Search Results (204)

A one-pot synthetic methodology that combines an Ugi-Zhu three-component reaction (UZ-3CR) with a cascade sequence (intermolecular aza Diels–Alder cycloaddition/intramolecular N-acylation/decarboxylation/dehydration) using microwave-heating conditions, ytterbium (III) triflate (Yb(OTf)₃) as the catalyst, and chlorobenzene (for the first time in a multi-component reaction (MCR)) as the solvent, was developed to synthesize twelve new fluorinated-pyrrolo[3,4-b]pyridin-5-ones containing a 4-amino-7-chloroquinoline moiety, yielding 50–77% in 95 min per product, with associated atom economies around 88%, also per product. Additionally, by in vitro tests, compounds 19d and 19i were found to effectively stop early SARS-CoV-2 replication, IC₅₀ = 6.74 µM and 5.29 µM, at 0 h and 1 h respectively, while cell viability remained above 90% relative to the control vehicle at 10 µM. Additional computer-based studies revealed that the most active compounds formed strong favorable interactions with important viral proteins (M_pro, NTDα and NTDo) of coronavirus, supporting a two-pronged approach that affects both how the virus infects the cells and how it replicates its genetic material. Finally, quantum chemistry analyses of non-covalent interactions were performed from Density-Functional Theory (DFT) to better understand how the active compounds hit the virus. Full article

This study aims to evaluate eco-innovative solutions in the fertilizer industry that allow for waste valorization in the context of a resource-efficient circular economy. A comprehensive reuse strategy was developed for low-rank peat and post-cultivation horticultural mineral wool, involving the extraction of valuable humic substances from peat and residual nutrients from used mineral wool, followed by the use of both post-extraction residues to produce organic–mineral substrates. The resulting products/semifinished products were characterized in terms of their composition and properties, which met the requirements necessary to obtain the admission of this type of product to the market in accordance with the Regulation of the Minister for Agriculture and Rural Development of 18 June 2008 on the implementation of certain provisions of the Act on fertilizers and fertilization (Journal of Laws No 119, item 765). Elemental analysis, FTIR spectroscopy, and solid-state CP-MAS ¹³C NMR spectroscopy suggest that post-extraction peat has a relatively condensed structure with a high C content (47.4%) and a reduced O/C atomic ratio and is rich in alkyl-like matter (63.2%) but devoid of some functional groups in favor of extracted fulvic acids. Therefore, it remains a valuable organic biowaste, which, in combination with post-extraction waste mineral wool in a ratio of 60:40 and possibly the addition of mineral nutrients, allows us to obtain a completely new substrate with a bulk density of 264 g/m³, a salinity of 7.8 g/dm³ and a pH of 5.3, with an appropriate content of heavy metals and with no impurities, meeting the requirements of this type of product. A liquid fertilizer based on an extract containing previously recovered nutrients also meets the criteria in terms of quality and content of impurities and can potentially be used as a fertilizing product suitable for agricultural crops. This study demonstrates a feasible pathway for transforming specific waste streams into valuable agricultural inputs, contributing to environmental protection and sustainable production. The production of a new liquid fertilizer using nutrients recovered from post-cultivation mineral wool and the preparation of an organic–mineral substrate using post-extraction solid residue is a rational strategy for recycling hard-to-biodegrade end-of-life products. Full article

Axially chiral compounds play a pivotal role in organic synthesis, materials science, and pharmaceutical development. Among the various strategies for their construction, enantioselective iodination and bromination have emerged as powerful and versatile approaches, enabling the introduction of halogen functionalities that serve as valuable synthetic handles for further transformations. This review highlights recent advances in atroposelective iodination and bromination, with a particular focus on the synthesis of axially chiral biaryl and heterobiaryl frameworks. Key catalytic systems are discussed, including transition metal complexes, small-molecule organocatalysts, and high-valent metal catalysts in combination with chiral ligands or transient directing groups. Representative case studies are presented to elucidate mechanistic pathways, stereochemical induction models, and synthetic applications. Despite notable progress, challenges remain, such as expanding substrate scope, improving atom economy, and achieving high levels of regio- and stereocontrol in complex molecular settings. This review aims to provide a comprehensive overview of these halogenation strategies and offers insights to guide future research in the atroposelective synthesis of axially chiral molecules. Full article

The current paper examines the sustainable possibility for recycling unused or expired Metoprolol (MET), a benzodiazepine derivative, as an effective corrosion inhibitor for carbon steel in saline solutions. Repurposing expired medicinal drugs aligns with green chemistry concepts and supports circular economy initiatives by reducing pharmaceutical waste and averting the production of new synthetic inhibitors. The technical benefit of recycling expired MET drugs pertains to the elimination of costs associated with organic inhibitor manufacturing and the decrease in disposal expenses for the expired medication. A combination of electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy) and quantum chemical calculations was employed to evaluate the inhibitory mechanism and efficacy of MET. At a concentration of 10⁻³ M, MET reduced the corrosion current density from 19.38 to 5.97 μA cm⁻², achieving a maximum IE of 69.1%. Adsorption Gibbs free energy, determined using different adsorption isotherms, revealed that interactions between metal atoms and MET adsorbed molecules have a chemical character with a ∆G^o_ads value of −50.7 kJ·mol⁻¹. Furthermore, quantum chemistry calculations indicate that the investigated drug, owing to its molecular structure (E_HOMO = −9.12 eV, E_LUMO = 0.21 eV, µ = 3.95 D), possesses the capacity to establish an adsorption layer on the metal surface, thereby impeding the diffusion of molecules and ions involved in the overall corrosion process. The results obtained using the different techniques were in good agreement and highlighted the effectiveness of MET in the corrosion inhibition of carbon steel. Full article

1,3-Dipolar cycloadditions on nitrone dipoles are key reactions to access five-membered heterocycles, which are useful intermediates in the synthesis of biologically relevant glycomimetics. The good atomic balance and high stereoselectivity characteristic of such reactions make them good candidates for the development of green protocols. In the present work, these features were maximized by avoiding the use of organic solvents and considering starting materials derived from biomass. Reactions involving (acyclic and cyclic) carbohydrate-derived nitrones as dipoles and levoglucosenone as dipolarophile were considered. Performing selected 1,3-dipolar cycloadditions in neat conditions showed reduced reaction times, maintaining similar selectivity and yields with respect to the classical protocols. The use of microwave irradiation and orbital shaking were also exploited to increase the sustainability of the synthetic protocols. The collected results highlight the potential of solvent-free 1,3-dipolar cycloadditions in the design of efficient synthetic routes according to green chemistry principles, such as prevention, atom economy, safer solvents and auxiliaries, and use of renewable feedstocks. Full article

Direct methanol fuel cells (DMFCs) represent a promising pathway for energy conversion, yet their reliance on platinum-group metal (PGM)-based anode catalysts poses critical sustainability challenges, which stem from finite mineral reserves, environmentally detrimental extraction processes, and prohibitive lifecycle costs. Current anode catalysts for DMFCs are dominated by platinum materials; therefore, this review systematically evaluates the following three emerging eco-efficient design paradigms using platinum materials as a starting point: (1) the atomic-level optimization of low-Pt alloy surfaces to maximize catalytic efficiency per metal atom, (2) Earth-abundant transition metal compounds (e.g., nitrides and sulfides) and coordination-tunable metal–organic frameworks as viable PGM-free alternatives, and (3) mechanically robust carbon architectures with engineered topological defects that enhance catalyst stability through covalent metal–carbon interactions. Through comparative analysis with pure Pt benchmarks, we critically examine how these strategic material innovations collectively mitigate CO intermediate poisoning risks and improve electrochemical durability. Such fundamental advances in catalyst design not only address immediate technical barriers, but also establish essential material foundations for the development of DMFC technologies compatible with circular economy frameworks and United Nations Sustainable Development Goal 7 targets. Full article

Additives are compounds used for material to increase specific properties. When used for polymers, they extend their life and contribute to environmental sustainability. This article presents the study findings related to 24 additives—antioxidants, UV stabilizers, and quenchers—using cheminformatics methods. The compounds’ characteristics (e.g., number of atoms, functional groups) were emphasized, followed by some descriptors. The Tanimoto coefficient, computed based on the maximum common structure algorithm, and the overlap coefficient indicated the degree of similarity between the molecules. The molecules were grouped by binning and hierarchical clustering (HC) based on the extracted results. In the last case, two scenarios were considered—with four (CL1–CL4) and six clusters (CL1.1, CL1.2, CL2, CL3, CL4.1, CL4.2) being built. Considering the mechanical properties of the compounds and the standard deviation and amplitude of their values, the most homogenous class was CL2 (respectively CL4.2). Considering the toxicity of additives, the highest possible negative impact on the environment is that of the compounds in CL1 and CL3. The clustering results guide the selection of additives with reduced environmental impact, thereby supporting the development of sustainable polymer formulations aligned with circular economy principles. Full article

Unsaturated macrolactones (UMs) have long attracted researchers’ attention due to a combination of a reactive ester fragment and C=C bond in their structures. UMs of natural origin are comparatively few in number, and the task of developing synthetic approaches to new UMs is relevant. Recent advances in the synthesis of UMs cannot be dissociated from the progress in design of metathesis catalysts, since this catalytic approach is an atom-economy alternative to conventional organochemical methods. In the present review, we summarized and discussed the use of ring-closing metathesis, catalyzed by Ru and Group 6 metal complexes, in the synthesis of Ums and the advantages and shortcomings of the catalytic approach to UMs in comparison with organochemical methods. In a separate section, the use of UMs in the synthesis of unsaturated polyesters, the functionalization of these (co)polymers, and the prospects for practical use of the material obtained are also presented. It is essential that the actual approaches to UMs are often based on the use of renewable feedstocks, thereby meeting Green Chemistry principles. Full article

This study presents a comprehensive uncertainty and sensitivity analysis of the effective neutron multiplication factor ($k_{\mathrm{eff}}$) in a large-scale sodium-cooled fast reactor (SFR) modeled after the European Sodium Fast Reactor. Utilizing the Serpent Monte Carlo code and the ENDF/B-VII.1 cross-section library, this research investigates the impact of cross-section perturbations in key isotopes (²³⁵U, ²³⁸U, and ²³⁹Pu for both mixed oxide (MOX) and metal fuels. Particular focus is placed on the capture, fission, and inelastic scattering reactions, as well as the effects of fuel temperature on reactivity through Doppler broadening. The findings reveal that reactivity in MOX fuel is highly sensitive to the fission cross sections of fissile isotopes (²³⁹Pu and ²³⁸U, while capture and inelastic scattering reactions in fertile isotopes such as ²³⁸U play a significant role in reducing reactivity, enhancing neutron economy. Additionally, this study highlights that metal fuel configurations generally achieve a higher ($k_{\mathrm{eff}}$) compared to MOX, attributed to their higher fissile atom density and favorable thermal properties. These results underscore the importance of accurate nuclear data libraries to minimize uncertainties in criticality evaluations, and they provide a foundation for optimizing fuel compositions and refining reactor control strategies. The insights gained from this analysis can contribute to the development of safer and more efficient next-generation SFR designs, ultimately improving operational margins and reactor performance. Full article

Herein, we report the first mechanochemical strategy for the Ru-catalyzed deoxygenative borylation of free phenols via C–O bond cleavage. This Ru-catalyzed phenolic borylation approach has been successfully extended to the Suzuki–Miyaura-type cross-coupling of phenols with aryl bromides. The protocol accepts a wide scope of phenolic substrates, allowing the synthesis of aryl pinacolboranes and biphenyl structures in excellent yields and serving as a better alternative to classical cross-coupling reactions in the context of pot, atom, and step economy synthesis. Full article

A novel method for the efficient and straightforward synthesis of tetrasubstituted furans is presented, employing a base-catalyzed reaction of α-hydroxy ketones and cyano compounds. The reaction proceeds under relatively mild conditions, utilizes readily available starting materials, and exhibits good functional group tolerance and high yields. Notably, this reaction obviates the need for expensive metal catalysts and introduces crucial functional groups such as amino and cyano moieties. Furthermore, it avoids the prerequisite functionalization of substrates, thereby enhancing atomic economy. Full article

The occurrence of heavy metals in aquatic ecosystems is a serious environmental hazard, and their effective removal is imperative. In this regard, the feasibility of living microalga Chlorella vulgaris (C. vulgaris) to remove heavy metals (Ni, Pb, Zn, Cd, and Cu) is investigated by using 1, 5, and 10 ppm concentrations of single- and multiple-metal-treated (MT) cultures. Experiments were performed in controlled laboratory conditions, and metal removal analysis was performed through atomic absorption spectroscopy (AAS). The cultures were also examined by means of optical microscopy, UV-Vis spectrophotometry, and Fourier transform infrared (FTIR) spectroscopy to follow the cultures’ pigment content, cell population, and functional group changes during cultivation. The removal efficiency results of both single and multiple MT cultures were evaluated using the Langmuir isotherm model. The results indicate that C. vulgaris presents potential for heavy metal bioremediation, even towards multi-MT conditions, despite the influence of a competitive uptake in multi-MT cultures. In mono-MT cultures, the removal efficiency of C. vulgaris presents values of 65–99% on Day 3 and 72–99% on Day 7 of cultivation, while the results for the multi-MT cultures are 49–99% and 62–99% for Days 3 and 7 of cultivation, respectively. The research illustrates the potential for C. vulgaris as a promising biosorbent for heavy metal remediation along with its post-treatment use in applications supporting the green circular economy. Full article

Common wheat (Triticum aestivum L.) is a key cereal in the global economy, providing essential nutrients for human and animal health. The European Union promotes less intensive farming systems as part of its sustainable development strategy. This study aimed to evaluate the impact of different farming systems on the concentration of macronutrients—potassium, phosphorus, magnesium, and calcium (K, P, Mg, and Ca)— and micronutrients—iron, zinc, manganese, and copper (Fe, Zn, Mn, and Cu)—in wheat grain, as well as the effect of grain processing on the distribution of these nutrients in bran, flour, and bread. This study included four spring wheat cultivars (Harenda, Kandela, Mandaryna, and Serenada) grown under organic (ORG), integrated (INT), and conventional (CONV) systems at the Osiny Experimental Station (Poland; 51°27′ N; 22°2′ E) between 2019 and 2021. The P concentration was determined using the colorimetric method, while the other nutrients were analyzed by atomic absorption spectrometry (AAS). The grain from the CONV system exhibited higher macronutrients concentrations, whereas grain from less intensive systems had higher micronutrients concentrations, except for Fe. The Fe concentration in grain from the INT and CONV systems was comparable. An interaction effect between cultivars and farming systems on P, Ca, Mn, Zn, and Cu concentrations in the grain was observed. In all research material, the highest concentrations of minerals were found in bran, followed by grain, with the lowest concentrations observed in flour and bread. Full article

This paper investigates a proposal for teaching Green Chemistry concepts through the implementation of a Problem-Based Learning (PBL) approach in a specific and optional course on the subject in higher education. The main objective was to analyze the effect of implementing Problem-Based Learning (PBL) didactics on understanding Green Chemistry principles within a course with 8 university students. Through this methodology, students analyzed case studies involving the identification of GC principles in industrial redesign processes and the problematization of controversial situations related to the importance of discussions on chemical processes. Two specific cases, bio-based butylene glycol and enzymatic treatment of paper, were used to test students’ ability to recognize and justify the relevance of these principles. Additionally, another activity about the synthesis of acetanilide allowed students to identify which of four methodologies could be considered the greenest, considering different aspects. The research revealed that although the PBL approach effectively engaged students and deepened their understanding of GC principles, some concepts presented challenges. Certain principles of Green Chemistry, such as atom economy and catalysis, proved complex for some students, leading to confusion and challenges in assessing the “greenness” of processes. Nonetheless, students demonstrated improved knowledge and practical application of GC principles, linking them to industrial processes like bio-based material production and analyzing the benefits and drawbacks of different methods for producing the same substance. This study highlighted the value of a dedicated PBL approach with adequate resources to foster discussions and understanding. However, elective courses often attract only those already familiar with the subject, limiting broader engagement and field expansion. Disparities in case material quality, particularly for bio-based butylene glycol and acetanilide production, underscored the need for well-structured resources. Future research should include larger sample sizes for statistical validation and more class time for discussions and supplemental activities. This study contributes to the literature on active learning strategies, showcasing PBL’s potential to enhance sustainable chemical education. Full article