Molecules

19 pages, 456 KiB

Open AccessArticle

Synthesis and Antiviral Evaluation of 5-(4-Aryl-1,3-Butadiyn-1-yl)-Uridines and Their Phosphoramidate Pronucleotides

by Evan Saillard, Otmane Bourzikat, Koffi Assa, Vincent Roy and Luigi A. Agrofoglio

Molecules 2025, 30(1), 96; https://doi.org/10.3390/molecules30010096 (registering DOI) - 29 Dec 2024

Abstract

The emergence of RNA viruses driven by global population growth and international trade highlights the urgent need for effective antiviral agents that can inhibit viral replication. Nucleoside analogs, which mimic natural nucleotides, have shown promise in targeting RNA-dependent RNA polymerases (RdRps). Starting from [...] Read more.

The emergence of RNA viruses driven by global population growth and international trade highlights the urgent need for effective antiviral agents that can inhibit viral replication. Nucleoside analogs, which mimic natural nucleotides, have shown promise in targeting RNA-dependent RNA polymerases (RdRps). Starting from protected 5-iodouridine, we report the synthesis of hitherto unknown C5-substituted-(1,3-diyne)-uridines nucleosides and their phosphoramidate prodrugs. The modifications at C5 include 4-(trifluoromethyl)benzene (a), 4-pentyl-benzene (b), 3,5-dimethoxy-benzene (c), 4-(trifluoromethoxy)benzene (d), 3-aniline (e), 4-pyridine (f), 3-thiophene (g), C₆H₁₃ (h), 2-pyrimidine (i), cyclopropyl (j), and phenyl (k) groups. These compounds were synthesized using Sonogashira palladium-catalyzed reactions and nickel–copper-catalyzed C-H activation between various alkynes, yielding between 25% and 67%. The antiviral activities of obtained compounds were measured through HTS against RNA viruses including influenza H1N1 and H3N2, human respiratory syncytial virus (RSV), SARS-CoV-2, Zika, hepatitis C virus (HCV), Hepatitis E virus (HEV), as well as against coronavirus (HCoV-229E). Unfortunately, none of them showed promising antiviral activity, with less than 85% inhibition observed in the cell viability screening of infected cells. Full article

(This article belongs to the Special Issue Bioorganic Chemistry in Europe)

14 pages, 690 KiB

Open AccessArticle

Conjugation of Triterpenic Acids with 3-Aminoquinuclidine Moiety: An Approach to Acetylcholinesterase Mixed or Uncompetitive Type Inhibitors

by Anastasiya V. Petrova, Ha T. T. Nguyen, Irina V. Zueva, Konstantin A. Petrov, Alexander N. Lobov and Oxana B. Kazakova

Molecules 2025, 30(1), 95; https://doi.org/10.3390/molecules30010095 (registering DOI) - 29 Dec 2024

Abstract

Alzheimer’s disease (AD) poses a significant public health issue. Despite the fact that today there are several methods of maintenance therapy, one of the most widely used methods is designed to correct the deficiency of acetylcholine. In the search for new potential inhibitors [...] Read more.

Alzheimer’s disease (AD) poses a significant public health issue. Despite the fact that today there are several methods of maintenance therapy, one of the most widely used methods is designed to correct the deficiency of acetylcholine. In the search for new potential inhibitors of cholinesterase enzymes, eight new derivatives of 3-oxo- or 2,3-indolo-triterpenic acid conjugated with amino-quinuclidine bicyclic cores were designed and synthesized. Then, the obtained compounds were screened in Ellman’s assays for their ability to inhibit acetylcholinesterase enzyme, and for each of the active compounds, the type of inhibition was determined. The obtained results demonstrate the dependence of the activity on the triterpenoid structure and the type of substituents. The best activity for ursolic acid derivatives was observed for the 3-oxoamide 8, with an IC₅₀ value of 0.43 µM, acting as a mixed-type inhibitor. In turn, for the oleanane type, the amide with an indole unit in the A ring 11 exhibited the best activity with an IC₅₀ value of 0.47 µM (while the ursane-type analog was weakly active) and led to an uncompetitive type of inhibition. Thus, 3-amidoquinuclidine-triterpenoids conjugates could be considered novel inhibitors of acetylcholinesterase with a different mechanism of action. Full article

(This article belongs to the Special Issue Enzyme Inhibitors: Design, Synthesis and Biological Evaluation, 2nd Edition)

13 pages, 1249 KiB

Open AccessArticle

Mechanochemical Functionalization of Oxidized Carbon Black with PLA

by Aida Kiani, Mattia Naddeo, Federica Santulli, Valentina Volpe, Mina Mazzeo and Maria Rosaria Acocella

Molecules 2025, 30(1), 94; https://doi.org/10.3390/molecules30010094 (registering DOI) - 29 Dec 2024

Abstract

Abstract: The functionalization of carbon black (CB) represents a promising strategy to enhance its compatibility with polymers while addressing sustainability concerns. In this study, a solvent-free mechanochemical approach (ball milling) is proposed for the functionalization of oxidized carbon black (oCB) with post-consumed polylactic [...] Read more.

Abstract: The functionalization of carbon black (CB) represents a promising strategy to enhance its compatibility with polymers while addressing sustainability concerns. In this study, a solvent-free mechanochemical approach (ball milling) is proposed for the functionalization of oxidized carbon black (oCB) with post-consumed polylactic acid (PLA), overcoming the environmental drawbacks of conventional methods that mostly rely on toxic solvents and catalysts. The functionalized carbon black (f-CB) was characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), and thermogravimetric analysis (TGA) to confirm the successful modification. At the same time, the influence of f-CB as a nanofiller of residual PLA waste was evaluated using differential scanning calorimetry (DSC) and gel permeation chromatography (GPC), demonstrating its stabilization effect during melt extrusion by preserving the molecular weight of the starting polymer. On the other hand, the dynamic mechanical analysis (DMA) revealed that the addition of f-CB did not negatively affect the mechanical properties of the resulting composite. In conclusion, mechanochemistry was used as a sustainable and unique strategy for the upcycling of waste PLA into a PLA-based composite stabilized by CB functionalized with the waste PLA itself. Full article

12 pages, 2162 KiB

Open AccessArticle

Stable RuIr Nanoalloy Catalyst for Levulinic Acid Hydrogenation Reaction

by Jingru Wang, Xianshu Dong, Yuping Fan, Yingyong Wang and Xiangyun Guo

Molecules 2025, 30(1), 93; https://doi.org/10.3390/molecules30010093 (registering DOI) - 29 Dec 2024

Abstract

Hydrogenation of levulinic acid (LA) represents a significant approach for producing the high-value biomass-based platform compound γ-valerolactone (GVL). In this study, an efficient RuIr alloy bimetallic catalyst supported on SiC was synthesized and applied for the aqueous hydrogenation of LA into GVL under [...] Read more.

Hydrogenation of levulinic acid (LA) represents a significant approach for producing the high-value biomass-based platform compound γ-valerolactone (GVL). In this study, an efficient RuIr alloy bimetallic catalyst supported on SiC was synthesized and applied for the aqueous hydrogenation of LA into GVL under mild conditions. The RuIr/SiC catalyst exhibited high LA conversion and GVL selectivity (both > 99%) in water at 0.2 MPa H₂ pressure and 25 °C. The excellent performance is attributed to the synergistic interaction between Ru and Ir nanoparticles on the semiconducting SiC support. Furthermore, the catalytic activity of the RuIr/SiC alloy remained basically unchanged after five cycles, confirming the high stability of the bimetallic alloy catalyst. Full article

(This article belongs to the Special Issue Separation, Recovery and Conversion of Low-Quality Materials via Physicochemical Technology)

21 pages, 26975 KiB

Open AccessArticle

Recovery of Nd³⁺ and Dy³⁺ from E-Waste Using Adsorbents from Spent Tyre Rubbers: Batch and Column Dynamic Assays

by Miguel Nogueira, Inês Matos, Maria Bernardo, Filomena Pinto, Isabel Fonseca and Nuno Lapa

Molecules 2025, 30(1), 92; https://doi.org/10.3390/molecules30010092 (registering DOI) - 29 Dec 2024

Abstract

This paper investigates the use of spent tyre rubber as a precursor for synthesising adsorbents to recover rare earth elements. Through pyrolysis and CO₂ activation, tyre rubber is converted into porous carbonaceous materials with surface properties suited for rare earth element adsorption. [...] Read more.

This paper investigates the use of spent tyre rubber as a precursor for synthesising adsorbents to recover rare earth elements. Through pyrolysis and CO₂ activation, tyre rubber is converted into porous carbonaceous materials with surface properties suited for rare earth element adsorption. The study also examines the efficiency of leaching rare earth elements from NdFeB magnets using optimised acid leaching methods, providing insights into recovery processes. The adsorption capacity of the materials was assessed through batch adsorption assays targeting neodymium (Nd³⁺) and dysprosium (Dy³⁺) ions. Results highlight the superior performance of activated carbon derived from tyre rubber following CO₂ activation, with the best-performing adsorbent achieving maximum uptake capacities of 24.7 mg·g⁻¹ for Nd³⁺ and 34.4 mg·g⁻¹ for Dy³⁺. Column studies revealed efficient adsorption of Nd³⁺ and Dy³⁺ from synthetic and real magnet leachates with a maximum uptake capacity of 1.36 mg·g⁻¹ for Nd³⁺ in real leachates and breakthrough times of 25 min. Bi-component assays showed no adverse effects when both ions were present, supporting their potential for simultaneous recovery. Furthermore, the adsorbents effectively recovered rare earth elements from e-waste magnet leachates, demonstrating practical applicability. This research underscores the potential of tyre rubber-derived adsorbents to enhance sustainability in critical raw material supply chains. By repurposing waste tyre rubber, these materials offer a sustainable solution for rare earth recovery, addressing resource scarcity while aligning with circular economy principles by diverting waste from landfills and creating value-added products. Full article

(This article belongs to the Special Issue Design and Synthesis of Novel Adsorbents for Pollutant Removal)

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21 pages, 2369 KiB

Open AccessReview

Review of Cathepsin K Inhibitor Development and the Potential Role of Phytochemicals

by Dong Oh Moon

Molecules 2025, 30(1), 91; https://doi.org/10.3390/molecules30010091 (registering DOI) - 29 Dec 2024

Abstract

Cathepsin K plays a pivotal role in bone resorption and has emerged as a prominent therapeutic target for treating bone-related diseases such as osteoporosis. Despite significant advances in synthetic inhibitor development, none have achieved FDA approval due to safety and efficacy challenges. This [...] Read more.

Cathepsin K plays a pivotal role in bone resorption and has emerged as a prominent therapeutic target for treating bone-related diseases such as osteoporosis. Despite significant advances in synthetic inhibitor development, none have achieved FDA approval due to safety and efficacy challenges. This review highlights the potential of phytochemicals as alternative inhibitors, emphasizing their natural origin, structural diversity, and minimal adverse effects. Key phytochemicals, including AC-5-1, Cycloaltilisin 6, Cycloaltilisin 7, Nicolaioidesin C, and Panduratin A, were examined for their inhibitory activities against cathepsin K. While these compounds exhibit varying IC₅₀ values, their docking studies revealed significant interactions within Cathepsin K’s active site, particularly involving critical residues such as Cys25 and His162. However, challenges such as lower potency compared to synthetic inhibitors and limited in vivo studies underscore the need for structural optimization and comprehensive preclinical evaluations. This review discusses biological insights, current limitations, and future strategies for advancing phytochemical-based inhibitors toward clinical applications in managing Cathepsin K-associated diseases. Full article

(This article belongs to the Special Issue Phytochemicals as Valuable Tools for Fighting Metabolic Disorders)

47 pages, 6151 KiB

Open AccessReview

Natural and Synthetic Flavylium Derivatives: Isolation/Synthesis, Characterization and Application

by Diana-Ionela Dăescu, Iulia Păușescu, Ioana Cristina Benea, Francisc Peter, Anamaria Todea, Federico Zappaterra, Andreea Anda Alexa and Alina Ramona Buzatu

Molecules 2025, 30(1), 90; https://doi.org/10.3390/molecules30010090 (registering DOI) - 29 Dec 2024

Abstract

Given the natural origins of flavylium derivatives, their chemical modifications, and their large potential uses in food, medicine, or green chemistry, the present review is a comprehensive study of flavylium-derived compounds. Several topics such as the green extraction and isolation techniques of flavylium [...] Read more.

Given the natural origins of flavylium derivatives, their chemical modifications, and their large potential uses in food, medicine, or green chemistry, the present review is a comprehensive study of flavylium-derived compounds. Several topics such as the green extraction and isolation techniques of flavylium derivatives including their chemical modifications and various characterization tools such as NMR, HPLC, and mass spectrometry are discussed in the review. Furthermore, the use of these derivatives in medicine, food, and materials science is presented, highlighting their relevance and the need for further investigation. Therefore, by examining the advantages and disadvantages of natural and synthetic sources, the review asserts the increased relevance of flavylium-based compounds in active molecules. Full article

(This article belongs to the Special Issue Study on Extraction and Chemical Constituents of Natural Extracts)

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11 pages, 10876 KiB

Open AccessArticle

Lignin-Derived Activated Carbon as Electrode Material for High-Performance Supercapacitor

by Chenghao Pan, Yongfeng Ji, Suxia Ren, Lili Dong and Tingzhou Lei

Molecules 2025, 30(1), 89; https://doi.org/10.3390/molecules30010089 (registering DOI) - 29 Dec 2024

Abstract

Utilizing lignin-derived activated carbon in supercapacitors has emerged as a promising approach to alleviating environmental pollution and promoting the high-value utilization of byproducts in the papermaking industry. In this study, activated carbons (LACs) were prepared using a simple one-step KOH activation approach and [...] Read more.

Utilizing lignin-derived activated carbon in supercapacitors has emerged as a promising approach to alleviating environmental pollution and promoting the high-value utilization of byproducts in the papermaking industry. In this study, activated carbons (LACs) were prepared using a simple one-step KOH activation approach and by employing enzymatic hydrolysis lignin (EHL). The impact of the KOH activation parameters on the microstructure and capacitive performance of the LACs was investigated by varying the KOH/EHL ratio and activation temperature. The optimized sample LAC_800-4 showed an interconnected porous structure with a high surface area of 2285 m²/g, abundant micropores, and a small number of mesopores, which makes it a suitable electrode material for supercapacitors. The sample LAC_800-4 demonstrated a high specific capacitance of 291.3 F/g in a three-electrode system. Under a symmetrical supercapacitor electrode system, the specific capacitance of the LAC_800-4 electrode reached 186.8 F/g at 0.5 A/g. After 10,000 cycles at 20 A/g, the capacitance retention rate remained at 96.1%. The symmetrical supercapacitor also demonstrated a superior energy density of 6.5 Wh/kg. This work provides valuable insights into the transformation of low-value natural biomass derivatives into environmentally friendly, high-performing supercapacitor electrode materials. Full article

(This article belongs to the Special Issue Carbon-Based Electrochemical Materials for Energy Storage)

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23 pages, 6258 KiB

Open AccessArticle

Equilibrium Adsorption of Organic Compounds (Nitrobenzene Derivative, Synthetic Pesticide, Dye, and Surfactant) on Activated Carbon from Single- and Multi-Component Systems

by Magdalena Blachnio, Malgorzata Zienkiewicz-Strzalka and Anna Derylo-Marczewska

Molecules 2025, 30(1), 88; https://doi.org/10.3390/molecules30010088 (registering DOI) - 29 Dec 2024

Abstract

This work aimed to investigate the adsorption of organic compounds (4-nitroaniline and 4-chlorophenoxyacetic acid) on activated carbon in the presence of selected dyes (uranine and Acid Red 88) and surfactants (sodium dodecyl sulfate and hexadecyltrimethylammonium bromide). The adsorbent, i.e., the activated carbon RIAA [...] Read more.

This work aimed to investigate the adsorption of organic compounds (4-nitroaniline and 4-chlorophenoxyacetic acid) on activated carbon in the presence of selected dyes (uranine and Acid Red 88) and surfactants (sodium dodecyl sulfate and hexadecyltrimethylammonium bromide). The adsorbent, i.e., the activated carbon RIAA (experimental activated carbon, Norit NV, Amersfoort, The Netherlands), was fully characterised by nitrogen adsorption/desorption isotherms, potentiometric titration, small-angle X-ray scattering, X-ray photoelectron spectroscopy, and transmission electron microscopy. The measurements of the adsorption isotherms of individual adsorbates from aqueous solutions were performed, and the Generalised Freundlich equation (GF) was used for their analysis. The influence of the properties of the co-adsorbates and the adsorbent on the efficiency of removal of 4-nitroaniline and 4-chlorophenoxyacetic acid from the water phase was discussed. A sieving effect was found—large dye and surfactant molecules do not penetrate the micropores but only locate at their entrances, limiting the availability of carbon adsorption space for the nitro compound and the pesticide. A very clear influence of the co-adsorbates’ concentration on the adsorption efficiency of the organic pollutants from the mixture was also observed. When the CMC (critical micelle concentration) value was exceeded in the system with surfactant as the co-adsorbent, a decrease in the competition effect on the adsorption of 4-chlorophenoxyacetic acid was observed. This is due to the formation of large aggregates of the surfactant in the solution, which are poorly adsorbed on the activated carbon. Full article

(This article belongs to the Special Issue Materials for Environmental Remediation and Catalysis)

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16 pages, 2523 KiB

Open AccessReview

Recent Progress in Polyolefin Plastic: Polyethylene and Polypropylene Transformation and Depolymerization Techniques

by Acácio Silva de Souza, Patricia Garcia Ferreira, Iva Souza de Jesus, Rafael Portugal Rizzo Franco de Oliveira, Alcione Silva de Carvalho, Debora Omena Futuro and Vitor Francisco Ferreira

Molecules 2025, 30(1), 87; https://doi.org/10.3390/molecules30010087 (registering DOI) - 29 Dec 2024

Abstract

This paper highlights the complexity and urgency of addressing plastic pollution, drawing attention to the environmental challenges posed by improperly discarded plastics. Petroleum-based plastic polymers, with their remarkable range of physical properties, have revolutionized industries worldwide. Their versatility—from flexible to rigid and hydrophilic [...] Read more.

This paper highlights the complexity and urgency of addressing plastic pollution, drawing attention to the environmental challenges posed by improperly discarded plastics. Petroleum-based plastic polymers, with their remarkable range of physical properties, have revolutionized industries worldwide. Their versatility—from flexible to rigid and hydrophilic to hydrophobic—has fueled an ever-growing demand. However, their versatility has also contributed to a massive global waste problem as plastics pervade virtually every ecosystem, from the depths of oceans to the most remote terrestrial landscapes. Plastic pollution manifests not just as visible waste—such as fishing nets, bottles, and garbage bags—but also as microplastics, infiltrating food chains and freshwater sources. This crisis is exacerbated by the unsustainable linear model of plastic production and consumption, which prioritizes convenience over long-term environmental health. The mismanagement of plastic waste not only pollutes ecosystems but also releases greenhouse gases like carbon dioxide during degradation and incineration, thereby complicating efforts to achieve global climate and sustainability goals. Given that mechanical recycling only addresses a fraction of macroplastics, innovative approaches are needed to improve this process. Methods like pyrolysis and hydrogenolysis offer promising solutions by enabling the chemical transformation and depolymerization of plastics into reusable materials or valuable chemical feedstocks. These advanced recycling methods can support a circular economy by reducing waste and creating high-value products. In this article, the focus on pyrolysis and hydrogenolysis underscores the need to move beyond traditional recycling. These methods exemplify the potential for science and technology to mitigate plastic pollution while aligning with sustainability objectives. Recent advances in the pyrolysis and hydrogenolysis of polyolefins focus on their potential for advanced recycling, breaking down plastics at a molecular level to create feedstocks for new products or fuels. Pyrolysis produces pyrolysis oil and syngas, with applications in renewable energy and chemicals. However, some challenges of this process include scalability, feedstock variety, and standardization, as well as environmental concerns about emissions. Companies like Shell and ExxonMobil are investing heavily to overcome these barriers and improve recycling efficiencies. By leveraging these transformative strategies, we can reimagine the lifecycle of plastics and address one of the most pressing environmental challenges of our time. This review updates the knowledge of the fields of pyrolysis and hydrogenolysis of plastics derived from polyolefins based on the most recent works available in the literature, highlighting the techniques used, the types of products obtained, and the highest yields. Full article

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12 pages, 3316 KiB

Open AccessArticle

Study of the Effect of Methyl Eugenol on Gastric Damage Produced by Spinal Cord Injury Model in the Rat

by Leticia Cruz-Antonio, María Elena Sánchez-Mendoza, Jazmín García-Machorro, Yaraset López-Lorenzo and Jesús Arrieta

Molecules 2025, 30(1), 86; https://doi.org/10.3390/molecules30010086 (registering DOI) - 29 Dec 2024

Abstract

Traumatic spinal cord injury (SCI) is a serious medical condition that places patients at high risk of developing gastric ulceration and gastrointestinal bleeding. One preventative strategy involves the use of omeprazole; however, its chronic use is associated with adverse effects, highlighting the need [...] Read more.

Traumatic spinal cord injury (SCI) is a serious medical condition that places patients at high risk of developing gastric ulceration and gastrointestinal bleeding. One preventative strategy involves the use of omeprazole; however, its chronic use is associated with adverse effects, highlighting the need for alternative therapies. This study evaluated the protective effects of methyl eugenol (ME) on gastric mucosal damage in a rat model of SCI. ME was administered orally at doses of 30, 100, and 177 mg/kg in SCI induced at the T9 level, alongside diclofenac or ketorolac (30 mg/kg each). The enzymatic activity of superoxide dismutase, catalase, and glutathione peroxidase was assessed, and the levels of total glutathione and malondialdehyde were determined using biochemical kits. Additionally, stomach histological sections were analyzed. ME exhibited dose-dependent gastroprotective effects, with maximal protection observed at 177 mg/kg in the presence of diclofenac (9.78 ± 2.16 mm²) or ketorolac (12.49 ± 2.17 mm²). A histological analysis confirmed these findings. In conclusion, methyl eugenol protects the gastric mucosa from SCI-induced damage, with glutathione peroxidase and catalase playing key roles in its mechanism of gastroprotection. Full article

(This article belongs to the Section Chemical Biology)

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18 pages, 3234 KiB

Open AccessArticle

Mechanistic Aspects of [3+2] Cycloaddition Reaction of Trifluoroacetonitrile with Diarylnitrilimines in Light of Molecular Electron Density Theory Quantum Chemical Study

by Agnieszka Łapczuk and Mar Ríos-Gutiérrez

Molecules 2025, 30(1), 85; https://doi.org/10.3390/molecules30010085 (registering DOI) - 29 Dec 2024

Abstract

In this study, we investigated the [3+2] cycloaddition reaction of CF₃CN (TFAN) with nitrilimine (NI) to produce 1,2,4-triazole and compared the resulting isomers. We determined the preferred reaction pathway by examining the electrophilic and nucleophilic properties of the reaction substrates, performing [...] Read more.

In this study, we investigated the [3+2] cycloaddition reaction of CF₃CN (TFAN) with nitrilimine (NI) to produce 1,2,4-triazole and compared the resulting isomers. We determined the preferred reaction pathway by examining the electrophilic and nucleophilic properties of the reaction substrates, performing thermodynamic calculations for the individual pathways, and comparing them with the experimental results. Full article

(This article belongs to the Special Issue Heterocyclic Compounds: Synthesis, Application and Theoretical Study)

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12 pages, 2493 KiB

Open AccessArticle

Tungsten Carbide/Tungsten Oxide Catalysts for Efficient Electrocatalytic Hydrogen Evolution

by Jian Ouyang, Yu Sun, Yiqiong Zhang, Juzhe Liu, Xin Bo and Zenglin Wang

Molecules 2025, 30(1), 84; https://doi.org/10.3390/molecules30010084 (registering DOI) - 29 Dec 2024

Abstract

Catalyzing hydrogen evolution reaction (HER) is a key process in high-efficiency proton exchange membrane water electrolysis (PEMWE) devices. To replace the use of Pt-based HER catalyst, tungsten carbide (W₂C) is one of the most promising non-noble-metal-based catalysts with low cost, replicable [...] Read more.

Catalyzing hydrogen evolution reaction (HER) is a key process in high-efficiency proton exchange membrane water electrolysis (PEMWE) devices. To replace the use of Pt-based HER catalyst, tungsten carbide (W₂C) is one of the most promising non-noble-metal-based catalysts with low cost, replicable catalytic performance, and durability. However, the preparation access to scalable production of W₂C catalysts is inevitable. Herein, we introduced a facile protocol to achieve the tungsten carbide species by plasma treatment under a CH₄ atmosphere from the WO₃ precursor. Moreover, the heterogeneous structure of the tungsten carbide/tungsten oxide nanosheets further enhances the catalytic activity for HER with the enlarged specific surface area and the synergism on the interfaces. The prepared tungsten carbide/tungsten oxide heterostructure nanosheets (WO_3-x-850-P) exhibit exceptional HER catalytic activity and stable longevity in acid electrolytes. This work provides a facile and effective method to construct high-performance and non-precious-metal-based electrocatalysts for industrial-scale water electrolysis. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion, 2nd Edition)

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21 pages, 10383 KiB

Open AccessArticle

Synthesis, Physicochemical Properties, and Ion Recognition Ability of Azulene-Based Bis-(Thio)Semicarbazone

by Anamaria Hanganu, Catalin Maxim, Andreea Dogaru, Adrian E. Ion, Coralia Bleotu, Augustin M. Madalan, Daniela Bala and Simona Nica

Molecules 2025, 30(1), 83; https://doi.org/10.3390/molecules30010083 (registering DOI) - 29 Dec 2024

Abstract

Azulene-1,3-bis(semicarbazone), 1, and azulene-1,3-bis(thiosemicarbazone), 2, were synthesized by the acid-catalyzed condensation reactions of semicarbazide and thiosemicarbazide, respectively, with azulene-1,3-dicarboxaldehyde in stoichiometric amounts. Compounds 1 and 2 were identified by high-resolution mass spectrometry and characterized by IR, ¹H-NMR, ¹³C-NMR, and [...] Read more.

Azulene-1,3-bis(semicarbazone), 1, and azulene-1,3-bis(thiosemicarbazone), 2, were synthesized by the acid-catalyzed condensation reactions of semicarbazide and thiosemicarbazide, respectively, with azulene-1,3-dicarboxaldehyde in stoichiometric amounts. Compounds 1 and 2 were identified by high-resolution mass spectrometry and characterized by IR, ¹H-NMR, ¹³C-NMR, and UV-vis spectroscopic techniques. Crystal structure determination of azulene-1,3-bis(thiosemicarbazone) shows that the thiosemicarbazone units exhibit a syn-closed conformation, with both arms oriented in the same direction and adopting an E configuration with respect to the imine linkages. Both hydrazones are redox active and showed fluorescence emission at 450 nm upon excitation at 350 nm. The bis-semicarbazone showed no affinity for anions nor for mercury(II) metal cation. Instead, the bis-thiosemicarbazone showed a lower affinity for chloride anions, but enhanced affinity for binding/poisoning Hg²⁺ ions. Both compounds were tested against osteosarcoma MG63 cell lines, exhibiting low antiproliferative activity with comparable IC₅₀ values of 473.08 μM and 472.40 μM for compounds 1 and 2, respectively. Despite this limited antiproliferative effect, further analysis using propidium iodide staining revealed a concentration-dependent decrease in cell viability, with high concentrations inducing a marked reduction in cell number, accompanied by morphological changes characteristic of apoptosis and necrosis. Full article

(This article belongs to the Special Issue Synthesis, Structural Analysis, and Applications of N, O-Donor Ligands and Their Coordination Polymers)

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18 pages, 10861 KiB

Open AccessArticle

Electrical Properties of Cu-Based Coordination Complexes: Insights from In Situ Impedance Spectroscopy

by Jana Pisk, Marko Dunatov, Martina Stojić, Nenad Judaš, Ivica Đilović, Marta Razum and Luka Pavić

Molecules 2025, 30(1), 82; https://doi.org/10.3390/molecules30010082 (registering DOI) - 29 Dec 2024

Abstract

This study examines the influence of ligand design on the structural, optical, and electrical properties of copper-based coordination complexes. Ligands H₂L¹ and H₂L² were synthesized via the reaction of 5-nitrosalicylaldehyde with 2-hydroxy- or 4-hydroxybenzhydrazide. H₄L [...] Read more.

This study examines the influence of ligand design on the structural, optical, and electrical properties of copper-based coordination complexes. Ligands H₂L¹ and H₂L² were synthesized via the reaction of 5-nitrosalicylaldehyde with 2-hydroxy- or 4-hydroxybenzhydrazide. H₄L³ was obtained from the reaction of carbohydrazide and salicylaldehyde, while H₄L⁴ was prepared by condensing 4-methoxysalicylaldehyde with thiocarbohydrazide. The research focuses on two key design elements: (1) the effect of hydroxyl group positioning on the aroyl ring in hydrazide ligands (H₂L¹ vs. H₂L²) and (2) the impact of carbonyl versus thiocarbonyl groups and aldehyde substituents in hydrazone ligands (H₄L³ vs. H₄L⁴). The resulting complexes, [Cu₂(L¹)₂], [Cu₂(L²)₂(MeOH)₃], [Cu₂(L³)(H₂O)₂], and [Cu₂(L⁴)(H₂O)₂], were synthesized and characterized using attenuated total reflectance infrared (IR-ATR) spectroscopy, thermogravimetric analysis (TG), and UV-Vis diffuse reflectance spectroscopy. Their electrical properties were investigated using solid-state impedance spectroscopy (IS). The crystal and molecular structure of the complex [Cu₂(L²)₂(MeOH)₃]∙MeOH was determined by single-crystal X-ray diffraction (SCXRD). This study underscores the pivotal role of ligand modifications in modulating the functional properties of coordination complexes, offering valuable insights for the advancement of materials chemistry. Full article

(This article belongs to the Special Issue Analysis and Characterization of Materials in Chemistry)

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11 pages, 594 KiB

Open AccessArticle

Impact of Polysorbate 80 on the Antimicrobial Activity of Oregano and Thyme

by Marta Carvalho, Joana Barbosa, Marcelo Belchior Rosendo da Silva, Helena Albano and Paula Teixeira

Molecules 2025, 30(1), 81; https://doi.org/10.3390/molecules30010081 (registering DOI) - 28 Dec 2024

Abstract

Plant-derived essential oils (EOs) possess significant antimicrobial potential against spoilage and pathogenic microorganisms. However, their efficacy can vary depending on the test method, making it difficult to standardise results. This study aimed to investigate the effect of polysorbate 80, a common surfactant used [...] Read more.

Plant-derived essential oils (EOs) possess significant antimicrobial potential against spoilage and pathogenic microorganisms. However, their efficacy can vary depending on the test method, making it difficult to standardise results. This study aimed to investigate the effect of polysorbate 80, a common surfactant used to emulsify EOs, on antimicrobial activity and minimum inhibitory concentration (MIC) determinations. The antimicrobial activity of oregano and thyme EOs was tested against 40 microorganisms with and without the presence of polysorbate 80. Antimicrobial activity was qualitatively assessed using the disc diffusion assay (DDA) and quantitatively via broth microdilution to determine MIC values. Both oregano and thyme EOs exhibited antimicrobial activity against all tested microorganisms in the DDA, regardless of the surfactant’s presence. However, MIC determinations revealed that higher EO concentrations were required to inhibit microbial growth when polysorbate 80 was included in the emulsification process. These findings indicate that polysorbate 80 influences antimicrobial test results by reducing EO efficacy while enhancing solution homogeneity and handling in aqueous media. The study highlights the critical role of emulsifiers in antimicrobial testing, as their use can significantly impact the interpretation of results and the perceived effectiveness of EOs in food preservation, pharmaceuticals, and other applications. Full article

(This article belongs to the Special Issue Extraction, Characterization, and Potential Applications of Bioactive Molecules from Natural Sources, 4th Edition)

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15 pages, 4467 KiB

Open AccessArticle

Constructing Neuron-Like Structured NiS₂/MOF Composites with Enhanced Regulation of Electron Transport and Active Sites for Oxygen Evolution

by Yanli Guo, Di Zhou, Yanyan Huang, Xiaolong Song and Wei He

Molecules 2025, 30(1), 80; https://doi.org/10.3390/molecules30010080 (registering DOI) - 28 Dec 2024

Abstract

Constructing fast electron transfer pathways and abundant electro-active sites is an effective strategy to improve the oxygen evolution reaction (OER) performance of catalysts. Herein, structural engineering and dual-phase engineering were employed to construct a NiS₂ nanoparticle-encapsulated MOF configured with a pseudo-neuronal structure [...] Read more.

Constructing fast electron transfer pathways and abundant electro-active sites is an effective strategy to improve the oxygen evolution reaction (OER) performance of catalysts. Herein, structural engineering and dual-phase engineering were employed to construct a NiS₂ nanoparticle-encapsulated MOF configured with a pseudo-neuronal structure (NiS₂/MOF/HT). It was found that the pseudo-neuronal structure, constructed with a carbon nanohorn (CNH) and carbon nanotube (CNT), provided fast electron transfer pathways and abundant exposed active sites. Moreover, the NiS₂/MOF/HT composite obtained via partial vulcanization not only inherited the pseudo-neuronal structure but also prevented the aggregation and growth of NiS₂ particles. NiS₂/MOF composites provide various active sites. With the combination of the promotion of electronic transfer and enrichment of electro-active sites (NiS₂, MOF), NiS₂/MOF/HT showed excellent performance, whose overpotential at 25 mA cm⁻² was reduced by 19.5% compared with MOF/HT. Full article

16 pages, 5499 KiB

Open AccessArticle

Nanobubbles Adsorption and Its Role in Enhancing Fine Argentite Flotation

by Shunde Yan, Xihui Fang, Guanfei Zhao, Tingsheng Qiu and Kaiwei Ding

Molecules 2025, 30(1), 79; https://doi.org/10.3390/molecules30010079 (registering DOI) - 28 Dec 2024

Abstract

The efficient recovery of fine argentite from polymetallic lead–zinc (Pb–Zn) sulfide ore is challenging. This study investigated nanobubble (NB) adsorption on the argentite surface and its role in enhancing fine argentite flotation using various analytical techniques, including contact angle measurements, adsorption capacity analysis, [...] Read more.

The efficient recovery of fine argentite from polymetallic lead–zinc (Pb–Zn) sulfide ore is challenging. This study investigated nanobubble (NB) adsorption on the argentite surface and its role in enhancing fine argentite flotation using various analytical techniques, including contact angle measurements, adsorption capacity analysis, infrared spectroscopy, zeta potential measurements, turbidity tests, microscopic imaging, scanning electron microscopy, and flotation experiments. Results indicated that the NBs exhibited long-term stability and were adsorbed onto the argentite surface, thereby enhancing surface hydrophobicity, reducing electrostatic repulsion between fine argentite particles, and promoting particle agglomeration. Furthermore, the NBs formed a thin film on the argentite surface, which decreased the adsorption of sodium diethyldithiocarbamate. Microflotation tests confirmed that the introduction of NBs considerably enhanced the recovery of argentite using flotation technology. Full article

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22 pages, 1018 KiB

Open AccessArticle

Rosa damascena Mill. Essential Oil: Analysis of In Vitro and In Vivo Genotoxic and Cytotoxic Potentials by Employing Three Cytogenetic Endpoints

by Tsvetelina Gerasimova, Svetla Gateva, Gabriele Jovtchev, Tsveta Angelova, Margarita Topashka-Ancheva, Ana Dobreva and Milka Mileva

Molecules 2025, 30(1), 78; https://doi.org/10.3390/molecules30010078 (registering DOI) - 28 Dec 2024

Abstract

The highly valued oil of Rosa damascena Mill. (Rosaceae), widely used in high perfumery, cosmetics, and other spheres of human life, obliges us to know and study the safety profile of the product obtained from the water–steam distillation of fresh rose petals. The [...] Read more.

The highly valued oil of Rosa damascena Mill. (Rosaceae), widely used in high perfumery, cosmetics, and other spheres of human life, obliges us to know and study the safety profile of the product obtained from the water–steam distillation of fresh rose petals. The genotoxicity of the essential oil (EsO) has not been thoroughly studied despite its wide range of applications. That predetermined the object of this study—to evaluate, through classical cytogenetic methods, the possible cytotoxic/genotoxic activities of R. damascena Mill. EsO (EsORdm) in three different test systems: plant root meristem cells, mammalian bone marrow cells, and human lymphocyte cultures. The rose essential oil showed varying concentration- and time-dependent cytotoxic and genotoxic effects depending on the test system used, and it was established that the oil showed moderate cytotoxicity in lymphocyte cultures and non-high cytotoxicity in ICR mice but none in barley. Both barley and human lymphocytes showed a genotoxic effect with a dose-dependent increase in chromosomal aberrations (CAs) and a substantial rise in micronucleus (MN) frequency, while no genotoxicity was observed in bone marrow cells at the applied concentrations. Human lymphocytes exhibited the highest susceptibility to cytotoxic and genotoxic actions of the EsO. As a valuable plant-derived aromatic product with versatile uses in human life, R. damascena Mill. essential oil should be used in an appropriate concentration range tailored to cellular sensitivity. Full article

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