Course Of Reaction Research Articles

Polymerization of six-membered propylene oxalate

Ring-opening polymerization (ROP) of the six-membered cyclic propylene oxalate was studied for the first time. The reaction proceeded with a high limiting conversion of about 96 % at 100 °C in the presence of tin(II) octoate. Linear macromolecules, Mw of 20–30 × 103, Ð ∼ 2, represented 86 % of the product, 4 % came from the equilibrium concentration of monomer, while the rest 10 % were cyclic oligomers consisting of 3–10 repeat units. ROP was accompanied by partial (about 30 %) conversion of the catalyst into the insoluble tin(II) oxalate in the course of polymer cross-linking reaction. The kinetics of polymerization obeyed first-order law, indicating typical for ROP constant number of active centers during the process. Polymerization without catalyst was 2000 times slower and also resulted in formation of polymer with Ð ∼ 2. Addition of benzyl alcohol to the polymerization mixture resulted in its inclusion into linear macromolecules and a decrease in their molecular weight. The results point to the possibility of synthesizing propylene oxalate block copolymers using macroinitiators with hydroxyl end groups.

Unexpected Course of Reaction Between (1E,3E)-1,4-Dinitro-1,3-butadiene and N-Methyl Azomethine Ylide—A Comprehensive Experimental and Quantum-Chemical Study

In recent times, interest in the chemistry of conjugated nitrodienes is still significantly increasing. In particular, the application of these compounds as building blocks to obtain heterocycles is a popular object of research. Therefore, in continuation of our research devoted to the topic of conjugated nitrodienes, experimental and quantum-chemical studies of a cycloaddition reaction between (1E,3E)-1,4-dinitro-1,3-butadiene and N-methyl azomethine ylide have been investigated. The computational results present that the tested reaction is realized through a pdr-type polar mechanism. In turn, the experimental study shows that in a course of this cycloaddition, only one reaction product in the form of 1-methyl-3-(trans-2-nitrovinyl)-Δ3-pyrroline is created. The constitution of this compound has been confirmed via spectroscopic methods. Finally, ADME analysis indicated that the synthesized Δ3-pyrroline exhibits biological potential, and it is a good drug candidate according to Lipinski, Veber and Egan rules. Nevertheless, PASS simulation showed that the compound exhibits weak antimicrobial, inhibitory and antagonist properties. Preliminary in silico research shows that although the obtained Δ3-pyrroline is not a good candidate for a drug, the presence of a nitrovinyl moiety in its structure indicates that the compound is an initial basis for further modifications.

Effect of Nucleophile Deprotonation on SuFEx: Synthesis of Sulfonamides

In a quest for efficient SuFEx-type transformations we studied reactions of amines with 4-fluorobenzenesulfonyl fluoride. The substrate may react by fluoride substitution at the aromatic ring (SNAr) and at the sulfonyl group (SuFEx). Analysis of the reaction course revealed that deprotonation of N-nucleophile controls the reaction course: neutral amines in DMF attack at the aromatic ring, whereas amine anions, generated in equilibrium with LiHMDS in toluene, favor sulfonyl substitution. Using the base-promoted conditions we synthesized a set of substituted sulfonamides in high yields.

Sustainable C-H Methylation Employing Dimethyl Carbonate.

The use of CO2 and CO2-derived chemicals offers society sustainable and biocompatible chemistry for a variety of applications, ranging from materials to medicines. In this context, dimethyl carbonate (DMC) stands out owing to its low toxicity, high biodegradability, tunable reactivity, and sustainable production. Further, the ability of DMC to act as an ambient electrophile at varied temperatures and reaction conditions in order to produce methoxycarbonylated (via BAC2) and methylated products (via BAL2) is very promising. While the methylation of hetero-H (N-, O-, and S-methylation) with DMC is established and well-reviewed, the C-H methylation reaction with DMC is limited, and there is no specific literature detailing the C-methylation reaction using DMC, creating new opportunities as well as challenges in the same domain. In this context, the present perspective focuses on the new breakthroughs, recent advances, and trends in C-H methylation reactions employing DMC. A critical analysis of the mechanistic course of reactions under each category was undertaken. We believe this timely perspective will offer an in-depth analysis of existing literature with critical remarks, which will certainly inspire fellow researchers across disciplines to understand and pursue cutting-edge research in the area of C-H methylation (alkylation) using DMC and related organic carbonates.

Features of the microbiome of burial soils

Introduction. On the territory of the Russian Federation, as well as worldwide, a large amount of space is allocated for burials. The soils found in the burial areas have their own characteristics. In the scientific literature there is a few works devoted to the problem of hygienic assessment of cemeteries from the point of view of their impact on the environment, as well as on the population living next to necrosols or working on them. Depending on the chemical and biological effects, the microbial composition of the soil changes. This process is influenced by many factors, including humidity, the initial content of organic and mineral substances, level of acidity, structure of the soil and peculiarities of the course of intra-soil gas-phase reactions. The key participants in the decomposition of organic material are bacteria and fungi, the diversity and dynamics of which directly depend on the degree of soil contamination with pollutants. The purpose of this study was to analyze the microbiota of cemetery soil in its various layers. Materials and methods. The cemeteries of Moscow (NikoloKhovanskoye, Nikolo-Arkhangelskoye, Perepechenskoye), Moscow (Mytishchenskoye, Domodedovo), Tula (Municipal Cemetery No. 1 of the Municipal State Enterprise of the Municipal Formation of the City of Tula Combine of Specialized Services), Kursk (old city cemetery Kurchatov), Krasnoyarsk (Zheleznogorsk) regions and Altai (Yarovoye) Krais were selected as research objects for assessing the microbiome of soils. Results. The most common bacterial pathogens were found to be Enterococcus spp. (81%), Bacillus spp. (75%) and E. coli (45.1%). Mushrooms of Penicillium spp.. were isolated from 61% of the samples. The revealed microbiota profiles of the samples of the studied cemetery soils reflect the microbial composition of humans, which allows substantiating the main methods and algorithm for identifying decomposition processes depending on the time frame of burials. Limitations. The limitation of the study is due to the risk of contact with cemetery soil was not assessed, since not all genera of isolated microorganisms could be identified by their biochemical properties. Conclusion. Studies conducted in cemetery areas have shown how diverse the soil microbiome is in burial sites and varies depending on the depth of sampling. The microbiota profiles of cemetery soil samples identified during the study reflect the lifetime microbial composition of the human body, which makes it possible to substantiate approaches to identifying decomposition processes depending on the time frame of burials.

Photochemistry with Plane-Polarized Light: Controlling Selectivity of a Photochemical Rearrangement.

Over the past 50 years, a principal approach to controlling conventional photochemical reactions has relied on imposing geometric constraints on reactant or transition state via conducting photochemistry in the organized or constraining media. Herein, we describe a fundamentally different approach to affect the course of photochemical reactions (photochemical rearrangements) by utilizing spatially selective excitation of specific electronic transitions with plane-polarized light in the reactant molecules uniformly aligned in the nematic liquid crystal phase. In particular, we focused on the Type B enone rearrangement of 4,4-diarylcyclohexenones -one of the most common photochemical rearrangements. We demonstrated that the aryl migratory aptitude in this reaction was attenuated in response to changing an angle between the polarization plane of the incident light and the alignment direction of nematic liquid crystal, with the enhanced aryl migration achieved when the polarization plane coincided with the transition dipole moment leading to the excited state responsible for this migration. The spatially-selective initial excitation therefore was overruling the electronic factors responsible for the relative ratio of the two alternative photoproducts. The experimental findings were further supported by the results of a computational study. This work showcases a new fundamental paradigm in controlling photochemical reactivity and selectivity of photoreactions.

Crystal Structure of Caryolan-1-ol Synthase, a Sesquiterpene Synthase Catalyzing an Initial Anti-Markovnikov Cyclization Reaction.

In a continuing effort to understand reaction mechanisms of terpene synthases catalyzing initial anti-Markovnikov cyclization reactions, we solved the X-ray crystal structure of (+)-caryolan-1-ol synthase (CS) from Streptomyces griseus, with and without an inactive analog of the farnesyl diphosphate (FPP) substrate, 2-fluorofarnesyl diphosphate (2FFPP), bound in the active site of the enzyme. The CS-2FFPP structure was solved to 2.65 Å resolution and showed the ligand in an elongated orientation, incapable of undergoing the initial cyclization event to form a C1-C11 bond. Intriguingly, the apo CS structure (2.2 Å) also had electron density in the active site, in this case, well fit by a curled-up tetraethylene glycol molecule recruited, presumably, from the crystallization medium. The density was also well fit by a molecule of farnesene suggesting that the structure may mimic an intermediate along the reaction coordinate. The curled-up conformation of tetraethylene glycol was accompanied by dramatic rotation of some active-site residues in comparison to the 2FFPP-structure. Most notably, W56 and F183 undergo 90° rotations between the 2FFPP complex and apoenzyme structures, suggesting that these residues provide interactions that help curl the tetraethylene glycol molecule in the active site, and by extension perhaps also a derivative of the FPP substrate in the normal course of the cyclization reaction. In support of this proposal, the CS W56L and F183A variants were observed to be severely restricted in their ability to catalyze C1-C11 cyclization of the FPP substrate and instead produced predominantly acyclic terpene products dominated by farnesol, β-farnesene, and nerolidol.

Evaluation of the reactivity of co-combustion of wheat straw and waste rubber thermolysis char

The co-combustion of wheat straw (WS) and waste rubber thermolysis char (WRTC) was examined with the perspective of utilizing WRTC as a high-calorific value fuel addition to agricultural biomass. The study investigated the effect of different proportions of WS-WRTC blends (10/15/25/49 wt% WRTC) and a maximum of 4 wt% binders, including potato starch and calcium oxide, on the reactivity of co-combustion and the distribution of products during the process. Thermogravimetric analysis with Fourier Transform Infrared Spectroscopy (TGA-FTIR) analyses was employed at a temperature range of 25–1000 ° C with a heating rate of 10 ° C/min. The kinetics of co-combustion were analyzed using the Fraser-Suzuki (FS) deconvolution method and a model-based kinetic modeling. The results indicate that a 10% addition of WRTC char reduces the intensity and rate of combustion and prolongs the combustion time. It was observed that the optimal addition to the blend is 25% WRCT, and it resulting in a reduction in activation energy and combustion indexes. However, it remains with no significant impact on process stability and efficiency. Kinetics of the decomposition of the WRTC25 mixture modeled by the deconvolution method indicates a 5-step reaction course, which is a combination of the characteristic combustion stages of both fuels. The main denoted functional group observed in the FTIR absorption spectra were C=O, C-O, O-H, and C-H related to the release of CO2, CO, H2O, CH4, aromatic compounds, and hydrocarbons.

ADAPTATION OF NAVAL PENTATHLON ATHLETES TO PHYSICAL TRAINING

Rationally planned training leads to adaptation and progress, and irrational planning leads to disruption of the course of adaptation reactions and overwork. For a rational periodization it is very important to identify training concepts based on detailed analysis of fatigue development mechanisms. Proper planning and execution of training will result in an increase in effort capacity. Adaptation, viewed from a biological point of view, is a complex defense mechanism against the demands caused by environmental changes. This requires an adequate response of the organism to environmental conditions in order to survive under the new conditions. For sports training, adaptation refers to the set of transformations that the athlete's body undergoes in training, in order to develop a superior state of bio-psycho-motor balance, materialized in the easy execution of a task. Research objectives: Initial evaluation of subjects; Development of the training program; Evaluation of the level of adaptation to physical effort obtained from specific naval pentathlon training; Development of a training planning model, allowing the improvement of physical effort capacity by means specific to the naval pentathlon. Methods: The research carried out started from the premise that the appropriate use of training means specific to the naval pentathlon can lead to an improvement of the effort capacity of military students, which fully satisfies their performance needs in fulfilling combat missions arising from the graduate's model. At a preliminary stage of the research, by applying general physical training tests, we obtained an initial assessment of the research subjects. These data were a benchmark in developing the training program and setting effort parameters. The training plan thus designed contains training sessions specific to naval pentathlon trials, adapted to the normal conditions of the naval academy training process. Results: The comparative analysis of the results, based on mathematical-statistical and graphical methods, reveals significant increases in performance recorded in the final testing stage. The dynamics of the results demonstrates a significant evolution of the results of the experimental group carried out during the training program, carried out according to the designed model. This confirms to us the effectiveness of applying the training program. The statistical results confirm a very good evolution of the results for the general motor tests and for the Ruffier test. Conclusions: Regular exercise is a particularly important stimulus for adaptation. Sports training, by its specific means, aims to increase the level of performance. In order to achieve this objective, it is necessary to apply a well-defined programme in great detail. Effective training requires constant variability in programming. In addition, in order to maximize the positive transfer of training, the means used in the training lesson should be as close as possible to the characteristics of the effort. Because of this, there is a permanent conflict in training programming, between diversity and specificity. This conflict can only be successfully managed through professional intervention on the part of the coach and involvement of the athlete according to training requirements.

Two targets, one strike: Efficient recovery of lithium and simultaneous removal of impurities from spent LFP batteries via ferric ions assisted air oxidation method

Recycling of spent lithium-ion batteries (LIBs) has become urgently imperative to address global environmental issues and achieve sustainable development of new energy industries. Prioritizing lithium and aluminum leaching is an ideal path for recovering lithium efficiently from spent LFP and preparing high-purity battery-grade FePO4. Here, a novel ferric ions-assisted air oxidation method was proposed for the simultaneous leaching of Li and Al. Fe3+ was ingeniously introduced playing two roles: acting as a catalyst for air oxidation and leaching aluminum. 98.8% Li and 95.2% Al are selectively leached under optimal conditions. The thermodynamic analysis indicated that the displacement reaction between Al and Fe3+ dominates the leaching of Al. Furthermore, Cl− can promote the leaching of Al by forming a stable complex [AlCl4]− with Al3+. The reaction course and mechanism were clarified by various characterizations, which indicate that the successful selective leaching of lithium does not destroy the original structure of LFP and the presence of carbon coatings. A cycling process was proposed for enriching the Li+ concentration and reusing Fe3+, and then Li2CO3 with a purity of 99wt.% was successfully prepared. This method demonstrates excellent economic efficiency and environmental friendliness, thus providing a sustainable and low-carbon recycling route for the spent LFP industry.

Large Molecular Rotation in Crystal Changes the Course of a Topochemical Diels-Alder Reaction from a Predicted Polymerization to an Unexpected Intramolecular Cyclization.

A designed anthracene-based monomer for topochemical Diels-Alder cycloaddition polymerization crystallized with head-to-tail arrangement of molecules, as revealed by single-crystal X-ray diffraction (SCXRD) analysis. The diene and dienophile units of adjacent monomer molecules are aligned at an average distance of 4.6 Å, suggesting a favorable crystalline arrangement for their intermolecular Diels-Alder cycloaddition reaction to form a linear polymer. Surprisingly, heating the monomer crystals at a temperature above 125 °C resulted in the formation of intramolecular Diels-Alder cycloadduct, which could be characterized by various spectroscopy and SCXRD analysis. Various time-dependent studies such as NMR, PXRD, and DSC, studies established that the reaction followed topochemical pathway. Schmidt's topochemical postulates are generally used to predict the topochemical reactivity and product, by analyzing the crystal structure of the reactant. Though the crystal arrangement predicted polymerization, upon heating, the molecule avoided this pathway by undergoing a large rotation to form an intramolecular cycloadduct. Theoretical calculations supported the feasibility of the rotation, exploiting the flexibility of the molecule and voids present. These findings caution that the reliance on Schmidt's criteria for topochemical reactions may sometimes be misleading, especially in heat-induced reactions.

Control Circuits for Potentiostatic/Galvanostatic Polarization and Simultaneous Chemical Sensing by a Light-Addressable Potentiometric Sensor.

A light-addressable potentiometric sensor (LAPS) is a semiconductor-based sensor platform for sensing and imaging of various chemical species. Being a potentiometric sensor, no faradaic current flows through its sensing surface, and no electrochemical reaction takes place in the course of LAPS measurement. In this study, a four-electrode system is proposed, in which a LAPS is combined with the conventional three-electrode electrochemical system. A LAPS is included as the fourth electrode for potentiometric sensing and imaging of the target analyte in the course of an electrochemical reaction taking place on the surface of the working electrode. The integrated system will be useful for analyzing dynamic processes, where both the electrochemical process on the electrode surface and the ion distribution in the solution need to be simultaneously investigated. Different grounding modes of control circuits that can simultaneously conduct potentiostatic/galvanostatic polarization and LAPS measurement are designed, and their functionalities are tested. The interference between polarization and LAPS measurement will also be discussed.

Hybrid Cellulosic Substrates Impregnated with Meta-PBI-Stabilized Carbon Nanotubes/Plant Extract-Synthesized Zinc Oxide-Antibacterial and Photocatalytic Dye Degradation Study.

Novel fibrous cellulosic substrates impregnated with meta-polybenzimidazole (PBI)-stabilized carbon nanotubes/zinc oxide with different weight content of ZnO and with the use of dimethylacetamide as dispersant media. The pristine ZnO nanoparticle powder was prepared by plant extract-mediated synthesis using Vaccinium vitis-idaea L. The green synthesized ZnO possesses an average crystallite size of 15 nm. The formation of agglomerates from ZnO NPs with size 250 nm-350 nm in the m-PBI@CNTs/ZnO was determined. The prepared materials were investigated by PXRD analysis, XPS, SEM, EDS, AFM, and TEM in order to establish the phase and surface composition, structure, and morphology of the hybrids. The potential of the synthesized hybrid composites to degrade methylene blue (MB) dye as a model contaminant in aqueous solutions under UV illumination was studied. The photocatalytic results show that in the course of the photocatalytic reaction, the m-PBI@CNTs/ZnO 1:3 photocatalyst leads to the highest degree of degradation of the methylene blue dye (67%) in comparison with the other two studied m-PBI@CNTs/ZnO 1:1 and 1:2 composites (48% and 41%). The antibacterial activity of ZnO nanoparticles and the hybrid CNT materials was evaluated by the RMDA and the dynamic contact method, respectively. The profound antibacterial effect of the m-PBI@CNTs/ZnO hybrids was monitored for 120 h of exposition in dark and UV illumination regimes. The photocatalytic property of ZnO nanoparticles significantly shortens the time for bactericidal action of the composites in both regimes. The m-PBI@CNTs/ZnO 1:2 combination achieved complete elimination of 5.105 CFU/mL E. coli cells after 10 min of UV irradiation.

Carbonization of golden shower pods to high surface area biochar for decontamination of cationic dyes and regeneration study by gamma radiations

Detoxification of water resources is the need of the hour and a number of environment friendly materials are proposed by scientist to deal with water pollution issues. The present study deals with preparation and characterization of porous activated carbon from golden shower pods, a waste ligno-cellulosic biomass, for the removal of dye contaminants from aqueous solution. The synthesized material, golden shower biochar (GSBC) was characterized using various analytical techniques to confirm the presence of active sites. The BET analysis of GSBC revealed high surface area of 1120 m2/g with total pore volume of 1.099 cm3/g and average pore radius 19.618 Å. Operational parameters were optimized using batch studies by taking GSBC dose of 50 mg which showed complete removal of target dyes with an initial dye concentration of 200 mg/L with just 60 min interaction time; based on these results, a fixed bed column of GSBC was designed and column studies were performed. Adsorption isotherm studies were carried out using Langmuir and Freundlich models, of which Langmuir model was found to be best-fit with maximum adsorption capacities of 208.86 mg/g, 284.35 mg/g and 327.56 mg/g for Crystal violet, Brilliant green and Methylene blue dyes respectively. Analysis of kinetics and thermodynamics revealed that the best-fit model was pseudo second-order with spontaneous reaction course and exothermic nature. Regeneration was carried out using gamma irradiation of dye loaded GSBC, followed by leaching in alcohol. It was observed that a 30 KGy dose was just sufficient to completely degrade the dye on the adsorbent surface. GSBC has shown immense potential for eradication of dyes from water effluents and it is easily recovered with negligible loss in efficacy.

Description of BCG and Tuberculosis Disease in a Cohort of 79 Patients with Chronic Granulomatous Disease.

Chronic granulomatous disease (CGD) is an inherited immunodeficiency caused by pathogenic variants of genes encoding the enzyme complex NADPH oxidase. In countries where tuberculosis (TB) is endemic and the Bacillus Calmette-Guérin (BCG) vaccine is routinely administered, mycobacteria are major disease-causing pathogens in CGD. However, information on the clinical evolution and treatment of mycobacterial diseases in patients with CGD is limited. The present study describes the adverse reactions to BCG and TB in Mexican patients with CGD. Patients with CGD who were evaluated at the Immunodeficiency Laboratory of the National Institute of Pediatrics between 2013 and 2024 were included. Medical records were reviewed to determine the clinical course and treatment of adverse reactions to BCG and TB disease. A total of 79 patients with CGD were included in this study. Adverse reactions to BCG were reported in 55 (72%) of 76 patients who received the vaccine. Tuberculosis was diagnosed in 19 (24%) patients. Relapse was documented in three (10%) of 31 patients with BGC-osis and six (32%) of 19 patients with TB, despite antituberculosis treatment. There was no difference in the frequency of BCG and TB disease between patients with pathogenic variants of the X-linked CYBB gene versus recessive variants. This report highlights the importance of considering TB in endemic areas and BCG complications in children with CGD to enable appropriate diagnostic and therapeutic approaches to improve prognosis and reduce the risk of relapse.

Investigation of Huisgen's Noble metal catalyst click reaction mechanism for the synthesis of 1,4-disubstituted 1,2,3-triazoles

The current study delves into the mechanistic intricacies of azide-alkyne cycloaddition reactions (MAAC) catalyzed by transition metals (M = Cu, Ag, and Au) bound to N-heterocyclic carbene (NHC) ligands, utilizing Density Functional Theory (DFT) calculations at the MN12-L/Def2-SVP level of theory, with Def2-TZVP for metal atoms, to shed light on the 1,4-regioisomer formation. A detailed comparison between mono- and bi-nuclear catalytic pathways for these metal complexes is presented. Our findings underscore the nuanced role of the metal identity in dictating the reaction's course, with a notable preference for a stepwise mechanism across the board, except in the mononuclear pathway of Au and Ag, which follows a concerted mechanism. The activation energies, analyzed in toluene solvent, underscore the efficiency of the binuclear pathway for all metals, showcasing significantly lower activation barriers (18.76 kcal/mol for Au and Ag, and 8.47 kcal/mol for Cu) compared to the mononuclear route. This distinction highlights the potential for optimizing catalytic performance through careful selection of metal-NHC combinations, providing valuable insights for the design of efficient catalysts in click chemistry applications. The study not only reaffirms the superior efficacy of the binuclear pathway but also enriches our understanding of metal-catalyzed MAAC reactions, contributing to the advancement of catalysis science and offering avenues for the development of novel synthetic strategies in organic chemistry.

Mystery of the Passerini Reaction for the Synthesis of the Antimicrobial Peptidomimetics against Nosocomial Pathogenic Bacteria.

The first example of applying salicylaldehyde derivatives, as well as coumarin with the formyl group at the C8 position in its structure, as carbonyl partners in a three-component Passerini reaction, is presented. As a result of research on the conditions of the Passerini reaction, the important role of the hydroxyl group in the salicylaldehyde used in the course of the multicomponent reaction was revealed. When an aldehyde with an unprotected hydroxyl group is used, only two-component α-hydroxy amide products are obtained. In contrast, the use of acylated aldehyde results in three-component α-acyloxy amide products with high efficiency. The developed protocol gives access to structurally diversified peptidomimetics with good yield. The compounds were also evaluated as antimicrobial agents against selected strains of nosocomial pathogenic bacteria. The structure-activity relationship revealed that inhibitory activity is strongly related to the presence of the trifluoromethyl group (CF3) or the methyl group at the C4 position in an unsaturated lactone ring of the coumarin scaffold. MIC and MBC studies were carried out on eight selected pathogenic bacteria strains (Gram-positive pathogenic Staphylococcus aureus strain (ATCC 23235), as well as on Gram-negative E. coli (K12 (ATCC 25404), R2 (ATCC 39544), R3 (ATCC 11775), and R4 (ATCC 39543)), Acinetobacter baumannii (ATCC 17978), Pseudomonas aeruginosa (ATCC 15442), and Enterobacter cloacae (ATCC 49141) have shown that the tested compounds show a strong bactericidal effect at low concentrations. Among all agents investigated, five exhibit higher antimicrobial activity than those observed for commonly used antibiotics. It should be noted that all the compounds tested showed very high activity against S. aureus, which is the main source of nosocomial infections that cause numerous fatalities. Additionally, the cytotoxicity of sixteen derivatives was measured with the use of the MTT test on BALB/c3T3 mouse fibroblast cell lines. The cytotoxicity studies revealed that the tested substances exert a similar or lower effect on cell proliferation than that observed for commonly used antibiotics within the range of therapeutic doses. A parallel MTT assay using ciprofloxacin, bleomycin, and cloxacillin showed that these antibiotics are more cytotoxic when tested in mammalian cells, and cell viability is in the range of 85.0-89.9%. Furthermore, we have shown that the studied coumarin-based peptidomimetics, depending on their structural characteristics, are nonselective and act efficiently against various Gram-positive and Gram-negative pathogens, which is of great importance for hospitalised patients.

Al-Ni-Co decagonal quasicrystal application as an energy-effective catalyst for phenylacetylene hydrogenation

Intermetallic catalysts, including quasicrystals, are considered a sustainable alternative to noble metal-based catalysts in hydrogenation reactions. This study discusses the manufacturing and catalytic potential of an Al-Ni-Co quasicrystalline alloy. Energy-effective and simple catalyst production was provided by a melt-spinning process. The obtained ribbons, characterized in terms of microstructure, phase and chemical composition using X-ray diffraction, scanning and transmission microscopy methods, were composed of a decagonal quasicrystalline phase with traces of crystalline phases. The form of the melt-spun ribbons ensured easy application in the phenylacetylene hydrogenation reaction. The catalyst provided a substrate conversion of approximately 80% and a styrene selectivity of 54% after 1 h of reaction carried out under mild conditions. The repeatability of the reaction course was verified, with a maximum deviation of 10%. Moreover, the catalyst recovered after the reaction was evaluated in terms of its phase composition and surface changes. X-ray diffractograms confirmed the phase stability, however, the surface degradation and oxidation occurred. The catalytic activity after three months of catalyst storage is also discussed.

Buildup and Consumption of Species in Emulsion Droplets during Aqueous Suzuki Coupling Correlate with Yield.

Fluorescence lifetime imaging microscopy (FLIM) provides spatiotemporal resolution of the changing composition of emulsion droplets during aqueous-surfactant Suzuki coupling. In contrast to previous investigations, the present experiments characterize the full course of a catalytic chemical reaction, addressing key questions about reaction species buildup and correlating these microscale behaviors with bench-scale product yields. At low concentrations of (active) catalyst, droplet environments are stable; however, at higher concentrations, emulsion droplet environments change markedly. These changes are consistent with the buildup and consumption of reaction species inside the droplets. A combination of FLIM and bright-field imaging pinpoints limitations in catalyst solubility as controlling rate and degree of buildup of species in droplets. These solubility limitations are also identified as the cause of a reaction induction period and an origin of the rate-and-reproducibility advantage obtained by adding THF cosolvent. The subsequent mechanistic model from these data led to a bench-scale reaction optimization, wherein premixing the catalyst components bypasses the catalyst induction period, resulting in a faster reaction. The understanding generated by FLIM thus provides an early example of how visualizing changes in droplet compositions on the microscale during ongoing aqueous-organic reactions can be leveraged for enhancing efficiencies in bench-scale reactions.

Conversion of Carbon Dioxide into a Series of CBxOy- Compounds Mediated by LaB3,4O2- Anions: Synergy of the Electron Transfer and Lewis Pair Mechanisms to Construct B-C Bonds.

Converting CO2 into value-added products containing B-C bonds is a great challenge, especially for multiple B-C bonds, which are versatile building blocks for organoborane chemistry. In the condensed phase, the B-C bond is typically formed through transition metal-catalyzed direct borylation of hydrocarbons via C-H bond activation or transition metal-catalyzed insertion of carbenes into B-H bonds. However, excessive amounts of powerful boryl reagents are required, and products containing B-C bonds are complex. Herein, a novel method to construct multiple B-C bonds at room temperature is proposed by the gas-phase reactions of CO2 with LaBmOn- (m = 1-4, n = 1 or 2). Mass spectrometry and density functional theory calculations are applied to investigate these reactions, and a series of new compounds, CB2O2-, CB3O3-, and CB3O2-, which possess B-C bonds, are generated in the reactions of LaB3,4O2- with CO2. When the number of B atoms in the clusters is reduced to 2 or 1, there is only CO-releasing channel, and no CBxOy- compounds are released. Two major factors are responsible for this quite intriguing reactivity: (1) Synergy of electron transfer and boron-boron Lewis acid-base pair mechanisms facilitates the rupture of C═O double bond in CO2. (2) The boron sites in the clusters can efficiently capture the newly formed CO units in the course of reactions, favoring the formation of B-C bonds. This finding may provide fundamental insights into the CO2 transformation driven by clusters containing lanthanide atoms and how to efficiently build B-C bonds under room temperature.