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The developed Pt/MgO@C with ultralow Pt loading (0.078 wt%) exhibited superior catalytic performance for synthesizing 2,1-benzisoxazole derivatives by a reductive heterocyclization route under very mild conditions (1 bar hydrogen pressure at 303 K).

Pd@HfO2 derived via two-step pyrolysis of Pd@NH2-UiO-66(Hf) exhibited high catalytic activity for the Suzuki–Miyaura coupling reactions.

The preferential capture of ethane (C2H6) over ethylene (C2H4) presents a very cost-effective and energy-saving means applied to adsorptive separation and purification of C2H4 with a high product purity, which is however challenged by low selectivity originating from their similar molecular sizes and physical properties. Substituent engineering has been widely employed for selectivity regulation and improvement, but its effect on C2H6/C2H4 separation has been rarely explored to date. In this work, four isoreticular coordination framework compounds based on 5-(pyridin-3-yl)isophthalate ligands bearing different substituents were rationally constructed. As revealed by isotherm measurements, thermodynamic studies, and IAST computations, they exhibited promising utility for C2H6/C2H4 separation with moderate adsorption heat and a high uptake amount at a relatively low-pressure domain. Furthermore, the C2H6/C2H4 separation potential can be finely tuned and optimized via purposeful substituent alteration. Most remarkably, functionalization with a nonpolar methyl group yielded an improved separation efficiency compared to its parent compound. This work offers a good reference value for enhancing the C2H6/C2H4 separation efficiency of MOFs by engineering the pore microenvironment and dimensions via substituent manipulation.

Background Perivascular epithelioid cell tumor (PEComa) is an uncommon tumor of mesenchymal origin. Cases of PEComa in the liver are extremely rare. Aim To analyze the clinicopathological features and treatment of hepatic PEComa and to evaluate the prognosis after different treatments. Methods Clinical and pathological data of 26 patients with hepatic PEComa were collected. All cases were analyzed by immunohistochemistry and clinical follow-up. Results This study included 17 females and 9 males, with a median age of 50 years. Lesions were located in the left hepatic lobe in 13 cases, in the right lobe in 11, and in the caudate lobe in 2. The median tumor diameter was 6.5 cm. Light microscopy revealed that the tumor cells were mainly composed of epithelioid cells. The cytoplasm contained heterogeneous eosinophilic granules. There were thick-walled blood vessels, around which tumor cells were radially arranged. Immunohistochemical analysis of pigment-derived and myogenic markers in PEComas revealed that 25 cases were HMB45 (+), 23 were Melan-A (+), and 22 SMA (+). TFE3 and Desmin were negative in all cases. All the fluorescence in situ hybridization samples were negative for TFE3 gene break-apart probe. Tumor tissues were collected by extended hepatic lobe resection or simple hepatic tumor resection as the main treatments. Median follow-up was 62.5 mo. None of the patients had metastasis or recurrence, and there were no deaths due to the disease. Conclusion Hepatic PEComa highly expresses melanin and smooth muscle markers, and generally exhibits an inert biological behavior. The prognosis after extended hepatic lobe resection and simple hepatic tumor resection is semblable.

Eleucanainones A and B are two structurally complex naphthoquinone-derived dimers whose structure identification is difficult. Large yellow fragments of the preliminary CASE (computer-assisted structure elucidation) analysis revealed that the original structures might be questionable. Structural revisions of the two compounds were proposed on the basis of NMR analysis, CASE methods, conformation analysis, and DFT (density functional theory) NMR calculations with a custom DP4+ analysis. In addition, a polyketide-folded biosynthetic pathway of the two revised structures was proposed.

The design of all-solid heterogeneous catalysts with frustrated Lewis pairs (FLPs) has attracted much attention recently because of their appealing low dissociation energy for H

S-scheme heterojunctions hold great potential for CO

This paper presents a design of a compact tri-band bandpass filter simply using a pair of the uniform impedance resonator loaded with an open-circuited stub. By introducing the variable impedance o...

Catalytic transfer hydrogenation (CTH) of α,β-unsaturated aldehydes using single metal atom catalysts supported on nitrogen-incorporated graphene sheet (M-N

Photocatalytic CO

Single-atom catalysts effectively integrate the respective advantages of homogeneous and heterogeneous catalysts and are a pioneering research frontier in catalysis by virtue of their maximized utility of metal atoms and distinct atomic configuration. However, development of such catalysts is still in the early stages. Herein, atomically dispersed vanadium (V) sites that are coordinated by N atoms and inlaid within N-incorporated porous carbon networks were prepared through a top-down strategy by annealing a V-containing metal-organic framework, NH2-MIL-101(V), followed by acid etching. The resulting V-N-C-600 catalyst exhibits unexpected catalytic reactivity, selectivity, and robust stability for the direct aerobic oxidation of benzylamine to generate N-benzylidene benzylamine with molecular oxygen under mild conditions. The turnover frequency reaches 53.9 h-1, which is much superior to those achieved over the commercial V2O5 and state-of-the-art non-noble metal heterogeneous catalysts reported in the literature. Kinetic analysis reveals a low activation energy barrier (37 kJ mol-1) for the benzylamine oxidation and indicates that a carbocationic intermediate is involved in the reaction mechanism. The synergistic effect between the isolated V single-atomic sites and N-doped hierarchically porous carbon network boosts the performance of V-N-C-600. Moreover, V-N-C-600 exhibits a wide generality for the efficient synthesis of a set of symmetrical imines, unsymmetrical imines, and imine derivatives.

Developing suitable catalysts capable of receiving injected electrons and possessing active sites for hydrogen evolution reaction (HER) is the key to building an efficient dye-sensitized system for hydrogen production. Fe3S4 is generally regarded as an inferior HER catalyst among the metal sulfide family, mainly due to its weak surface adsorption toward H atoms. In this work, we demonstrate a facile metal-organic framework-derived method to synthesize uniform Fe3S4 nanorods and active them for HER by Ni doping. Our experimental results and theoretical calculations reveal that Ni doping can greatly modify the electronic structure of Fe3S4 nanorods, improving their electron conductivity and optimizing their surface adsorption energy toward H atoms. Sensitized by a commercial organic dye (eosin-Y), 1%Ni-doped Fe3S4 nanorods display a high H2 production rate of 3240 μmol gcat-1 h-1 with an apparent quantum yield of 12% under 500 nm wavelength, which is significantly higher than that of pristine Fe3S4 and even higher than that of 1% Pt-deposited Fe3S4. The working mechanism of this dye-sensitized system is explored, and the effect of Ni-doping concentration has been studied. This work presents a facile strategy to synthesize metal-doped sulfide nanocatalysts with greatly enhanced activity toward photocatalytic H2 production.

The development of a low-cost and efficient transition-metal-based heterogeneous catalyst for catalytic hydrogenation reactions is urgently desired, and yet great challenges remain. Herein, isolate...

Improving the reaction selectivity and activity for challenging substrates such as nitroaromatics bearing two reducible functional groups is important in industry, yet remains a great challenge using traditional metal nanoparticle based catalysts. In this study, single metal atom doped M-C2N catalysts were theoretically screened for selective hydrogenation of 3-nitrostyrene to 3-vinylaniline with H2 as the H-source. Among 20 M-C2N catalysts, the non-noble Mn-C2N catalyst was found to have excellent reaction selectivity. Importantly, due to the solid frustrated Lewis pair sites in the pores of Mn-C2N, a low H2 activation energy is achieved on high-spin Mn-C2N and the rate-determining step for the hydrogenation reactions is the H diffusion from the metal site to the N site. The unraveled mechanism of the hydrogenation of 3-nitrostyrene using Mn-C2N enriches the applications of Mn based catalysts and demonstrates its excellent properties for catalyzing the challenging hydrogenation reaction of substrates with two reducible functional groups.

This work delineates the first attempt to tune the product distribution between methanol and ethanol in the direct oxidation of methane reaction by incorporating Lewis acids Ni2+, Co2+/3+ or Zn2+ into IrO2/CuO. The electrophilicity of Ir4+ and the (LAS–BAS)/LAS ratio (LAS: Lewis acid sites, BAS: Bronsted acid sites) are demonstrated to be two reactivity descriptors motivating CH4 activation and ethanol formation, respectively. Electron-deficient Ir4+ motivates enriched *CH3 concentration and subsequent C–C coupling for C2H4 formation, while the Lewis acid promotes ethanol formation from C2H4 involving lattice O and H2O. The ethanol selectivity presents a quasi-linear relationship with (LAS–BAS)/LAS.

Separation and purification of C2H4 produced by thermal decomposition of C2H6 involve the elimination of C2H2 impurities and unconverted C2H6 from C2H4, which is of great practical importance but a great challenge in the petrochemical industry. Herein, a new MOF [Cu4L3Cl]Cl·2.7DMF (H2L = 5-(pyrimidine-5-yl)isophthalic acid, DMF = N,N-dimethylformamide) based on a heterotopic N,O-donor ligand was solvothermally constructed, featuring saturated metal centers as well as inorganic chloride ions immobilized in the aromatic cage surface that offers a favourable pore environment for binding C2H2 and C2H6 in preference to C2H4. Pure component isotherm measurements and IAST selectivity calculations revealed that the resultant MOF solid displayed the potential for the separation and purification of C2H4 by simultaneously trapping C2H2 and C2H6 from C2H4 under ambient conditions. Furthermore, the mechanism on preferential adsorption of C2H2 and C2H6 over C2H4 was comprehensively investigated by DFT theoretical calculations, revealing the crucial role of the electronegative chloride ion and aromatic π-electron surface.

Transition-metal cluster-encapsulated UiO-66 composites have attracted great interest because of their excellent properties in catalysis, yet it is still a great challenge to explore the structures...

It is well-known that functional groups should greatly affect the electronic properties of the metal cluster-encapsulated metal–organic frameworks and thus change their catalytic properties; howeve...

Utilizing sunlight to convert CO

The hierarchically structured flower-like CaF2 microspheres with nanopetals, named FL-CaF2, were synthesized via a hydrothermal method using calcium acetate Ca(Ac)2 and NaBF4 as calcium and fluorine sources, respectively, assisted by the chelating reagent trisodium citrate (Na3Cit) with the optimal pH of the synthesis solution. Meanwhile, a reference sample, named FL-CaF2-R, was reproduced using ethylenediaminetetraacetic acid disodium salt (Na2EDTA) as the chelating reagent, based on the recipe and synthesis procedure from the literature. Various techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform-infrared spectroscopy, and N2 adsorption-desorption at 77 K were then used to characterize the synthesized samples. The results show that FL-CaF2 with a larger diameter has a much higher thermal stability than FL-CaF2-R because the larger the nanocrystallite size, the higher the thermal stability. The adsorption of water vapor on CaF2 is irreversible because CaF2 can interact with the adsorbed water molecules strongly. The dual-site Langmuir model was used to describe the measured adsorption isotherms of water vapor on FL-CaF2 at low water vapor pressures and 298, 308, and 318 K. FL-CaF2 has a much higher water-adsorption capacity than those reported in the literature. Furthermore, the isosteric heat of adsorption as a function of loading, derived from the measured isotherms, varies from ca. 46 to 43 kJ mol-1 in the whole loading range investigated. Finally, the applications of FL-CaF2 are anticipated in the dehydration of hydrogen fluoride gas as well as in catalysis.

Various computational methods were employed to investigate the zwitterion formation, a critical step for the reaction of monoethanolamine with CO2, in five solvents (water, monoethanolamine, propylamine, methanol and chloroform) to probe the effect of hydrogen bond capacity of solvents on the reaction of amine with CO2 occurring in the amine-based CO2 capture process. The results indicate that the zwitterion can be formed in all considered solvents except chloroform. For two pairs of solvents (methanol and monoethanolamine, propylamine and chloroform) with similar dielectric constant but different hydrogen bond capacity, the solvents with higher hydrogen bond capacity (monoethanolamine and propylamine) facilitate the zwitterion formation. More importantly, kinetics parameters such as activation free energy for the zwitterion formation are more relevant to the hydrogen bond capacity than to dielectric constant of the considered solvents, clarifying the hydrogen bond capacity could be more important than dielectric constant in determining the kinetics of monoethanolamine with CO2.

Two naphthoquinone-derived heterodimers with unprecedented carbon skeletons, eleucanainones A (1) and B (2), were isolated from the bulbs of Eleutherine americana. Their structures were elucidated ...

The adsorption and dissociation of H2O molecule on various surfaces of MgF2 and CaF2 have been investigated theoretically by using a dispersion-corrected density functional theory based method. The...

The development of porous metal–organic framework (MOF) solids displaying efficient separation and purification of acetylene is of cardinal significance but challenging in the chemical industry. Am...

The selective capture of C2H2 from C2H2-C2H4 and C2H2-CO2-CH4 mixtures is a very essential but highly challenging process during C2H4 and C2H2 purification in the chemical industry. In this work, by virtue of using oxygen-atom-rich C2H2 recognition sites, we, for the first time, designed and synthesized an N-oxide-functionalized tricarboxylate ligand and utilized it to successfully construct a copper-based MOF. N-Oxide functionalization exerted a significant effect on the ligand conformation, thus resulting in a new topological network that is different from that of the unoxidized parent compound. With a moderate surface area and the immobilization of N-oxide functionality and carboxylate oxygen atoms in two nanocages, the title MOF exhibited promising potential for the multifunctional separation of C2H2/C2H4 and C2H2/CO2/CH4 mixtures under ambient conditions, as shown by pure-composition isotherm measurements, IAST predictions, and molecular modeling studies.

This paper presents a miniaturized bandpass filter, which uses half mode substrate integrated waveguide (HMSIW) structure with embedded step impedance structure (SIS). By embedding the stepped impedance structure into the top metal of the waveguide cavity, the center frequency can be quickly shifted to a lower frequency. The operating center frequency of the proposed bandpass filter (BPF) using HMSIW resonators with embedded SIS is tunable as functions of the parameters of the SIS. The design curve is provided. A filter example of the center frequency of the filter at 3.5 GHz is fabricated and measured, having the insertion loss |S21| less than 3 dB, and the return loss |S11| greater than 10 dB. The transmission zeros are located at 2.95 GHz and 3.95 GHz on both sides of the passband, both of which are lower than 30 dB. The simulation result and the measured response conform to the proposed design concept. The proposed HMSIW filter design is in line with the current 5G communication trend.