Betalain Dyes Research Articles

A DFT study on natural sensitizers with donor-π-acceptor architecture based on 1,7-diazaheptametine for applications in Dye-Sensitized Solar Cells (DSSC)

Nature offers a wide range of organic dyes with potential as sensitizers in DSSC technology. Among them, some natural dyes contain a 1,7-diazaheptamethine system, influencing their chromatic properties. In this investigation, we computationally analyzed 21 natural betalain dyes featuring a common structural moiety through Density Functional Theory calculations. Among them, eight dyes were classified under the betacyanin subfamily, while the remaining thirteen were attributed to the betaxanthin subfamily. These dyes were examined both in isolation and when bound to titanium dioxide (dye@TiO2). The betaxanthin subfamily showed more twisted geometries, while the betacyanin subfamily exhibited a smaller energy gap. All isolated dyes or dyes@TiO2 exhibit maximum absorption peaks within the visible region (350–700 nm), showcasing their light-capturing capacity. Stability, evidenced by negative adsorption energies, suggests the spontaneity of the adsorption process. Furthermore, our results indicate that the nature of bonding significantly influences the electronic properties of dye@TiO2 complexes. Collectively, these results underscore the importance of the 1,7-diazaheptamethine system in imparting color and structure to these dyes. Our thorough analysis, encompassing molecular interactions, geometric attributes—especially the configuration of donor groups—electronic properties, and absorption spectra, provides valuable insights into the potential applications and effectiveness of these dyes for incorporation in dye-sensitized solar cells (DSSC).

Properties and application of betalaine dye isolated from regional beet variety

Relevance. Consumers in todayʼs society are concerned about the safety of using synthetic dyes to color food. The development and use in the food industry of natural dyes compositions based on available plant materials remains relevant. The use of natural dye based on betalains — pigments of beets (Beta vulgaris) — in the production of food products, allows not only to improve the color range of products, but also to enrich them with biologically active compounds. The objects of the study are beetroot pigments betalaines, concentrated natural dye and cream «Glace» with the addition of concentrated betalain dye.Results. Depending on the experimental conditions, betalains were extracted from plant materials. The organoleptic and physico-chemical parameters of the concentrated natural dye and cream «Glasse» with its addition were studied.Results. It has been shown that the optimal conditions for isolating betalains from beets are their extraction with 95% ethanol, ultrasonic extraction at 25 ºC, and extraction with an aqueous solution at 60 ºC for 30 min. It has been determined that the most stable color of the pigment is maintained in the range of pH = 3.7–8.2. In the region of pH > 10 there is a sharp change of the color. Betalain extracts at a pH > 10 acquire a rich dark red color. It was shown that the betalain dye obtained by the concentration method is a dark red liquid, which has antiradical activity (1,49 мМ) and contains 11 mg/cm3 of betalains. The best organoleptic characteristics were found in the cream «Glasse» with the addition of 5% concentrated betalain dye.

Anar Phali (Opuntia ficus) juice extract as a novel pollution-free source of natural betalain dye for wool yarn.

Green products such as plant pigments in all filed are gaining fame globally due to their excellent ayurvedic and biological characteristics. In this study, microwave rays have been employed for the isolation of colorants from Anar Phali while bio-mordant have been included to get color-fast shades. The colorant was isolated in an acidic medium before and after microwave rays for 2min. For getting darker shades with different tints, sustainable chemical and plant-based extracts as bio-mordant have been employed before and after bio coloration of wool yarn at given conditions. CIE Lab system computed in Colori-spectrophotometer (CS-410) was used to observe the change in color depth and tonal variation of dyed fabrics, and ISO standard methods have been employed to rate the colorfastness to light, washing, and rubbing at grey scale. It is concluded that microwave rays have an excellent sustainable efficacy to isolate colorant from Anar Phali powder for wool dyeing, whereas the addition of bio-mordants has made the process more sustainable and eco-friendly.

Betacyanins are plant-based dyes with potential as histological stains

ABSTRACT Interest is increasing in certain parts of the world in replacing synthetic dyes with dyes from natural sources, particularly from plants. Although textile dyers have used various groups of natural dyes, microscopists generally have restricted their use to anthocyanins. Recently, however, another class of plant-based dyes has found some favor, the betacyanins. Betacyanins are a group of red and violet betalain dyes found only in certain plants of the order Caryophyalles and in Basidiomycetes mushrooms. Although the chemical structures of betacyanins are known, little use has been made of that information to understand or predict their behavior with biomedical specimens. We investigated two common, widely distributed betacyanin-containing plants, edible beets (Beta vulgaris) and wild pokeweed (Phytolacca americana). Aqueous alcoholic extracts were made from beet root and pokeweed berries, adjusted to pH 4.1 or 5.3 and used together with Harris’ hematoxylin to stain histological sections. We used a methanolic extract of pokeweed berries, pH 3.0, to stain cultured mycological specimens. Both extracts produced satisfactory staining that was equivalent to that of eosin Y, although the colors were more muted with the beet root extract. Epithelial cytoplasm, muscle, collagen and erythrocytes were well demonstrated. Betanin is the predominant component of beet root extract; it possesses one delocalized positive charge and three carboxylic acid substituents. The dyes are weak acids and the carboxylate anions are more diffuse than for eosin Y; this produces weaker bonding to tissue cations. The principal colored component of pokeweed berries, prebetanin, possesses a sulfonic acid group as well as carboxylic acids, which favors acid dyeing and more intense coloration. Both dyes show potential for hydrogen bonding and to a much lesser extent for some types of van der Waals forces. Complex formation with metals such as aluminum to create a nuclear stain is not likely with beet root dyes nor is it possible with pokeweed dyes. Betacyanins are suitable for staining microscopy preparations in place of other red acid dyes such as eosin. Of the two dyes tested here, prebetanin from pokeweed berries was superior to betanin from red beet roots. These berries are widely distributed and readily collected; the extraction procedure is simple and does not require expensive solvents.

Effect of Some Heavy Metal Ion on the Efficiency of Some Natural Dyes Solar Cells with Titanium Dioxide

Solar cells were made from natural pigments such as the anthocyanin pigment extracted from berry juice, henna leaves and roselle, betalain dye extracted from beets and red cabbage, and yellow curcumin dye extracted from turmeric with titanium dioxide. The ions of some metals are used with some dyes in the formation of cell electrodes with titanium oxide and zinc oxide. The mixture is heated to 450 ºC and makes electrodes that have a higher ability to absorb natural dyes, which increased the cell current and raised the percentage of cell efficiency. Natural red dyes (anthocyanins dye with the metals Cd, Zn, Pb, Hg, and Cu, dye-sensitized DSSCs have cell efficiency of 1.340%, 1.326%, 1,147%, 1,369%, and 1,325%, respectively. Betalain dyes, with the metals Zn, Hg, and Cu, dye-sensitized DSSCs have the cell efficiency of 1.369%, 1.385%, and 1.261%, respectively,) and natural yellow(curcumin dye) with the metals Zn, and Pb, dye-sensitized DSSCs have the cell efficiency of 1.301%, and 1.384%, respectively. This worked to increase the electrical conductivity of the electrodes. Possibly these inorganic substances act as aggregation factors for these pigments on the poles of the cell, which increases the efficiency of the cell.

Ternary Ni0.5Zn0.5Fe2O4/carbon nanocomposite as counter electrode for natural dye-sensitized solar cells: Electro-photovoltaic characterizations

The most notable counter electrode (CE) in dye-sensitized solar cells is platinum (Pt), which is expensive and scarce. Here, Ni0.5Zn0.5Fe2O4/carbon (NZF/C) composites containing different ratios of carbon were synthesized and used as novel counter electrodes. NZF/Cs have specific surface areas of 109.3–128.6 m2 g−1, pore sizes of 99.4–119.6 Å, and bandgap energies of 2.36–2.99 eV, according to the characterization results. The catalytic activities of NZF/C CEs were verified by electrochemical impedance spectroscopy and cyclic voltammetry. NZF/Cs demonstrated outstanding catalytic activities in the reduction of I3− and had performance comparable to Pt CEs in the dye-sensitized AgNP/TiO2 DSSCs. For the natural betalain dye, NZF/C-1 CE demonstrated a 2.75% efficiency with a short circuit current density of 4.13 mA cm−2 and a fill factor of 50.71%, which was very competitive with Pt CE's 2.83% efficiency. During 30 days of stability testing, NZF/C-1 CE maintained a photon conversion efficiency of 7.18% and a fill factor of 55.57% for Z-907 synthetic dye. The high electrocatalytic activity of NZF coupled with the good conductivity of carbon black account for NZF/C performance. The results herein show that NZF/C can be used as a cost-effective and efficient substitute for Pt in DSSCs.

Application of Natural Betalain Dye from Beetroot for Improved Efficiency in Dye Sensitized Solar Cell

C, N, S co-doped TiO2 (TU-TiO2) synthesized through solid state method using high energy ball milling was applied onto fluorine doped tin oxide (FTO) glass substrate and sintered at 450° C for half hour for use as a photoanode of dye-sensitized solar cells (DSSCs). Natural Betalain containing dye extracted from beetroot was used as sensitizer, Iodide triodide was used as electrolyte and graphite as counter electrode to obtain FTO/C, N, S-TiO2/Dye/Electrolyte/Graphite/FTO DSSC. X-ray Diffraction analysis established the formation of single phased materials retaining the basic TiO2 structure. Optical properties were enhanced with increase in molar concentration of thiourea in TiO2. Fourier Transform Infrared spectroscopy confirmed the incorporation of sulphur into TiO2. The highest of 94% relative increase is observed in solar to electric conversion efficiency for C, N, S co-doped TiO2 compared to un-doped TiO2. Along with decrease in the band gap making the cell more sensitive to visible light, the improved performance is also due to the rise in charge injection from betalain dye to the C, N, S co-doped TiO2.

Enhancement in photostability of betalain dye from basella Alba fruits using zinc oxide nanoparticles

Recently environmental pollution due to industrial effluents is a major concern for researchers, so the development of natural dyes is widely accepted due to their low cost, biodegradability, low toxicity, and non -carcinogenic nature and also replaces existing hazardous chemicals in industries. Many plants and fruit extracts can be used as natural dyes, but their efficiency depends on photostability and photo degradation activity. Herein reported extraction of natural dye fromBasella Alba fruit using different solvents and photo stability was investigated under UV and visible light. To enhance the stability of extracted pure dye, zinc oxide nanoparticles were added and it acts as an excellent photostabilizer that shows better performance over betalain dye. UV visible spectrum of pure dye shows an absorbance peak of 480 nm and functional groups of both dye and zinc oxide were identified by FTIR spectrum. The structure and surface morphology of the synthesized nanoparticle was confirmed by UV–Visible, XRD, SEM-EDAX and TEM analysis. The crystalline structure of zinc oxide was confirmed by XRD and composition was analyzed by EDAX studies. The wurtzite type structure of zinc nanoparticle was confirmed by XRD. The external morphology of prepared zinc oxide nanoparticles is captured using FESEM. The HRTEM and SAED images are confirmed the crystalline structure of the synthesized material. The photostability and photodegradation studies were performed under UV light and at various temperatures like 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C. These results clearly show a piece of evidence for the usage of nanoparticles for enhancing photostability of natural dyes.

Fabrication of natural dye sensitized solar cell using tridax procumbens leaf and beetroot extract mixer as a sensitizer

Chlorophyll and betalain dye pigment extracted from tridax procumbens leaf and beetroot, which was used as a sensitizer for natural dye sensitized solar cell (NDSSC). Titanium dioxide (TiO2) powder was synthesized by co-precipitation method with cetyltrimethylammonium bromide (CTAB) act as a surfactant. The prepared TiO2 sample was characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and UV–Vis absorption spectra to analysis the structural, morphological and optical properties studies were carried out. The as prepared TiO2 nanopowder was pasted on conducting surface of FTO glass slide by using doctor blade method and triton X-100 used as a binder. The optical properties of the natural dyes were also investigated and present work aqueous lugol’s iodine was used as electrolyte. The 1:1 ratio of Chlorophyll and betalain dye mixer was used as a sensitizer in NDSSC and shown solar cell efficiency about 0.11% was achieved under one sun solar simulator (1.5 AMG).

A bioinspired nitrone precursor to a stabilized nitroxide radical

Nitrones derived from natural antioxidants are emerging as highly specific therapeutics against various human diseases, including stroke, neurodegenerative pathologies, and cancer. However, the development of useful pseudo-natural nitrones requires the judicious choice of a secondary metabolite as the precursor. Betalains are nitrogen-containing natural pigments that exhibit marked antioxidant capacity and pharmacological properties and, hence, are ideal candidates for designing multifunctional nitrones. In this work, we describe the semisynthesis and properties of a biocompatible and antioxidant betalain-nitrone called OxiBeet. This bio-based compound is a better radical scavenger than ascorbic acid, gallic acid, and most non-phenolic antioxidants and undergoes concerted proton-coupled electron transfer. The autoxidation of OxiBeet produces a persistent nitroxide radical, which, herein, is studied via electron paramagnetic resonance spectroscopy. In addition, femtosecond transient absorption spectroscopy reveals that excited state formation is not required for the oxidation of OxiBeet. The results are compared with those obtained using betanin, a natural betalain, and pBeet, the imine analog of OxiBeet. The findings of this study will enable the development of antioxidant and spin-trap nitrones based on the novel N-oxide 1,7-diazaheptamethinium scaffold and betalain dyes with enhanced hydrolytic stability in aqueous alkaline media.

Enhancing the Conversion Efficiency of Dye-Sensitized Solar Cells based on Betalain Natural Dye as The Potential Photosensitizer: A Review

Natural dyes have gained much attentions as the cheap photosensitizer for dye-sensitized solar cells because of their abundant availability in nature. One of potential natural dyes is betalain dye. Betalain dye mostly can be found in family plant of Caryophyllales. This dye has carboxyl groups and can absorb light until wavelength of 600 nm since betalain dye can be in red-purple color. However, betalain dye is still reported to give a lower efficiency in dye-sensitized solar cells device because of its nature properties as compared to the synthetic dyes. This encourages many researchers to investigate the method for developing betalain ability in purpose to enhance the cell device efficiency. To date, there are two methods having been reported for their positive results in increasing the efficiency of cell device based on betalain dye, i.e., combining the betalain dye with other natural dyes, and selecting the suitable solvent and pH in betalain dye extraction. Therefore, in this review, the summary about potential of betalain dye as photosensitizer and what properties of this dye have as the photosensitizer would be described. The summary of methods for optimizing betalain dye in improving the conversion efficiency of dye-sensitized solar cell also will be presented for better understanding the potential of this dye.

A Comparative of Nutritional Impacts of Pomegranate and Beetroot on Female Mice Bearing Ehrlich Ascites Carcinoma

The present research was pointed to the protective impact of anthocyanin and betalain dye of pomegranate juice (P), beetroot juice (BR), and their mixture (PB) versus Ehrlich-ascites-carcinoma (EAC)-bearing female mice. Female mice were orally administrated with pomegranate, beetroot juices and their mixture (1 ml/ day), for sequential 15 days then, injected (i.p) by EAC. Cisplatin drug was injected two times as a comparative chemical drug. The results manifested that P BR and PB juices as antho

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.

Study of Sulphur doped TiO2 dye sensetized solar cell

The commercially available and relatively cheap TiO2 was doped with sulphur (source of sulphur used was thiourea) by simple and effective mechanical process of ball milling and has been used as a photoanode of dye- sensitized solar cells (DSSCs).These TiO2 films were synthesized on to the fluorine doped tin oxide (FTO) coated glass substrates followed by sintering at 450°C for half an hour. Betalain dye was extracted from fresh beetroot and graphite was used as counter electrode. The film shows tetragonal structure having high crystallinity. The solar to electric conversion efficiency for these solar cells have increased on doping it with sulphur. A relative 21% increase in conversion efficiency is observed for sulphur doped TiO2 than that of un-doped TiO2. The improved performance is attributed to the rise in charge injection from dye to the sulphur doped TiO2

Electron injection in anthocyanidin and betalain dyes for dye-sensitized solar cells: a DFT approach

A theoretical investigation was carried out using density functional theory at the MN12SX/6-311+G(d,p) level of theory to calculate and compare the photoinduced electron injection for selected members of the anthocyanidin and betalain families. The rate constant of the injection for both families was calculated, and it was verified that the regeneration in the dye during the DSSC operation is caused by an energetic electron injection of the matched electrons in the dye. The present research shows that the rate constant of electron injection of the selected anthocyanidin family was very rapid: Aurantinidin has the overall best injection rate for both families. Aromaticity, the open-circuit voltage \({V}_{{\mathrm{oc}}}\), the \(\Delta {G}_{\mathrm{inject}}\) and \(\Delta {G}_{\mathrm{reg}}\) values for the selected molecule play a vital role in the comparison of both selected families. A prediction of the best dye based on the above properties was made for the maximum efficiency of the DSSC to be achieved.

Natural dyes from red amaranth leaves as light-harvesting pigments for dye-sensitized solar cells

This study reports red amaranth as a source of two natural dyes to be used as low cost sensitizers for wide bandgap semiconductors in dye sensitized solar cells. The two dyes were identified as Chlorophyll and Betalain from their characteristic absorption spectra. The photo electrochemical properties of dye sensitized solar cells using natural pigments containing Chlorophyll and Betalain was investigated in this work. The results indicate that the Chlorophyll dye shows a maximum photocurrent density of 1.3mA/cm2 with an energy conversion efficiency (η) of 0.53%. The Betalain dye showed a photocurrent density of 0.87mA/cm2 with energy conversion efficiency (η) of 0.23%. The better performance of chlorophyll dye as sensitizer for dye sensitized solar cells was supported by electrochemical impedance spectroscopy and bode plot measurements.

Extraction, preparation and application of pigments from Cordyline fruticosa and Hylocereus polyrhizus as sensitizers for dye-sensitized solar cells

Current study employs mixture of chlorophyll-anthocyanin dye extracted from leaves of Cordyline fruticosa as new sensitizers for dye-sensitized solar cell (DSSCs), as well as betalains dye obtained from fruit of Hylocereus polyrhizus. Among ten pigments solvents, the ethanol and methanol extracts revealed higher absorption spectra of pigments extracted from C. fruticosa and H. polyrhizus respectively. A major effect of temperature increase was studied to increase the extraction yield. The results indicated that extraction temperature between 70 and 80°C exhibited a high dye concentration of each plant than other temperatures. The optimal temperature was around 80°C and there was a sharp decrease of dye concentration at temperatures higher than this temperature. According to experimental results, the conversion efficiency of DSSC fabricated by mixture of chlorophyll and anthocyanin dyes from C. fruticosa leaves is 0.5% with short-circuit current (Isc) of 1.3mA/cm−2, open-circuit voltage (Voc) of 0.62V and fill factor (FF) of 60.16%. The higher photoelectric conversion efficiency of the DSSC prepared from the extract of H. polyrhizus was 0.16%, with Voc of 0.5V, Isc of 0.4mA/cm−2 and FF of 79.16%. The DSSC based betalain dye extracted from fruit of H. polyrhizus shows higher maximum IPCE of 44% than that of the DSSCs sensitized with mixed chlorophyll-anthocyanin dye from C. fruticosa (42%).

Stability comparison between microencapsulated red-glycosidic pigments and commercial FD&C Red 40 dye for food coloring

In a previous work, we obtained a betalain red dye from Beta vulgaris L. (beet) encapsulated with tetraethyl orthosilicate (TEOS) and studied its stabilities against changes of UV light, pH, and temperature. In the current research, we prepared betalain dyes from B. vulgaris L. and Myrtillocactus geometrizans (bilberry cactus), then we studied the effect of TEOS in the chemical structure by STEM and EDS analyses and its performance compared with a commercial dye FDC it is not comparable in color appearance with FD&C Red 40, but its degradation is minimal, and in the yogurt model system, it is similar to the colorant of commercial strawberry yogurt. As a result, the red dye from M. geometrizans is a viable alternative to production in large scale.

Betalain and anthocyanin dye-sensitized solar cells

In the present work, the mechanism behind the functioning of the eco-friendly dye-sensitized solar cell was explored. Dye-sensitized solar cells were fabricated using natural dyes extracted from common pear (Opuntia dillenii) and red tamarind (Tamarindus indica), and 1:1 mixture. Betalain and anthocyanin were identified as the main pigments that sensitize the semiconductor TiO2 film. The best conversion efficiency of 0.47 % was achieved from betalain dyes and 0.14 % from anthocyanin dye-sensitized solar cell [under standard Air Mass 1.5 illumination (85 mW cm−2)]. The mixture of dye (1:1 mixture) adsorbed onto TiO2 exhibited an efficiency of 0.20 %. The light absorption behavior of extracted dyes was studied using ultraviolet–visible analysis. The influence of the binding nature of the dyes with TiO2 surface on the efficiency of the solar cells was analyzed through Fourier transform infra-red analysis. The electrochemical impedance spectroscopy was used to find out the internal charge transfer resistance of the cells. The device incident photon-to-current efficiency was obtained from 5 to 25 % for different natural dyes and found to coincide with the photocurrent–voltage characteristics and electrochemical impedance spectroscopy analysis.

Visible light absorption and photo-sensitizing properties of spinach leaves and beetroot extracted natural dyes

Herein, chlorophyll and betalain dyes are extracted from fresh spinach leaves and beetroots. Fourier transform infrared spectra are used to identify the characteristic peaks of the extracted dyes. UV–vis light absorption characteristics of the dyes and their mixed counterpart are investigated by varying their pH and temperature. These dyes are used as photo sensitizer for fabrication of zinc oxide photo-anode based dye sensitized solar cells (DSSCs). The photo-voltaic characteristics of the developed DSSCs are measured under simulated solar light (power of incident light 100mWcm−2 from Air Mass 1.5G). The solar to electric conversion efficiencies for the chlorophyll, betalain and mixed dye based solar cells are estimated as 0.148%, 0.197% and 0.294% respectively. The highest conversion efficiency for mixed dye based solar cell is attributed due to the absorption of wider range of solar spectrum.