Search Results (175)

Fluorescent chemosensors are increasingly becoming relevant in recognition chemistry due to their sensitivity, selectivity, fast response time, real-time detection capability, and low cost. Boronic acids have been reported for the recognition of mycolactone, the cytotoxin responsible for tissue damage in Buruli ulcer disease. A library of fluorescent arylboronic acid chemosensors with various signaling moieties with certain beneficial photophysical characteristics (i.e., aminoacridine, aminoquinoline, azo, BODIPY, coumarin, fluorescein, and rhodamine variants) and a recognition moiety (i.e., boronic acid unit) were rationally designed and synthesised using combinatorial approaches, purified, and fully characterised using a set of complementary spectrometric and spectroscopic techniques such as NMR, LC-MS, FT-IR, and X-ray crystallography. In addition, a complete set of basic photophysical quantities such as absorption maxima (λ_abs^max), emission maxima (λ_em^max), Stokes shift (∆λ), molar extinction coefficient (ε), fluorescence quantum yield (Φ_F), and brightness were determined using UV-vis absorption and fluorescence emission spectroscopy techniques. The synthesised arylboronic acid chemosensors were investigated as chemosensors for mycolactone detection using the fluorescent-thin layer chromatography (f-TLC) method. Compound 7 (with a coumarin core) emerged the best (λ_abs^max = 456 nm, λ_em^max = 590 nm, ∆λ = 134 nm, ε = 52816 M⁻¹cm⁻¹, Φ_F = 0.78, and brightness = 41,197 M⁻¹cm⁻¹). Full article

The authentication of high-value spices such as paprika and cinnamon is critical due to increasing food fraud. This study explored the potential of a multi-analytical approach, combined with chemometric tools, to differentiate 45 paprika and 46 cinnamon samples from the Slovenian market based on their geographic origin, production methods, and possible adulteration. The applied techniques included stable isotope ratio analysis (δ¹³C, δ¹⁵N, δ³⁴S), multi-elemental profiling, FTIR, and antioxidant compound analysis. Distinct isotopic and elemental markers (e.g., δ¹³C, δ³⁴S, Rb, Cs, V, Fe, Al) contributed to classification by geographic origin, with preliminary classification accuracies of 90% for paprika (Hungary, Serbia, Spain) and 89% for cinnamon (Sri Lanka, Madagascar, Indonesia). Organic paprika samples showed higher values of δ¹⁵N, δ³⁴S, and Zn, whereas conventional ones had more Na, Al, V, and Cr. For cinnamon, a 95% discrimination accuracy was achieved between production practice using δ³⁴S and Ba, as well as As, Rb, Na, δ¹³C, S, Mg, Fe, V, Al, and Cu. FTIR differentiated Ceylon from cassia cinnamon and suggested possible paprika adulteration, as indicated by spectral features consistent with oleoresin removal or azo dye addition, although further verification is required. Antioxidant profiling supported quality assessment, although the high antioxidant activity in cassia cinnamon may reflect non-phenolic contributors. Overall, the results demonstrate the promising potential of the applied analytical techniques to support spice authentication. However, further studies on larger, more balanced datasets are essential to validate and generalize these findings. Full article

Eugenol-based azo dyes illustrate how bio-sourced compounds like eugenol can be transformed through synthetic processes into functional and colorful compounds. The main purpose of the present work was to develop new responsive colorimetric sensors for metal cations based on eugenol-derived azo compounds. The incorporation of the azo group into the eugenol framework allows for strong electronic interactions with metal cations, leading to distinct color changes observable to the naked eye. These azo-eugenol dyes exhibit shifts in their UV-Vis absorption spectra upon complexation with metal cations such as copper (Cu²⁺) and lead (Pb²⁺), making them effective sensors for environmental and analytical applications. The eugenol-based azo dyes were subjected to photophysical studies to understand selectivity, response time, and stability in relation to metal cations, which will be a starting point for the monitoring of toxic metal contaminants in aqueous environments. Full article

The safety concerns associated with sensitivity issues regarding long nitrogen chain-based energetic compounds, especially for eight or more catenated nitrogen atoms in backbones, need to be resolved. Incorporating specific functional groups represents a key approach for enhancing stability in organic energetic materials. This study reports the synthesis of 1,1′-(diazene-1,2-diyl)bis(4-nitro-1H-1,2,3-triazole-5-carboxamide) (S8), an N8-chain compound featuring strategically placed amide groups. Employing THA(O-tosylhydroxylamine) and KMnO₄, 1,1′-(diazene-1,2-diyl)bis(4-nitro-1H-1,2,3-triazole-5-carboxamide) (S8) was synthesized and underwent N-amination and oxidative azo coupling. Comprehensive characterization, including X-ray diffraction, mechanical sensitivity testing, and theoretical analysis, alongside comparative studies with known N8 compounds, revealed that S8 exhibits unprecedented stability within its class. Among reported N8-catenated nitrogen chain compounds, attributed to the incorporation of the amide functionality, S8 demonstrates the highest impact sensitivity (IS = 10 J) and friction sensitivity (FS = 40 N) while maintaining excellent detonation performance (D = 8317 ms⁻¹, P = 28.27 GPa). This work highlights the amide group as a critical structural part for achieving high stability in sensitive long-nitrogen-chain energetic materials without compromising performance. Full article

This review discusses natural and synthetic azo compounds found in bacteria, fungal endophytes, fungi, plants, and invertebrates. More than 100 of these compounds have demonstrated significant pharmacological activity, including antitumor, antimicrobial, and antibacterial effects. Using mathematical algorithms and the PASS program, researchers predict new potential applications based on their structure–activity relationships. This review emphasizes the importance of natural azo compounds as promising drug prototypes and key players in drug discovery. It also explores the synthesis and degradation of azo dyes and their potential uses in medicine, food, cosmetics, and related fields. Additionally, the role of microorganisms in producing natural azo compounds and their synthetic counterparts is examined, showcasing their potential in drug development and human health advancements. Full article

This paper presents novel soluble (co)poly(hydroxyimide)s ((co)PIOH) based on 4,4′-oxydiphthalic anhydride (ODPA), 3,3′-dihydroxybenzidine (HAB), and 3,6-diaminodurene (D) with the 3/1, 1/1, and 1/3 HAB/D ratios. This chemical structure of the compounds provides the possibility of their future modification through the thermal rearrangement (polybenzoxazoles) or functionalization via Mitsunobu reaction (azo side-chain polyimides), i.e., obtaining new materials with interesting properties and therefore with expanded applications. Copolymers were characterized via FTIR, NMR, XRD, and GPC methods to confirm their structure, composition, and molar masses. The effect of copolymer composition on the thermal, mechanical, optical, and permeation properties studied for He, O₂, N₂, and CO₂, as well as hydrophobicity, was investigated. They exhibited a large interval between the glass transition temperature and the decomposition temperature, making them promising for the thermoforming technique. Transmittance above 90% was noted in the visible range for all (co)PIOH films deposited on a glass substrate. Young’s modulus of fabricated membranes was in the range of 2.37 to 3.38 GPa. The highest permeability coefficients were recorded for (co)PIOH with a 1:3 HAB-to D-ratio. Full article

Bacterial antibiotic resistance represents a major healthcare problem. In 2019, 4.95 million deaths were associated with antibiotic resistance, and it is estimated that, by 2050, up to 3.8% of the global gross domestic product could be lost due to this problem. Methicillin-resistant Staphylococcus aureus is one of the leading sources of hospital-acquired infections associated with increased mortality, length of hospital stay, and higher cost of treatment. Here, we describe the de novo synthesis of a library of 22 triazeneindole derivatives with high activity against a wide panel of multidrug-resistant MRSA clinical isolates. Leading compound BX-SI043 (ethyl 6-fluoro-3-[pyrrolidin-1-yl-azo]-1H-indole-2-carboxylate) showed high activity (minimal inhibitory concentration range, 0.125–0.5 mg/L) against 41 multidrug-resistant MRSA strains, as well as relatively low in vitro cytotoxicity (selectivity index, 76) and in vivo acute toxicity (maximum tolerated dose, 600 mg/kg), via intragastric administration in rats. These data suggest that BX-SI043 is a promising drug candidate for the development a novel MRSA treatment. Full article

Regenerative agriculture and the use of bioinputs have been gaining prominence in the global agribusiness sector, driven by the growing demand for healthier foods produced with minimal impact on ecosystems. In this context, compost and its derivatives (compost extracts and teas) are used to provide effective microorganisms to crops, although production processes affect the efficiency of compost extracts, as well as the soil microbiota. Thus, the hypothesis raised was that the organic matter source used for compost formation affects the agronomic efficiency of compost extracts. The objective of this study was to evaluate the effect of compost extracts based on litterfall of angiosperm (AC) and gymnosperm (GC) species, and the use of inoculation with the nitrogen-fixing bacteria Bradyrhizobium japonicum and Azospirillum brasilense (Bra+Azo), on soil quality, crop growth, grain yield, and disease control in soybean (Glycine max L.) crops. Using AC and GC resulted in varying effects on soybean growth and soil microbial biomass carbon (SMBC), confirming the hypothesis that the organic matter source affects the agronomic efficiency of compost extracts. Plants inoculated with Bra+Azo exhibited higher chlorophyll contents, resulting in a higher photochemical yield than for those treated with compost extracts (AC and GC). However, plants inoculated with AC and GC exhibited high plasticity in mitigating photochemical stress, reaching similar photosynthetic and transpiration rates to those observed in plants inoculated with Bra+Azo. Additionally, inoculation with Bra+Azo, overall, improved the photosynthetic efficiency of soybean plants, and the compost extracts (AC and GC) were more effective than the inoculation with Bra+Azo in increasing soybean 1000-grain weight, probably due to improvements in root development. The growth promotion observed with AC and GC is likely attributed to increases in SMBC by these compounds, denoting improvements in soil quality and biocontrol of damage caused by insect attacks. Full article

This study primarily focuses on the analysis of volatile organic compounds using GC–MS, with ICP-MS employed as a complementary method to quantify trace metal content. Headspace GC–MS was conducted to detect alkylphenol ethoxylates (APEOs), formaldehyde, aromatic amines derived from azo dyes, perfluorinated carboxylic acids, chlorophenols (PCPs), tetrachlorophenols (TPCs), and phthalates in textile samples of different origin and composition. Principal component analysis was used to detect patterns in the volatilome according to the origin and the textile composition. In addition, seven metals (Cr, Ni, Cu, Mo, Cd, Hg, and Pb) were quantified in a subset of samples. The study revealed distinct chemical profiles in textiles based on their origin, with GC–MS identifying key volatile organic compounds and ICP-MS quantifying heavy metals in a subset of samples. Principal component analysis highlighted cotton content as a critical factor in differentiating textile profiles. While most samples adhered to regulatory standards, some exceeded thresholds for metals like copper and nickel, underscoring the need for enhanced quality control in manufacturing processes. By integrating advanced analytical methods, this study provides insights into sustainable and safe textile production, offering valuable benchmarks for regulatory compliance and industry best practices. The outcomes contribute to improving product safety, promoting responsible manufacturing, and supporting regulatory bodies in the enforcement of environmental and safety standards, aligning with the growing demand for sustainability in the textile sector. Full article

Congo Red is a complex aromatic azo dye whose metabolites can be toxic due to their carcinogenicity, mutagenicity, and various associated toxic effects on flora, fauna, and humans. Different technologies have been employed to degrade this dye, including biodegradation, radiation-based degradation, and chemical degradation with catalysts and photocatalysis. Among these, the use of TiO₂-based materials combined with photocatalysis has proven to be an effective technology for its degradation. However, the wide bandgap of TiO₂ limits its efficiency under visible light, prompting the need for modifications such as doping with metals, metalloids, and organic compounds. These modifications enhance its photocatalytic performance under visible light, achieving degradation efficiencies of up to 100% under optimal conditions. This article explores recent advances (from 2020 to the present) in the degradation of Congo Red using TiO₂-based photocatalysts under visible light, focusing on their characteristics, synthesis methods, and degradation efficiencies. Additionally, it compares the TiO₂-based photocatalysis with visible light to other available technologies, emphasizing its potential as a sustainable and efficient approach while addressing the importance of monitoring degradation byproducts to prevent the generation of equally or more toxic compounds. Full article

This research focuses on the removal of emerging contaminants (CEC) present in synthetic aqueous matrices. Azole compounds were selected as CEC of interest due to their persistence and toxicity, particularly the triazole and oxazole groups. These compounds are also trace contaminants listed in the proposed revision of Directive 91/271/EEC on urban wastewater treatment and the 3rd European Union Observation List (Implementing Decision EU 2020/116), highlighting their regulatory importance. The draft Directive includes the implementation of quaternary treatments to achieve the highest possible removal rates of micropollutants. Among the technologies used on a large scale are some advanced oxidation processes (AOP), often combined with adsorption on activated carbon (AC). Laboratory-scale pilot plants have been designed and operated in this research, including UV photolysis and oxidation with H₂O₂ and adsorption with GAC. The results demonstrate that UV photolysis is able to remove all the selected CECs except fluconazole, reaching eliminations higher than 86% at high doses of 31.000 J/m². Treatment by H₂O₂ achieved removals of 4 to 55%, proving to be ineffective in the degradation of persistent compounds when acting as a single technology. Adsorption by AC is improved with longer contact times, reaching removals above 80% for benzotriazole and methyl benzotriazole at short contact times, followed by sulfamethoxazole and tebuconazole. Fluconazole had a mean adsorption capacity at low contact times, while metconazole and penconazole showed low adsorption capacities. Full article

In this study, a novel natural food colorant based on anthocyanins was developed from wild barberry (Berberis vulgaris L.) fruits using ultrasound-assisted extraction, which was optimized through RSM. Four extraction variables (ultrasound power, time, S/L ratio, and extraction solvent pH) were evaluated in combination. The response criteria used were the total anthocyanin content (TAC) and color parameters. The optimal TAC was achieved at 2.5 min, 345 W, pH 3, and 22.12 g/L. The fruit sample (without seeds) (BVFF) and its optimized extract (BVE) were characterized in terms of chemical composition and bioactivities. Delphinidin-3-O-glucoside was identified as the predominant anthocyanin. BVE exhibited a total phenolic content of 290.72 mg/g. Additionally, both BVFF and BVE presented significant antioxidant, antibacterial, and antifungal activity, especially in the case of BVE, which inhibited the growth of several foodborne bacteria and fungi and even showed bactericidal capacity against most of the tested bacteria, particularly against E. cloacae, E. coli, P. aeruginosa, and B. cereus. These results highlight the richness of BVFF and BVE in bioactive compounds, especially anthocyanins, underscoring their potential as natural food colorants that can be used in food product formulations instead of synthetic azo colorants. Full article

Globalization has increased production in various industries, including textiles, food, and pharmaceuticals. These industries employ different dyes in production, leading to undesired discharge, which conventional treatment fails to remove from the water. The present study aims to synthesize, characterize, and use different pure catalysts (TiO₂ and Zn₂SnO₄) and their compounds doped with CoFe₂O₄ together with ozone (O₃) for the degradation of the azo dye yellow tartrazine (TZ), evaluating the process. For this characterization, N₂ porosimeter, zeta potential, X-ray diffraction, SEM-EDS, and diffuse reflectance spectra were used. Specific surface areas (m² g⁻¹) of 109, 106, 65, and 83 were used for TiO₂, CoFe₂O₄/TiO₂, Zn₂SnO₄, and CoFe₂O₄/Zn₂SnO₄, respectively. Both compounds are characterized as nanocatalysts as they have a band gap of 2.75 and 2.83 eV and average particle size of 98 and 85 nm for CoFe₂O₄/TiO₂ and Zn₂SnO₄, respectively. We employed a reactional model, which was able to describe the catalytic ozonation for all cases, with a low R² of 0.9731. The combination of processes increased TZ degradation from 57% to 74% compared to O₃ alone, achieving a maximum degradation of 98.5% within 50 min of catalysis at a low ozone flow rate. This highlights the potential of the produced catalysts for energy-efficient effluent treatment. Full article

The discovery of a multi-target scaffold in medicinal chemistry is an important goal for the development of new drugs with different biological effects. Azobenzene is one of the frameworks in medicinal chemistry used for its simple synthetic methods and for the possibility to obtain a great variety of derivatives by simple chemical modifications or substitutions. Phenyldiazenyl-containing compounds show a wide spectrum of pharmacological activities, such as antimicrobial, anti-inflammatory, anti-neurodegenerative, anti-cancer, and anti-enzymatic. The aim of this review is to highlight the importance of azobenzene as a scaffold in medicinal chemistry, with particular attention to the chemical modifications and structure–activity relationships (SARs). This review emphasizes the main therapeutic applications of phenyldiazenyl derivatives, with a particular focus on structural modification and its influence on activity, with the aim of inspiring medicinal chemists to obtain new, increasingly powerful azobenzenes useful in therapy. Full article

The single-atom catalyst (SAC) activated persulfate process has emerged as a highly efficient technology for eliminating refractory organic compounds in aqueous environments. This review delves into the intricacies of utilizing SACs for the effective removal of various contaminants in water. The common supports and the preparation procedures of SACs are summarized at first. The synthesis methods of SACs (i.e., wet chemical method, one-pot hydrothermal method, and high-temperature pyrolysis method) are also described. Then, a comprehensive overview of the diverse reaction mechanisms in SAC-activated persulfate systems is presented, including a radical oxidation process via sulfate or hydroxyl radicals and superoxide radicals, or a nonradical process via single oxygen, surface active complex, and high-valent metal-oxo species oxidation. The impact of key factors such as peroxides concentration, SAC dosage, reaction pH, inorganic anions, organic matter, operando stability, and real water is also delved. The removal of various pollutants (i.e., azo dyes, phenolic compounds, pharmaceuticals, and bacteria) by this process is further summarized. Finally, the challenges and perspectives in the field of water treatment utilizing SACs are discussed. Full article