Journal Description
Colorants
Colorants
is an international, peer-reviewed, open access journal on all aspects of coloring matters published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 14.3 days after submission; acceptance to publication is undertaken in 10.7 days (median values for papers published in this journal in the first half of 2023).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review, and reviewer names published annually in the journal.
Latest Articles
Gold Nanoparticles as Monoanion Sensors through Modified Electrophilicity
Colorants 2023, 2(4), 591-600; https://doi.org/10.3390/colorants2040030 - 29 Sep 2023
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Derived from malachite green, new triaryl-carbonium-ion-functionalized gold nanoparticles have been synthesized for detecting anions. The detection process, and concomitant colour change, is based on charge compensation on the surface of nanoparticles, which triggers their aggregation, resulting in a bathochromic shift of the plasmon
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Derived from malachite green, new triaryl-carbonium-ion-functionalized gold nanoparticles have been synthesized for detecting anions. The detection process, and concomitant colour change, is based on charge compensation on the surface of nanoparticles, which triggers their aggregation, resulting in a bathochromic shift of the plasmon resonance band. The difference in electrophilicity of the malachite green triaryl ions in solution or on gold nanoparticles makes it possible to distinguish different anions related to their nucleophilic character.
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Open AccessArticle
Repurposing the Strontium Ranelate Antiosteoporotic Drug as a New Outstanding Biocompatible Blue Dye
Colorants 2023, 2(3), 578-590; https://doi.org/10.3390/colorants2030029 - 13 Sep 2023
Abstract
Blue dyes are relatively uncommon in nature, and a novel dithiophene dye (RanB) is reported in this paper. This dye is derived from an old anti-osteoporotic drug and is a metal ion complexing agent, displaying a planar molecular structure, with two sets of
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Blue dyes are relatively uncommon in nature, and a novel dithiophene dye (RanB) is reported in this paper. This dye is derived from an old anti-osteoporotic drug and is a metal ion complexing agent, displaying a planar molecular structure, with two sets of carboxylate, isonitrile, thiophene, and iminodiacetate groups. The blue color originates from a strong absorption peak at 648 nm, accompanied by an unusual fluorescence at 555 nm, with higher energy compared to the main absorption band. RanB forms complexes with lanthanoid ions through the iminodiacetate groups and serves as an effective sensitizer for Tb3+ ions, heightening their emission and improving their use as luminescent agents. Its photo-physical properties and the interaction with Tb3+ have been investigated using absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy, along with computational methods (ZINDO/S and DFT). The RanB toxicity in human umbilical vein endothelial cells has also been tested, showing a lack of toxicity, holding promising prospects for application as a luminescent and coloring agent in pharmaceuticals and food.
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(This article belongs to the Special Issue Feature Papers in Colorant Chemistry)
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Adsorption Process of Methyl Orange Dye onto Zinc Hydroxide Nitrate: Kinetic and Thermodynamic Studies
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Colorants 2023, 2(3), 565-577; https://doi.org/10.3390/colorants2030028 - 06 Sep 2023
Abstract
Zinc hydroxide nitrate (ZHN) was used as an anionic adsorbent for the removal of methyl orange (MO) dye from aqueous solutions. ZHN was characterized via X-ray diffraction (XRD) and infrared spectroscopy (FTIR) techniques. Investigations were carried out to see how the adsorption of
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Zinc hydroxide nitrate (ZHN) was used as an anionic adsorbent for the removal of methyl orange (MO) dye from aqueous solutions. ZHN was characterized via X-ray diffraction (XRD) and infrared spectroscopy (FTIR) techniques. Investigations were carried out to see how the adsorption of MO was affected by factors such as initial MO concentration, contact time and temperature. Adsorption isotherms were analyzed using the Langmuir and Freundlich equations, with the first one being the better result for the equilibrium data. Adsorption kinetics was studied through applying pseudo-first and pseudo-second-order kinetic models, and the experimental data were better fitted to the pseudo-second-order model. The activation energy was determined using the Arrhenius equation to be 105.45 kJ mol−1, revealing the chemical nature of the adsorption process. The thermodynamic parameters were also determined, showing the adsorption of MO onto ZHN to be a non-spontaneous and exothermic process. The experimental results showed ZHN as a potential adsorbent with adsorption capacity for removing anionic dyes from water medium.
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(This article belongs to the Special Issue Feature Papers in Colorant Chemistry)
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Enhanced Dyeing of Polypropylene Using Fluorine–Oxygen Gas Mixtures
Colorants 2023, 2(3), 552-564; https://doi.org/10.3390/colorants2030027 - 31 Aug 2023
Abstract
Surface fluorination with pure F2 gas can easily make the surface on PP (polypropylene) hydrophobic, and it causes limited dyeability, as reported in a previous paper. In this study, to produce a more hydrophilic surface, surface fluorination of PP was performed at
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Surface fluorination with pure F2 gas can easily make the surface on PP (polypropylene) hydrophobic, and it causes limited dyeability, as reported in a previous paper. In this study, to produce a more hydrophilic surface, surface fluorination of PP was performed at 25 °C, total gas pressure of 13.3 kPa, and reaction time of 1 h using F2 and O2 mixtures with different proportions of F2 gas. The surface roughness of the fluorinated PP samples was about 1.5 times higher than that of the untreated sample (5 nm). Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) results showed that the PP-derived bonds (-C-C- and -CHx) decreased because they were converted into polar groups (-C–O, -CHF-, and -CFx), which increased the surface electronegativity of the PP. The variation in the F2 gas proportion in the gas mixture significantly affected the hydrophilicity and surface composition of the PP. At F2 gas proportions of <70%, the hydrophilicity of the fluorinated PP samples was increased. Notably, the hydrophilic and negatively charged PP surface enhanced the dyeing of the polymer with basic methylene blue (MB). In contrast, at F2 gas proportions of >90%, the PP surface became hydrophobic owing to increased numbers of hydrophobic -CF3 bonds. Thus, enhanced PP dyeing can be controlled based on the composition of the F2 and O2 gas mixture.
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(This article belongs to the Special Issue Feature Papers in Colorant Chemistry)
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Tiles from Aosta: A Peculiar Glaze Roof Covering
Colorants 2023, 2(3), 533-551; https://doi.org/10.3390/colorants2030026 - 14 Aug 2023
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The 18th century roof tiles from the “Casa delle vigne”, located in the Aosta region (north-east Italy), were investigated as an example of a peculiar historical roof covering: ceramic tiles with a lead-based glaze finishing to waterproof them are used to create colourful
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The 18th century roof tiles from the “Casa delle vigne”, located in the Aosta region (north-east Italy), were investigated as an example of a peculiar historical roof covering: ceramic tiles with a lead-based glaze finishing to waterproof them are used to create colourful patterns. A conservation project proposed the integration of the original tiles with new ones, produced according to traditional methods. Ancient and new tiles were analysed with Fiber Optics Reflectance Spectroscopy, micro-Raman, Fourier Transform Infrared Spectroscopy and X-ray Fluorescence Spectrometry, Thermogravimetry and Differential Scanning Calorimetry for understanding the composition and the production technology of this manufacture. Their resistance to freezing and thawing cycles was then tested, considering their exposure in the severe alpine climate of Aosta. The use of pure clays with low calcium contents, high firing temperature and lead-rich glazes was found in ancient tiles, able to outstand several freezing-thawing cycles without damages. Iron and copper pigments were used in old yellow and green glazes. Zinc-based pigment, low lead and calcium-rich glazes are used in the new ones, which remained mainly coherent to the ceramic body during the freeze-thaw test.
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Comparative Study of the Synthesis of a Red Ceramic Pigment Using Microwave Heat Treatment
Colorants 2023, 2(3), 518-532; https://doi.org/10.3390/colorants2030025 - 08 Aug 2023
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In this study, a new red ceramic pigment has been developed within a perovskite structure, and microwave heat treatments have been applied. Those red ceramic pigments within the YAlO3 system doped with chromium with the nominal composition Y0.98Al0.98Cr
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In this study, a new red ceramic pigment has been developed within a perovskite structure, and microwave heat treatments have been applied. Those red ceramic pigments within the YAlO3 system doped with chromium with the nominal composition Y0.98Al0.98Cr0.04O3 were synthesized by traditional routes and alternative methods like coprecipitation. Also, heat treatment has been studied comparing a traditional electric and microwave kiln. Different flux agents have been incorporated to improve the synthesis reaction. Prepared pigments have been characterized by X-ray diffraction (XRD) as having a predominant phase of perovskite structure, which is responsible for the red shade, and a minority garnet phase that causes more brown colorations. Studies by Ultraviolet-Visible spectroscopy gave rise to a series of absorption bands that indicate the presence of Cr(III) in the octahedral position corresponding to perovskite and Cr(IV) corresponding to garnet in both the octahedral and tetrahedral positions. The perovskite phase is favored with the use of flux mix, corroborating the UV-visible results and being more pronounced in traditional high temperature thermal treatments. The coprecipitation route has been studied to increase the reactivity of the particles given their nanometric size; however, this reactivity favors a greater appearance of undesirable garnet phases with both types of flux. Scanning Electron Microscopy (SEM) micrographs offer information obtained from the secondary electrons of predominantly cubic crystalline phases with sizes between 1 µm and 2 µm in pigments synthesized via the traditional method and sizes less than 1µm together with the glassy phase in pigments synthesized via coprecipitation. Microwave thermal treatments have been studied, obtaining pigments with a majority structure of perovskite and garnet at lower temperatures and relatively short synthesis times. The feasibility of use in porous single-fired ceramic glazes has been studied, whose chromatic coordinates have been collected using an Ultraviolet-Visible Spectrophotometer based on the CIEL*a*b* system.
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3′-Nitro- and 3′-Aminofluoresceins: Appearance of Previously Missing Dyes
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Colorants 2023, 2(3), 500-517; https://doi.org/10.3390/colorants2030024 - 30 Jul 2023
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Contrary to the 4′- and 5′-nitro- and aminofluoresceins, the corresponding 3′-derivatives are practically unexplored. In this paper, we describe the synthesis and spectral properties of 3′-nitrofluorescein and 3′-aminofluorescein, as well as their methyl esters. Among other methods, X-ray analysis, 13C NMR spectroscopy,
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Contrary to the 4′- and 5′-nitro- and aminofluoresceins, the corresponding 3′-derivatives are practically unexplored. In this paper, we describe the synthesis and spectral properties of 3′-nitrofluorescein and 3′-aminofluorescein, as well as their methyl esters. Among other methods, X-ray analysis, 13C NMR spectroscopy, and ESI mass spectrometry made it possible to establish the molecular structure of the target compounds as well as intermediates and by-products. Some unexpected products, though in small amounts, were revealed within the course of study. Whereas the fluorescence of the double-charged R2− ion of 3′-nitrofluorescein in both aqueous and organic solvents is weak, the R2− anion of 3′-aminofluorescein in a non-hydrogen bonding donor solvent, but not in water, exhibits intensive fluorescence, analogous to the case of 4′- and 5′-aminofluoresceins. Interestingly, the values in water of the R2− ions bearing an NO2 group in the 3′- and 6′-positions are 7 to 10 nm higher than those of the 4′- and 5′-nitro derivatives. The difference was also observed in dimethyl sulfoxide. This correlates with the angles between the xanthene and phthalic planes of the dyes. The dye 3′-aminofluorescein could be used as a fluorescent indicator sensitive to hydrogen bonding ability of the solvent. It could also serve as a platform for synthesizing fluorescent molecular probes for biochemical research, analogous to the very popular application of 4′- and 5′-amino derivatives.
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Rock Powder Applied in the Discoloration of Industry Dye of Molded Pulp Packages Effluent
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Colorants 2023, 2(3), 487-499; https://doi.org/10.3390/colorants2030023 - 07 Jul 2023
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In the present work, rock dust was evaluated as an adsorbent and heterogeneous photocatalyst in the discoloration of Basazol Yellow 46 L dye, which is widely used in the dyeing of molded pulp packages. Although rock dust is produced in large quantities in
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In the present work, rock dust was evaluated as an adsorbent and heterogeneous photocatalyst in the discoloration of Basazol Yellow 46 L dye, which is widely used in the dyeing of molded pulp packages. Although rock dust is produced in large quantities in quarries as a byproduct of rock exploration, little is known about its application as a photocatalyst. Rock dust was characterized by XRD, SEM/EDS, photoacoustic spectroscopy, and N2 physisorption and had its photocatalytic activity assessed through phenol and salicylic acid degradation tests. The characterization results showed that the rock dust is mainly composed of silica and alumina in a triclinic structure, has a bandgap energy of 2.36 eV, and has a specific area of 1.5 m2/g. Rock dust was proven to be photocatalytically active in phenol and salicylic acid degradation tests and also presented the adsorptive and photocatalytic capacity for the discoloration of effluent containing Basazol Yellow 46 L dye.
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Material and Technical Analysis as a Support for Art-Historical Characterization of Selected Mural Paintings in Austria around 1400
Colorants 2023, 2(3), 471-486; https://doi.org/10.3390/colorants2030022 - 04 Jul 2023
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Several medieval mural cycles in Austria were studied from the material and technical point of view, aiming to confirm (or reject) the art-historical hypothesis of their stylistic and workshop connection. These paintings can be found in the churches of Rust (“Fischerkirche”), Marz (Virgin’s
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Several medieval mural cycles in Austria were studied from the material and technical point of view, aiming to confirm (or reject) the art-historical hypothesis of their stylistic and workshop connection. These paintings can be found in the churches of Rust (“Fischerkirche”), Marz (Virgin’s Coronation parish church), Kobenz (St. Ruprecht parish church), Ofenbach (St. Veid parish church), and St. Johann am Steinfelde (St. John parish church). They were carried out around 1400 in the International Gothic style. Their workshop connections based on the style are doubtful, therefore, a material and technical study was carried out. Results showed different plaster composition, similar pigment palette, and diverse painting procedures. The murals in Marz, St. Johann, and the older register in Rust reveal important similarities such as plaster composition, predominant a fresco painting technique, the use of natural inorganic pigments, as well as many aspects of the painting procedure and modeling. On the contrary, those in Kobenz, Ofenbach, and the younger register in Rust differ considerably. The second group reveals lower quality in plaster composition, larger a secco parts, addition of synthetic pigments (Kobenz), and a rougher color modeling, indicating less skilled artists. The lower quality also results in a worse conservation state of these murals. The obtained results confirm the same workshop, but different artists in the first group, while in the second group no clear workshop/artist connection could be established.
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A Physicochemical Examination of Blue Shades in Pottery: Rich, Deep and Endless
Colorants 2023, 2(2), 453-470; https://doi.org/10.3390/colorants2020021 - 19 Jun 2023
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This study attempts to take aspects of pottery technology into account while concentrating on the blue pigment and glaze recipes of various kinds of glazed pottery types; that is to say, Iznik ware, Kütahya ware, Miletus ware, glazed fritware, porcelain, polychrome glazed ware,
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This study attempts to take aspects of pottery technology into account while concentrating on the blue pigment and glaze recipes of various kinds of glazed pottery types; that is to say, Iznik ware, Kütahya ware, Miletus ware, glazed fritware, porcelain, polychrome glazed ware, and monochrome glazed ware were collected from a rescue excavation site within the Castle of Mytilene in Lesvos Island, Greece. The decoration, surface treatment, and production technology were investigated on the basis of 23 ceramic fragments that can be dated to the Turkish/Venetian period. The present study concerns the manufacture of glazed pottery, and in particular, colour recipes and issues of glaze technology. This study endeavoured to look into the specifics of the medieval colour recipes used on the glazed ceramics from Mytilene. This was accomplished by using an analytical process that took into account the compositional information of blue pigments, glazes, and slip coatings. The chemical analysis was conducted using scanning electron microscopy (SEM-EDS), Raman spectroscopy provided information about the compositional variation, and the optical examination via optical microscopy (OM) and scanning electron microscopy (SEM-EDS) yielded information about the sample stratigraphy of the examined ceramic sections. This investigation into glazed ceramics was able to define and reflect the key aspects of each society’s perception of colour through a large variety of colour and glaze recipes.
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Metal-Free Counter Electrodes for DSSCs Based on Nitrogen-Doped Reduced Graphene Oxide Materials
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Colorants 2023, 2(2), 443-452; https://doi.org/10.3390/colorants2020020 - 16 Jun 2023
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The importance of counter electrodes in Dye Sensitized Solar Cells (DSSCs) cannot be neglected as they enable the transfer of electrons across the outer circuit, thereby facilitating the reduction reaction of the I3−/I− redox electrolyte. However, the dissolution and
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The importance of counter electrodes in Dye Sensitized Solar Cells (DSSCs) cannot be neglected as they enable the transfer of electrons across the outer circuit, thereby facilitating the reduction reaction of the I3−/I− redox electrolyte. However, the dissolution and deposition of the usual platinum layer on the counter electrode has resulted in contamination concerns. To address this issue, metal-free counter electrodes made of reduced graphene oxide (rGO) aerogels were developed and their catalytic performance towards I3− reduction was evaluated. The reduced graphene materials were characterized, and the fitting analysis of XPS revealed the presence of various nitrogen species, with the primary peaks attributed to pyridinic and pyrrolic nitrogen. The hydrothermal treatment of graphene oxide (GO) resulted in a higher graphitic character and the intensification of the contacts between graphene nanosheets, which should entail higher electrical conductivity, both in-plane and between rGO sheets. Additionally, the presence of nitrogen-provided active sites promoted the catalytic reduction of the electrolyte. Encouragingly, good charge transfer rates were observed between the counter electrode and the electrolyte in the assembled DSSCs, resulting in good photocurrents and exceptional stability over the course of nearly 1200 h after cell assembly. The results obtained suggest that these GO-based systems are promising candidates for developing metal-free counter electrodes for DSSC, supporting the interest of further study.
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(This article belongs to the Special Issue Recent Progress on Functional Dyes and Their Applications)
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Synergistic Effect of BiVO4/P-g-C3N4 Heterojunction with Enhanced Optoelectronic Properties on Synthetic Colorants under Visible Light
Colorants 2023, 2(2), 426-442; https://doi.org/10.3390/colorants2020019 - 08 Jun 2023
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Environmental remediation in the presence of robust semiconductor photocatalysts by utilizing renewable energy sources is of keen interest among researchers. In this study, we synthesize a BiVO4/P-g-C3N4 semiconductor heterojunction photocatalytic system through a hydrothermal route followed by utilizing
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Environmental remediation in the presence of robust semiconductor photocatalysts by utilizing renewable energy sources is of keen interest among researchers. In this study, we synthesize a BiVO4/P-g-C3N4 semiconductor heterojunction photocatalytic system through a hydrothermal route followed by utilizing a total-solvent evaporation method. The optical and electronic properties of the as-prepared heterojunction are characterized via various spectroscopic techniques. Rhodamine B (RhB) and Congo Red (CR) are used as synthetic colorants to evaluate the photocatalytic performances of BiVO4/P-g-C3N4. In addition, the chemical environment of the photocatalyst and its mechanistic pathways are confirmed through X-ray photoelectron spectroscopy and electrochemical Mott–Schottky analysis. The BiVO4/P-g-C3N4 photocatalyst shows higher photodegradation (96.94%) of the mixed synthetic dyes under simulated solar-light irradiation. The as-synthesized BiVO4/P-g-C3N4 heterojunction significantly promotes the quick separation of photoexcited carriers due to the excellent synergetic properties, the extended light absorption, and the photoelectrochemical response. Furthermore, a possible type-II charge transfer mechanism is adopted for the BiVO4/P-g-C3N4 system after investigating the band potentials, active species, and charge carrier migration over the heterojunction interface.
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Open AccessReview
Multicomponent Crystals of Phthalocyanines–A Possibility of Fine-Tuning Properties
Colorants 2023, 2(2), 405-425; https://doi.org/10.3390/colorants2020018 - 07 Jun 2023
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Phthalocyanines (Pcs) are 18-electron π-conjugated macrocyclic ring systems with proven activities in diverse fields, including pharmaceuticals and catalysis. These demonstrated activities are often alluded to as their fascinating photophysical and photochemical dispositions, which are usually dependent on their molecular structures. However, many of
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Phthalocyanines (Pcs) are 18-electron π-conjugated macrocyclic ring systems with proven activities in diverse fields, including pharmaceuticals and catalysis. These demonstrated activities are often alluded to as their fascinating photophysical and photochemical dispositions, which are usually dependent on their molecular structures. However, many of these molecules suffer from aggregation due to π–π stacking and have limited insolubility in hydrophilic media, which limits their extensive utilisation in pharmaceutical applications. This review will explore the possibility of fine-tuning the physicochemical properties of phthalocyanines when designed as multicomponent crystals. Among the proven and SMART approaches that have been shown to enhance drug solubility without altering the molecular structure is co-crystallisation. This protocol involves the design and formation of non-covalent interactions between two or more molecular entities to create a supramolecular assembly and subsequently afford multicomponent crystals (MCCs). A systematic review of the Cambridge Structural Database repository yielded several single and multicomponent crystals of Pcs; however, most of them were either salts or solvates, with only a few reports on their co-crystals.
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Open AccessReview
5′-Substituted Indoline Spiropyrans: Synthesis and Applications
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Colorants 2023, 2(2), 264-404; https://doi.org/10.3390/colorants2020017 - 05 Jun 2023
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Methods for preparation of 5′-substituted spiropyrans, their chemical properties, and the effects of various factors on the relative stabilities of the spiropyrans and their isomeric merocyanine forms are examined, reviewed, and discussed.
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Diphenyl-Furanones and Diphenyl-Oxopyrrole Derivatives: From Analytical Reagents for Amino Groups to New Fluorochromes for Cytochemical Staining of Chromatin DNA and Chromosomes: Proposal for Intercalative Binding and Fluorescence Mechanism
Colorants 2023, 2(2), 245-263; https://doi.org/10.3390/colorants2020016 - 15 May 2023
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Diaryl-furanones are specific analytical reagents for the biochemical detection of primary amines by fluorescence techniques. Well-known reagents are fluorescamine (Fluram) and 2-methoxy-2,4-diphenyl-3(2H)-furanone (MDPF), yielding fluorescent products with λem at 480–490 nm. Although the reaction products claim to be pyrrolinones, recent studies show that
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Diaryl-furanones are specific analytical reagents for the biochemical detection of primary amines by fluorescence techniques. Well-known reagents are fluorescamine (Fluram) and 2-methoxy-2,4-diphenyl-3(2H)-furanone (MDPF), yielding fluorescent products with λem at 480–490 nm. Although the reaction products claim to be pyrrolinones, recent studies show that they are really 3-oxopyrrole (pyrrolone) derivatives. Both reagents have been used for the cytochemical demonstration of primary amines. In this work, we have applied the fluorescent products of MDPF with amines (n-butylamine, BA; glucosamine, GA; and spermine, Sp), which showed interesting fluorescence reactions with chromatin DNA. 2,4-diphenyl-3-oxopyrrole products (diPOPy) can be easily synthesized according to well-known procedures, by mixing solutions of MDPF in acetone with water at pH 9 containing the amino compounds. DiPOPy derivatives of BA, GA, and Sp were used for spectroscopic, microscopic, and molecular modeling studies, showing a bright and selective blue–green fluorescence on DNA substrates, mainly chromatin, kinetoplast DNA, and stretched chromatin fibers. The cationic diPOPy fluorophore is planar, with a high partial positive charge in the N atom, and suitable for intercalative binding to DNA. A mechanism of fluorescamine fluorescence due to an inner-salt isomeric form is proposed, and an astonishing correlation between adenine–thymine-rich centromeric heterochromatin in mouse metaphase chromosomes after reaction of the fluorescamine reagent with protein amino groups is also discussed.
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Open AccessArticle
Dragon Fruit (Hylocereus polyrhizus): A Green Colorant for Cotton Fabric
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Colorants 2023, 2(2), 230-244; https://doi.org/10.3390/colorants2020015 - 11 May 2023
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The textile industry has been exploring sustainable chemicals and natural alternatives to replace harmful and carcinogenic substances used in different stages of textile production for dyeing textiles. Natural dyes are gaining popularity, as they are environmentally friendly and less harmful. Betacyanin, a type
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The textile industry has been exploring sustainable chemicals and natural alternatives to replace harmful and carcinogenic substances used in different stages of textile production for dyeing textiles. Natural dyes are gaining popularity, as they are environmentally friendly and less harmful. Betacyanin, a type of pigment obtained from red pitahaya, commonly known as red dragon fruit (Hylocereus polyrhizus), has peels that are available as agricultural waste and can be used to meet the demand for natural dye production. This study aimed to explore and utilize dragon fruit’s peel as a natural colorant for dyeing 100% cotton knit fabric (scoured and bleached single jersey plain knit) of 170 g/m2, which could transform a low-value material into a valuable product. However, cotton’s phenolic nature and oxidation process result in negative charges on its surface, making natural dyeing challenging. Cationization with cationic agents (ForCat NCH, a mixture of cationic polyamine and 1,3,dichlori-2-propanol) and mordanting (potassium alum or potassium aluminum sulfate) were carried to improve dye exhaustion and enhance colorfastness properties. Spectrophotometer 800 was used to measure color strength (K/S), and several fastness tests, including wash, perspiration, and rubbing were conducted to assess the final product’s performance. The process parameters, such as temperatures, times, pH levels, and dye concentrations were varied to understand better the optimum conditions.
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Effective Removal of Methyl Orange Dyes Using an Adsorbent Prepared from Porous Starch Aerogel and Organoclay
Colorants 2023, 2(2), 209-229; https://doi.org/10.3390/colorants2020014 - 01 May 2023
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Intending to provide efficient and compact wastewater remediation, the present work is exploiting and introducing a novel composite prepared from porous starch aerogel (PSA) and organically modified Ca-montmorillonite (OMMT) for the removal of dyes from aqueous samples. First, potato starch components were used
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Intending to provide efficient and compact wastewater remediation, the present work is exploiting and introducing a novel composite prepared from porous starch aerogel (PSA) and organically modified Ca-montmorillonite (OMMT) for the removal of dyes from aqueous samples. First, potato starch components were used as a hydrolysis precursor to obtain PSA. The organoclay samples were prepared by co-intercalation of octadecylamine (ODA) into Ca-MMT using a low-temperature melting procedure. Composites with different starch-to-organoclay ratios of 10:1, 1:1, and 1:10 were then prepared by a blending process in distilled water and used for methyl orange (MO) uptake. The removal of methyl orange dyes increased with the amount of organoclay in the PSA matrix. Characterization revealed that organoclay synergy improved the PSA surface chemistry, while an important improvement in textural properties and thermal stability was also observed. The composite’s efficiency was demonstrated by high removal capabilities towards MO in most experimental runs, with a maximum adsorption capacity beyond 344.7 mg/g. The fitting result showed that MO adsorption follows a monolayer adsorption model, and chemisorption was the rate-controlling step. Nonetheless, this study proved the great potential of PSA/OMMT in dyeing wastewater treatment. Furthermore, starch modification is proven as an effective approach to enhancing the performance of starch-derived adsorbents.
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Open AccessArticle
Is There an International Klein Pink?
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Colorants 2023, 2(2), 194-208; https://doi.org/10.3390/colorants2020013 - 25 Apr 2023
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Yves Klein (1928–1962) is best known for his intensely blue monochromatic works made with International Klein Blue (IKB), a synthetic ultramarine blue pigment bound in a poly(vinyl acetate) binder. However, he also made monochromes in other colors, including red and pink, the pigments
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Yves Klein (1928–1962) is best known for his intensely blue monochromatic works made with International Klein Blue (IKB), a synthetic ultramarine blue pigment bound in a poly(vinyl acetate) binder. However, he also made monochromes in other colors, including red and pink, the pigments of which have never been elucidated. Analysis of one sculpture, three paintings, and one screenprint by micro-Fourier transform infrared spectroscopy (µ-FTIR), Raman and surface-enhanced Raman (SERS) spectroscopies, portable X-ray fluorescence spectroscopy (p-XRF), and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX), revealed that Klein used, knowingly or unknowingly, a variety of pink and red pigments, including Para Red, rhodamine 6G, rhodamine B, eosin Y, and alizarin lakes. The unexpected variety of pigments contrasts with his use of a single blue pigment and suggests he may not have held a singular vision of what constituted an iconic red or pink color.
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Open AccessArticle
Long-Alkyl Chain Functionalized Imidazo[1,5-a]pyridine Derivatives as Blue Emissive Dyes
Colorants 2023, 2(2), 179-193; https://doi.org/10.3390/colorants2020012 - 10 Apr 2023
Cited by 1
Abstract
A series of boron difluoride compounds with 2-(imidazo[1,5-a]pyridin-3-yl)phenols bearing alkylic chains at the 1-position has been synthesized and characterized both with 1H and 13C NMR and infrared spectroscopy. This series of compounds displayed blue emission in solution and in
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A series of boron difluoride compounds with 2-(imidazo[1,5-a]pyridin-3-yl)phenols bearing alkylic chains at the 1-position has been synthesized and characterized both with 1H and 13C NMR and infrared spectroscopy. This series of compounds displayed blue emission in solution and in thin polymeric films, with interesting features like large Stokes shifts and good fluorescence quantum yields. Time-Dependent Density Functional Theory (TD-DFT) calculations allowed for the identification of the main electronic transitions as intra ligand transitions (1ILT), as corroborated by the Natural Transition Orbitals (NTOs) shapes.
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(This article belongs to the Special Issue Recent Progress on Functional Dyes and Their Applications)
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N-Annulated Perylene Diimide Non-Fullerene Acceptors for Organic Photovoltaics
Colorants 2023, 2(1), 151-178; https://doi.org/10.3390/colorants2010011 - 21 Mar 2023
Abstract
This work covers the development of non-fullerene acceptors for use in organic photovoltaics built using the N-annulated perylene diimide dye. The classic perylene diimide dye has been extensively used to construct non-fullerene acceptors, leading to device power conversion efficiencies of over 10%. Strong
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This work covers the development of non-fullerene acceptors for use in organic photovoltaics built using the N-annulated perylene diimide dye. The classic perylene diimide dye has been extensively used to construct non-fullerene acceptors, leading to device power conversion efficiencies of over 10%. Strong visible light absorption and deep frontier molecular energy levels have made such materials (both molecular and polymeric) near ideal for pairing with narrow-gap conjugated polymers in bulk-heterojunction active layers. The N-annulation of the dye provides an extra site for side-chain engineering and alters the electronic structure of the polycyclic aromatic core. In addition, N-annulation allows for selective bromination of the perylene core, leading to building blocks that are useful for the construction of large molecular frameworks using the atom-economical direct heteroarylation cross-coupling method. Herein, we detail a series of molecules developed by our team that are based on the N-annulated perylene diimide in the form of dimers with different cores (both electron-rich and electron-deficient); dimers with varied side chains; tetramers with varying geometries; and large, asymmetric molecules with internal energy cascades. The use of these molecules as non-fullerene acceptors in organic photovoltaic devices (binary and ternary blends, outdoor and indoor light applications, and spin-coated vs. slot-die-coated photoactive layers) is presented.
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