loaded zeolite,L crystals, approximately 1.4,,m long and 650,nm in diameter, are organized in a hexagonal network by a surface-tension-driven autoassembly process. A polydimethylsiloxane (PDMS) film presenting a trigonal ordering of spherical protuberances, including a polystyrene (PS) hexagonal network occupying their interstices, is chosen as the platform for the assembly. The overall wettability and the difference in surface tension between PDMS and PS surfaces are found to offer good conditions for ordering micrometric dye-loaded zeolite,L crystals in a 2D hexagonal network. The resulting film displays a regular hexagonal pattern of polarized fluorescence, reflecting the polarization properties of the dye molecules inserted in the parallel nanochannels of the zeolites. [source] Energy Collection, Transport, and Trapping by a Supramolecular Organization of Dyes in Hexagonal Zeolite Nanocrystals,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2006C. Minkowski Abstract The incorporation of guest molecules into the cavities of molecular sieves leads to a large variety of highly interesting materials. Zeolite,L,an aluminosilicate with one-dimensional channels of open diameter 7.1,Å,is a very versatile material for building highly organized host,guest systems. We present materials where organic dye molecules have been incorporated into the channels of zeolite,L by means of diffusion, to build artificial photonic antenna systems. The channel entrance can be plugged by adding closure molecules that then connect the guest molecules inside with materials or molecules outside of the zeolite channels, since they can act as extensions of the interior of the zeolite crystal. The photophysical processes taking place in such dye-loaded zeolite,L antennae can be studied either on single-micrometer- or submicrometer-sized crystals or on crystals dispersed in a solvent or coated as thin layers on a support. The energy-transfer process occurring is of the Förster-type, and its transfer rate can be tuned by separating the donor dyes and the acceptor dyes locally by varying amounts of spacer molecules. The distribution of the dye molecules and empty sites within a zeolite crystal has been modeled by means of a Monte Carlo simulation. The Förster energy migration and transfer steps are described as a random walk. [source] Formation of Highly Efficient Dye-Sensitized Solar Cells by Hierarchical Pore Generation with Nanoporous TiO2 SpheresADVANCED MATERIALS, Issue 36 2009Yong Joo Kim Nanoporous TiO2 structures were successfully applied for the fabrication of DSC electrodes, providing high surface areas and large pore sizes at the same time. High photocurrent was induced in these DSCs by great adsorption of dye molecules and efficient electrolyte diffusion, caused by the generated hierarchical pore structures in the TiO2 layer. [source] Multicolor Emission on Prepatterned Substrates Using a Single Dye Species,ADVANCED MATERIALS, Issue 16 2007W. Hu A new strategy for realizing patterned surfaces with different emission colors is demonstrated. This approach relies on the gas-phase deposition of dye molecules onto solid substrates that are prepatterned by nanoimprint lithography (see figure). Only a single molecular species is involved. Thus, the observed color change and corresponding spectral shift in the emission properties depends on the substrate used and can be tuned by surface engineering. [source] The removal of reactive azo dyes by natural and modified zeolitesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2003B Arma Abstract The adsorption mechanism of three reactive dyes by zeolite has been examined with the aim of identifying the ability of zeolite to remove textile dyes from aqueous solutions. Towards this aim, a series of batch adsorption experiments was carried out, along with determination of the electrokinetic properties of both natural and modified zeolites. The adsorbent in this study is a clinoptilolite from the Gördes region of Turkey. The reactive dyes CI Reactive Black 5, Red 239 and Yellow 176 are typical azo dyes extensively used in textile dyeing. Adsorption tests were carried out as a function of mixing time, solids concentration, dye concentration and pH. The adsorption results indicate that the natural zeolite has a limited adsorption capacity for reactive dyes but is substantially improved upon modifying its surfaces with quaternary amines. An electrostatic adsorption mechanism involving the formation of a bilayer of amine molecules on the clinoptilolite surface onto which anionic dye molecules adsorb, depending on their polarities, is proposed. The results are also supported by electrokinetic measurements. The adsorption data were fitted to the Langmuir isotherm and it was found that the modified sepiolite yields adsorption capacities (qe) of 111, 89 and 61 mg g,1 for Red, Yellow and Black, respectively. These results are comparable to a popular adsorbent, activated carbon. Copyright © 2003 Society of Chemical Industry [source] Anodic oxidation of the dye materials methylene blue, acid blue 25, reactive blue 2 and reactive blue 15 and the characterisation of novel intermediate compounds in the anodic oxidation of methylene blueJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2002John D Donaldson Abstract Anodic oxidation of the dye molecules, methylene blue, acid blue 25, reactive blue 2 and reactive blue 15 in chloride solution leads to colour destruction but UV and TOC data show that the oxidation reactions do not lead to complete destruction of the organic molecules. Analysis of the anodic oxidation products of [3,7-bis (dimethylamino) phenothiazinium] chloride (methylene blue) in a chloride solution provides evidence for formation of seven neutral and two charged intermediates. The main intermediate is identified by its X-ray diffraction crystal structure and accurate mass spectrometry as the novel leuco dye 4,6-dichloro-7-dimethylamino-3H -phenothiazin-3-one, C14H10Cl2N2OS (I) formed by replacement of one of the dimethylamino groups of methylene blue with oxygen accompanied by regiospecific chlorination of the carbocyclic systems. The mass spectra of other intermediates formed are interpreted in terms of the structure of I. © 2002 Society of Chemical Industry [source] Application of solid-phase concentration-dependent HSDM to the acid dye adsorption systemAICHE JOURNAL, Issue 1 2005Vinci K. C. Lee Abstract The fixed-bed adsorption of acid dyes onto granular activated carbon (Chemviron Filtrasorb 400) has been studied using a homogeneous surface diffusion model (HSDM). The model incorporates the external boundary layer mass transport and homogeneous diffusion inside the particle. A new orthogonal collocation method has been developed and used to solve the diffusion equations. This orthogonal collocation gives a faster solution method compared with the numerical Crank,Nicolson method. The surface diffusivity has been determined by an optimization procedure with minimization of sum of the error squared. The equilibrium relationship between the liquid-phase concentration and the solid-phase concentration has been described by the Redlich,Peterson isotherm. A solid-phase concentration-dependent surface diffusivity was introduced. The Darken model with the Redlich,Peterson isotherm was found to be a suitable correlation model for the adsorption of the acid dyes on carbon. The magnitude of the averaged Ds0 of each dye is in the order of AR114 > AB80 > AY117, which implies that, under the same solid-phase concentration gradient, the rate of mass transport diffusion is higher in AR114 than that in AB80 and AY117. This phenomenon may be explained by the different mobilities of the dye molecules present in the solution by the different arrangements of two sulfonic acid groups in the dye structures. © 2004 American Institute of Chemical Engineers AIChE J, 51: 323-332, 2005 [source] Protein adsorption drastically reduces surface-enhanced Raman signal of dye moleculesJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2010Dongmao Zhang Abstract There is an increasing interest in developing surface enhancement Raman spectroscopy methods for intracellular biomolecule and for in vitro protein detection that involve dye or protein,dye conjugates. In this work, we have demonstrated that protein adsorption on silver nanoparticle (AgNP) can significantly attenuate the surface-enhanced Raman spectroscopy (SERS) signal of dye molecules in both protein/dye mixtures and protein/dye conjugates. SERS spectra of 12 protein/dye mixtures were acquired using 4 proteins [bovine serum albumin (BSA), lysozyme, trypsin, and concanavalin A] and three dyes [Rhodamine 6G, adenine, and fluorescein isothiocyanate (FITC)]. Besides the protein/dye mixtures, spectra were also obtained for the free dyes and four FITC-conjugated proteins. While no SERS signal was observed in protein/FITC mixtures or conjugates, a significantly reduced SERS intensity (up to 3 orders of magnitude) was observed for both R6G and adenine in their respective protein mixtures. Quantitative estimation of the number of dye molecules absorbed onto AgNP implied that the degree of R6G SERS signal reduction in the R6G/BSA sample is 2 to 3 orders of magnitude higher than what could be accounted for by the difference in the amount of the absorbed dyes. This finding has significant implications for both intracellular SERS analyses and in vitro protein detection using SERS tagging strategies that rely on Raman dyes as reporter molecules. Copyright © 2009 John Wiley & Sons, Ltd. [source] Sign inversion of the optical torque on the nematic director enhanced by anthraquinone dye dopants stable to the light actionLASER PHYSICS LETTERS, Issue 11 2006V. Ya. Abstract By analyzing the total and on-axis transmittance of the laser beam we studied the enhanced light-induced director reorientation (Jánossy effect) in a nematic liquid crystal doped with anthraquinone dye molecules that do not have photoinduced conformational transformations. The obtained dependence on the angle between the light polarization E and the initial director n0 shows: first order director reorientation (DR) transition with hysteresis for E , n0; second order reversible DR transition with the extremely low threshold intensity for E , n0; sign inversion of the nonlinear refractive index and DR in the intermediate geometry. The data suggest a presence of two different kinds of dipoles in the system: those absorbing light and those giving rise to the nonlinear refractive index. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Fluorescence saturation of dye molecules in water pools of reversed micellesLASER PHYSICS LETTERS, Issue 10 2005A. V. Potapov Abstract Rhodamine 6G has been used as a fluorescence probe in AOT reversed micelles systems with the different amounts of solubilized water (hydratation power ,). The saturation of fluorescence and the lifetime of dye molecules were measured. The absorption cross section values were calculated from the saturation curves. We showed the differences in values of the absorption cross section, lifetime and velocity of fluorescence saturation in micellar phase with different , and in comparison to bulk phase. Additionally, the structure of hydrated reversed micelles has been studied by the method of correlation spectroscopy. The influence of , on size and shape of micelles was detected. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] | |||||||||||||||||||||||||||||||