Interaction Of Dyes Research Articles

Decolorization of safranin using Fissidens species and its ecotoxicological assessments: An in vitro and in silico approach

Decolorization of safranin was investigated using Fissidens species in a batch system under optimized conditions. The decolorization efficiency was improved by optimizing the conditions such as initial pH (3–9), temperature (25–45 °C), initial dye concentration (10–50 mg/L), biosorbent dosage (100–500 mg/L) and contact time (1–6 days). Maximum decolorization (95%) was recorded at initial pH of 6 with dye concentration of 20 mg/L, biosorbent dosage of 200 mg/L at 30 °C and contact time of 2 days. Desorption studies revealed 0.1 N NaOH as the best desorbing agent with 92% recovery on third day. Experimental data well fitted to Langmuir isotherm and Pseudo-second order kinetic model. The negative values of ΔGo and positive value of ΔSo and ΔHo indicates that the reaction is spontaneous, favorable and endothermic. The biosorbent - dye interactions were confirmed using UV–Vis, FT-IR, XRD and FE-SEM with EDX studies. The detoxified nature of the dye degraded metabolites was confirmed by the significant growth of green gram. The color fastness and color strength of the fabrics dyed using Fissidens species treated dye solution were compared with the tap water dyed fabrics which indicated the reuse potential of treated water in textile sector. The decolorization efficiency was further confirmed through in silico approach, where safranin well docked with the active sites of Photosystem II protein D1 of the Fissidens species. Thus, the present study proves that Fissidens species is a promising biosorbent for safranin decolorization and will lay a platform for the control and management of environmental pollution.

Interactions of Novel Phosphonium Dye with Lipid Bilayers: A Molecular Dynamics Study

In the present work the 100-ns molecular dynamics simulations (MD) were performed in the CHARMM36m force field using the GROMACS package to estimate the bilayer location and mechanisms of the interaction between the novel phosphonium dye TDV and the model lipid membranes composed of the phosphatidylcholine (PC) and its mixtures with cholesterol (Chol) or/and anionic phospholipid cardiolipin (CL). Varying the dye initial position relative to the membrane midplane, the dye relative orientation and the charge state of the TDV molecule it was found that the one charge form of TDV, which was initially translated to a distance of 20 Å from the membrane midplane along the bilayer normal, readily penetrates deeper into the membrane interior and remains within the lipid bilayer during the entire simulation time. It was revealed that the probe partitioning into the model membranes was accompanied by the reorientation of TDV molecule from perpendicular to nearly parallel to the membrane surface. The analysis of the MD simulation results showed that the lipid bilayer partitioning and location of the one charge form of TDV depend on the membrane composition. The dye binds more rapidly to the neat PC bilayer than to CL- and Chol-containing model membranes. It was found that in the neat PC and CL-containing membranes the one charge TDV resides at the level of carbonyl groups of lipids (the distances ~ 1.1 nm, 1.2 nm and 1.3 nm from the bilayer center for the PC, CL10 and CL20 lipid membranes, respectively), whereas in the Chol-containing membranes the probe is located at the level of glycerol moiety (~ 1.5 nm and 1.6 nm for the Chol30 and CL10/Chol30 lipid membranes, respectively). It was demonstrated that the dye partitioning into the lipid bilayer does not affect the membrane structural properties.

Fe2+/Fe3+ based MOIFs + dye interaction study: Thermodynamic and kinetic analysis estimated through spectrophotometrically

Herein, the interaction study of organic dyes with newly reported metal organic ionic frameworks (MOIF) based on [Fe(CN)6]3-/[Fe(CN)6]4-/[Fe(CN)5NO]2- and cetylpyridinium cation, investigated through spectrophotometric method. Measurements were carried out at 303.15, 308.15 and 313.15 K where interaction found to be decreased with increase in temperatures. The 60–90% maximum interaction was noted for [Fe(CN)5NO]2- based MOIF with all chosen dyes at 303.15 K inferring the high interaction ability associated with dissymmetry of this MOIF due to presence of different ligands. The oxidation state and hydrophilicophobic domains of MOIFs have been found accountable for the stronger interaction where Fe2+ with high hydrophobicity was found more interacting as compared to Fe3+ with less hydrophobicity. The activation parameters ΔG0, ΔH0 have been found greater for MOIFs and methylene blue dye systems due to stronger interaction of their hydrophobic domains. The ΔS0 noted greater for [Fe(CN)5NO]2- based MOIF showing the impact of availability of interacting sites and distortion in symmetry. The isotherm analysis has inferred about the maximum uniform distribution of binding energy, favorability of interaction, interaction capacity and intensity, was associated with methylene blue and MOIFs systems. The positive slope (2.303/K) of a plot of log(Ao/At) vs t (time) inferred the first order kinetic of MOIF and chosen dyes.

Delineating molecular interactions within surface active ionic liquids + tartrazine dye solutions: A comparative study with conventional surfactant-DTAC

Surface active ionic liquids (SAILs) have been used in various technological fields. Moreover, the deep understanding of interactions exist in SAIL and dye systems will enhance their utility in various fields. In this study, the interactions of cationic Ionic liquids/surfactant 1-Methyl-3-octylimidazoilum chloride [C8mim][Cl], 1-Methyl-3-decylimidazolium chloride[C10mim][Cl], Dodecyl trimethylammonium chloride (DTAC) with anionic dye tartrazine were investigated by state of the art techniques i.e., conductivity, UV–visible spectroscopy, fluorescence spectroscopy and surface tension. The Critical micelle concentration (CMC) of tartrazine-added aqueous ILs/surfactant solutions were obtained, and a decrease is observed after addition of dye. Further, with the increase in alkyl chain length of ILs, the CMC is considerably reduced. Spectroscopic studies reveal a change in spectra of dye which hints ILs/surfactant dye interaction. The binding constant (Kb) is calculated by conductivity, UV-visible, fluorescence methods, which follows the order DTAC>[C10mim][Cl]>[C8mim][Cl]. Computational studies give an idea of the HOMO – LUMO energy gap between the donor and acceptor orbitals of ILs/surfactant and dye, which can be useful in the prediction of the feasibility of interaction between two entities.

Anti-cooperative Self-Assembly with Maintained Emission Regulated by Conformational and Steric Effects.

Herein, we present a strategy to enable a maintained emissive behavior in the self‐assembled state by enforcing an anti‐cooperative self‐assembly involving weak intermolecular dye interactions. To achieve this goal, we designed a conformationally flexible monomer unit 1 with a central 1,3‐substituted (diphenyl)urea hydrogen bonding synthon that is tethered to two BODIPY dyes featuring sterically bulky trialkoxybenzene substituents at the meso‐position. The competition between attractive forces (H‐bonding and aromatic interactions) and destabilizing effects (steric and competing conformational effects) limits the assembly, halting the supramolecular growth at the stage of small oligomers. Given the presence of weak dye–dye interactions, the emission properties of molecularly dissolved 1 are negligibly affected upon aggregation. Our findings contribute to broadening the scope of emissive supramolecular assemblies and controlled supramolecular polymerization.

Study on the effects of cationic dyes species on the structure and performance of sepiolite hybrid pigments

In this work, sepiolite hybrid pigments were prepared with four kinds of cationic dyes with different structures and functional groups, Basic orange 2 (BO2), Mytheme blue (MB), Basic red 18 (BR18) and Basic red 2 (BR2), by the vacuum method. The obtained samples were respectively named as BO2/Sep, MB/Sep, BR18/Sep and BR2/Sep. The sepiolite hybrid pigments were characterized and tested by XRD, FT-IR, Microporous physical/chemical adsorption analyzer, thermal analyzer, et al. The effects of cationic dyes structure and functional groups types on the positions and loading capacity of cationic dyes in sepiolite hybrid pigments were investigated. The results indicated that positions and loading capacity of cationic dyes in sepiolite hybrid pigments are not only related to the size of the cationic dyes but also related to the functional groups and electrical properties of the cationic dyes. The smaller the size of the cationic dyes, the greater the positive charge, and the stronger the functional groups interact with the sepiolite, the greater the amount that enters the sepiolite channel and is adsorbed. The loading capacity of cationic dyes in hybrid pigments dropped as the order MB/Sep, BO2/Sep, BR18/Sep, BR2/Sep. In addition, the position and interaction of cationic dye in sepiolite determine the stability of hybrid pigments. The resistance of hybrid pigments to the acid decreased as the order MB/Sep, BR18/Sep, BO2/Sep, BR2/Sep. In the base medium, the order is MB/Sep, BO2/Sep, BR18/Sep, BR2/Sep. The weatherability of the hybrid pigments was also better than pure cationic dyes.

Polyelectrolyte-Dye Interactions: An Overview.

Polyelectrolytes are polymers with repeating units of ionizable groups coupled with counterions. Recently, polyelectrolytes have drawn significant attention as highly promising macromolecular materials with potential for applications in almost every sector of our daily lives. Dyes are another class of chemical compounds that can interact with substrates and subsequently impart color through the selective absorption of electromagnetic radiation in the visible range. This overview begins with an introduction to polyelectrolytes and dyes with their respective definitions, classifications (based on origin, molecular architecture, etc.), and applications in diverse fields. Thereafter, it explores the different possible interactions between polyelectrolytes and dyes, which is the main focus of this study. The various mechanisms involved in dye–polyelectrolyte interactions and the factors that influence them are also surveyed. Finally, these discussions are summarized, and their future perspectives are presented.

Effect of the Ancillary Ligand on the Performance of Heteroleptic Cu(I) Diimine Complexes as Dyes in Dye-Sensitized Solar Cells.

A series of heteroleptic Cu(I) diimine complexes with different ancillary ligands and 6,6′-dimethyl-2,2′-bipyridine-4,4′-dibenzoic acid (dbda) as the anchoring ligand were self-assembled on TiO2 surfaces and used as dyes for dye-sensitized solar cells (DSSCs). The binding to the TiO2 surface was studied by hard X-ray photoelectron spectroscopy for a bromine-containing complex, confirming the complex formation. The performance of all complexes was assessed and rationalized on the basis of their respective ancillary ligand. The DSSC photocurrent–voltage characteristics, incident photon-to-current conversion efficiency (IPCE) spectra, and calculated lowest unoccupied molecular orbital (LUMO) distributions collectively show a push–pull structural dye design, in which the ancillary ligand exhibits an electron-donating effect that can lead to improved solar cell performance. By analyzing the optical properties of the dyes and their solar cell performance, we can conclude that the presence of ancillary ligands with bulky substituents protects the Cu(I) metal center from solvent coordination constituting a critical factor in the design of efficient Cu(I)-based dyes. Moreover, we have identified some components in the I–/I3–-based electrolyte that causes dissociation of the ancillary ligand, i.e., TiO2 photoelectrode bleaching. Finally, the detailed studies on one of the dyes revealed an electrolyte–dye interaction, leading to a dramatic change of the dye properties when adsorbed on the TiO2 surface.

Adsorption of organic dyes on macroporous melamine sponge incorporating conducting polypyrrole nanotubes

AbstractThe macropores of melamine sponge were coated with globular polypyrrole or polypyrrole nanotubes. The resulting materials have been tested for the adsorptive removal of organic dyes from aqueous medium. The nanotubes deposited on the sponge were able to remove Reactive Black 5 dye while the adsorption on analogous polypyrrole globules was marginal. For that reason, the macroporous open‐cell melamine sponge with embedded nanotubes was tested for the adsorption of five anionic and five cationic dyes. The anionic dyes were adsorbed efficiently in the contrast to cationic ones. This can be explained by the electrostatic interaction of anionic dyes with polypyrrole polycation. The fast‐starting adsorption occurred within a few minutes and was followed by a slower process extending for days. The nanotubes deposited on the sponge have always been more efficient adsorbents than free polypyrrole nanotubes or melamine sponge alone. Better organization of polymer chains in the polypyrrole nanotubes and especially those deposited on the melamine sponge is proposed to be responsible for this effect. Cationic dyes were adsorbed even by neat melamine sponge while the adsorption by polypyrrole was negligible. In this case, the indifferent role of polypyrrole can be assigned to the electrostatic repulsion of the dye.

Interaction of Indigo carmine with naturally occurring clay minerals: An approach for the synthesis of nanopigments

Dyes are organic colorants used in textile, paint, printing and many more industries for different purposes, especially to make the products more attractive. However, these organic compounds can not be removed easily from water bodies due to their non-biodegradable nature. In this context, this paper aims at the application of clay minerals and their organo forms which were used to remove the anionic dye, Indigo Carmine from aqueous media at different conditions such as pH, contact time and initial concentration by employing batch extraction method. Synthesis of organo clay was done through ion-exchange method using cationic surfactant (Cetylpyridinium chloride). The adsorbents (before and after adsorption of dye) were characterized using different analytical techniques like X – Ray diffraction, Fourier Transform Infra-Red spectroscopy, UV–vis spectroscopy. During the study, it was found that the efficiency for uptake of anionic dye was more for organo clay (Organo Montmorillonite − 330 mg g−1 and Organo Bentonite − 468 mg g−1) at favorable acidic condition as the surface of Montmorillonite and Bentonite become positively charged after interaction with surfactant results in electrostatic interaction between dye and organo clays. As there was no significant change in diffraction peak of adsorbent after interaction with dye suggested the surface interaction of dye which was further supported by FT-IR studies.

A Study of Methylene Blue Dye Interaction and Adsorption by Monolayer Graphene Oxide

The graphene oxide (GO) interaction with methylene blue (MB) cationic dye was studied in an aqueous solution at different pH during MB adsorption. The mutual interaction of MB with GO surface was studied and evaluated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The π- π and electrostatic interaction of MB with GO surface are the main types of interactions, and the XRD data show the monomeric arrangement of MB cation with GO. The GO surface functional groups and point of zero charge (PZC) were determined by acid-base titration. Suitability of zeta-potential measurement and acid-base titration method was briefly discussed. The quality of prepared GO was evaluated by Raman spectroscopy, XRD, and atomic force microscope (AFM). The experimental adsorption equilibrium data were analyzed using Langmuir, Langmuir-Freundlich, Freundlich, and Temkin isotherms. The GO maximum adsorption capacity increases with higher pH, that is ascribed to the facile interaction of negatively charged GO with positively charged MB structure.

Enhanced fluorescence signal using stray light shutter in a quantitative PCR chip

Quantitative polymerase chain reaction (qPCR) is the most important quantitative sensing technique for pathogens, especially for emerging pandemics such as the coronavirus outbreak this year. The qPCR chip and device were investigated to meet the unmet needs of ultrafast inspection time, high accuracy, and small system volume. Therein, the fluorescence intensity was the most important signal in qPCR quantification of DNA amplifications, which is essential not only in the confirmative diagnosis of positive or negative infection, but also in the assessment of viral load for therapeutic and quarantine decision making. As the target DNAs got amplified, the interaction of fluorescence dye and double strand DNA will generate fluorescence signal proportional to amplified DNA in the intensity when excited by certain wavelength. A miniature spectro-detector was employed to receive the fluorescence scattering for digital output of the intensity in the qPCR chip in this study, and the optical simulation and actual experimental design and results according to the optical simulation results were performed to study the effect of the stray light shutter (SLS) in the improvement of the signal in fluorescence detection. The analysis results showed that the signal-to-noise ratio (SNR) of the fluorescence can be enhanced significantly for five times of the control using the SLS with a shape of extended component aperture, where the protruding structure was positioned away from the center. The experimental results showed that fluorescence intensity can be enhanced by 15.50% and 9.86% when adding the above shape of SLS in resin- and in glass-based chip, respectively. The results also demonstrated that the optical setup had good stability and repeatability in fluorescence detection, and variation was less than 1.00%. Our results can provide important reference to the development of qPCR chip to obtain the high SNR fluorescence signal in DNA quantification process.

Cyclic oligosaccharides as controlled release complexes with food additives (TZ) for reducing hazardous effects

The host–guest interaction of an important dye, Tartrazine, with α and β-Cyclodextrins, was inspected. To evaluate the inclusion's saturation concentration and stoichiometry, two simple although dependable physicochemical approaches, conductance, and surface tension, were initially used. The UV–Vis research validated the 1:1 stoichiometry of the inclusion complexes and was also used to investigate the feasibility of this inclusion procedure by evaluating the stability constants and thermodynamic parameters with great accuracy. The mechanism of inclusion was exposed by 1H NMR and FTIR spectroscopic analysis, and the surface structures were shown by SEM examination. The development of inclusion complexes is supported by all characteristics, which are described by hydrophobic effects, H-bonds, electrostatic forces, and structural effects. Without any chemical modifications, this study predicts the releasing behavior of TZ in the presence of CT-DNA. The Fenton and Photo-Fenton processes were used to study the degradation of the inclusion complexes formed found to be prominent results upon environmental aspects. Optimized geometries, adsorption energies, Non-Covalent Interaction (NCI), and electrostatic potential maps (ESP) are also assessed using Density Functional Theory to confirm experimental results.

Cation–Anionic Interactions of Dyes in Aqueous Solutions: Bromocresol Purple in the Processes of Dissimilar Association

The interaction between single- or double-charged anions of bromocresol purple (BP) and cyanine cations (quinaldine blue, QB, or quinaldine red, QR) at concentrations of dyes 5.0·10−7–4.0·10−5 mol/L has been investigated by vis-spectroscopy. The thermodynamic constants of dissimilar associations (Kas) have been studied. Comparison of the values of lg Kas shows that QB− associates of BP− are more stable (6.61 ± 0.07) than QR associates (4.84 ± 0.06); a similar phenomenon is observed for associates of the BP2− anion. Semi-empirical calculations (PM3 method) are in agreement with the vis-spectroscopy data and indicate that the association of dye into an associate is possible. The standard enthalpies of formation of associates (ΔfHo) and energy diagrams have been determined. The ΔfHo data indicate that the formation of an associate between dye ions is an energetically favourable process. The gain in energy significantly exceeds the systematic error of semi-empirical calculations and increases from 157 kJ/mol (associate ”BP− + QB+”) to 729 kJ/mol (associate “BP2− + QR+”). The most probable structures of dissimilar associates are presented. The study of the dissimilar association develops the concept of intermolecular interactions in solutions.

Polythiophene based fluorimetric insight into minute styrene concentration in solution and gas phase

Water immiscible organic solvents dispersed in aqueous phase raise concerns due to persistence in environment and high toxicity. Fast and operation-simple approaches to assess their contents outside specialized laboratories are required. In this work an original approach allowing quantification of minute amounts of styrene present in solution or in gas phase is proposed. Polythiophene - poly[3-(ethyl-6-hexanoate)thiophene-2,5-diyl] (PeHT) - nanoparticles were applied as probes, offering an increase of emission intensity upon the rise of styrene contents in the sample. The response mechanism is based on the interaction of the polymer dye with analyte; at lower concentrations, the increase of emission at wavelengths typical for nanoparticles emission suggests interactions of the analyte with polymer chains in nanostructural form and offers selectivity. On the other hand, with increasing styrene contents in solution, polythiophene tends to form nano-dispersion droplets in the analyte resulting in appearance of emission peak characteristic for solvent dispersed polymer. A linear dependence of emission intensity on styrene concentration in solution was observed within the range from 0 to 200 ppm. The proposed approach benefits from full reversibility of sensors, upon spontaneous evaporation of styrene from solution. Finally, the nanoparticle suspension allows to detect the presence of styrene also in the vapor phase due to its solubilization in water (Henry's Law). Emission changes were observed in case of 0–2100 ppm of styrene vapor in the probe headspace, corresponding to 0–80 ppm styrene in solution. For the sake of comparison another polythiophene derivative, poly(3-octylthiophene-2,5-diyl) (POT), was investigated showing no changes in fluorescence emission spectra in the presence of styrene up to 200 ppm.

Interactions of Novel Phosphonium Dye with Lipid Bilayers: A Fluorescence Study

The phosphonium-based optical probes attract ever growing interest due to their excellent chemical and photophysical stability, high aqueous solubility, long wavelength absorption and emission, large extinction coefficient, high fluorescence quantum yield, low cytotoxicity, etc. The present study was focused on assessing the ability of the novel phosphonium dye TDV to monitor the changes in physicochemical properties of the model lipid membranes. To this end, the fluorescence spectral properties of TDV have been explored in lipid bilayers composed of zwitterionic lipid phosphatidylcholine (PC) and its mixtures with cholesterol (Chol) or/and anionic phospholipid cardiolipin (CL). It was observed that in the buffer solution TDV possesses one well-defined fluorescence peak with the emission maximum at 533 nm. The dye transfer from the aqueous to lipid phase was followed by the enhancement of the fluorescence intensity coupled with a red shift of the emission maximum up to 67 nm, depending on the liposome composition. The quantitative information about the dye partitioning into lipid phase of the model membranes was obtained through approximating the experimental dependencies of the fluorescence intensity increase vs lipid concentration by the partition model. Analysis of the partition coefficients showed that TDV has a rather high lipid-associating ability and displays sensitivity to the changes in physicochemical properties of the model lipid membranes. The addition of CL, Chol or both lipids to the PC bilayer gives rise to the increase of the TDV partition coefficients compared to the neat PC membranes. The enhancement of the phosphonium dye partitioning in the CL and Chol-containing lipid bilayers has been attributed to the cardiolopin- and cholesterol-induced changes in the structure and physicochemical characteristics of the polar membrane region.

THE RESEARCH OF QUALITY OF THERMOTRANSFER PRINT IMAGES ON COTTON TEXTILE MATERIAL

The article presents thermogravimetric studies of cotton textile material before and after printing by thermal transfer printing. Thermal transfer printing on garments and knitwear, umbrellas, bags, advertising banners, posters, etc. is popular. Transfer printing technology involves the transfer of the image to the textile material using an intermediate medium. First, the desired image is formed on a special paper or film using screen printing. Then, with the help of temperature in special presses, it is transferred to the textile material. If the image is multicolored, the whole process is repeated separately for each color. Heat transfer technology allows to apply high- and multi-color images to finished products or semi-finished products with high accuracy; to carry out personalized printing. Since thermal transfer printing involves the presence of high temperatures to obtain an image on the material, a comprehensive thermal analysis of cotton fabric was performed before and after printing. A test scale with a raster line from 100 to 140 lines / cm was used for research. Densitometric indicators of quality of the formed thermotransfer images by plastezol paints are given. It is established that with the increase of the line of raster images the color indicators of the prints on the textile material decrease slightly, which must be taken into account when fulfilling orders in industrial conditions. Using electron microscopy, the process of interaction of dye with cotton fibers in the fixation of printed images was studied. Significant influence on the quality of prints on textile material of surface structure of cotton fibers, their structure, dye composition and printing modes is confirmed. It is established that cotton fabric with printed image at 140 oC provides high quality color printed thermal transfer images. This is confirmed by such qualimetric indicators as optical density, image contrast, brightness. Modeling the mechanism of fixing the printed image on the fabric during thermal transfer printing can be divided into four stages: diffusion of the dye from the environment to the surface of the fibers; sorption of the dye on the surface; diffusion of dye inside the fiber; sorption of the dye on the inner surface of the fiber, which require more detailed and in-depth studies.

ADSORPTION OF TURQUOISE BLUE DYE FROM AQUEOUS SOLUTION ONTO ACID ACTIVATED CARBON PREPARED FROM PTEROCARPUS MARSUPIUM BARKS

Adsorption interaction of Turquoise Blue dye from aqueous solution onto acid and base surface modified activated carbons prepared from Pterocarpus Marsupium barks using microwave and phosphoric acid were investigated. Batch method adsorptions were carried out. Influences of the parameters such as agitation time, initial dye concentrations and temperature on adsorption were studied. Equilibrium data were fitted with Langmuir, Freundlich, Tempkin and Dubinin-Raduskevich isotherms. Best describing isotherms were ordered based on R2 values.

Molecular interaction of Sunset Yellow with whey protein: Multi-spectroscopic techniques and computational study

Sunset Yellow (SY) dye is an essential component in the food, pharmaceutical, and cosmetic, industries. Therefore, we studied its interaction with whey protein (β-lactoglobulin (β-LG)) using spectroscopic and molecular modeling techniques at pH 7.4. Intrinsic fluorescence data at three different temperatures suggested that the fluorescence intensity decreased upon the addition of SY dye. The fluorescence quenching constant (Ksv) values decreases in response to increase in temperature which signified the a static quenching mechanism was taking place between SY and β-LG. The thermodynamic data revealed that hydrophobic interaction was dominantly involved in the SY–β-LG interaction. The negative sign of standard Gibbs free energy (ΔG°) denoted that the SY-β-LG complex formed via spontaneous molecular interaction. The UV–Vis spectroscopy results showed that the absorbance of β-LG increased with increasing SY concentration because of complex formation. The far-UV CD data suggested that the secondary structure of β-LG increased in the presence of SY dye and the overall β-LG conformation changed. Molecular docking results showed the high-affinity binding (-11.27 kcal/mol) of SY with β-LG through hydrogen bonds and hydrophobic interactions. This study provides detailed information about food additive dye interactions with dairy products and shows conformational changes of dairy proteins due to interaction with dye.

Effect of Adsorption Structure upon Directional Charge Transfer and Electronic Coupling in a Hybrid Dye Sensitizer based on a Cadmium Sulfide Quantum Dot

Dye‐functionalized quantum dots (QDs) show promise for solar photovoltaic and photocatalytic applications. However, the energy conversion efficiencies are very sensitive to the chemical environment at the QD–dye interface, which is dependent upon how the QDs and dye interact. Herein, the effect of different surface orientations for an N749 dye attached to a CdS QD upon QD–dye interactions is investigated. The results reveal that the electronic couplings for binding configurations that involve isothiocyanate anchors are generally larger than those involving carboxylate anchors. Furthermore, for some binding modes, the electronic couplings for hole transfer are comparable to those for electron transfer, implying efficient charge separation at the QD–dye interface and reduced electron–hole recombination within the QD. It is also found that the most stable adsorption geometries for the dye are those with double carboxylate anchors, which exhibit weaker electronic coupling than isothiocyanate anchors and provide favorable energy alignment for hole transfer. Overall, the current computational study reveals some fundamental aspects concerning the relationship between interfacial charge transfer for QD/dye composites and their morphologies, such as the binding geometry of the dye, interfacial energetics and donor–acceptor interactions, which benefits the design of QD‐based nanomaterials for photovoltaic and photocatalytic applications.