Stability Of Dyes Research Articles

Assessment of Structural Stability of Pure and Xylenol Orange Dye Doped Potassium Dihydroegn Phosphate Probed by Shock Waves

In the present research article, we report the impact of shock waves and the crystallographic structural stability of pure, 0.001 M and 0.01M xylenol orange doped potassium dihydroegn phosphate (KDP) powder samples. The structural stability and crystalline nature of the test samples are demonstrated by powder X-ray diffraction and Raman spectroscopy. The obtained structural properties clearly show that the control sample has a highly stable crystallographic phase at the atomic level. But several shoulder peaks have appeared at shocked conditions due to the lattice distortions and lattice disorders in atomic sites. Among the three samples, 0.001M dye doped KDP exhibits the least shock resistance. The interesting results obtained such as crystallographic phase stability and degree of crystalline stability of the test samples during the course of the experiment are discussed.

Complexation of an Azo Dye by Cyclodextrins: A Potential Strategy for Water Purification.

The chemistry of the host–guest complex formation has received much attention as a highly efficient approach for use to develop economical adsorbents for water purification. In the present study, the synthesis of three β-cyclodextrin (β-CD) inclusion complexes with the oil orange SS (OOSS) azo dye as a guest molecule and their potential applications in water purification are described. The complexes were synthesized by the coprecipitation method and characterized by Fourier transform infrared (FTIR) spectroscopy, UV–vis spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). FTIR and thermal analyses confirmed the encapsulation of OOSS dye within the hydrophobic cavity of β-CD. The encapsulation of hydrophobic dye inside the β-CD cavity was mainly due to the hydrophobic–hydrophobic interaction. The results showed that the stability of the OOSS dye had been improved after the complexation. The effect of three different compositions of the host–guest complexes was analyzed. The present study demonstrated that the hydrophobic dye could be removed from aqueous solution via inclusion complex formation. Thus, it can play a significant role in removing the highly toxic OOSS dye from the industrial effluent.

Enhancement stability and color fastness of natural dye: A review

Abstract Consumer awareness of the adverse biological effects of synthetic dyes makes the demand for commercial foods and drinks with natural ingredients increase. The use of natural dyes is increasing and is in demand by consumers in the industrial world. Natural dyes have been used in several sectors such as food, clothing, arts, coatings, and energy. The low stability and brightness of the natural red color are affected by exposure to light, temperature, pH and etc. The co-pigmentation process makes the stability and brightness of natural dyes. The copigmentation method is known that there are two type, liquid and powder. In addition, the combination of copigmentation additives and the correct configuration of the spray dryer process can increase quality color fastness and stability.

Selection of Antioxidants to Increase the Stability of Natural Dyes Against Uv-Radiation and High Temperature

Selection of Antioxidants to Increase the Stability of Natural Dyes Against Uv-Radiation and High Temperature

Ekstraksi dan Uji Stabilitas Zat Warna Alami dari Bayam Merah (Alternanthera amoena Voss)

Research on the extraction and stability test of natural dye from red spinach (Alternanthera amoena Voss) has been carried out. This study aims to determine the effect of pH and length of sun exposure on the stability of the dye from red spinach. Extraction using the maceration method with ethanol solvent and measurement using a UV-Vis spectrophotometer. Stability testing is carried out at pH 2-5 and sun exposure for 1-4 hours using a dark and light container. The results obtained, at pH 2 and pH 3, anthocyanins were more stable, compared to pH 4 and 5 which had greater color degradation. In exposure to sunlight, dark containers with a degradation percentage of 31.70% were better than clear containers with a percentage of 48.78%.
 Keywords: Anthocyanin, red spinach, natural dyes stability.

Enhanced Stability and Emission Properties of Perylene Dyes by Surface Tethering: Preparation of Fluorescent Ru Nanoparticle Suspensions by Alkyne Linker Chemistry

Spherical ruthenium nanoparticles (NPs) with a narrow size distribution were synthesised in ethanol by a facile low-temperature solvothermal process without the assistance of templates, structure-directing agents or post annealing/reduction treatments. Surface passivation with a fluorescent perylene dye (EP), and with silane ligands (ETMS), both initially bearing alkyne groups and subsequently forming vinylidene linkages, provided stable suspensions of the marginally soluble free EP. Quantitative analysis of the suspension gave an estimated EP surface coverage of 15 %, corresponding to an EP/ETMS mole ratio of ≈1:6. Photophysical evaluation of the bound and free dye revealed similar absorption bands and extinction coefficients and improved properties for the bound state, including enhanced fluorescence in the visible range for the bound dye, an extended absorption range into the near-UV providing strong emission in the visible, and significantly improved photostability. The physical basis of the enhanced photophysical properties, potential routes to further improvements and the implications for applications are discussed.

Adsorption of resazurin by poly(acrylic acid) hydrogels and evaluation of its use in reduction assay for quantification of cell viability

Resazurin is a nonfluorescent blue dye which is reduced to a fluorescent pink resorufin via enzymatic activity of living cells. Therefore, a resazurin reduction-based assay serves as an effective method for evaluating cell viability. In this study, resazurin was adsorbed on poly(acrylic acid) (PAA) hydrogels and evaluated for its effectiveness in bacterial and mammalian cell viability assay. The effects of PAA hydrogel and resazurin amounts, pH, temperature, light and agitation on adsorption capacity were examined. The experimental data were fitted to the Langmuir isotherm and pseudo-second order kinetic models with Radj2 of 0.991 and 0.986, respectively, indicating a chemical monolayer adsorption at fixed adsorption sites via physicochemical interaction between resazurin and PAA hydrogel. In the cell viability assay, resazurin adsorbed on hydrogels gave higher percent reduction at lower bacterial cell concentration. For starting inoculums higher than 1.0 × 104 CFU/mL Escherichia coli (E. coli), the percent reductions of resazurin adsorbed on hydrogels were not significantly different than that of resazurin free in the growth medium, however, the stability of resazurin in the growth medium was higher when adsorbed on hydrogels. The assays utilizing MCF-7 at three concentrations gave higher reduction results with higher dye stability in the growth medium. It was concluded that adsorption of resazurin on PAA hydrogels improved its stability in medium and thus provided better viability assay conditions for both bacteria and mammalian cell.

Introducing Bluish-Green Light-Emitting Diodes (OLEDs) and Tuning Their Color Intensity by Uranium Complexes: Synthesis, Characterization, and Photoluminescence Studies of 8-Hydroxyquinoline Complexes of Uranium.

To improve our understanding of the chemistry of actinide complexes and to spur their development in the field of actinide markers, two new uranium complexes were synthesized using 8-hydroxyquinoline and 5,7-dichloro-8-hydroxyquinoline. The prepared complexes were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet-visible spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The impact of the electron-withdrawing group of the ligand on the photoluminescence spectra of the complexes in solution and in the solid state was scrutinized. The bandgap of the complexes was calculated using the density functional theory (DFT) method to investigate the effects of the electron-withdrawing groups on energy levels. The synthesized uranium complexes demonstrated appropriate levels of the lowest unoccupied molecular orbital energy, leading to favorable dye stability. The prepared uranium complexes showed blue fluorescent emission, and the sample with the most intense fluorescence was used to construct bluish-green organic light-emitting diodes using simple solution processing fabrication methods. Absorbance spectra, emission spectra, DFT-calculated energy levels, and comparisons of the fabricated organic light-emitting diodes indicated that the electron-withdrawing group was a key factor in photoluminescence behavior.

The "blue bottle" experiment in the colloidal dispersions of smectites

The Blue Bottle Experiment involves a reversible redox process of decolorizing methylene blue (MB) by reaction with glucose (Glc) at basic pH. The direction of the reaction is affected by the concentration of dissolved O2. In this work, the reactions that took place in the presence and absence of nanoparticles of smectites (a group of layered silicates) were compared. The method of absorption spectroscopy with a diode-array detector was chosen for studying the reaction. It was possible to measure the full spectrum in a fraction of a second, and thus several hundred spectra were obtained for each experiment. Spectral matrices were analyzed using the chemometric method of multivariate curve resolution (MCR). Analysis of the results revealed not only the formation of known reaction products (a leuco-form of MB, the oxidation products of Glc) but also some other processes related to the changes of the reactants in a basic environment, slow dye decomposition, glucose isomerization, and the formation of MB molecular aggregates. The injection of colloidal smectite particles into the reaction system effectively stopped the redox reaction of MB with Glc, which may be important for dye stabilization in hybrid materials with smectites. This property was not related to the type of smectite, which instead affected the molecular aggregation occurring in the heterogeneous systems.

Extraction and Stability of Natural Dyes From The skin of Red Dragon Fruit

Dragon fruit skin contains anthocyanin dyes which are quite high. Anthocyanins are dyes that give red color and can be used as natural dyes for food. This study aims to determine the ratio of the 10% citric acid solution with the time of maceration to obtain the highest anthocyanin levels and to determine the stability of the red dragon fruit peel extract. The research design used was a factorial completely randomized design (CRD) with two factors, namely the ratio of red dragon fruit peel pulp with 10% citric acid solvent consisting of three levels: 1: 3; 1: 6; 1: 9. The second factor is the length of maceration of the red dragon fruit skin which consists of three levels: 3 days; 3.5 days; 4 days. Analysis of red dragon fruit peel extract includes: yield, anthocyanin levels, pH value, color intensity, and stability test. The best treatment of red dragon fruit peel extraction was obtained in the sample ratio of 10% citric acid solution (1: 3) and the duration of maceration for 4 days with a yield of 22.92%; pH value of 1.84; anthocyanin levels of 52.27 mg / L; L * color intensity of 16.54; color intensity a * of 75.57; color intensity b * was 9.63 and the best anthocyanin dye stability test was obtained at a pH of 3 and a temperature of 7 ° C.

Synthesis and Characterization of New Azo Compounds Linked to 1,8-Naphthalimide as New Fluorescent Dispersed Dyes for Cotton Fibers

New Azo compounds containing of 1,8-naphthalimide moiety had been synthesized from 1,8-naphthalic anhydride by reaction with p-phenylenediamine or benzidine to give 1,8-naphthalimide derivatives [1 or 2], which converted into its diazonium salt derivatives that undergo to coupling reaction with different substituted phenol in alkaline media to produce azo compounds derivatives [3-6]. The prepared compounds had been characterized by measuring some of physical properties (melting point), FTIR, 1HNMR and 13CNMR. Also, absorption spectra (UV-Vis spectrophotometry), fluorescence spectra (Fluorescence spectrophotometry) and quantum yield of prepared azo dyes [3 - 6] had been studied in four different solvents of different polarities (EtOH, dioxane, CHCl3 and DMSO). Also, the photo stability of the dyes [3 - 6] was studied by exposing to the ultraviolet light at room temperature for three hours. Thermal stability of dyes (3 & 4) was studied by TGA / DTG. The prepared dyes [3 - 6] were used for the dyeing of raw cotton dyeing at high temperatures and studying their fastness properties such as washing fastness using standard soap (SDS) and rubbing fastness (wet and dry) under controlled conditions of pressure, speed and moisture.

Use of a Zwitterionic Surfactant to Improve the Biofunctional Properties of Wool Dyed with an Onion (Allium cepa L.) Skin Extract.

To improve the loadability and antioxidant properties of wool impregnated with onion skin extract, the introduction of SB3-14 surfactant in the dyeing process was evaluated. A preliminary investigation on the surfactant–quercetin interaction indicated that the optimal conditions for dye solubility, stability, and surfactant affinity require double-distilled water (pH = 5.5) as a medium and SB3-14 in a concentration above the c.m.c. (2.5 × 10−3 M). The absorption profile of textiles showed the flavonoid absorption band (390 nm) and a bathochromic feature (510 nm), suggesting flavonoid aggregates. The higher absorbance for the sample dyed with SB3-14 indicated greater dye uptake, which was further confirmed by HPLC analysis. The Folin–Ciocalteu method was applied to evaluate the total phenol content (TPC) released from the treated wool, while the assays FRAP, DPPH, ABTS, and ORAC were applied to evaluate the corresponding total antioxidant activity (TAC). Higher TPCs (about 20%) and TACs (5–55%) were measured with SB3-14, highlighting textiles with improved biofunctional properties. Spectrophotometric analyses were also performed with an artificial sweat. The potential cytotoxic effect of SB3-14 in both monomeric and aggregated forms, cell viability, and induction of apoptosis were evaluated in RAW 264.7 cells. These analyses revealed that SB3-14 is safe at concentrations below the c.m.c.

A comparative structural and photocatalytic study on SnO2 nanoparticles fabricated in batch reactor and microreactor

Controlling of scalability, agglomeration and monodispersity of nanoparticles are fundamental to be exploited in diverse application-based fields such as catalysis, sensing, drug delivery, bio-imaging etc. Currently fabrication of scalable, non-agglomerated and monodispersed nanoparticles by using continuous flow microreactor technology pay severe consideration as it offers a variety of advantages such as competent heat transfer and better intermixing of the reactants compare to the conventional batch reactor technology. In this contribution, we advance the prior art by introducing a straightforward, scalable, cost-effective and environmentally benign continuous flow microreactor synthetic approach for the fabrication of pristine SnO2 nanoparticles at a reasonably low reaction temperature and short reaction period. A PTFE (polytetrafluoroethylene)-based helical tubular microreactor is being exploited that comprises compact structure and offers enhanced heat and mass transport as well as better intermixing among the reactants. To discriminate this technique with the conventional batch reactor method herein SnO2 nanoparticles have been synthesized by using both techniques by maintain the identical reaction temperature and reaction time in both cases. Inherent crystal phases, lattice strain, lattice parameters and oxygen vacancies of the as-synthesized SnO2 nanoparticles have been investigated by using XRD/Rietveld analysis. High resolution (HR) -Transmission electron microscopy (TEM) is carried out to investigate the size, shape, crystallinity and agglomeration behaviour of the SnO2 nanoparticles fabricated by each method. SnO2 nanoparticles fabricated by microreactor technology demonstrate excellent activity in the degradation of methylene blue (MB) dye and good stability in response to irradiation. Results demonstrate that altering the synthetic technique amends both surface properties (extent of oxygen vacancies and defects at the surface) and optical band gaps and that these alterations are eventually reflected in the photocatalytic properties of the SnO2 nanoparticles.

Spectrophotometrical purity and stability testing of a photosensitizer based on an indotricarbocyanine dye

The express method for testing purity and stability of an indotricarbocyanine dye based photosensitizer for photodynamic therapy was developed. Storage of the hydrophilic photosensitizer under unfavorable conditions resulted in contamination with a hydrophobic dye. The absorption spectrum of the hydrophobic dye was characterized by a new band at 514 nm that was absent in the absorption spectrum of the photosensitizer. There was no spectral overlap between this absorption band and the absorbance of the photosensitizer. Therefore, presence of the band at 514 nm allowed us to detect contamination of the photosensitizer substance with the hydrophobic dye. It was established that the optimal photosensitizer concentration for purity testing is ca. 0.8 mmol/L, when as little as 0.6 wt. % of the impurity can be detected. The developed method is not time consuming and requires accessible equipment only. Data obtained with this method was verified with the aid of liquid chromatography-mass spectrometry.

Dye Stabilization and Wavelength Tunability in Lasing Fibers Based on DNA.

Lasers based on biological materials are attracting an increasing interest in view of their use in integrated and transient photonics. Deoxyribonucleic acid (DNA) as optical biopolymer in combination with highly emissive dyes has been reported to have excellent potential in this respect. However, achieving miniaturized lasing systems based on solid‐state DNA shaped in different geometries to confine and enhance emission is still a challenge, and the physicochemical mechanisms originating fluorescence enhancement are not fully understood. Herein, a class of wavelength‐tunable lasers based on DNA nanofibers is demonstrated, for which optical properties are highly controlled through the system morphology. A synergistic effect is highlighted at the basis of lasing action. Through a quantum chemical investigation, it is shown that the interaction of DNA with the encapsulated dye leads to hindered twisting and suppressed channels for the nonradiative decay. This is combined with effective waveguiding, optical gain, and tailored mode confinement to promote morphologically controlled lasing in DNA‐based nanofibers. The results establish design rules for the development of bright and tunable nanolasers and optical networks based on DNA nanostructures.

Theoretical Study of the Effect of π-Bridge on Optical and Electronic Properties of Carbazole-Based Sensitizers for DSSCs.

Eight novel metal-free organic sensitizers were proposed for dye-sensitized solar cells (DSSCs), theoretically calculated and studied via density functional theory with D-π-A structure. These proposals were formed to study the effect of novel π-bridges, using carbazole as the donor group and cyanoacrylic acid as the anchorage group. Through the M06/6-31G(d) level of theory, ground state geometry optimization, vibrational frequencies, the highest occupied molecular orbital, the lowest unoccupied molecular orbital, and their energy levels were calculated. Further, chemical reactivity parameters were obtained and analyzed, such as chemical hardness (η), electrophilicity index (ω), electroaccepting power (ω+) and electrodonating power (ω-). Free energy of electron injection (ΔGinj) and light-harvesting efficiency (LHE) also were calculated and discussed. On the other hand, absorption wavelengths, oscillator strengths, and electron transitions were calculated through time-dependent density functional theory with the M06-2X/6-31G(d) level of theory. In conclusion, the inclusion of thiophene groups and the Si heteroatom in the π-bridge improved charge transfer, chemical stability, and other optoelectronic properties of carbazole-based dyes.

Comparison of the effect of N-methyl and N-aryl groups on the hydrolytic stability and electronic properties of betalain dyes

Betalains are antioxidant secondary metabolites that emerged as safe color additives for food and cosmetics, fluorescent dyes, and redox mediators. Herein, we describe the semisynthesis of N-methyl phenylbetalain (mepBeets) and N-aryl phenylbetalain (dipBeets) dyes and compare the effect of the structure on their hydrolytic stability and electronic properties. Eight model compounds were semisynthesized by coupling betalamic acid with either N-methyl anilines or N-aryl anilines in ethyl acetate using p-toluenesulfonic acid as catalyst. The presence of electron-withdrawing substituents in the aryl moiety of mepBeets and dipBeets results in faster hydrolysis, lower anodic potentials and increased fluorescence quantum yields compared to the corresponding unsubstituted parent compounds. The results are rationalized by considering the charge distribution in the 1,7-diazaheptamethinium chromophore and are useful for the development of new hydrolytically stable betalain dyes with tunable redox and optical properties.

Design and Synthesis of Near-Infrared Mechanically Interlocked Molecules for Specific Targeting of Mitochondria.

The entrapment of squaraine (SQ) within a molecular container to form rotaxane has been shown to improve the dye stability and the fluorescence proficiency inside the mitochondria. The macrocycle provides shelter and protects the near-infrared (NIR) SQ chromophore from nucleophilic attacks made by the exposed thiol of Cys-containing mitochondrial proteins and mitochondrial glutathione. Herein a microwave-assisted template-directed clipping reaction on low-loading 2-chlorotrityl chloride resin is used to develop an NIR unsymmetrical squaraine rotaxane in high quantum yield.

An accomplished procedure of horseradish peroxidase immobilization for removal of acid yellow 11 in aqueous solutions.

Horseradish peroxidase (HRP) characteristics were improved by two techniques, Na-alginate entrapment and glutaraldehyde crosslinking prior to alginate entrapment, in order to enhance the stability, functionality and removal of dyes in waste water. Free, entrapped and crosslinked-entrapped enzymes were compared by activity assays, which indicated the optimum temperature is 25 °C and pH 4.0-5.0. Kinetics results showed that alginate entrapment and crosslinking prior to entrapment increased Vmax and did not cause any significant decrease in Km. The thermal resistance of the free enzyme was short-term, zero residual activity after 250 min, while the immobilized enzymes preserved more than 50% of their activity for 5 h at 60 °C. Immobilized HRP was resistant to methanol, ethanol, DMSO and THF. The storage stability of free HRP ended in 35 days whereas entrapped and crosslinked-entrapped HRPs had 87 and 92% residual activity at the 60th day, respectively. HRP was used in the decolorization of azo dye Acid yellow 11 and total decolorization (>99%) was obtained using crosslinked-entrapped HRP. Reusability studies presented the improvement that crosslinked-entrapped HRP reached 74% decolorization after 10 batches. The results demonstrated that the novel immobilized HRP can be used as an effective catalyst for dye degradation of industrial waste effluents.

Characterization of planar phosphorescence based oxygen sensors on a TCSPC-PLIM macro-imager

A set of phosphorescent materials were evaluated using a new macro-imager based on fast time-stamping Tpx3Cam camera with phosphorescent lifetime imaging (PLIM) capabilities. The near-infrared emitting O2-sensitive dye PtBP was embedded in several polymers having different permeability for O2 and applied as solid-state coatings on polyester film support. These sensor materials were placed on a temperature-controlled stage of the imager and imaged under pulsed excitation with a 627 nm LED. The resulting PLIM images showed good uniformity, accuracy and contrast of measured lifetime values for the different phosphorescent materials, and the anticipated lifetime changes with altered temperature or oxygenation conditions, proving the dynamic mechanism of quenching by O2. By imaging the coatings with decreasing dye concentration, stability and limits of sensitivity of the PLIM mode were determined and compared with intensity-based imaging. Several commercial O2 sensors were also imaged and compared with the hand-made sensors, while lifetime measurements on the new imager were compared with those performed on the confocal TCSPC-PLIM microscope.