Oxidative dehydrogenation of propane over supported nickel single‐atom catalyst

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Comprehensive Summary

Oxidative dehydrogenation of propane has been an ever-growing field for propylene production due to its exothermic properties, of which overoxidation is the major drawback, with CO and even CO2 as undesired by-products. For the purpose of getting higher propylene selectivity as well as yield, herein we report Ni single atoms supported on calcium aluminate as an efficient catalyst candidate for propane oxidative dehydrogenation. Beneficial from higher valence states of Ni1 species, it shows 2~3 times as much propylene selectivity as that of Ni nanoparticles. About 14.2 % C3H6 yield with 47.3 % propylene selectivity have been achieved on the 2% Ni single atom catalyst and a good stability during 20 h test can be obtained as well.

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Pincer Ligands as Multifunctional Agents for Alzheimer’s Copper Dysregulation and Oxidative Stress: A Computational Evaluation

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Alzheimer’s disease (AD) is the most common form of dementia worldwide, affecting millions of people around the globe. AD is characterized by different pathologies being beta-amyloid (Aβ) plaque formation, metal ion dysregulation, and oxidative stress central topics under investigation. Copper-Aβ complexes have been shown to induce catalytic hydrogen peroxide formation and increase OS in the brain leading to neuronal death. Pincer-type compounds are tridentate ligands that coordinate metals in a planar fashion whose properties can be tuned via group substitutions, giving rise to many possibilities in catalysis and drug discovery. In this work we evaluated the potential pharmaceutical activity of 26 pincer compounds in AD’s copper ion-related oxidative stress framework. In this sense, four key aspects were considered: 1) Lipinski’s rule of five, 2) blood-brain barrier permeation, 3) standard reduction potential (SRP) of the formed copper complexes, and 4) the ligand’s affinity towards copper cations. The evaluation of these criteria was performed by means of bioinformatic tools and electronic structure calculations at the DFT level of theory. Our results suggest that two compounds from this set are potential antioxidant agents, whereas five of them are promissory distributor-like compounds in the context of AD.

Sirtuins and autophagy in lipid metabolism

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Abstract

Sirtuins are a family of NAD+-dependent deacetylases that regulate some important biological processes, including lipid metabolism and autophagy, through their deacetylase function. Autophagy is a new discovery in the field of lipid metabolism, which may provide a new idea for the regulation of lipid metabolism. There are many tandem parts in the regulation process of lipid metabolism and autophagy of sirtuins protein family. This paper summarized these tandem parts and proposed the possibility of sirtuins regulating lipid autophagy, as well as the interaction and synergy between sirtuins protein family. Currently, some natural drugs have been reported to affect metabolism by regulating sirtuins, some of which regulate autophagy by targeting sirtuins.

Facile construction of alloy‐metal oxide interfaces boosting the one‐pot conversion of methyl levulinate to 1,4‐pentanediol

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In this work, a series of N-doped carbon supported FeCo bimetallic catalysts with plentiful FeCo alloy-FeO interfaces, which are derived from metal-organic frameworks (MOFs) ZIF-67, are designed for the one-pot direct conversion of methyl levulinate to 1,4-pentanediol. The FeCo alloy-FeO interfaces are precisely controlled via tuning the reduction temperatures and Fe/Co ratios. The optimal catalyst gives a high 1,4-pentanediol yield of 90.5% along with complete conversion of methyl levulinate. These catalysts are carefully characterized by multiple techniques, such as HRTEM, XRD, XPS, NH3-TPD, Py-IR and so on. It is found that Co presents in electron deficiency caused by the electron transference from Co to Fe in FeCo alloy, which in turn enhances the heterolysis of H2. In addition, plentiful Lewis acid sites derived from interfacial FeO species favour the re-adsorption and the ring-opening reaction of GVL. With the synergy between FeCo alloy and Lewis acid, the FeCo alloy-FeO interfaces exhibit excellent catalytic activity for selective hydrogenation of methyl levulinate to 1,4-pentanediol.

A Pair of Undescribed Alkaloid Enantiomers from Marine Sponge‐Derived Fungus Hamigera avellanea and Their Antimicrobial and Cytotoxic Activities

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From marine sponge-associated fungus Hamigera avellanea, thirteen secondary metabolies including a pair of undescribed alkaloid enantiomers (+)-hamiavemin A (4S) (+)-1 and (-)-hamiavemin A (4R) (-)-1. Compound 1 was enantiomers resolved by the Chiralpak AS-3 column, using a n-hexane/isopropanol mobile phase. Their structures were determined based on extensive analyses of HR-ESI-MS, 1D and 2D NMR spectra. The absolute configuration of (+)-1 and (-)-1 were assigned tentatively by ECD calculations. Among the isolates, compound 6 showed strongest antibacterial activity against Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus,  Escherichia coli, Salmonella enterica, and Candida albicans with the MIC values of 2, 2, 16, 32, 64, and 16 μg/mL, respectively, which were stronger than that of the positive control compound, kanamycin (MIC values ranging from 4 to 128 μg/mL). In addition, compounds 1, 2, and 9 showed moderate cytotoxic activity against three cancer cell lines, HepG2, A549, and MCF-7 with the IC50 values ranging from 55.35±1.70 to 83.02±2.85 mg/mL

Cross‐Electrophile Coupling between Two Different Tosylates Enabled by Nickel/Palladium Cooperative Catalysis

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Cross-Electrophile Coupling between Two Different Tosylates Enabled by Nickel/Palladium Cooperative Catalysis

A cross-electrophile coupling reaction of gem-difluoroalkenyl tosylate with α-CF3 benzyl tosylate is presented. This protocol is the first example of cross-electrophile coupling between two different tosylates by Pd/Ni cooperative catalysis.


Abstract

Cross-electrophile coupling reactions are efficient for the construction of carbon-carbon bonds under relatively mild conditions, and hence widely used for making new molecules. Among various electrophiles, the cross-electrophile coupling reaction between two different tosylates has been rarely studied. Herein, we present a cross-electrophile coupling of gem-difluoroalkenyl tosylate (C(sp2)−OTs) and α-CF3 benzyl tosylate (C(sp3)−OTs) by nickel/palladium cooperative catalysis. Mechanistic investigation indicated that the activation of C(sp2)−OTs bond and C(sp3)−OTs bond was facilitated by nickel and palladium respectively.

B−N Co‐Doped Biphenylene as a Metal‐Free Cathode Catalyst for Li−O2 Batteries: a Computational Study

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B−N Co-Doped Biphenylene as a Metal-Free Cathode Catalyst for Li−O2 Batteries: a Computational Study

B−N co-doped biphenylene is proposed as a promising metal-free cathode catalyst for Li−O2 batteries, based on density functional theory calculations. Specially, the modeling results reveal that strengthening the Li−O bond reduces the overpotential during the discharge process, and that a moderate adsorption energy of *Li2O2 facilitates the charge process.


Abstract

Lithium-oxygen batteries (LOBs) meet the growing demand for long-distance transportation over electric vehicles but face challenges because of the lack of high-performance cathode catalysts. Herein, using density functional theory calculations, we report a unique graphene allotrope, biphenylene, of which the doping structures exhibit great potential as metal-free catalysts for LOBs. Our modeling results demonstrate that the biphenylene nanosheets retain metallic properties after B doping, N doping, or B−N co-doping. Compared with the pristine biphenylene, the catalytic activity of the doped biphenylene is greatly improved due to charge redistributions. Notably, the overpotentials of the B−N co-doped biphenylene are as low as 0.19 and 0.18 V for the discharge and charge processes, respectively. Based on the electronic structure and bonding analysis, we identify two factors, i. e., Li−O bond strength and *Li2O2 adsorption energy, that can influence the Li−O2 electrochemical reactions. This study not only proposes a promising cathode catalyst but also provides insights into optimizing cathode catalysts for LOBs.

Palladium‐Catalyzed Enantioselective Hydrofunctionalization of Alkenes: Recent Advances

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Palladium-Catalyzed Enantioselective Hydrofunctionalization of Alkenes: Recent Advances

Asymmetric hydrofunctionalization of alkenes represents a powerful method to obtain valuable enantioenriched molecules from cheap and readily available materials. In this review, the recent advances in Palladium catalyzed asymmetric hydrofunctionalization of alkenes covering mainly contributions over the past decade are summarized. The remained challenges and opportunities in this field are also discussed.


Abstract

Palladium-catalyzed asymmetric hydrofunctionalization of alkenes is one of the most powerful and straightforward methods to forge a new C−H bond and a new C−X (X=C, N, O, F, Si etc) bond, which provides an efficient way to obtain valuable enantioenriched molecules from cheap and readily available feedstocks. Catalytic asymmetric hydrofunctionalization of simple alkenes is challenging but still highly sought after. This review will mainly focus on the recent advances in Palladium catalyzed asymmetric hydrofunctionalization of alkenes over the past decade, including hydroamination, hydrooxygenation, hydrofluorination, hydrosilylation, hydroarylation, hydroalkenylation and hydrocarbonylation.

Radical Dearomatising Spirocyclisation of Benzisoxazole‐Tethered Ynones

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Radical Dearomatising Spirocyclisation of Benzisoxazole-Tethered Ynones

The synthesis of densely functionalised spirocyclic products through a radical dearomative spirocyclisation chain mechanism is described. The spirocyclic products were converted into other spirocyclic scaffolds through a two-step ring expansion sequence.


Abstract

The dearomative spirocyclisation of benzisoxazoles through a radical chain mechanism is described. Densely functionalised spirocycles were prepared in high yields by reacting benzisoxazole-tethered ynones with aryl thiols in 1,2-dichloroethane (DCE) at 60 °C. The identification of stabilising three-electron interactions was key to the development of this new radical cascade reaction. The obtained spirocyclic products were converted into other spirocyclic scaffolds through a two-step hydrogenolysis-cyclisation sequence.

Structural and Chemical Properties of NiOx Thin Films: Oxygen Vacancy Formation in O2 Atmosphere

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Structural and Chemical Properties of NiOx Thin Films: Oxygen Vacancy Formation in O2 Atmosphere

The formation and properties of oxygen vacancies on thin NiOx films were investigated in situ at elevated temperatures and high oxygen pressures. Due to charge redistribution and altered bond lengths of the atoms surrounding the oxygen vacancies, they appear as distinct spectral features in O1s and O K-edge spectra, clearly distinguishable from all other peaks.


Abstract

NiOx films on Si(111) were put in contact with oxygen at elevated temperatures. During heating and cooling in oxygen atmosphere Near Ambient Pressure (NAP)-XPS and -XAS and work function (WF) measurements reveal the creation and replenishing of oxygen vacancies in dependence of temperature. Oxygen vacancies manifest themselves as a distinct O1s feature at 528.9 eV on the low binding energy side of the main NiO peak as well as by a distinct deviation of the Ni2p3/2 spectral features from the typical NiO spectra. DFT calculations reveal that the presence of oxygen vacancies leads to a charge redistribution and altered bond lengths of the atoms surrounding the vacancies causing the observed spectral changes. Furthermore, we observed that a broadening of the lowest energy peak in the O K-edge spectra can be attributed to oxygen vacancies. In the presence of oxygen vacancies, the WF is lowered by 0.1 eV.