Colorants

13 pages, 5044 KiB

Open AccessArticle

Photostability of Indium Phthalocyanines in Organic Solvents

by Gabriela Maria Dyrda and Tomasz Pędziński

Colorants 2025, 4(1), 4; https://doi.org/10.3390/colorants4010004 - 20 Jan 2025

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The effects of photochemical reactions induced by UV radiation in solutions of metal phthalocyanines were carried out to determine the factors that might influence the photostability of photosensitized phthalocyanines. Three different indium phthalocyanines, including the diindium triple-decker phthalocyanine, In₂Pc₃ (1), sandwich indium phthalocyanine, InPc₂ (2) and iodoindium phthalocyanine, InPcI (3) in benzene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dichloromethane (DCM) and 1-chloronaphtalene, were studied. The rate of decay of absorption is explained by a decomposition reaction that is of first-order kinetics with respect to the phthalocyanine concentration. In general, the presence of ligand I⁻ in phthalocyanine InPcI enhances the rate of decomposition. The kinetics of the degradation process proved to depend on the molecular structure of the complex and seems to be controlled by interactions of the macrocycle bridging nitrogen atoms with the solvent molecules. The indium phthalocyanines in benzene displayed the capacity for singlet oxygen generation. Full article

(This article belongs to the Special Issue Feature Papers in Colorant Chemistry)

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19 pages, 23307 KiB

Open AccessArticle

Application of Κ-Carrageenan for One-Pot Synthesis of Hybrids of Natural Curcumin with Iron and Copper: Stability Analysis and Application in Papilloscopy

by Danielle Tapia Bueno, Amanda Fonseca Leitzke, Juliana Porciúncula da Silva, Daisa Hakbart Bonemann, Gabrielly Quartieri Sejanes, Bruno Nunes da Rosa, Taís Poletti, Guilherme Kurz Maron, Bruno Vasconcellos Lopes, Matheus de Paula Goularte, Darci Alberto Gatto, André Luiz Missio, Neftali Lenin Villarreal Carreno and Claudio Martin Pereira de Pereira

Colorants 2025, 4(1), 3; https://doi.org/10.3390/colorants4010003 - 15 Jan 2025

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Abstract

In this study, hybrid materials were synthesized incorporating curcumin, Cu²⁺ or Fe³⁺, and Kappa-carrageenan as a reducing agent to improve stability, considering that curcumin has low thermal and solution stability, which limits its applications. Colorimetric analysis showed color changes in the hybrids, ultraviolet–visible spectroscopy revealed band shifts in the hybrids, and infrared analysis indicated shifts in wavenumbers, suggesting changes in the vibrational state of curcumin after bonding with metal ions. These techniques confirmed the formation of hybrid materials. Thermogravimetric and chromatographic analyses demonstrated greater thermal and solution stability for the hybrids compared to curcumin. Additionally, the hybrid composites effectively developed natural and sebaceous latent fingerprints with good clarity and contrast on glass surfaces. Both composites performed similarly to commercial Gold^® powder. When applied to surfaces representative of forensic scenarios, the composites were versatile, revealing sufficient fingerprint details for human identification on both porous and non-porous surfaces. Scanning electron microscopy images showed greater clarity in sebaceous and natural fingerprints developed with the Fe composite compared to the Cu composite. Full article

(This article belongs to the Special Issue Feature Papers in Colorant Chemistry)

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18 pages, 5061 KiB

Open AccessArticle

Durable Textile Dyeing/Printing Using Natural Indigo Dyes and Leaves, and Mayan-Inspired Blue Indigo Pigments

by Nemeshwaree Behary and Nicolas Volle

Colorants 2025, 4(1), 2; https://doi.org/10.3390/colorants4010002 - 14 Jan 2025

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Abstract

Indigo leaves from various plant species are sources of dyes/pigments, not fully exploited for making sustainable textiles. Blue indigo vat dye extracted from indigo leaves yields high wash color fastness but fades slowly with light, and is not easily used for direct printing. Indigo leaves can be used to produce textiles of various color shades, while light-resistant Mayan-inspired hybrid pigments have not yet been used for textile coloring. Using blue indigo dyes from three plant species, with exhaustion dyeing, intense wash-resistant blue-colored textiles are produced, and in the case of Indigofera Persicaria tinctoria, textiles have antibacterial activity against S. epidermis and E. coli. A 100% natural Mayan-inspired blue indigo pigment, made from sepiolite clay and natural indigo dye, was used both in powdered and paste forms to perform pigment textile dyeing by pad cure process, and direct screen printing on textiles. A water-based bio-binder was used efficiently for both padding and printing. Bio-based Na Alginate thickener allowed to produce prints with good color-fastness on both polyester and cotton fabrics, while bio-based glycerin produced excellent print color fastness on polyester only: wash fastness (5/5), dry and wet rub fastness (5/5) and light fastness (7/8). Full article

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14 pages, 2420 KiB

Open AccessArticle

Biosynthetic Gene Clusters and Liquid Chromatography Coupled to Mass Spectrometry Analysis of Aryl Polyene Pigments from Chryseobacterium sp. kr6 and Lysobacter sp. A03

by Maria Elisa Pailliè-Jiménez, Jamile Queiroz Pereira, Eliseu Rodrigues and Adriano Brandelli

Colorants 2025, 4(1), 1; https://doi.org/10.3390/colorants4010001 - 2 Jan 2025

Viewed by 618

Abstract

Aryl polyene (APE) are bacterial pigments which show great biotechnological potential because of their biological activities. In this study, the presence of gene clusters associated with APE synthesis was investigated in the genome of Chryseobacterium sp. kr6 and Lysobacter sp. A03. The pigments extracted from strains kr6 and A03 were further characterized by liquid chromatography coupled to a high-resolution mass spectrometer (LC-DAD-MS). These bacteria harbor the relevant genes for APE biosynthesis; while kr6 may produce flexirubin pigments and have a 75% similarity with the flexirubin cluster from Flavobacterium johnsoniae UW101, Lysobacter sp. A03 showed a 50% similarity with the xanthomonadin I gene cluster from Xanthomonas oryzae pv. oryzae. A comparison with the gene clusters of APE-producing bacteria revealed that kr6 and A03 harbor genes for key proteins that participate in APE biosynthesis, such as acyl carrier proteins, acyl dehydratases and acyl reductases. The LC-DAD-MS analysis revealed that kr6 produces a possible mixture of flexirubins, whereas the yellow pigment from A03 is proposed to be a xanthomonadin-like pigment. Although the fine molecular structure of these pigments are not yet fully elucidated, strains kr6 and A03 present great potential for the production of natural bioactive pigments. Full article

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Colorants, Volume 4, Issue 1 (March 2025) – 4 articles

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