Good Substrate Research Articles

WOx boosted hollow Ni nanoreactors for the hydrodeoxygenation of lignin derivatives

Reasonable design of non-noble metal catalysts with hollow open structure for hydrodeoxygenation (HDO) of lignin derivatives to value-added chemicals is of great significance but challenging. Herein, a novel MOF-derived multilayer hollow sphere coated nickel‑tungsten bimetallic catalyst (Ni2-WOx@CN-700) was fabricated via by confined pyrolysis strategy using bimetallic MOFs as a self-sacrificial template, which exhibits robust activity for the typical model HDO of vanillin to 2-methoxy-4-methylphenol (Yield of 100 % at 140 °C for no less than 10 cycles). The characterizations revealed that WOx facilitated the dispersion of Ni nanoparticles and adjusted the acidic capacity of the catalyst through the formed Ni-WOx heterojunction. Density functional theory (DFT) calculations confirms that WOx species enhanced the electron-rich nature of the active sites, while the adsorption energies of H2 and vanillin on Ni-WOx decreased from −0.572 eV and − 0.622 eV on Ni to −3.969 eV and − 4.922 eV, respectively. These results further indicated that the high activity of Ni2-WOx@CN-700 was attributed to the Ni-WOx heterojunction. Based on the characterizations and the thermodynamic calculations, the reaction mechanism was proposed. In addition, the catalyst shows good substrate universality, which enables its good commercial application prospect.

EMM-Promoted Pd-Catalyzed Solid State Intramolecular Heck-Type Cyclization/Boronation and Suzuki Couplings: Access to Functionalized Indolines.

EMM (electromagnetic mill)-promoted Pd-catalyzed solid state intramolecular Heck-type cyclization/boronation and Suzuki couplings are reported. Compared to previous mechanochemistry that constructed one chemical bond through a cross-coupling reaction, this strategy realizes cascade transformation along with multiple chemical bond formation. This conversion does not require organic solvents or additional heating, and it shows a good substrate scope and high functional group tolerance.

Titanium dioxide/nitrogen-doped graphene-biopolymer based nanocomposite films for pollutant photodegradation and laser desorption ionization mass spectrometry of biomarkers

Titanium dioxide (TiO2)/nitrogen-doped graphene (NG) nanocomposite is prepared via a solvent-free hydrothermal reaction. The resulting TiO2/NG materials exhibit a reduction of the band gap energy compared to pristine TiO2 from 3.27 eV to 2.69 eV. These materials are characterized by scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). To prepare biopolymer films with photocatalytic properties, TiO2 and NG are mixed with biodegradable chitosan and spin-coated on a silicon wafer. Film roughness and thickness are evaluated by atomic force microscopy (AFM). These films are then tested for ciprofloxacin photodegradation by irradiating with visible light. In comparison to the TiO2/chitosan films, the addition of NG substantially enhances photodegradation efficiency by up to 34 % upon the addition of 5 % w/w of NG. Furthermore, this film is shown to be a good substrate for biomarker detection using laser desorption ionization mass spectrometry (LDI-MS). In summary, this nanocomposite-biopolymer film provides good photocatalytic activity towards ciprofloxacin degradation and enhances the ionization efficiency of peptide biomarkers in LDI-MS owing to high efficiency of laser absorption/desorption. This nanocomposite film might be useful for environmental-related and medical application.

Organic Acid‐Assisted Preparation of Hydroxyapatite‐supported Ni Catalysts for Arene Hydrogenation

Developing non‐noble metal catalysts that can efficiently and selectively hydrogenate arenes remains a significant challenge. In this study, we developed efficient Ni catalysts for the arene hydrogenation based on an organic acid‐regulated impregnation strategy. These easily accessible Ni catalysts demonstrated exceptional efficiency, selectivity, reusability, and good substrate compatibility. The influence of carbon chain lengths and side‐chain hydroxyl or amino groups on dicarboxylic acids used in the catalyst preparation was comprehensively investigated. Characterizations and kinetic studies demonstrated the influence of organic acids on the size of Ni nanoparticles, the proportion of metallic nickel, and the strength of surface acidity. These factors influenced the activation of arene and hydrogen, thereby affecting the hydrogenative activity. Notably, hydroxyapatite‐supported Ni catalyst, assisted by tartaric acid (Ni‐TA/HAP) with an appropriate tartaric acid‐to‐nickel ratio, resulted in relatively smaller Ni nanoparticles, an increased proportion of Ni0, and more acidic sites, thereby exhibiting the best hydrogenation performance.

I2–DMSO‐Mediated Multicomponent [2+1+1+1] Annulation Reaction via Ethyl Nitroacetate C—NO2 Bond Cleavage as a C1 Synthon: A Route to Multisubstituted β‐Pyrrolidinones Derivatives with a Quaternary Center

Comprehensive SummaryA [2 + 1 + 1 + 1] cyclization reaction has been developed for the synthesis of multisubstituted β‐pyrrolidinones from commercially available aryl methyl ketones, primary amines, and ethyl nitroacetate. In this I2–DMSO‐meditated process, the C—NO2 bond of ethyl nitroacetate is cleaved, affording a C1 synthon, and the formation of two C—C and two C—N bonds and a quaternary carbon center are constructed in one pot. This method has good substrate compatibility and permits the late‐stage modification of pharmaceutical compounds.

A Mild and Metal Free Effective Route for the Synthesis of the Benzofuro[3,2‐c]quinoline Frame Work via Pictet‐Spengler Reaction

AbstractWe have reported an effective, metal free, one‐pot methodology for synthesising benzofuro[3,2‐c]quinolines via a Pictet‐Spengler reaction under mild conditions in open air. Our approach has a few advantages over the traditional two‐component synthesis as it is step and atom economic, environmentally benign and a convergent synthetic method. We have discussed here the good substrate scope of this novel methodology.

Ruthenium-Catalyzed Difunctionalization of Vinyl Cyclopropanes for Double m-C(sp2)-H/C-5(sp3)-H Functionalization.

With in-depth research on 1,2-difunctionalization, remote difunctionalization has garnered widespread attention for achieving multifunctionality. Herein, we report a strategy for achieving remote difunctionalization under mild conditions. This strategy exhibited good substrate suitability and functional group tolerance. In addition, the significance of this method is further evidenced by its successful application in scaling up and conducting additional transformations of target compounds. Mechanistic studies showed that a radical might be involved in this process.

Upper Subcell Impacts on Perovskite/u-CIGS Tandem Solar Cell Performance

In this paper, the two-terminal perovskite/u-CIGS tandem cells have been numerically performed and studied by using TCAD tools. The investigated planar perovskite model has been performed accordingly in order to match the fabricated structure and to be used as a top cell for tandem cells. The ultrathin CIGS solar cell has been also calibrated according to the fabricated model in order to be used as a good substrate (bottom cell) for the top cell (perovskite). These two cells have been simulated individually and they have revealed an efficiency of up to 20 % and 12.51 % for perovskite and u-CIGS models, respectively. The 2-terminal tandem model is then developed by comprising the top cell with the bottom cell by transparent contact that connects the two sub-cells in series electrically. The influence of changing the defect density in the perovskite film (absorber) and at ETL/absorber and absorber/HTL interfaces on tandem cell characteristics are analyzed. Moreover, we show that the power conversion efficiency of this investigated tandem model can reach over 30% by reducing defect densities and adjusting some sub-cell parameters that were already optimized in our previously published work. These approaches allow us to gain a better understanding of the physical dimensions and defect densities’ effect on the performance of the tandem devices.

Self-regulated secretory materials for long-term icephobicity

Passive icephobic coatings attract increasing attention due to their harmless strategy for preventing undesirable ice accumulation. Slippery liquid-infused surfaces display extremely low ice adhesion (τice) but are argued for their poor stabilities and longevities due to inevitable liquid consumption. Herein we reported a class of lubricated polysiloxane coatings that can maintain low τice (∼2.2 kPa) for a long time (>800 icing/deicing cycle). The coatings have slippery lubricated surfaces and switchable porous matrices loading a large amount of liquid in isolated porevoids. Such droplet-embedded structure allows the surfaces to continuously maintain highly swelling states in a self-adaptive manner, i.e., only in the conditions icing or oil consumption occur dose oil is released, and thus show excellent long-term icephobicity. Besides, these materials exhibit good mechanical properties, antifatigue, and substrate adhesion. Because the coatings can be prepared via facile and green method from cheap starting materials, we foresee their broad application prospect in many fields.

Fabrication of the Ag/silk fibers for electrically conductive textiles

As a good substrate, silk fibers are widely employed in the field of intelligent textiles. In this work, the surface of silk fibers were firstly roughened by formic acid and sensitized by tannic acid, and then the silver ammonia solution was reduced by glucose to synthesize nano-silver in situ on the silk surface to obtain composite conductive silk fibers with resistivity as low as 0.24 mΩ·cm. It was proved by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) tests that a uniformly deposited nano-silver layer was fabricated on the silk surface. The prepared silk fibers had stable mechanical, thermal, electrical, and antibacterial properties and can be used for human sensing.

Palladium Catalyzed Carbonyl Amination of Fluorinated Olefins for Synthesis of α‐CF3‐Acrylamides

AbstractAcrylamides are a class of important organic compounds that play key roles in biomedical chemistry, materials science, life science, and other fields. Due to the strong electron‐withdrawing effect of trifluoromethyl, the synthesis of trifluoromethylated acrylamides, especially those containing double bonds, has long been a challenge. Here, we report an example of the formation of trifluoromethyl acrylamides through palladium catalyzedcarbonylation of fluorinated olefins. By optimizing the reaction conditions, we can obtain different amide compounds, including alkyl acrylamides. aromatic acrylamides and heterocyclic acrylamides. This method has good substrate adaptability and functional group tolerance,so it is expected to be used in the synthesis of key amides in the fields of medicine and other fields.

Perspective of probiotic bacteria in the production of soy-based fermented products

Relevance. It is worth noting that consumers’ awareness of the environmental burden that milk production carries continues to grow. Consumers are looking for alternatives that are more environmentally friendly and have high nutritional value. The demand for plant-based products is increasing for various reasons, namely, 65% of the world’s population has a reduced ability to digest lactose and 6% of the population is allergic to milk protein. According to statistics, 49% of women and 36.6% of men experience symptoms of functional gastrointestinal disorders. Soybeans are one of the most widely grown and consumed legumes worldwide. Thus, the development of new plant-based fermented products is a particularly actual issue.Methods. The objects of study were soybean dispersion and microorganisms Lactobacillus, Bifidobacterium and Propionibacterium. The quality indicators of the resulting soy dispersion were determined. The process of acid accumulation during fermentation with probiotic microorganisms were studied. Data on the accumulation of bacterial biomass during the fermentation process were obtained and the effect of the use of selected starter microorganisms on the change in the antioxidant status of fermented dispersions during storage were investigated.Results. Research results showed that soybean dispersion is a good substrate to produce fermented beverages using Lactobacillus, Bifidobacterium and Propionibacterium microorganisms. The most rapid process occurs when L. bulgaricus and P. schermanii KM-186 are used and the fermentation lasted for 6 hours. All selected strains adapt well to the plant-based media, but the greatest increase in biomass occurs during fermentation with L. bulgaricus, B. longum B379M and B. bifidum. Lactic acid and propionic acid bacteria provide high and stable levels of antioxidant activity on both the 1st and 6th and 12th days of storage.

C(sp2)‐H Imination of Imidazo[1,2‐a]pyridines: A Catalyst‐Free, Multicomponent Approach

AbstractWe report here a catalyst‐free, (sp2)C−H imination reaction of in‐situ formed imidazo[1,2‐a]pyridines and α‐iminoketones. This one‐pot, multicomponent, and atom economic reaction is performed at moderate to room temperature without the need for any catalyst and inert conditions. The reaction showed good substrate tolerance with appreciable yields. Gram‐scale synthesis and post‐synthetic modifications to obtain 1,2‐diketones are also described.

More than a colour; how pigment influences colourblind microbes.

Many animals have pigments when they themselves cannot see colour. Perhaps those pigments enable the animal to avoid predators, or to attract mates. Maybe even those pigmented surfaces are hosts for microbes, even when the microbes do not see colour. Do some pigments then serve as a chemical signal for a good or bad microbial substrate? Maybe pigments attract or repel various microbe types? Echinoderms serve as an important model to test the mechanisms of pigment-based microbial interactions. Echinoderms are marine benthic organisms, ranging from intertidal habitats to depths of thousands of metres and are exposed to large varieties of microbes. They are also highly pigmented, with a diverse variety of colours between and even within species. Here we focus on one type of pigment (naphthoquinones) made by polyketide synthase, modified by flavin-dependent monoxygenases, and on one type of function, microbial interaction. Recent successes in targeted gene inactivation by CRISPR/Cas9 in sea urchins supports the contention that colour is more than it seems. Here we dissect the players, and their interactions to better understand how such host factors influence a microbial colonization. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.

Acceptorless ambient-temperature dehydrogenation and reversible hydrogenation of N-heterocycles over single-atom Co-N-C catalysts

Reversible hydrogen storage via Liquid organic hydrogen carriers (LOHCs) is one of the key technologies for efficient utilization of hydrogen energy. How to construct efficient dehydrogenation/hydrogenation catalysts that enable low-temperature catalysis still remains challenging. Herein, we present the design and construction of single-atom Co-N-C(x) catalysts allowing significantly improved acceptorless dehydrogenation of 1,2,3,4-tetrahydroquinoline (THQ). By varying the ligand/Co ratio, the optimal Co-N-C(1.5) can achieve 97.5% dehydrogenated product and 0.82 h−1 TOF value at ambient temperature, overperforming many reported non-noble metal even noble metal catalysts. This catalyst exhibits good recyclability and substrate versatility, enabling ambient temperature dehydrogenation of various N-heterocycles and efficient reverse hydrogenation of aromatic N-heterocycles, thus achieving the loop of reversible hydrogen storage. The active catalyst centers consist of specific Co-Nx moieties and nitrogen species within the carbon support. Controlled experiments reveal that the different performance of Co-N-C(x) is determined by density of the Co-Nx, and the rate-determining step of THQ dehydrogenation is correlated with the bond cleavages in surface-bound THQ. This work offers a promising pathway for energy-efficient and cost-effective hydrogen energy utilization under practical conditions.

Catalytic Light-Driven Strategy for Transforming Oximes to Carbonyls.

Oxime and carbonyl functional groups serve as powerful chemical hubs for constructing complex synthetic targets and valuable molecular scaffolds. In furthering this value, we report a photopromoted catalytic deoximation protocol for converting oximes and their derivatives to carbonyl functional groups. This strategic approach benefits from the use of renewable light energy input and ambient air conditions, in addition to demonstrating good substrate scope, functional group tolerance, and product yields. In offering, insights into these reactivity mechanistic studies are communicated, and the value of this protocol is further shown through one-pot operations.

Supercapacitor Electrodes: Is Nickel Foam the Right Substrate for Active Materials?

Ni foam is an extensively used current collector and substrate in investigations of electrochemically active materials such as supercapacitors and electrocatalysts for oxygen and hydrogen evolution reactions. This material is relatively cheap, porous, and conductive and has a large specific surface area, all of which make it a good substrate. We investigated Ni-Mg ferrites and NiMn2O4 as active materials for electrochemical energy storage. These materials, when loaded on Ni foam, gave promising capacitance values: 172 F/g (at 2 mV/s) for NiMn2O4 in 6 M KOH and 242 F/g (at 2 mV/s) for MgFe2O4 in 3 M KOH. Nevertheless, during the authors' work, many experimental problems occurred. Inconsistencies in the results directed further investigation towards measuring the capacitance of the active materials using GCE and platinum electrodes as substrates to discover if Ni foam was the culprit of the inconsistencies. When non-nickel substrates were used, both NiMn2O4 and MgFe2O4 showed reduced capacitance. Experimental problems associated with the utilization of Ni foam as a substrate for active materials in supercapacitor electrodes are discussed here, combined with other problems already addressed in the scientific literature.

Effective Synthesis of N-Alkyl-3-(Indol-3-yl)Pyrazoles from Ag2CO3-Catalyzed Regioselective Aza-Michael Addition of 5-(Indol-3-yl)-1HPyrazoles

Abstract: In this study, the synthesis of N-alkyl-3-(indol-3-yl)pyrazoles was carried out from Ag2CO3 catalyzed regioselective aza-Michael addition of 5-(indol-3-yl)-1H-pyrazoles to a, bunsaturated carbonyl compounds. In the presence of 10 mol% of Ag2CO3, the reaction smoothly occurred in dichloroethane (DCE) at 120oC to preferentially afford a series of N-alkyl-3-(indol-3- yl)pyrazoles in high yields with good regioselectivity. It was found that 1-methyl-3-(3-methyl-1Hpyrazol- 5-yl)-2-phenyl-1H-indole, 1-benzyl-3-(3-methyl-1H-pyrazol-5-yl)-1H-indole, a, b-unsaturated ketone, and a, b-unsaturated amide exclusively gave 3-(pyrazol-3-yl)indoles in good yields. This reaction features high regioselectivity, mild reaction conditions, good substrate scope and yields, and a commercially available catalyst. Meanwhile, the reaction was also proven to be quite practical by the gram-scale synthesis of N-alkyl-3-(indol-3-yl)pyrazoles in excellent yields with good regioselectivity.

Fabrication of polydopamine functionalized AgNF SERS substrate: Applications for sensitive detection of nivalenol in food samples and cell biocompatibility

Surface-enhanced Raman spectroscopy (SERS) is a robust analytical tool applicable for the quick and accurate determination of mycotoxins. However, there hasn't been any attempt to use SERS for the quantitative detection of nivalenol (NIV) thus far. To improve the Raman signals of NIV, we fabricated a polydopamine-coated silver nanoflower (PDA-AgNFs) SERS substrate with strong “hot-spots”. The PDA-AgNFs substrates showed superior SERS enhancement activities in the target analyte detection and quantification. It produced good substrate uniformity (relative standard deviation of SERS signals, RSD = 4.1% for substrate-to-substrate test, and 3.24% for spot-to-spot test), an enhancement factor of 2.87 × 106 towards rhodamine 6B (R6G), and detection sensitivity as low as 1 femtomolar (10−15 M) against R6G probe molecule. Moreover, the PDA-AgNFs SERS substrates were successfully used, for the first time, to detect NIV in corn, horse beans, and mushroom samples. The calibration curve showed a satisfactory linear fit based on the SERS intensities of different NIV concentrations. The detection limit (LOD) for the suggested approach was 0.22 nM (S/N = 3). Interestingly, the MTT assay experiment demonstrated that PDA-AgNFs had no toxicity against mammalian NIH-3T3 cells. The biocompatible PDA-AgNFs substrates with intense plasmonic effects and binding sites demonstrated impressive Raman enhancement, and could serve as an effective, label-free, and fast SERS-based analysis of NIV in real samples.

The Role of Reactive Natural Deep Eutectic Solvents in Sustainable Biocatalysis

AbstractDeep eutectic solvents (DESs) advanced in the past decade as the new generation of green and sustainable extraction and reaction media in biorefineries and in a multitude of chemical and biotechnological processes. Particularly, enzyme catalyzed reactions benefit from the specific properties of DESs, which not only ensure good substrate solubility but also enhance enzyme stability and operational efficiency. Recent studies showed that natural deep eutectic solvents (NADESs) comprising choline chloride or betaine as hydrogen bond acceptor and a large spectrum of natural compounds, such as carbohydrates, polyols carboxylic acids, as hydrogen bond donors, can have multiple functions, acting simultaneously as extraction solvent, reaction medium, source of substrate and source as catalyst. This novel approach for the utilization of multifunctional reactive natural deep eutectic solvents (R‐NADESs) in catalytic conversions opens the way to the development of greener biocatalytic and chemo‐catalytic processes, with simpler downstream processing and minimal discarded wastes, which will speed up their durable implementation in industry. This paper reviews the innovative applications of R‐NADESs in biocatalytic reactions for the synthesis of a large diversity of high value chemicals and materials, including biosurfactants, flavors, biobased building blocks and biobased polymers, with highlight on esterification, transesterification, glycerolysis, polymerization, and redox reactions.