Structure Of Dyes Research Articles

Coumarin based sensitizers with ortho-halides substituted phenylene spacer for dye sensitized solar cells

The performance of DSSCs (dye sensitized solar cells) with a new series of dyes having different halide groups (i.e. F, Cl and Br) on o-position substituted phenyl spacers with same coumarin donor moieties have been reported. Optical, electrochemical, molecular orbital and photovoltaic properties were studied by varying the halide groups using these dyes. The replacement of halide atoms in same coumarin based dye had a significant effect on the short circuit current density (Jsc), open circuit voltage (Voc), and photo conversion efficiency (PCE). The Jsc and PCE of dye CD-1 (fluorine substituted) are 10.3 mA/cm2 and 5.2% respectively, which is higher than CD-2 (chlorine substituted) and CD-3 (bromine substituted) dyes (having PCE 4.1% and 3.5% respectively) devices. The optimized geometry calculation of o-halide phenyl π-spacer dyes were ascertained by density functional theory (DFT) using the B3LYP/6-31G(d,p) basis set. Moreover, we have checked the effect of various substituents in the same dye structure by DFT analysis.

A novel reactive dye system based on diazonium salts

Azo dyes, possessing a primary aromatic amino group, on diazotisation in presence of cotton followed by treatment with soda ash at 60–65 °C were found to ‘reactively’ dye cotton with varying degrees of fixation depending on the chemical structure of the azo dye. Evidence of dye-fibre reaction is indirectly inferred from poor to fair colour values obtained in absence of added soda ash. Dyed cotton retained significant colour even after three treatments with boiling dimethyl formamide (DMF). Coloured cellulose precipitated when a solution of dyed cotton in 85% w/w phosphoric acid was diluted with dimethyl sulfoxide (DMSO). The phosphoric acid-DMSO mixture was colourless. These two tests prove the existence of a dye-fibre covalent bond. A new class of reactive dyes without an externally attached reactive system is therefore, in principle, available. It will have the advantage of reduced raw material and manufacturing costs.

Effect of donor terminal group and polymethine chain length on structure of merocyanine dyes in the crystal state

X-ray diffraction study of the merocyanine series with different sign of solvatochromism but of the same structural type revealed the effects of donor-acceptor properties of terminal groups and polymethine chain length on their electronic structure in the solid state. The bond length alternation in the negatively solvatochromic dyes corresponds to the dipolar polyene limiting structure, contribution of which, in contrast to solutions, increases for higher vinylogues. Conversely, the nonpolar polyene structure prevails for the positively solvatochromic merocyanines, its contribution increases for higher vinylogues in both solid state and solutions. The DFT (in vacuo and PCM) calculations reproduce tendencies observed for the positively solvatochromic merocyanines but do not reflect the dipolarity growth in higher vinylogues of the negatively solvatochromic ones. The calculations results can be improved taking explicitly into account intermolecular interactions in the crystal.

Azo dyes degradation using TiO2-Pt/graphene oxide and TiO2-Pt/reduced graphene oxide photocatalysts under UV and natural sunlight irradiation

The photocatalytic degradation of azo dyes with different structures (amaranth, sunset yellow and tartrazine) using TiO2-Pt nanoparticles (TPt), TiO2-Pt/graphene oxide (TPt-GO) and TiO2-Pt/reduced graphene oxide (TPt-rGO) composites were investigated in the presence of UV and natural sunlight irradiation. The composites were prepared by a combined chemical-thermal method and characterized by Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Infrared (FTIR) and UV–Vis spectroscopy. The modification of TiO2-Pt with graphene oxide shifted its optical absorption edge towards the visible region and increased its photocatalytic activity under UV and natural sunlight irradiation. The efficiency of catalysts on azo dyes degradation (in similar conditions) reached high values (above 99%) under sunlight conditions, proving the remarkable photocatalytic activities of obtained composites. TPt-GO nanocomposite exhibited higher photoactivity than TPt or TPt-rGO, demonstrating degradation efficiencies of 99.56% for amaranth, 99.15% for sunset yellow and 96.23% for tartrazine. The dye photodegradation process follows a pseudo-first-order kinetic with respect to the Langmuir-Hinshelwood reaction mechanism. A direct dependence between azo dyes degradation rate and chemical structure of dyes has been observed.

Degradation of methyl orange and removing Pb2+ from the water with ZnO–Fe nano photocatalyst

In this work, ZnO–Fe nanostructures with different morphologies were synthesized via a simple hydrothermal method. Different parameters such as surfactant, reaction time and temperature, Fe source value, and Zn source kind were changed to the investigation of each parameter on the product size and morphology. The results obtained from SEM images showed each parameter has a significant effect on the product size and morphology. Also, the TEM images confirmed the SEM results. The optical properties of the synthesized products were studied by UV–Vis spectroscopy and the results showed that by doping Fe3+ into the ZnO crystal lattice, the band gap is decreased and hence it can absorb more light than the bare ZnO. The photocatalytic activity of the product was examined by decomposition of methyl orange under ultraviolet radiation. The results showed that the product has high photocatalytic activity and it can decomposed dye structure by 62% that is mainly due to a decrease of the band gap of doped ZnO with respect to the bare ZnO one. The surface activity of the product was investigated by surface adsorption of the dye molecules on the nanostructure surface. The results showed due to high surface to volume ratio of the nanostructures, they could adsorb more than 65% of the dye and remove them from the solution. Another surface activity of the product was examined by removing Pb2+ from the water and the results were obtained by atomic absorption spectroscopy. The results showed that the product could remove Pb2+ more than 44% from the water.

Tautomerism, crystal structure, and copper(ii) complexation of pyridonylazo dyes derived from methyl 4‐aminobenzoate

Four heterocyclic dyes, derived from methyl 4‐aminobenzoate and pyridine‐2,4‐dione components, with different N‐substituents in the latter [CH3, CH2CH3, CH2CH2OH, CH2CH2CH2OCH(CH3)2], were synthesised by the traditional diazotisation‐coupling strategy. Furthermore, a Cu(ii) dye–metal complex was prepared and characterised by X‐ray single‐crystal diffraction for comparison, where the configuration transformation from hydrazone to deprotonated azo forms was found before and after Cu(ii) ion complexation. In addition, the azo–hydrazone transformation could be observed by acid–base titration experiments. To the best of our knowledge, this work is the first structural study of pyridone dyes based on methyl 4‐aminobenzoate and the corresponding dye–metal complex.

Prominent adsorption performance of amino-functionalized ultra-light graphene aerogel for methyl orange and amaranth

Amino-functionalization is an effective and facile way to modify the surface of adsorbent. A facile strategy to fabricate polyethyleneimine-functionalized graphene aerogel (PFGA) integrating superhigh adsorption ability, selectivity, pH-sensitivity and reusability was developed. The maximum adsorption capacities of the PFGA for methyl orange and amaranth were as high as 3059.2mgg−1 and 2043.7mgg−1, respectively, the highest capabilities among the reported adsorbents for both dyes. The microcosmic interaction models of the two dyes and PFGA were outlined to describe the relationships between dye structures and adsorption behaviors. Owing to the different affinities of PFGA for anionic and cationic dye, anionic dye methyl orange was able to be selectively separated from the dye mixture. In the experiment of competitive adsorption of acid dyes with different structures, amaranth with more sulphonate groups was preferentially adsorbed. In addition, PFGA showed meaningful pH-sensitive adsorption ability, enabling dye-adsorbed PFGAto be fully regenerated as soon as it was exposed to the solution of pH 11. The study on polyethyleneimine-functionalization is meaningful for the development of high adsorption capacity adsorbents and amino-functionalization or other functionalized materials.

Relationship between structure and dyeing properties of reactive dyes for cotton dyeing

Heterofunctional reactive dyes were studied for their dye fixation and colour strength for cotton fiber. Reactive dyes with different reactive groups (monochlorotriazine and sulphatoethylsulphone) were applied on to cotton fabric with pad thermofix method to explore the role of functional group on colour strength and fastness properties. Dye fixation and colour strength of cotton fabric revealed that dye with different functional groups have different reactivity and affinity for the cotton fiber. Reactive dyes exhibited high colour strength at optimum conditions of temperature, pH and reaction time. Among dyes under investigation, D-6 (ester vinylsulphone at Para position) showed the highest colour strength (82%) and D-2 (ester vinylsulphone at Meta position) furnished minimum colour strength of 67%. The dyes having linear and planar structure offer higher reactivity. The fastness properties of cotton fiber for all reactive dyes were good to excellent in comparison to commercial Reactive Red 195 dye.

A Stable Panchromatic Green Dual Acceptor, Dual Donor Organic Dye for Dye-Sensitized Solar Cells

A novel organic sensitizer (AP3) with dual donors and dual anchor-acceptors based on an electron deficient thieno[3,4-b]pyrazine (TPz) π-bridge was synthesized, which shows an impressively high Jsc of 17.6 mA/cm2 when cosensitized with D35 (12.4 mA/cm2 as a single dye). Device power conversion efficiencies were observed at 7.5% under full sun intensity and in excess of 10% under reduced sun intensity. This novel dye design approach allows for devices showing photostability beyond 500 h for continuous irradiation and a tunable dye structure with an incident power conversion efficiency breadth reaching 800 nm from a simple-to-synthesize organic dye. Dye characterization with cyclic voltammetry, solution and film absorption, and computational analysis are all presented. Additionally, device characterization was performed through IV curves, IPCE, electron lifetime measurements, transient absorption spectroscopy, and current dynamic measurements at varying sun intensities to better understand the origin of the...

Synthesis and spectral properties of preorganized BODIPYs in solutions and Langmuir-Schaefer films

Abstract In order to investigate the influence of molecular structure peculiarities of boron-dipyrrine dyes (BODIPYs) on their properties in solutions and supramolecular organization in Langmuir-Schaefer (LS) films, four new BODIPY dyes with various aliphatic, aromatic or mixed nature meso-subtituents were synthesized and investigated. Spectral characteristics (electronic absorption and fluorescence) of the synthesized compounds in organic solvents and LS-films were studied. Floating monolayers of the BODIPYs were formed from chloroform solutions placed onto water subphase in Langmuir-Blodgett through. Thin films were prepared using the Langmuir-Schaefer technique by the transfer of floating monolayers onto standard polished glass, ITO covered glass or pure silicon substrate. The variation of the dye structure we consider as a preorganization aiming to influence the structure of LS-films. The morphology and structure of the LS-films was examined by fluorescent microscopy, scanning electron microscopy, atomic force microscopy and small angle X-ray diffraction analysis. It was found that the introduced substituents have no substantial influence on the position of the absorption and fluorescence bands in dilute solutions. In contrast, the fluorescent characteristics of the LS-films significantly depend on the substituent nature. Therefore, this strategy could be used for the direct tuning of compounds fluorescent properties in LS-films. Concerning the LS-film surface characteristics it was proved that the films are homogeneous, without disruptions and only some widely-spaced microcrystals could be observed. With respect to the LS-film structure, the change of the substituents introduced to the BODIPY molecule did not influence the average given periodicity of layers (d = 0.3–0.4 nm). This value corresponds to a single-layer arrangement of BODIPY molecules located parallel to the substrate surface. Nevertheless, the diffraction peak intensities depended on the molecular structure of BODIPYs and therefore the structurization in thin films. Moreover, the combination of the rigid phenyl moiety with long alkyl chains in one compound completely suppresses the aggregation of molecules maintaining the intense fluorescence in thin films. On the basis of used range of experimental and calculation methods the intralayer and interlayer structures were proposed. Intermolecular hydrogen bond formation and π-π staking of the BODIPY cores were found to be the structure forming forces during the films manufacturing, resulting the differences in crystallinity of the materials. While the alkyl-substituents prevent the type of interactions and suppress the association of the dyes and formation of excimers. Compounds under investigation show a manifestation of the intense solvatochromic properties which allow their application as sensors, including naked eye sensorics for solution polarity. Besides, the obtained results broaden prospective of functional materials usage based on BODIPY thin films as components of optoelectronics.

Tracking Antibody Distribution with Near-Infrared Fluorescent Dyes: Impact of Dye Structure and Degree of Labeling on Plasma Clearance

Monoclonal antibodies labeled with near-infrared (NIR) fluorophores have potential use in disease detection, intraoperative imaging, and pharmacokinetic characterization of therapeutic antibodies in both the preclinical and clinical setting. Recent work has shown conjugation of NIR fluorophores to antibodies can potentially alter antibody disposition at a sufficiently high degree of labeling (DoL); however, other reports show minimal impact after labeling with NIR fluorophores. In this work, we label two clinically approved antibodies, Herceptin (trastuzumab) and Avastin (bevacizumab), with NIR dyes IRDye 800CW (800CW) or Alexa Fluor 680 (AF680), at 1.2 and 0.3 dyes/antibody and examine the impact of fluorophore conjugation on antibody plasma clearance and tissue distribution. At 0.3 DoL, AF680 conjugates exhibited similar clearance to unlabeled antibody over 17 days while 800CW conjugates diverged after 4 days, suggesting AF680 is a more suitable choice for long-term pharmacokinetic studies. At the 1.2 DoL, 800CW conjugates cleared faster than unlabeled antibodies after several hours, in agreement with other published reports. The tissue biodistribution for bevacizumab–800CW and −AF680 conjugates agreed well with literature reported biodistributions using radiolabels. However, the greater tissue autofluorescence at 680 nm resulted in limited detection above background at low (∼2 mg/kg) doses and 0.3 DoL for AF680, indicating that 800CW is more appropriate for short-term biodistribution measurements and intraoperative imaging. Overall, our work shows a DoL of 0.3 or less for non-site-specifically labeled antibodies (with a Poisson distribution) is ideal for limiting the impact of NIR fluorophores on antibody pharmacokinetics.

Influence of amine groups in the chemical structure of photochromic dyes on the rheological and mechanical properties of poly(methyl methacrylate) (PMMA)

Polymer modification has been used as a means to improve the adhesion/bonding of compounds and/or particles to polymer chains, but this goal is not always achieved. Some compounds contain naturally reactive groups which, in contact with the polymer, can modify its properties. This work focused on the rheological (torque and parallel plates rheometry) and mechanical (tensile and impact) characterization of PMMA containing the DV31, DBL3 and DB79 aminic dyes and the DR73 inert dye. The rheological results indicated that the final torque (torque rheometry) varied in response to increasing dye concentrations, and that the various dyes under study exhibited distinct behaviors (parallel plates rheometry). The mechanical tests revealed that, overall, the effect of the dyes on the properties of PMMA was negligible, except for DV31, that led to the decrease in the impact strength, possibly due to the bond between chains or segments of chains of the polymer. The presence, amount and type of amine in the dyes gave rise to significant rheological changes in PMMA because of the reactivity between the amine and the ether group of PMMA.

Visible and near infrared light active photocatalysis based on conjugated polymers

Abstract Conjugated polymers have been used to produce solar energy conversion materials in photovoltaics due to their outstanding light harvesting properties and low-cost processing. However, their photocatalytic activity has only recently been highlighted with the preparation of robust, metal-free, and visible or near-infrared light active photocatalysts. This review describes why the study of photocatalysis based on conjugated polymers has become vivid these days in comparison to inorganic or metal-based photocatalysts, and further illustrates the developed technologies concerning exclusively conjugated polymers but also hybrid structures. The different forms of the conjugated polymer photocatalysts include linear, graphitic C,N-based, porous, nanostructured, and coordinated polymers or polymers with units made of small molecular dye structures. The hybrid systems contain combinations of conjugated polymers with graphene, metals, or metal oxides. A perspective on the challenges posed by the future exploration of photocatalysts based on conjugated polymers is also provided, covering the inherent instability issues of conjugated polymers during the harsh photocatalytic reaction conditions. This review aims to provide an insight for the utilization of conjugated polymers in the fields of photocatalysis, energy conversion, and environment-friendly applications of solar energy.

A novel black crystalline composite based on a fluoran dye and a bisphenol S derivative for high performance thermal papers

A novel black crystalline composite was prepared using a fluoran dye and a bisphenol S derivative for high performance thermal paper. This composite can be potentially applied as a functional black ink without near-infrared absorption. In addition, the coloured structure of the fluoran dye with the developer was successfully analysed.

Biosorption of six basic and acidic dyes on brown alga Sargassum ilicifolium: optimization, kinetic and isotherm studies.

Biosorption of Methyl Blue (MB), Fuchsin Acid (FA), Rhodamine B (RB), Methylene Blue (MEB), Bromocresol purple (BC) and Methyl Orange (MO) onto Sargassum ilicifolium was studied in a batch system. Effect of dye structure on biosorption by Sargassum ilicifolium was studied to define the correlation between chemical structure and biosorption capacity. Different dye groups such as triarylmethane (MB, FA and BC), monoazo (MO), thiazine (MEB) and xanthene (RB) were studied. At optimum experimental conditions for each dye, biosorption capacity was determined and compared. The results indicate that the chemical structure (triarylmethane, monoazo, thiazine, xanthene), number of sulfonic groups, basicity (element of chromophore group: S, N, O) and molecular weight of dye molecules influence their biosorption capacity. Experimental parameters such as biosorbent dose, pH, contact time, and initial dye concentration were optimized for each dye. The biosorption kinetic data were successfully described by the pseudo second-order model. The biosorption results were also analyzed by the Langmuir and Freundlich isotherms. Finally, biosorption capacities obtained using Sargassum ilicifolium were compared with the ones presented in the literature.

Investigation of optical, photocatalytic and physical adsorption of a new nanocomposite synthesized via a simple co-precipitation method

In this experimental work, different morphologies of the CdxZn1-xS/ZnO nanocomposite were synthesized via a simple co-precipitation method. The effect of Zn2+: Cd2+ mole ratio on the product size and morphology was investigated and it was found that the mole ratio has a significant effect on the morphology of the products. To study the crystallinity and purity of the product, X-ray diffraction (XRD) pattern was served. Scanning electron microscopy (SEM) was used to study the morphology of the products. The optical properties of the as-synthesized nanocomposites were studied by ultraviolet-visible (UV-Vis) spectra. Photocatalytic activity of the nanocomposite was carried out by decomposition of Acid Black 1 dye, and it was found after 60min, almost all the dye structure was decomposed under UV radiation. Finally, to study the nanocomposite performance in removing heavy metal ions from water, three different solutions containing Zn2+, Cd2+ and Pb2+ with 0.01 molar concentration were prepared in the aqueous medium and the absorption of them with the nanocomposite was investigated by atomic absorption spectroscopy (AAS). The results showed that the synthesized nanocomposite has a unique performance and it can remove almost 80% of heavy metal ions from the water.

Nano-TiO2-SiO2 powder as inorganic support for hybrid pigment preparation

A study was made of the adsorption of three selected food dyes (C.I. Food Black 1, C.I. Food Brown 3 and C.I. Food Green 4) on the surface of an inorganic, synthetic TiO2-SiO2 support of anatase form. This produces new hybrid pigments having desirable physicochemical and functional properties due to the presence in their structure of the TiO2-SiO2 support. The process of adsorption was conducted for dye concentrations ranging from 10 to 50mg/dm3. The physicochemical properties of the inorganic support and the resulting hybrid pigments were determined. The characterisation included determination of the dispersion and morphology of the systems (particle size distribution, SEM images), porous structure parameters (BET isotherms) and electrokinetic properties (zeta potential and electrophoretic mobility), as well as thermal stability and colorimetric parameters. The efficiency of food dye adsorption on TiO2-SiO2 was examined, and the degree of coverage of the inorganic support with the food dyes was also estimated based on elemental analysis results. The results were used to evaluate the quality of the functional hybrid pigments obtained using selected food dyes and TiO2-SiO2 support, and to determine how the adsorption efficiency is affected by the dye structure. Selected diazo food dyes were more effectively adsorbed on the surface of the synthetic TiO2-SiO2 support. The hybrid pigments obtained have desirable physicochemical and functional properties. The synthesised food dye/TiO2-SiO2 hybrids may be used in pharmaceutical products.

Fine-tuning π-spacer for high efficiency performance DSSC: A theoretical exploration with [formula omitted] based organic dye

Based on density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches, a series of triphenylamine based organic dyes that modified by electron-withdrawing (EW) or electron-deficient (ED) substituent groups are investigated. The properties of all the isolated dyes, including frontier molecular orbital, intramolecular charge transfer, absorption spectra, maximal photon generated current (Jph) and intermolecular interaction between dye and I2 are investigated theoretically to confirm which dyes can produce great performance for dye-sensitized solar cell (DSSC). Subsequently, the structures of dye combined with (TiO2)64 cluster are optimized by means of Vienna ab initio simulation package (VASP) code. Then the interfacial interaction between the dye and semiconductor is further discussed to reveal the interfacial charge injection process by means of interfacial electron transfer code. The importance of fine-tuning π-spacer is also demonstrated by the density of state (DOS) plot and photo-induced charge transfer dynamics. Compared with other dyes, TA-CN dye shows outstanding performance because of the strong coupling of the absorbed dye's orbitals with substrate orbitals and the fast as well as complete charge injection process. The purpose of our study is expected to provide a promising way to design possible candidate sensitizers for DSSC.

A characteristic study on generation and interactive effect of electrocoagulated floc with Direct Green 1 and Reactive Red 2

Abstract The present investigation involves an optimization of the electrocoagulation on aqueous organic dye solutions with two different group of operational conditions namely reactor design such as applied voltage, effective surface area, inter electrode distance, stirring speed and nature of the organic dye solutions such as pH, conductivity, dye concentration, temperature. The experiments are focused on the maximum colour and COD removal with minimum energy and electrode consumption. The kinetic study reveals the colour removal efficiency of two organic dye solutions is decreases from 0.142 to 0.026 min− 1 for DG1 and from 0.119 to 0.023 min− 1 for RR2 with increase in pH. Thermodynamic parameter of ΔH and ΔS shows the endothermic nature of adsorption of dyes. Freundlich constant evidenced the adsorption of both dyes over floc surface is spontaneous. The maximum dye removed per unit area of electrode is 26.8 ppm/cm2 for DG1 and 21.2 ppm/cm2 for RR2 observed at the 10 cm2 effective surface area. The FTIR analysis of floc residue, peak values at 3452.56 and 1496.93 cm− 1 of RR2 alone shifted to 3418.31 and 1425.78 cm− 1 in electrocoagulated floc residue suggests the adsorption of RR2 over iron flocs. The peak at 1493.32 cm− 1 supports the presence of azo group in the parent dye structure of DG1 and disappearance of the peak in electrocoagulated flocs residue evidenced the adsorption of partially degraded dyes on electrocoagulated flocs.

Luminescent Difluoroboron β-Diketonate PLA-PEG Nanoparticle.

Luminescent difluoroboron β-diketonate poly(lactic acid) (BF2bdkPLA) materials serve as biological imaging agents. In this study, dye structures were modified to achieve emission colors that span the visible region with potential for multiplexing applications. Four dyes with varying π-conjugation (phenyl, naphthyl) and donor groups (-OMe, -NMe2) were coupled to PLLA-PEG block copolymers (∼11 kDa) by a postpolymerization Mitsunobu reaction. The resulting dye-polymer conjugates were fabricated as nanoparticles (∼55 nm diameter) to produce nanomaterials with a range of emission colors (420-640 nm). For increased stability, dye-PLLA-PEG conjugates were also blended with dye-free PDLA-PEG to form stereocomplex nanoparticles of smaller size (∼45 nm diameter). The decreased dye loading in the stereoblocks blue-shifted the emission, generating a broader range of fluorescence colors (410-620 nm). Tumor accumulation was confirmed in a murine model through biodistribution studies with a red emitting dimethyl amino-substituted dye-polymer analogue. The synthesis, optical properties, oxygen-sensing capabilities, and stability of these block copolymer nanoparticles are presented.