Chemical Transformations Research Articles

Study on K-modified Ca-based dual-functional materials for carbon capture and in-situ methane dry reforming

Integrated carbon capture and in-situ methane dry reforming (ICCU-DRM) is a promising technology for chemical looping transformation, this process involves the sequential switching of feedstocks within a single reactor, allowing CO2 capture to occur before methane dry reforming without direct CO2-CH4 contact. However, a significant challenge in the ICCU-DRM process is the disparity between the optimal temperatures required for carbon capture and dry reforming, with the latter necessitating considerably higher temperatures. This could lead to substantial CO2 losses when the reaction temperature is elevated to the optimal level for dry reforming. To address this issue and improve CO2 conversion efficiency, this study explores K doping in synthesizing a dual-functional material, NiCa1.6K0.4@Al2O3, through extrusion-spheronization. The synthesized material exhibits a stable pore structure and a large internal surface area, crucial for enhancing CO2 capture. The optimum temperature for DRM is around 800 °C. Notably, the formation of 1K2Ca(CO3)2 during the calcination of NiCa1.6K0.4@Al2O3, with a thermal decomposition temperature of approximately 800°C, plays a crucial role in minimizing CO2 release during the heating process, thereby significantly improving the CO2 conversion. To evaluate the impact of K doping on the material, the samples were subjected to carbon capture at 650 °C and dry reforming of methane at 750 °C. The results showed that the CO2 conversion rate of NiCa1.6K0.4@Al2O3 reached 52.8%, compared to only 18.9% for NiCa2@Al2O3 under the same conditions. Moreover, this study also investigates the impact of carbon capture temperature, dry reforming temperature, and catalytic metal loading on the performance of the ICCU-DRM process.

Synthesis and biological activity of some new podophyllotoxin bearing pyrimidine moiety

Podophyllotoxin (PPT), a naturally occurring aryltetralin-type lignan obtained from Podophyllin, an ethanolic extract of Podophyllum peltatum L. (syn. P. hexandnum Royle), exhibits marked biological activity as strong antineoplastic drugs and antiviral agents. Chemical transformations performed on PPT resulted in analogs which also display potent cytotoxic, antiviral, and immunosuppressive activities. In the present research, ten new compounds of PPTs 2a-l bearing pyrimidine moiety were synthesized by the reaction of PPT (1) with 2-methyl sulphonyl pyrimidines in the presence of tetrahydrofuran solvent and base sodium hydride. All the synthesized compounds were tested for antimicrobial activities.. KEYWORDS :4,6-Dimethoxy-2-methylsulfonylpyrimidine, Antimicrobial activity, Podophyllotoxin.

Excited State Bond Homolysis of Vanadium(V) Photocatalysts for Alkoxy Radical Generation.

Advancements in photocatalysis have transformed synthetic organic chemistry, using light as a powerful tool to drive selective chemical transformations. Recent approaches have focused on metal-halide ligand-to-metal charge transfer (LMCT) photoactivated bond homolysis reactions leveraged by earth-abundant elements to generate valuable synthons for radical-mediated cross-coupling reactions. Of recent utility, oxovanadium(V) LMCT photocatalysts exhibit selective alkoxy radical generation from aliphatic alcohols upon blue light (UVA) irradiation under mild conditions. The selective photochemical liberation of alkoxy radicals is valuable for applying late-stage fragmentation approaches in organic synthesis and depolymerization strategies for nonbiodegradable polymers. Steady-state and time-resolved spectroscopy were used to assign the electronic structure of three well-defined V(V) photocatalysts in their ground and excited states. We assign the excited state for this transformation at earth-abundant vanadium(V), interrogating the electronic structure using static UV-visible absorption, ultrafast transient absorption, and electron paramagnetic resonance spectroscopy coupled to computational approaches. These findings afford assignments of the short-lived excited state intermediates that dictate selective homolytic bond cleavage in metal alkoxides, illustrating the valuable insight gleaned from fundamental investigations of the molecular photochemistry responsible for light-escalated chemical transformations.

Air-Stable Boranes and Borinanes Encapsulated in Organogels for Anionic Ring-Opening (Co)Polymerization.

Organoborane reagents play a pivotal role as Lewis acids in acid-base pairs used in anionic polymerization and in other reactions; yet their high sensitivity to oxygen and moisture necessitates effective stabilization to prevent their oxidation and thus maintain their catalytic activity. In this study, we present novel encapsulation methods employing a cost-effective hexatriacontane (C36H74, C36) organogel to stabilize sensitive organoborane reagents, including triethyl borane (TEB) and a borinane-based ammonium salt (B3NBr). These organoboranes encapsulated in stable, self-standing organogel blocks enable their safe handling in open laboratory environments without the need for a glovebox. Upon heating such borane-containing organogel blocks organoboranes could be freed from the organogel and used to mediate both the homopolymerization of propylene oxide (PO) and the copolymerization of PO with CO2. Furthermore, efficient recovery of the C36 gelator from polymerization mixtures is achieved, with mass recovery ranging from 70 % to 90 %. This encapsulation method offers a practical and efficient solution for stabilizing, storing, and handling highly reactive organoborane reagents, thereby broadening their applicability and utilization in various chemical transformations.

Axial coordination engineering of atomic Co–N4 sites for exceptional aromatic nitroreduction

Optimizing the local environment of metal active centers bonded by nitrogen ligands (M−N4) through additional axial coordination provides a promising approach to enhance the reaction kinetics of heterogeneous catalysis. However, achieving precise targeting and construction of efficient active sites remains a major challenge. In this study, under the guidance of density functional theory (DFT) calculations, we precisely position and engineer atomic Co–N4 active sites with axial O coordination on porous carbon nanosheets (Co1/NOC) for boosted aromatic nitroreduction through a novel template-anchoring strategy. The resulting Co1/NOC catalyst exhibited unprecedented catalytic activities towards a series of functionalized nitroaromatics with a record overall turnover frequency (TOF) of 38022 h−1 under mild reaction conditions, 7.6- and 38 times higher than that of Co–N4 sites (Co1/NC) and commercial Pd/C catalysts, respectively, standing ahead of the reported catalysts. Targeted DFT calculations reveal that axial oxygen coordination efficiently promotes the electronic delocalization of the Co center, which dramatically facilitates the formation and utilization of reactive H* species, enhances the selective adsorption of nitroaromatics, and accelerates the conversion of aromatic nitroreduction, eventually attaining exceptional catalytic performance. This work offers a new avenue for precisely tailoring the coordination environment of single-atom catalysts to achieve advanced catalytic performance in chemical transformations.

Plasmon-driven chemical transformation of a secondary amide probed by surface enhanced Raman scattering

Plasmon-driven chemical conversion is gaining burgeoning interest in the field of heterogeneous catalysis. Herein, we study the reactivity of N-methyl-4-sulfanylbenzamide (NMSB) at nanocavities of gold and silver nanoparticle aggregates under plasmonic excitation to gain understanding of the respective reaction mechanism. NMSB is a secondary amide, which is a frequent binding motive found in peptides and a common coupling product of organic molecules and biomolecules. Surface-enhanced Raman scattering (SERS) is used as a two-in-one in-situ spectroscopic tool to initiate the molecular transformation process and simultaneously monitor and analyze the reaction products. Supported by dissociative electron attachment (DEA) studies with the gas phase molecule, a hot electron-mediated conversion of NMSB to p-mercaptobenzamide and p-mercaptobenzonitrile is proposed at the plasmonic nanocavities. The reaction rate showed negligible dependence on the external temperature, ruling out the dominant role of heat in the chemical transformation at the plasmonic interface. This is reflected in the absence of a superlinear relationship between the reaction rate constant and the laser power density, and DEA and SERS studies indicate a hot-electron mediated pathway. We conclude that the overall reaction rate is limited by the availability of energetic hot electrons to the NMSB molecule.

Initial pedogenic processes, mineral and chemical transformations and mobility of trace elements in Technosols on dumps of the former copper mines in Miedziana Góra and Miedzianka, the Świętokrzyskie Mts., south-central Poland

Technosols develop, among others, on dumps of former copper mines which became overgrown in spontaneous plant succession. The aim of the study was to determine the effect of pedogenesis on soil properties, mineral and geochemical composition, as well as operationally defined forms of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in Technosols developed on former mine dumps of the Miedziana Góra and Miedzianka former mining areas in south-central Poland. The studied Technosols were weakly developed soils with a simple soil profile comprising (1) C horizons in the subsoil and (2) O and A (or AC) horizons in the topsoil. The pHH2O of soils was 5.5–8.1. High soil pHH2O values were due to occurrence of carbonates (up to 25 %). The highest content of total organic carbon (TOC) and total nitrogen (TN) was found in O horizons as well as in A and AC horizons including buried A horizon. Soil magnetic susceptibility (χ) was 6.0–171.3 × 10–8 m3 kg−1. In each profile, the highest χ values were typical of A horizons including the buried A horizon. The most common minerals present in all profiles were quartz, kaolinite and mica. There were also admixtures of carbonates (dolomite, calcite), feldspars (orthoclase and albite), jarosite, goethite and traces of Fe sulphides. SEM-EDS analyses showed that soil substrate was subject to transformations of sulphides into Fe oxides. Moreover, pedogenic Cu carbonates were found in pores and on coarse materials. Technosols were enriched in Ag, As, Cd, Co, Cu, Hg, Mo, Ni, Pb, Sb, Zn, U and Th. The most mobile trace elements in the studied Technosols were Cd, Cu and Zn. Topsoil horizons of the studied soils contained a considerable share of Pb, Cu, Zn and Ni bound with soil organic matter. Arsenic was mostly bound with Fe oxides. First indicators of pedogenesis in the studied Technosols are (1) accumulation of soil organic matter in the topsoil followed by the decrease of soil pH and leaching of carbonates, (2) mineral transformations in the soil substrate (alteration of sulphides into Fe oxides and jarosite; origin of pedogenic Cu carbonates due to crystallization from soil solutions), (3) increase of magnetic susceptibility in the topsoil which may be an effect of atmospheric dust fall out or pedogenic transformation of Fe oxides into the phases with higher magnetic susceptibility and (4) the effect of soil properties, mineral composition and soil organic matter on geochemical forms of potentially toxic trace elements. The novelty value of the study lies in the identification of pedogenic Cu carbonates and the potential effect of soil-forming processes on the increase of topsoil magnetic susceptibility.

Multimodal Molecular Motion in the Rotaxanes and Catenanes Incorporating Flexible Calix[n]phyrin Stations

The synthesis of [2]rotaxanes stoppered with one or two dipyrromethane groups opened a route for the construction of mechanically interlocked molecules incorporating various porphyrinoid stations. The exploitation of those precursors allowed for the creation of [3]rotaxanes and [2]catenanes based on the calix[4]phyrin motif, presenting intriguing molecular dynamics. The intrinsic flexibility of the porphyrinoid allowed the introduction of a new type of molecular motion within the rotaxanes, termed fluttering. The latter involved a bending of the axle, interconverting two angular‐shaped stereoisomers of the rotaxane through a planarised transition state. Simple chemical transformations, i.e. methylation and (de)protonation of [3]rotaxane and [2]catenane allowed for the controllable transformations within the conformationally flexible calix[4]phyrin‐incorporated mechanically interlocked porphyrinoids.

Spectroscopic elucidation, quantum chemical computations (FMO, HOMO–LUMO, MEP, NLO), and biological activity on some novel heterocyclic compounds using 3-substituted-6,8-dimethylchromones

The chemical transformations of substituted chromones 1a–c were examined toward some nucleophiles namely dimedone (R1), 4-hydroxycoumarin (R2) and 4-hydroxy-1-methylquinolin-2(1H)-one (R3). DFT computation at the B3LYP/6-311 G(d,p) level of theory was used to perform the theoretical computations for the produced compounds. HOMO and LUMO analyses were performed to determine the electronic charge distribution and reactivity of the molecules. Molecular electrostatic potential (MEP) surface analysis was utilized to predict the molecule’s reactive sites. Moreover, the studied compounds showed NLO characteristics, where they have first order hyperpolarizability greater than urea. In addition, the GIAO method was used to estimate the 1H-NMR and 13C-NMR chemical shifts; and the findings were compared with experimental values. Testing the generated compounds for antibacterial and anticancer activities revealed varied degrees of inhibitory effect. According to the Lipinski, Veber, and Egen rules, these compounds exhibit physicochemical properties.

Tailoring photocatalytic performance: Lanthanum doping in nickel oxide for efficient degradation of some industrial cationic dyes in visible light radiation

Metal oxide nanoparticles have emerged as an important component in heterogeneous photocatalysis, which uses light-induced reactions on the surface of a catalyst to drive chemical transformations. The improved photocatalytic activity of lanthanum-doped metal oxide nanoparticles has been the subject of research due to their special qualities, which include enhanced photocatalytic performance, stability and absorption of visible light. This study involves co-precipitation approach to synthesize nickel oxide nanoparticles and nickel oxide nanoparticles doped with lanthanum. The nanoparticles were determined using UV-Visible absorption spectrophotometry, X-ray diffraction spectroscopy, Energy-disperse spectroscopy, Photoluminescence spectroscopy and Field emission scanning electron microscopy. For the photodegradation of malachite green and rhodamine B dyes, synthesized nanoparticles were employed as photocatalysts. Compared to pure NiO, the photochemical activity of 4 % Lanthanum-doped NiO was higher. The degrading efficiency of 4 % La-doped NiO is 89 % effective towards rhodamine B and 87 % for malachite green. In addition, entrapment was done to identify primary active species responsible for photocatalytic activity. The present study likely provides new insights and novelty into the photocatalytic mechanisms at play, including how lanthanum doping affects the generation and dynamics of reactive oxygen species (ROS) like hydroxyl radicals and superoxide anions, which are responsible for the breakdown of dye molecules.

A step to microplastic formation: Microcracking and associated surface transformations of recycled LDPE, LLDPE, HDPE, and PP plastics exposed to UV radiation

Plastics when exposed to UV radiation start to degrade via photooxidative aging including free radical formation, oxidation, chain scission and/or crosslinking reactions. These chemical changes can cause loss in mechanical strength, surface embrittlement, and eventually surface erosion. The eroded particles are microplastics (MPs), which have been identified as a potentially serious threat to the environment and its inhabitants. In general, photodegradation of virgin plastics has been studied extensively, but there is not much literature on the degradation of recycled plastics. The goal of the study was to investigate the changes caused by photodegradation in recycled plastics and assess the potential risks of MPs formation. And eventually, knowing the chemical and physical transformations occurring on the surface understand the mechanism behind surface microcracking, which is the first step of MPs formation. Pellets of five industrially recycled plastics (low-density polyethylene (rLDPE), linear low-density polyethylene (rLLDPE), high-density polyethylene (rHDPE), and two polypropylenes (rPP)) from different waste sources were analysed. UV irradiation was performed in an accelerated weathering chamber for milled (< 400 µm) plastic powder to ensure homogeneous changes throughout the sample. The properties were investigated by ATR-FTIR, HT-SEC, XPS and DSC. Formation of microcracks was studied on plastic pellets by SEM. The results showed that the degradation significantly differed between the recycled plastics, and the waste source was more important than the plastic type. rLDPE and one of the rPP samples showed a significant increase in carbonyl index as well as decrease in molar mass during the first 500 h of UV exposure. The other rPP and rHDPE samples showed first considerable signs of degradation only after 1000 h of UV exposure. Minor changes were observed for the rLLDPE sample during the whole test. The SEM revealed microcracking on the surface of all samples, which also had noticeable degradation identified by other methods. These recycled plastics can be considered the ones with the highest potential of MPs formation. From the chemical and physical transformations identified on the surface, the mechanism leading to microcracking, which is the first step in the formation of MPs, is proposed.

CATALYTIC OXIDATION OF AROMATIC ALDEHYDES TO CARBOXYLIC ACIDS IN MILD CONDITIONS WITH NaClO2

This study aimed to improve the conditions for the oxidation of benzaldehyde to benzoic acid using chlorine dioxide generated from sodium chlorite, across various pH ranges and different catalysts. The powerful oxidation capability of chlorine dioxide played a crucial role in enhancing the kinetic efficiency of the reactions. In our research, we examined various reaction conditions, including sodium dihydrogen phosphate, sodium dihydrogen phosphate together with sodium chlorite, sodium dihydrogen phosphate combined with sodium chlorite and potassium permanganate, and sodium dihydrogen phosphate with sodium chlorite and V2O5. Additionally, different oxidation combinations were tested, such as sodium chlorite with sodium tripolyphosphate (STPP), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), and formic acid, as well. The stabilized chlorine dioxide solution was also used directly as an oxidation reagent. The role of chlorine dioxide in these combinations significantly impacted the selectivity and yield in terms of product. Furthermore, some Mn (III) complexes (Cat.1 and Cat.2) were used as catalysts in this study, and the findings revealed that chlorine dioxide is an effective oxidant in the selective oxidation of aromatic aldehydes to aromatic acids. For the catalytic application in buffer solutions, a leveling effect was observed. When Mn (III) complexes were used, it showed a similar leveling effect in buffer solutions with a pH &gt;1, which was resulting in slow ClO₂ formation. With these findings it was found that the use of Mn (III) complexes in NaH2PO4+NaClO2 combination provided the highest yield in the oxidation of aromatic aldehydes to acids. These results underscore the importance of chlorine dioxide as a powerful oxidant in chemical transformation processes.

Functional Materials from Biomass-Derived Terpyridines: State of the Art and Few Possible Perspectives.

This review focuses on functional materials that contain terpyridine (terpy) units, which can be synthesized from biomass-derived platform chemicals. The latter are obtained by the chemical conversion of raw biopolymers such as cellulose (e.g., 2-furaldehyde) or lignin (e.g., syringaldehyde). These biomass-derived platform chemicals serve as starting reagents for the preparation of many different terpyridine derivatives using various synthetic strategies (e.g., Kröhnke reaction, cross-coupling reactions). Chemical transformations of these terpyridines provide a broad range of different ligands with various functionalities to be used for the modification or construction of various materials. Either inorganic materials (such as oxides) or organic ones (such as polymers) can be combined with terpyridines to provide functional materials. Different strategies are presented for grafting terpy to materials, such as covalent grafting through a carboxylic acid or silanization. Furthermore, terpy can be used directly for the elaboration of functional materials via complexation with metals. The so-obtained functional materials find various applications, such as photovoltaic devices, heterogeneous catalysts, metal-organic frameworks (MOF), and metallopolymers. Finally, some possible developments are presented.

3D Printed Concrete: Fresh and Hardened Properties

3D concrete printing (3D CP) is an advanced form of additive manufacturing (AM), that allows for the creation of complex geometrical structures using concrete. This technology has the potential to reduce construction time and labour costs while minimizing material waste. However, there are also challenges related to material properties, structural integrity, and standardization of construction practices. The primary challenge in developing 3D printable cementitious materials lies in engineering specific fresh properties that enable extrusion-based printing. Unlike cast concrete, where formwork provides dimensional stability during the printing process, the absence of formwork in 3D printing necessitates fresh mixtures with low-slump and high-thixotropy to be suitable for concrete 3D printing. Additionally, the orthotropic nature of the resulting 3D printed object due to the extrusion process impacts its mechanical properties. Therefore, this research aims to study the effect of water content and loading directions on 3D printed concrete. A pre-mix material from Sika was used in this study. Three mixes were prepared by using three different water to dry material (w/d) ratios, 0.140 l/kg, 0.145 l/kg and 0.150 l/kg. The experiments focused on analysing flowability, green strength, mechanical properties (compressive strength, flexural strength, and modulus of elasticity), water absorption, porosity, and chemical transformations at high temperatures through thermoanalytical measurement. The results showed that the mixture containing 0.145 l/kg (w/d) exhibited satisfactory 3D printability, optimal mechanical performance, lower porosities compared with mixtures 0.140 and 0.150, and same total porosity compared with cast specimen.

Impact of thermal processing on polyphenols, carotenoids, glucosinolates, and ascorbic acid in fruit and vegetables and their cardiovascular benefits.

Bioactive compounds in fruit and vegetables have a positive impact on human health by reducing oxidative stress, inflammation, and the risk of chronic diseases such as cancer, cardiovascular (CV) diseases, and metabolic disorders. However, some fruit and vegetables must be heated before consumption and thermal processes can modify the amount of nutraceuticals, that is, polyphenols, carotenoids, glucosinolates, and ascorbic acid, that can increase or decrease in relation to different factors such as type of processing, temperature, and time but also the plant part (e.g., flower, leaf, tuber, and root) utilized as food. Another important aspect is related to the bioaccessibility and bioavailability of nutraceuticals. Indeed, the key stage of nutraceutical bioefficiency is oral bioavailability, which involves the release of nutraceuticals from fruit and vegetables in gastrointestinal fluids, the solubilization of nutraceuticals and their interaction with other components of gastrointestinal fluids, the absorption of nutraceuticals by the epithelial layer, and the chemical and biochemical transformations into epithelial cells. Several studies have shown that thermal processing can enhance the absorption of nutraceuticals from fruit and vegetable. Once absorbed, they reach the blood vessels and promote multiple biological effects (e.g., antioxidant, anti-inflammatory, antihypertensive, vasoprotective, and cardioprotective). In this review, we described the impact of different thermal processes (such as boiling, steaming and superheated steaming, blanching, and microwaving) on the retention/degradation of bioactive compounds and their health-promoting effects after the intake. We then summarized the impact of heating on the absorption of nutraceuticals and the biological effects promoted by natural compounds in the CV system to provide a comprehensive overview of the potential impact of thermal processing on the CV benefits of fruit and vegetables.

Recognition and order of multiple sidechains by metal-organic framework enhances the separation of hexane isomers.

Porous materials perform molecular sorting, separation and transformation by interaction between their framework structures and the substrates. Proteins also interact with molecules to effect chemical transformations, but rely on the precise sequence of the amino acid building units along a common polypeptide backbone to maximise their performance. Design strategies that positionally order sidechains over a defined porous framework to diversify the internal surface chemistry would enhance control of substrate processing. Here we show that different sidechains can be ordered over a metal-organic framework through recognition of their distinct chemistries during synthesis. The sidechains are recognised because each one forces the common building unit that defines the backbone of the framework into a different conformation in order to form the extended structure. The resulting sidechain ordering affords hexane isomer separation performance superior to that of the same framework decorated only with sidechains of a single kind. The separated molecules adopt distinct arrangements within the resulting modified pore geometry, reflecting their strongly differentiated environments precisely created by the ordered sidechains. The development of frameworks that recognise andorder multiple sidechain functionality by conformational control offers tailoring of the internal surfaces within families of porous materials to direct interactions at the molecular level.

Sustainable (-)-Ambrox Production: Chemistry Meets Biocatalysis.

(-)-Ambrox, the most prominent olfactive component of ambergris, is one of the most widely used biodegradable fragrance ingredients. It is traditionally produced from the diterpene sclareol chemically modified and cyclized into (-)-ambrox. The availability of the new feedstock (E)-β-farnesene produced by fermentation opened new routes to (E,E)-homofarnesol as a precursor to (-)-ambrox. Combining the chemical transformation of (E)-β-farnesene to (E,E)-homofarnesol and its enzymatic cyclization with an engineered Squalene Hopene Cyclase provided a new sustainable route for the production of (-)-ambrox at industrial scale. Compared to the traditional synthesis from sclareol, the new and innovative route from (E)-β-farnesene improves atom and step economy, reduces waste production, solvent and energy consumption.

Aqueous‐Phase Preparation of Core–Shell Perovskite Nanorods Encapsulated in Polydopamine with Ultrahigh Water Stability

All‐inorganic perovskite CsPbBr3 (CPB) nanocrystals (NCs) are not widely applied in aqueous environments due to their readily decomposable nature. Therefore, the aqueous‐phase preparation of CPB NCs has been a considerable challenge. In this work, a feasible method is proposed for preparing aqueous‐phase core–shell CPB nanorods (NRs) encapsulated with polydopamine (PDA) by employing a multifunctional additive cesium trifluoroacetate (Cs‐TFA). Highly luminescent TFA‐CPB NRs are obtained via a chemical transformation of Cs4PbBr6 NCs in water. Subsequently, PDA constitutes a robust shell on the surface of TFA‐CPB NRs through the covalent oxidative polymerization, which effectively reduces the original dynamic properties of surface ligands, retards the decomposition of ligands and inhibits the leakage of Pb2+ ions. The results demonstrate that the fluorescence intensity of TFA‐CPB@PDA NRs maintains 49.3% of the initial intensity after 136 days. Meanwhile, the NRs exhibit low cytotoxicity, and the cell viability remains at 80% when the concentration of the NRs is 200 μg mL−1. The reliable preparation of aqueous‐phase core–shell perovskite NRs (PNRs) will facilitate their development in many fields, such as materials science, biology, medicine, and their applications in aqueous environments.

N‐heterocyclic carbene complexes RuII(arene) and their application as ROMP catalysts, antioxidant and anticancer agents

N‐Heterocyclic carbenes (NHCs) play an important role in metal complex catalysis and stabilisation, providing stability under non‐inert conditions and a high σ‐donor capacity. They are crucial ligands for the synthesis of organometallic compounds like RuII‐complexes, which can operate as very active catalysts for a variety of chemical transformations and functionalizations. RA(Ruthenium‐arene)NHC complexes, known for their piano‐stool structure, stabilise Ru(II) oxidation by occupying three ruthenium coordination sites with a η6‐coordinated arene ligand. The development of dual‐acting RuII‐arene complexes has sparked increased interest in their catalytic and biological properties. Because of their broad spectrum, metal complexes can give distinct mechanisms of pharmacological action than organic drugs. This study aimed to explore the impact of ligand amphiphilicity and counterion on bioactivity, designing a family of compounds with the NHC ligand bearing an ester moiety and switching the wingtip substituent from methyl to benzyl units. All synthesized compounds were tested in norbornene ROMP, a benchmark reaction for RuII potential catalysts and as anticancer and antioxidant compounds.

Catalytic Activity of Incorporated Palladium Nanoparticles on Recycled Carbon Black from Scrap Tires.

A stable support substrate for catalytically active metal nanoparticles (NPs) plays an important role in various chemical transformation reactions. This study describes the effective integration of catalytically active palladium nanoparticles (PdNPs) into recycled carbon black (rCB) obtained from scrap tires. The loading efficiency and dispersion degree of PdNPs prepared via a deposition-precipitation method are thoroughly compared to those prepared with conventional Vulcan CB. As the rCB powder exhibits relatively larger surface areas and wider pore size distributions, slightly polydisperse and more PdNPs are integrated across rCB than those on CB. These composite materials are subsequently tested as catalysts in the Suzuki coupling and styrene hydrogenation reactions. For the Suzuki reaction using phenylboronic acid and bromobenzene, the PdNPs on rCB exhibit slightly higher reactivity than those on CB (TOF of ∼9/h vs ∼8/h), presumably due to the structural features of the integrated PdNPs and the relatively hydrophobic characteristics of the rCB substrate. For the hydrogenation reaction, both composite materials easily result in over 99% yield under ambient conditions with similar activation energies of ∼32 kcal/mol. These composite materials are also recyclable in both reactions without a detectable loss of the PdNP catalyst and its activity. Understanding the physicochemical properties of rCB and demonstrating their potential use as a catalyst support substrate evidently suggest the possibility of replacing conventional CB, which also provides an idea of upcycling waste tires in the development of practical and green reaction systems.