Direct Reaction Research Articles

Toward soluble high-performance electrochromic polymer: Optimizing cross-link density

Cross-linked conjugated polymers attract great attentions in optoelectronic field due to their unique properties resulting from the existence of intramolecular pore and network structure. However, the poor solubility restricts the application of cross-linked polymers in photoelectric device. Here, the strategy of changing cross-link density is employed to optimize solubility and properties of cross-linked conjugated polymer. Five polythiophene derivatives with different cross-link densities were synthesized through direct arylation reaction. The cross-linked conjugated polymers achieve good solubility in organic solvent through decreasing cross-link density, and possess similar optical absorption regions compared to conjugated polymer without cross-linked structure. Through optimizing cross-link density, the electrochromic properties of conjugated polymers could be enhanced, including optical contrast (55 %), response time (0.6 s), coloration efficiency (CEox = 510 cm2 C-1; CEred = 3567 cm2 C-1), and stability, which is more excellent than that of reported cross-linked polymers. And, the flexible electrochromic device based on PET-(1,9) was constructed by simple solution processing and could achieve fast color change between wine red and light blue in low voltage driving force, which indicating the applicability of soluble cross-linked conjugated polymer. Besides, the mechanism about ionic transport and stability improvement of cross-linked conjugated polymers is discussed. These results demonstrate that changing cross-link density is an effective strategy to optimize the properties of cross-linked conjugated polymers.

N-dodecane partial oxidative reforming in gliding arc discharge plasma and kinetic model

A gliding arc discharge (GAD) plasma reactor was developed for partial oxidative reforming (POR) H2 production. Air was used as carrier gas and oxidant. The effects of the molar ratio of oxygen to carbon(O/C), input power and residence time on POR reaction were investigated. Under O/C ratio 0.75, input power 35 W and residence time 35 s, the energy yield of H2 was 68.7 L/kWh and the main products were H2 and CO. The GAD plasma was diagnosed with OES. A zero-dimensional(0-D) reaction kinetic model of was established. The simulation results were consistent with the experimental ones. The mechanism of C12H26 conversion, the generation and consumption of products were discussed in detail. The experiment results were in good agreement with the simulated ones. The primary path of n-dodecane conversion was the direct cracking reaction and H2 mainly derived from the recombination reaction between H atom and CH4, C3H6 and C2H6.

New sugar-incorporated N-heterocyclic carbene precursors and their Ag(I) and Pd(II) complexes: Synthesis, characterization, and cytotoxicity studies

In the present work, a new series of sugar-incorporated N-heterocyclic carbene precursors namely 1-(3,4,5-trimethoxybenzyl)-3-[2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl]imidazolium bromide (7a), 4-methyl-1-(3,4,5-trimethoxybenzyl)-3-[2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl]imidazolium bromide (7b), 4,5-diphenyl-1-(3,4,5-trimethoxybenzyl)-3-[2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl]imidazolium bromide (7c), and 1-(3,4,5-trimethoxybenzyl)-3-[2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl]benzimidazolium bromide (8) were synthesized by the direct reaction of the N-alkylated benzimidazoles with 2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl bromide. Ag(I)–NHC complexes (9a-c, 10) of the abovementioned precursors were synthesized by in-situ reaction with Ag2O in light-excluded conditions. The transmetallation reaction technique was used to synthesize Pd(II)–NHC complexes (11a-c, 12) by the reaction of [PdCl2(MeCN)2] with corresponding Ag(I)–NHC complexes. All NHC precursors and their corresponding Ag(I) and Pd(II) complexes were spectrally characterized using 1H &13C NMR, and mass spectrometry. Further, Pd(II) complexes were evaluated for their anticancer activity against eight diverse cancer cell lines, namely; Pancreatic Adenocarcinoma (Capan-1), Colorectal Carcinoma (HCT-116), Glioblastoma (LN229), Lung Carcinoma (NCI-H1975), Acute Lymphoblastic Leukemia (DND-41), Acute Myeloid Leukemia (HL-60), Chronic Myeloid Leukemia (K562), and non-Hodgkin Lymphoma (Z138). Standard antineoplastic drugs docetaxel and etoposide were included as reference compounds. Among the tested complexes, complex 11c displayed broad activity against all tested cancer types, albeit at higher concentrations when compared to the reference drugs.

Synthesis, Antiviral and Cytostatic Activity of New Series of Naphthalimide Derivatives

A new series of N-(diethylphosphonoalkyl)-1,8-naphthalimides were synthesized via direct reaction of 1,8-naphthalic anhydride or its 3-nitro- and 4-bromo- derivatives with selected ɷ-aminoalkylphosphonates and evaluated against a broad-spectrum of viruses as well as for their cytostatic properties toward selected cell lines. N-(diethylphosphonomethyl)-3-nitro-1,8-naphthalimide 15a exhibited inhibitory activity toward coxsackie virus B4 in Vero cells (EC50 = 9.45 μM), whereas 3-nitro-1,8-naphthalimides 15b and 15d containing short 2-carbon linker showed moderate activity against herpes simplex virus-2 (G) and herpes simplex virus-1 TK– KOS ACVr. Furthermore, compounds 15a, 15b and 15d showed antiviral potency against human coronavirus. Several naphthalimides exhibited cytostatic activity toward tested cancerous cell lines as well as normal retina cells. Transformation of selected diethyl phosphonates 13, 14 and 15 into ammonium phosphonates 21, 22 and 23 improved the solubility, however, did not result in the enhancement of antiviral and cytostatic potency of the compounds.

Hydrothermal Carbonization of Cellulose with Ammonium Sulfate and Thiourea for the Production of Supercapacitor Carbon.

Doping with heteroatoms is the main method used to enhance energy storage with carbon materials, and polyatomic doping is one of the main challenges. Hydrothermal carbonization of cellulose was performed at 240 °C for 1 h. Ammonium sulfate and thiourea dopants were selected as the sources of inorganic nitrogen and organic nitrogen in the preparation of supercapacitor carbon. The effects of boric acid on the properties of the resulting hydrochar after KOH activation were examined. The results showed that the proportion of functional groups and the specific surface area of the activated hydrochar were reduced by the addition of boric acid, and the formation of micropores was inhibited. The hydrochar obtained from the reaction of cellulose and organic nitrogen compounds had a better pore size distribution and electrochemical properties after activation. The largest specific surface area (952.27 m2/g) was obtained when thiourea was used as the sole dopant. In a three-electrode system, the specific capacitance of the activated hydrochar reached 235.8 F/g at a current density of 1 A/g. After 20,000 charging and discharging cycles at a current density of 10 A/g, the capacitance retention rate was 99.96%. Therefore, this study showed that supercapacitor carbon with good electrochemical properties was obtained by the direct reactions of cellulose with organic nitrogen compounds.

Niosomal formulation of mefenamic acid for enhanced cancer targeting; preparation, characterization and biodistribution study using radiolabeling technique

BackgroundThis work aimed to prepare niosomal formulations of an anticancer agent [mefenamic acid (MEF)] to enhance its cancer targeting. 131I was utilized as a radiolabeling isotope to study the radio-kinetics of MEF niosomes.Methodsniosomal formulations were prepared by the ether injection method and assessed for entrapment efficiency (EE%), zeta potential (ZP), polydispersity index (PDI) and particle size (PS). MEF was labeled with 131I by direct electrophilic substitution reaction through optimization of radiolabeling-related parameters. In the radio-kinetic study, the optimal 131I-MEF niosomal formula was administered intravenously (I.V.) to solid tumor-bearing mice and compared to I.V. 131I-MEF solution as a control.Resultsthe average PS and ZP values of the optimal formulation were 247.23 ± 2.32 nm and − 28.3 ± 1.21, respectively. The highest 131I-MEF labeling yield was 98.7 ± 0.8%. The biodistribution study revealed that the highest tumor uptake of 131I-MEF niosomal formula and 131I-MEF solution at 60 min post-injection were 2.73 and 1.94% ID/g, respectively.ConclusionMEF-loaded niosomes could be a hopeful candidate in cancer treatment due to their potent tumor uptake. Such high targeting was attributed to passive targeting of the nanosized niosomes and confirmed by radiokinetic evaluation.

BlueSTEAl: A pair of silicon arrays and a zero-degree phoswich detector for studies of scattering and reactions in inverse kinematics

BlueSTEAl, the Blue (aluminum chamber of) Silicon TElescope Arrays for light nuclei, has been developed to study direct reactions in inverse kinematics, as well as scattering and breakup reactions using radioactive ion beams. It is a detector system consisting of a pair of annular silicon detector arrays and a zero-degree phoswich plastic scintillator. For typical binary reaction studies in inverse kinematics, light ions are detected by the Si array in coincidence with heavy recoils detected by the phoswich placed at the focal-plane of a zero-degree magnetic spectrometer. The Si array can also be used to detect light nuclei such as beryllium and carbon with clear isotope separation, while the phoswich can also be placed at zero degrees without a spectrometer and used as a high-efficiency beam counting monitor with particle identification capability at the rate of up to ∼5 × 104 particles per second. This paper reports on the capabilities of BlueSTEAl as determined by recent experiments performed at the Texas A&M Cyclotron Institute. The device is also anticipated to be used in future experiments at other radioactive ion beam facilities.

Development of an LFD-RPA Assay for Rapid Detection of Pentatrichomonas hominis Infection in Dogs.

Pentatrichomonas hominis is a trichomonad protozoan that infects the cecum and colon of humans and other mammals. It is a zoonotic pathogen that causes diarrhea in both animals and humans. As companion animals, dogs infected with P. hominis pose a risk of transmitting it to humans. Current methods, such as direct smears and polymerase chain reaction (PCR), used for P. hominis detection have limitations, including low detection rates and the need for specialized equipment. Therefore, there is an urgent need to develop rapid, sensitive, and simple detection methods for clinical application. Recombinase polymerase amplification (RPA) has emerged as a technology for rapid pathogen detection. In this study, we developed a lateral flow dipstick (LFD)-RPA method based on the highly conserved SPO11-1 gene for detecting P. hominis infection by optimizing the primers, probes, and reaction conditions, and evaluating cross-reactivity with genomes of Giardia duodenalis and other parasites. The LFD-RPA method was then used to test 128 dog fecal samples collected from Changchun. The results confirmed the high specificity of the method with no cross-reactivity with the five other parasites. The lowest detection limit of the method was 102 copies/µL, and its sensitivity was 100 times higher than that of the conventional PCR method. Consistent with the positivity rate observed using nested PCR, 12 samples (out of 128) tested positive using this method (positivity rate, 9.38%). In conclusion, the LFD-RPA method developed in this study represents a simple and sensitive assay that allows for the rapid detection of P. hominis infection in dogs, especially in this field.

The impacts of CO2 mineralization reaction on the physicochemical characteristics of fly ash: A study under different reaction conditions of the water-to-solid ratio and the pressure of CO2

Utilizing fly ash (FA) directly to mineralize CO2 and injecting carbon sequestration products into goafs of coal mines is a novel and promising technology. The impact mechanisms of CO2 direct mineralization reactions on the characteristics of key groups, physical phases, surface micromorphology, particle size and pore structure of FA are discussed systematically in detail. The focus is imposed on the impacts of different reaction conditions (water-to-solid ratios and pressures of CO2). Based on the FT-IR, XRD and ESEM-EDS analysis, CO2 is transformed into carbonates of five vibrational models after mineralization and largely sequestered as calcite by portlandite, which forms a passivated layer on the FA surface. The particle size of carbonated FA particles gets smaller and less uniform, and the variation laws of the particle size at full scale are analyzed by particle size intervals. The variation process of the pore can be divided into the dissolution of FA for pore expansion, the low degree of CO2 mineralization reaction for further expanding the pore and the high reaction degree for pore shrinkage. This paper provides theoretical bases for improving the direct CO2 sequestration capacity and research directions for the subsequent application properties of carbon sequestration products.

Boosting the efficiency of supported undecamolybdophosphate catalyst by tailoring acid-redox properties for direct oxidative cross-esterification of aldehydes

Aiming to develop a novel heterogeneous catalyst for single-step oxidative cross-esterification of aldehydes to ester with enhanced activity and selectivity under benign conditions, here we report the synthesis of defect-regulated undecamolybdophosphate supported on ZSM-5. The enhancement in acidity was achieved by exchanging the available Na+ with protons using an ion-exchange protocol. The structural and morphological features of synthesized catalysts (20 % PMo11/ZSM-5-H) were confirmed by in-depth characterization such as acidity measurement, FT-IR, TGA, surface area measurement SEM, TEM, and PXRD. The synthesized catalysts were used for direct oxidative esterification reaction with environmentally benign oxidants (O2 and H2O2). The effect of various reaction parameters such as %loading of PMo11, amount of catalyst, reaction time, and reaction temperature and volume of methanol on activity and selectivity was studied. The comparative studies of supported analogous phosphomolybdates with the present catalyst showed that the enhancement in acidity and modulation in redox properties of 20 % PMo11/ZSM-5-H was found propitious. The novelty lies in obtaining excellent selectivity of the ester (>95 %) with an exceptionally high turnover number (>15323) with an environmentally benign oxidant O2. The scope and limitations of the present catalytic system were also explored by employing different aldehydes and alcohols under optimized conditions. The stability and recycling studies showed that the synthesized catalyst is truly heterogeneous and can be recycled at a minimum of six cycles. From the comparative data of the reported catalysts as well as control experiments, it was concluded that the synergistic effects of enhanced acidities and tailored redox sites played vital roles in the superior performance of the present catalytic system. Based on the results, a plausible reaction mechanism was also proposed.

Facile access to benzofuran derivatives through radical reactions with heteroatom-centered super-electron-donors

The development of suitable electron donors is critical to single-electron-transfer (SET) processes. The use of heteroatom-centered anions as super-electron-donors (SEDs) for direct SET reactions has rarely been studied. Here we show that heteroatom anions can be applied as SEDs to initiate radical reactions for facile synthesis of 3-substituted benzofurans. Phosphines, thiols and anilines bearing different substitution patterns work well in this inter-molecular radical coupling reaction and the 3-functionalized benzofuran products bearing heteroatomic functionalities are given in moderate to excellent yields. The reaction mechanism is elucidated via control experiments and computational methods. The afforded products show promising applications in both organic synthesis and pesticide development.

Water-resistant FLPs-polymer as recyclable catalysts for selective hydrogenation of alkynes

The frustrated Lewis pairs (FLPs) have attracted much attention as hydrogenation catalysts due to their metal-free properties and considerable catalytic activity. However, the sensitivity to water and the difficulty of recycling greatly limit the practical application of FLPs catalysts. In the light of above problems, we innovatively present a strategy of using Lewis acid-base complex to construct water-resistant FLPs polymer via a direct Friedel-Crafts reaction knitting method. The B-P bond of the prepared FLPs-polymer reversibly breaks at elevated temperature, activating H2 to selectively reduce alkynes into alkenes with good conversion and selectivity. This water-resistant FLPs catalyst can not only be reused up to ten times, but also highlights excellent stability and high reactivity even in the presence of water. This work presents an example of how to bring water-tolerant and recyclable FLPs catalysts to the industrial catalysis.

Synergistic Roles of the CoO/Co Heterostructure and Pt Single Atoms for High-Efficiency Electrocatalytic Hydrogenation of Lignin-Derived Bio-Oils.

Electrochemical hydrogeneration (ECH) of biomass-derived platform molecules, which avoids the disadvantages in utilizing fossil fuel and gaseous hydrogen, is a promising route toward value-added chemicals production. Herein, we reported a CoO/Co heterostructure-supported Pt single atoms electrocatalyst (Pt1-CoO/Co) that exhibited an outstanding performance with a high conversion (>99%), a high Faradaic efficiency (87.6%), and robust stability (24 recyclability) at -20 mA/cm2 for electrochemical phenol hydrogenation to high-valued KA oil (a mixture of cyclohexanol and cyclohexanone). Experimental results and the density functional theory calculations demonstrated that Pt1-CoO/Co presented strong adsorption of phenol and hydrogen on the catalyst surface simultaneously, which was conducive to the transfer of the adsorbed hydrogen generated on the single atom Pt sites to activated phenol, and then, ECH of phenol with high performance was achieved instead of the direct hydrogen evolution reaction. This work described that the multicomponent synergistic single atom catalysts could effectively accelerate the ECH of phenol, which could help the achievement of large-scale biomass upgrading.

Secondary reactions of propylene on Ga/γ-Al2O3 propane dehydrogenation catalysts

Supported Ga catalysts have been widely studied for propane dehydrogenation (PDH). In this study, Ga/γ-Al2O3 catalysts were evaluated for PDH. The propylene selectivity decreased with increasing propane conversion. It is generally thought that propylene and light gas by-products occur from chemisorbed propane and are, therefore, primary products. By extrapolating the product selectivities to zero per cent propane conversion, the initial propylene selectivity was near 100% and is a primary product. The light gas selectivities, however, are near 0% indicating that these are secondary products. The direct reaction of propylene produced the same light gas products, e.g., methane, ethylene, propane, butenes and pentenes, observed for PDH and confirmed that these occur by an independent reaction of propylene. Thus, while the intrinsic PDH propylene selectivity is high, these secondary propylene reactions lower the selectivity, especially, at higher conversions and higher partial pressures.

Organo‐Catalyzed Enantioselective [4+2] Annulation of Glutaraldehyde and C3‐Indolyl‐imines To Access Indol‐3‐yl‐piperidines

AbstractA simple and straightforward method is developed for the enantioselective synthesis of indol‐3‐yl‐piperidine. The reaction proceeds through a proline‐catalyzed direct Mannich reaction between glutaraldehyde and C3‐indolyl‐imines, followed by intramolecular reductive cyclization as an overall [4+2] annulation in one‐pot fashion. A series of indol‐3‐yl‐piperidine have been accessed with good yields up to 71 % and high enantioselectivity up to >99 % ee.

Hybrid Zn-β-Aminoporphyrin–Carbon Nanotubes: Pyrrolidine and Direct Covalent Linkage Recognition, and Multiple-Photo Response

To unveil and shape the molecular connectivity in (metallo)porphyrin–carbon nanotube hybrids are of main relevance for the multiple medicinal, photoelectronic, catalytic, and photocatalytic applications of these materials. Multi-walled carbon nanotubes (MWCNTs) were modified through 1,3-dipolar cycloaddition reactions with azomethine ylides generated in situ and carrying pentafluorophenyl groups, followed by immobilization of the β-amino-tetraphenylporphyrinate Zn(II). The functionalities were confirmed via XPS and FTIR, whereas Raman spectroscopy showed disruptions on the graphitic carbon nanotube surface upon both steps. The functionalization extension, measured via TGA mass loss and corroborated via XPS, was 0.2 mmol·g−1. Photophysical studies attest to the presence of the different porphyrin–carbon nanotube connectivity in the nanohybrid. Significantly different emission spectra and fluorescence anisotropy of 0.15–0.3 were observed upon variation of excitation wavelength. Vis-NIR absorption and flash photolysis experiments showed energy/charge transfer in the photoactivated nanohybrid. Moreover, evidence was found for direct reaction of amino groups with a carbon nanotube surface in the presence of molecular dipoles such as the zwitterionic sarcosine amino acid.

Kinetic Analysis of Dry Reforming of Methane on Traditional and Membrane Catalysts

The article presents an analysis of the results of a kinetic study of dry reforming of methane (UCM) in reactors with traditional (TC) and membrane catalysts (MC). The kinetic experiment in reactors with MC and TC was performed in the temperature range of 820–900°C and the ratio CH4 : CO2 = 1 : 1. In the experiment, an intensification of the process of the methane cracking reaction was established, the rate constant of which increases by an order of magnitude. Such a difference in the results of the DRM on the studied catalysts are due to the intensification of mass transfer on the MC, which is based on the phenomenon of thermal slip. A mathematical description corresponding to the kinetic scheme of DRM process is proposed, and the rates constants of direct and reverse reactions in both reactors are found. In the DRM process, water gas is formed on the TC, and synthesis gas is formed on the MC. At TC, the DRM process is accompanied by the accumulation of carbon deposits (CD), and at MC this accumulation is absent. The DRM process on both catalysts is characterized by three main reactions (methane cracking, gasification of the CD with carbon dioxide and/or water vapor and the reverse water gas shift), which were assumed to be reversible under experimental conditions. It turned out that on TC the gasification of the CD occurs in the reverse reaction of methane cracking, and on the MC—in the reactions of gasification by water vapor (mainly) and carbon dioxide. The process on the MC is characterized by irreversible reactions of methane cracking, gasification of the CD with water vapor and carbon dioxide. The reverse water gas shift reaction on the MC remains reversible, and its rate constants of the direct and inverse reactions turned out to be an order of magnitude lower than similar constants on the TC.

Circulating-infiltrating preparation of hydrophilic nylon 6 membrane to hydrophobic MWCNT@nylon composite membrane

The ion adsorption capacity has been added to the nylon 6 microfiltration (MF) membrane by grafting the fibers in its structure with carboxylated multi-walled carbon nanotubes (MWCNT-COOH). Through a direct three-step functionalization reaction with hexamethylenediamine (HMDA) and MWCNT-COOH, the multi-walled carbon nanotubes grafted nylon (MWCNT@nylon) fibers are made up of original nylon 6 and intermediate amino-enriched (nylon-NH2) membranes. Chemical structure analysis shows that HMDA and MWCNTs were grafted to the nylon 6 fiber side wall, without causing damage to either the nylon 6 backbone or the pore size of the original membrane. The SEM images confirm this and further confirm that the plexus of MWCNT-COOH has a pore size of approximately 50 nm, covering the nylon 6 fibers. The sidewall of nylon-NH2 and MWCNT@nylon fibers contains hydrophilic groups (amino and carboxylic), allowing the as-prepared membranes to reduce the wetting angle from about 70.3° to about 108.1°. This special structure opens new possibilities for polyamide membranes as well as mass production by the proposed simple method.

Effects of hydrogen on PAH and soot formation in laminar diffusion flames of RP-3 jet kerosene and its surrogate

PAH and soot are harmful substances that can be produced in any type of combustion equipment including aircraft engines. The co-combustion of hydrogen and jet fuel has been applied in aero-engine combustors and large-scale hydrogen addition is a promising solution for reducing the consumption of fossil fuels in the aviation industry. However, it remains unclear how H2 influences the soot and PAH formation characteristics of jet kerosene. In this study, to investigate the impact of H2 on soot and PAH formation, planar laser-induced incandescence (PLII), planar laser-induced fluorescence of PAH (PAH-PLIF) and chemical kinetic simulation were conducted for the laminar diffusion flames of RP-3 jet kerosene and its surrogate S1 with different H2 doping rates. It is found that the introduction of H2 leads to the increased soot formation. However, the promotion effect of H2 on the PAH formation weakens as the number of PAH rings increases, and the formation of A4 is significantly inhibited. But the rapidly increase of benzene and alkynes in the H2-doped kerosene flame may ultimately lead to the promotion of soot formation. Furthermore, the changes in direct synthesis reactions and PAH=>PAH- jointly affect the converse changes in A1 and A4 formation. These findings will contribute to the development of the soot model and soot/PAH-reduction strategy for the co-combustion of jet fuels and hydrogen.

Proton Energy Spectra From Deuteron Induced Reaction on Copper At 14,5 MeV Deuteron Energy

Double differential cross sections have been measured for light-charged particle production in deuteron-induced reactions on nat Cu at incident energies of 14.5 MeV. The experiment was performed at the isochronous cyclotron of the Institute of Nuclear Physics (Kazakhstan). Charged particles were detected using a set of Si and CsI detectors from 30° to 135°, by step of 15°. The integral cross-sections were determined by integrating over the angle the double differential cross-sections. Double differential and integral charged particle emission cross-sections have been calculated by the TALYS 1.9 nuclear reaction which code based on a modified version of the exciton model of the pre-equilibrium nuclear decay. Direct, compound, and pre-equilibrium reaction contributions have been determined for the emission of proton particles.