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Atomically dispersed single-atom catalysts (SACs) have been extensively studied over the past decade because of their high atom utilization efficiencies and specific selectivities. Although numerous strategies have been proposed to obtain SACs with high densities and stabilities, the transformation mechanism that occurs during the reaction is still unclear. This review summarizes the structural evolution of SACs in the preparation process and reaction with various electron microscopy techniques at atomic scale under environmental conditions. Current state-of-the-art environmental electron microscopy studies on SACs mainly focus on porous carbons, metals or metal oxides, and some specific composite materials. The dynamic evolution of SACs under various reaction conditions is also investigated in this study. Finally, we highlight the challenges and drawbacks of the current studies and the prospects for the future exploration of SACs with environmental strategies. [ABSTRACT FROM AUTHOR]

Chemical cross-linking mass spectrometry (CXMS) is being increasingly used to study protein assemblies and complex protein interaction networks. Existing CXMS chemical cross-linkers target only Lys, Cys, Glu, and Asp residues, limiting the information measurable. Here we report a "plant-and-cast" cross-linking strategy that employs a heterobifunctional cross-linker that contains a highly reactive succinimide ester as well as a less reactive sulfonyl fluoride. The succinimide ester reacts rapidlywith surface Lys residues "planting" the reagent at fixed locations on protein. The pendant aryl sulfonyl fluoride is then "cast" across a limited range of the protein surface, where it can react with multiple weakly nucleophilic amino acid sidechains in a proximityenhanced sulfur-fluoride exchange (SuFEx) reaction. Using proteins of known structures, we demonstrated that the heterobifunctional agent formed cross-links between Lys residues and His, Ser, Thr, Tyr, and Lys sidechains. This geometric specificity contrasts with current bis-succinimide esters, which often generate nonspecific cross-links between lysines brought into proximity by rare thermal fluctuations. Thus, the current method can provide diverse and robust distance restraints to guide integrative modeling. This work provides a chemical cross-linker targeting unactivated Ser, Thr, His, and Tyr residues using sulfonyl fluorides. In addition, this methodology yielded a variety of cross-links when applied to the complex Escherichia coli cell lysate. Finally, in combination with genetically encoded chemical crosslinking, cross-linking using this reagent markedly increased the identification of weak and transient enzyme-substrate interactions in live cells. Proximity-dependent cross-linking will dramatically expand the scope and power of CXMS for defining the identities and structures of protein complexes. [ABSTRACT FROM AUTHOR]

An efficient protocol for the synthesis of novel glycosyl-containing 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives starting from the commercially available d-glucosamine hydrochloride is described by reaction of glycosyl isothiocyanate with various aminotriazoles in DMF. Glycosyl isothiocyanate is an important intermediate and synthetic methods are discussed. The acetylcholinesterase inhibitory activity of these compounds was tested by Ellman's method. It was found that most compounds exhibited over 90% inhibition and they were subsequently evaluated for their IC50 values. [ABSTRACT FROM AUTHOR]

Trifluoromethanesulfonic acid (TfOH) is one of the superior catalysts for acylation. The catalytic activity of TfOH in C- and/or O-acylation has broadened the use of various substrates under mild and neat or forced conditions. In this review, the salient catalytic features of TfOH are summarized, and the unique controllability of its catalytic activity in the tendency of C-acylation and/or O-acylation is discussed. [ABSTRACT FROM AUTHOR]

A series of Cs(NH4)xH3-xPMo11VO40 with different x values were synthesized to catalyze the selective oxidation of methacrolein to methacrylic acid. The effects of ammonium on both structure and catalytic activity were explored in this study. Compared with CsH3PMo11VO40, the surface area, amount of acid sites, and active species (V4+/VO2+) were found to be strongly dependent on the content of ammonium. The optimum structure of Cs(NH4) 1.5H1.5PMo11VO40 shows comparable large surface area of 50.33 m²/g, large amount of acid sites, and active species (V4+/VO2+), consequently offering a higher methacrolein conversion (83%) and methacrylic acid selectivity (93%). Furthermore, the steady activity of Cs(NH4)1.5H1.5PMo11VO40 was not affected much by the decomposition of ammonium, and the catalyst exhibited good stability. [ABSTRACT FROM AUTHOR]

In this work, we develop a modified mussel-inspired method to enhance interfacial adhesion of aramid fiber to a rubber matrix. Through a simple dip-coating procedure, catechol and polyamine could initially codeposit as a poly(catechol-polyamine) (PCPA) coating on the surface of the aramid fiber. Then, the PCPA layer could be further grafted with silane coupling agent γ-(glycidyloxypropyltrimethoxysilane) (GPTMS). Results indicated that GPTMS was successfully grafted onto the aramid fiber surface via the bridging of the PCPA layer. The interfacial adhesion between the aramid fibers and the rubber matrix was improved compared to that achieved by polydopamine in our previous study. In addition, this method is more applicable to the rubber industry than polydopamine coating because of its cost-effectiveness and short reaction time. [ABSTRACT FROM AUTHOR]

The asymmetric aldol addition of 2-butanone and 4-nitrobenzaldehyde catalyzed by a novel thermophilic esterase (APE1547) from the archaeonAeropyrum pernixK1 was successfully conducted in organic solvents. APE1547 exhibited a good enzyme activity and enantioselectivity in the reaction. The effects of organic solvent, temperature, water content, and substrate concentration were investigated. The reaction provided optically active secondary alcohol with satisfying enantioselectivity (71.2 %ee) and enzyme activity (38.1 µmol/g/h) under the optimum conditions. A high yield (68.7%) could be obtained when the reaction time was approximately 120 h. [ABSTRACT FROM AUTHOR]

Aryl-keto-containing α-amino acids are of great importance in organic chemistry and biochemistry. They are valuable intermediates for the construction of hydroxyl α-amino acids, nonproteinogenic α-amino acids, as well as other biofunctional components. Friedel-Crafts acylation is an effective method to prepare aryl-keto derivatives. In this review, we summarize the preparation of aryl-keto containing α-amino acids by Friedel-Crafts acylation using acidic α-amino acids as acyl-donors and Lewis acids or Brönsted acids as catalysts. [ABSTRACT FROM AUTHOR]

In this study we used anionic living polymerization to prepare two different homopolymers: a poly(methyl methacrylate) (PMMA) and a PMMA derivative presenting polyhedral oligomeric silsesquioxane (PMA-POSS) units as its side chains. We then employed differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and wide-angle X-ray diffraction (WAXD) to investigate the miscibility and specific interactions of PMMA and PMA-POSS with three hydrogen bonding donor compounds: poly(vinyl phenol) (PVPh), phenolic resin, and bisphenol A (BPA). DSC revealed that all of the PVPh/PMMA, phenolic/PMMA, and BPA/PMMA blends exhibited a single glass transition temperature, characteristic of miscible systems; FTIR spectroscopic analyses revealed that such miscibility resulted from hydrogen bonding interactions between the C=O groups of PMMA and the OH groups of these three hydrogen bonding donor compounds. In contrast, all of the PVPh/PMA-POSS, phenolic/PMA-POSS, and BPA/PMA-POSS blends were immiscible: DSC revealed two glass transition temperatures arising from strong screening effects (FTIR spectroscopy) and high degrees of aggregation (WAXD) of the POSS nanoparticles. We propose that the value of the intramolecular screening effect (γ) should be very close to 1 for all PMA-POSS blend systems when POSS nanoparticles appear as the side chains of PMMA, such that the OH groups of the hydrogen bonding donor compounds cannot interact with the C=O groups of PMA-POSS. [ABSTRACT FROM AUTHOR]

Many enzymes catalyzing biological redox chemistry depend on the omnipresent cofactor, nicotinamide adenine dinucleotide (NAD). NAD is also involved in various nonredox processes. It remains challenging to disconnect one particular NAD-dependent reaction from all others. Here we present a bioorthogonal system that catalyzes the oxidative decarboxylation of l-malate with a dedicated abiotic cofactor, nicotinamide flucytosine dinucleotide (NFCD). By screening the multisite saturated mutagenesis libraries of the NAD-dependent malic enzyme (ME), we identified the mutant ME-L310R/Q401C, which showed excellent activity with NFCD, yet marginal activity with NAD. We found that another synthetic cofactor, nicotinamide cytosine dinucleotide (NCD), also displayed similar activity with the ME mutants. Inspired by these observations, we mutated d-lactate dehydrogenase (DLDH) and malate dehydrogenase (MDH) to DLDH-V152R and MDH-L6R, respectively, and both mutants showed fully active with NFCD. When coupled with DLDH-V152R, ME-L310R/Q401C required only a catalytic amount of NFCD to convert l-malate. Our results opened the window to engineer bioorthogonal redox systems for a wide variety of applications in systems biology and synthetic biology. [ABSTRACT FROM AUTHOR]

Monolayer behaviors of newly synthesized viologens (Vs) containing tolunitrile substituents have been investigated at the air–water interfaces. Surface pressure–area isotherms indicated that these viologens could not form stable monolayers on the surfaces of the subphases of pure water, Fe(BF4)2 and anionic polyelectrolyte of PSS (PSS: poly(styrenesulfonic acid-o-maleic) acid), while they could form insoluble monolayers on the surface of the subphase containing mixtures of Fe(BF4)2 and PSS, which was attributed to the formation of Fe–V metal–organic polyelectrolytes based on an interfacial coordinative reaction between the Fe2+ ions and viologen derivatives. With the use of Langmuir–Blodgett (LB) method, monolayers of Fe–V polyelectrolytes were transferred on the substrate surfaces. X-ray photoelectron spectra indicated that the LB film was composed of the elements of S, C, N, O and Fe, suggesting the formation of Fe–V/PSS hybrid multilayers. Cyclic voltammograms of the viologens revealed two reversible redox couples in the solutions, corresponding to two electron transfers of V2+ ↔V+· and V+· ↔ V0, respectively. For the indium tin oxide electrode covered by the LB films of Fe–V/PSS, only one broad redox couple was recorded in the potential range of 0 and −1.0V vs Ag/AgCl, which was attributed to the first redox couple of V2+ ↔V+· The charger transfer process of viologens in the solutions and Fe–V/PSS multilayers was investigated by the potential chronocoulometry method. [ABSTRACT FROM AUTHOR]

A new series of degradable and water-swellable cross-linked PEG phosphoester polymers (CPPs) based on a facile cross-linked reaction between diphosphoesters of polyethylene glycol (P-PEG-P) and diglycidyl ether of polyethylene glycol (E-PEG-E) has been prepared and characterized. The molecular weights and ratios of the prepolymers played an important role for the properties of CPPs polymers, such as mechanical property, swelling, and degradation rates. In the curing process, the glycidyl ether was consumed by both hydroxyl of the phosphoester (P–OH) and hydroxyl generated from the opened glycidyl ethers (C–OH) with the presence of acid, which generated degradable phosphate esters as cross-linked points and ether bonds as the short branches, respectively. Drug entrapment and release test and biological cytotoxicity studies in vitro suggested that the polymers and generated hydrogels have great potential applications in drug delivery system and biological materials. [ABSTRACT FROM AUTHOR]

A tridentate cyclometalating ligand, 1,3-di(1,2,3-triazol-4-yl)benzene (dtab), has been prepared and used for the syntheses of a number of cyclometalated RuIIcomplexes. A comparison of the electrochemical and spectroscopic properties of cyclometalated complexes made from dtab or 1,3-di(2-pyridyl)benzene is presented as well. [ABSTRACT FROM AUTHOR]

Polystyrene-block-poly(ε-caprolactone)-block-poly(n-butyl acrylate) (PS-b-PCL-b-PBA) triblock copolymer was synthesized through the combination of atom transfer radical polymerization, copper-catalyzed Huisgen 1,3-dipolar cycloaddition and ring-opening polymerization. The PS-b-PCL-b-PBA ABC triblock copolymer was incorporated into epoxy to access the nanostructures in the thermoset. The microphase-separated morphology was investigated by means of atomic force microscopy (AFM), small-angle X-ray scattering (SAXS) and dynamic mechanical thermal analysis (DMTA). It was found that depending on the concentration of the triblock copolymer in the thermosets several kinds of nanodomains were formed and they were arranged in lamellar lattice. The formation of the nanostructures was ascribed to the tandem reaction-induced microphase separation of PBA and PS blocks in the thermosetting blends. The investigation of the model binary thermosetting blends showed that the phase separation of PBA occurred at the conversion much lower than that of PS. It is proposed that the PBA nanophases were formed prior to the PS nanophases in the thermosetting blends and the microdomains of PBA subchains could behave as the template for the demixing of PS blocks. The coupling of the two-stage reaction-induced microphase separation exerted a profound impact on the formation of nanostructures in the epoxy thermosets containing the ABC triblock copolymer. Thermal analysis shows that with the formation of the nanostructures in the thermosets a part of poly(ε-caprolactone) subchains were demixed from epoxy matrix; the fractions of demixed PCL blocks have been estimated according to the Tg-composition relation of the model binary blends of epoxy and PCL. [ABSTRACT FROM AUTHOR]

Photoinduced reactions of the 1,2-dicarbonyl compounds phenanthrenequinone (PQ), 1-acetylisatin (IS), and benzil (BZ) with the oxazoles 1a-j have been investigated. In photoreactions of PQ with the oxazoles, in addition to the 1,4-dioxins derived from [4 + 2] cycloaddition and the oxetanes from the Patemó-Büchi [2 + 2] reactions, [4 + 4] cycloaddition products are formed in the reactions with 1a, 1c, 1g, 1i, and 1j, with the quinone's dicarbonyl unit (O=C-C=O) and the oxazole's C=N-C=C moiety as two 4πr addends. Photoreactions of IS with the oxazoles If and 1g give the [4 + 4] cycloaddition products exclusively, while in photoreactions of IS with 1a, 1c, 1e, 1h, and 1i, [4 + 4] products are formed together with the [2 + 2] products. Reaction pathway partitioning in these photocycloaddtions strongly depends on the substitution pattern on the oxazole ring. The presence of a substituent at the oxazole's C2 atom hampers the [4 + 4] pathway by causing steric hindrance to radical pair recombination in the corresponding 1,7-diradical intermediate to form the [4 + 4] cycloaddition products. A substituent at the C4 atom results in steric hindrance for ring closure of the 1,4-diradicats in the [2 + 2] cycloaddition pathway, therefore favoring the [4 + 4] and [4 + 2] cycloaddition pathways. Regio- and diastereoselectivity in the [2 + 2] and [4 + 4] cycloadditions have been discussed based on the thermodynamic stability of the relevant triplet diradical intermediates and the conformations of these diradicals suitable for the intersystem crossing process. Photoreactions of BZ with the oxazoles afford only [2 + 2] cycloaddition products. [ABSTRACT FROM AUTHOR]

Many core oscillator components of the circadian clock are nuclear localized but how the phase and rate of their entry contribute to clock function is unknown. TOC1/PRR1, a pseudoresponse regulator (PRR) protein, is a central element in one of the feedback loops of the Arabidopsis clock, but how it functions is unknown. Both TOC1 and a closely related protein, PRR5, are nuclear localized, expressed in the same phase, and shorten period when deficient, but their molecular relationship is unclear. Here, we find that both proteins interact in vitro and in vivo through their conserved N-termini. TOC1–PRR5 oligomerization enhances TOC1 nuclear accumulation two-fold, most likely through enhanced nuclear import. In addition, PRR5 recruits TOC1 to large subnuclear foci and promotes phosphorylation of the TOC1 N-terminus. Our results show that nuclear TOC1 is essential for normal clock function and reveal a mechanism to enhance phase-specific TOC1 nuclear accumulation. Interestingly, this process of regulated nuclear import is reminiscent of similar oligomeric pairings in animal clock systems (e.g. timeless/period and clock/cycle), suggesting evolutionary convergence of a conserved mechanism across kingdoms. [ABSTRACT FROM AUTHOR]

An organic–inorganic hybrid material derived from covalently grafting a palladium complex of the type (L)2PdCl2(L = Si(OMe)3functionalized PPh3) on silica was synthesized, characterized and sucessfully applied as a catalyst for the Suzuki reaction. [ABSTRACT FROM AUTHOR]

The article presents a study on the optimization of trehalose production by a novel strain of Brevibacterium sp. SY361 in submerged fermentation. It examines the increase trehalose productivity with the reactions of different chemical and physical parameters including carbon and nitrogen sources, inoculum level, and aeration and time-course of fermentation. It identifies concentration for trehalose production in the reaction of an optimal production medium containing 3% (w/v) glucose, 0.9% (v/v) corn steep liquor, and 0.5% (w/v) KH2PO4. It presents the optimal levels of other parameters and the reaction of optimized parameters for the maximum trehalose.

The circadian clock controls the period, phasing, and amplitude of processes that oscillate with a near 24-h rhythm. One core group of clock components in Arabidopsis that controls the pace of the central oscillator is comprised of five PRR (pseudo-response regulator) proteins whose biochemical function in the clock remains unclear, Peak expression of TOC1 (timing of cab expression 1)/PRR1, PRR3, PRR5, PRR7, and PRR9 are each phased differently over the course of the day and loss of any PRR protein alters period. Here we show that, together with TOC1, PRR5 is the only other likely proteolytic substrate of the E3 ubiquitin ligase SCFZTL within this PRR family. We further demonstrate a functional significance for the phosphorylated forms of PRR5, TOC1, and PRR3. Each PRR protein examined is nuclear-localized and is differentially phosphorylated over the circadian cycle. The more highly phosphorylated forms of PRR5 and TOC1 interact best with the F-box protein ZTL (ZEITLUPE), suggesting a mechanism to modulate their proteolysis. In vivo degradation of both PRR5 and ZTL is inhibited by blue light, likely the result of blue light photoperception by ZTL. TOC1 and PRR3 interact in vivo and phosphorylation of both is necessary for their optimal binding in vitro. Additionally, because PRR3 and ZTL both interact with TOC1 in vivo via the TOC1 N terminus, taken together these data suggest that the TOC1/PRR3 phosphorylation-dependent interaction may protect TOC1 from ZTL-mediated degradation, resulting in an enhanced amplitude of TOC1 cycling. [ABSTRACT FROM AUTHOR]

n organic/inorganic nanocomposite of polyethylene (PE) was prepared by compounding techniques. Uniform mono-dispersed spherical MCM-41 nano-particles were modified with polyethylene (PE) prepared by in situ Ziegler-Natta polymerization. The catalyst was first supported on the surface or in the mesopores of MCM-41 particles to subsequently initiate the polymerization of ethylene on the surface or in the mesopores of MCM-41. XRD and N2 adsorption analysis attested to ethylene polymerization within the mesopores of MCM-41. When MCM-41 modified with a PE layer was mixed with commercialized PE by melt blending, the strong interaction between the dispersed MCM-41 nano-particles and the resin matrix resulted in the formation of a kind of organic/inorganic network, which provided better mechanical performance than the composite from MCM-41 without a PE layer. The tensile modulus, tensile strength and elongation at break were improved by 24.7, 28.3, and 23.5% in comparison with pure PE composites. [ABSTRACT FROM AUTHOR]

Polysulfides with narrow polydispersity and variable chain length and density of polymerizable units have been synthesized through the use of a methacrylate-bearing and thiol-reactive compound as an end-capper for episulfide anionic polymerization. These macromonomers have been photopolymerized to yield materials with controlled cross-linking density, which translates into a controlled number of cross-links, branching points, and dead-ends. The resulting networks show elastomeric behavior that can be easily described through a simple affine chain model; in the analysis of the network behavior we here also present the calculation of a solvent-independent parameter for rationalizing the behavior of the Flory−Huggins parameters. These materials combine simple preparation (→ in situ processes), easy description of the mechanical properties, and responsiveness (to oxidationnot studied here), features that could make them attractive for biomedical applications. [ABSTRACT FROM AUTHOR]

A functionalized ionic liquid, 1-(2-hydroxyethyl)-3- methylimidazolium tetrafluoroborate ([HEmim][BF4]), was found to be as an efficient and recyclable reaction medium for palladiumcatalyzed Heck reaction. The olefination of iodoarenes and bromoarenes with olefins generated the corresponding products in good to excellent yields under phosphine-free reaction conditions. The reaction involved the use of [HEmim][BF4] as the solvent, potassium phosphate as the base, and palladium acetate as the catalyst. In addition, palladium and ionic liquid could be recovered and recycled for six consecutive trials without significant loss of its reactivity. [ABSTRACT FROM AUTHOR]

Multifunctional amphiphilic hollow carbonaceous spheres assembled into Pickering emulsions exhibit reversible pH-dependent phase-transfer behavior and can efficiently catalyze water/oil biphasic reactions, facilitating the recycling of the catalysts and separation of the products. [ABSTRACT FROM AUTHOR]

The article focuses on the synthesis of difluorodiazirine (DFD) and the absolute reactivity of difluorocarbene. It is stated that difluorocarbene (CF2) is the most stabilized of the dihalocarnes and its computed stabilization energy is 62.8 kilocalorie/mole (kcal/mol) which is greater than the stabilization energies of chlorofluorocarbene. Meanwhile, DFD generates CF2 upon photolysis or pyrolysis.

Graphitic carbon nanocapsules, nanosheets and nanoplates were selectively obtained viaa solid-state pyrolysis route from various ion-exchange resin–iron complexes. [ABSTRACT FROM AUTHOR]

This article focuses on the synthesis of partially fluorinated poly(arylene ether)s containing sulfofluorenyl groups. Particular focus is given to the reaction mixture, as well as the filtering of the solution. The steps involved in preparing polymer films are also provided. It notes that during the sulfonation reaction, the polymer main chain remained intact. It highlights remarkable changes in the peaks of fluorenyl groups, along with the stability of the sulfonated polymer 3 to oxidation.

The article presents a study which reveals enthalpy versus entropy in chlorocarbene/alkene addition reactions. Researchers have reported the first activation parameters for additions of carbenes to alkenes by adding CCl2 and CClF to the moderately reactive alkenes cyclohexene and 1-hexene. Results prove that entropic factors control the additions of carbenes to the highly reactive alkene, tetramethylene.

A functionalized chiral ionic liquid (CIL) containing L-proline unit exhibits as a highly efficient and recyclable asymmetric organocatalyst for aldol condensation of aldehydes and ketones in [Bmim][BF4] at room temperature, which afford the corresponding products with satisfactory isolated yields and enantiomeric excesses. [ABSTRACT FROM AUTHOR]

A magnetically recyclable catalyst was prepared by embedding magnetic nanoparticle in poly(phosphotungstate-based ionic liquid) matrix. The obtained hybrid material was characterized by XRD, FT-IR, SEM, TEM, TGA, and VSM. The results indicated that Fe3O4 was successfully implanted in multilayer poly(ionic liquid), and the catalyst possessed open active sites (see SEM) to reactants and a high magnetization value. The combination of poly(ionic liquid) matrix with magnetic nanoparticle enhanced the structure stability and favored the separation performance. Esterification of oleic acid with ethanol was conducted in the presence of prepared catalyst, and the Box-Behnken response surface methodology was applied for maximizing the oleic acid conversion by optimizing process variables at 90 °C. Under the optimum conditions (reaction time, 5 h; catalyst amount, 13 wt %; alcohol/acid molar ratio, 12:1), the conversion of oleic acid reached 93.4%. Besides, the catalyst presented fine reusability after six runs and could be facilely recovered in magnetic field based on its superparamagnetism property. [ABSTRACT FROM AUTHOR]

Pentafluorophenylchlorocarbene and pentafluorophenylfluorocarbene are highly reactive species and effective carriers of fluorine labels via addition to alkenes and insertion into C–H bonds. [ABSTRACT FROM AUTHOR]

A room temperature decarboxylative ortho-acylation of acetanilides with α-oxocarboxylic acids has been developed via a novel Eosin Y with Pd dual catalytic system. This dual catalytic reaction shows a broad substrate scope and good functional group tolerance, and an array of ortho-acylacetanilides can be afforded in high yields under mild conditions. [ABSTRACT FROM AUTHOR]

Highly efficient nBu3P-catalyzeddesulfonylative [3 + 2] cycloadditions of allylic carbonates witharylazosulfones were developed for the synthesis of pyrazole derivatives.The reactions proceed smoothly under mild conditions to generate correspondingannulation products in good to excellent yields. [ABSTRACT FROM AUTHOR]

A noveland efficient electrophilic sulfenylation of indoles witharylsulfinic acids is realized. The reaction utilizes readily availablestarting materials in water under catalyst- and additive-free conditions,providing an alternative and attractive approach to 3-arylsulfinylindoleswith high yields. Preliminary mechanistic investigation suggestedthat the reaction is through an electrophilic substitution process. [ABSTRACT FROM AUTHOR]

Rare earth (RE) based coordination polymer (CP) submicrospheres have been prepared from pyridine-2,5-dicarboxylic acid and RE(NO3)3 via a facile microwave heating method in 5 min, with N,N-dimethylformamide (DMF) as solvent. The submicrospheres have diameters of 100-400 nm. Furthermore, the surface of the microspheres is smooth and the microspheres are solid. Several CP submicrospheres (RE = La, Gd, Y) were selected and calcined under different atmospheres (including air, N2, and NH3). After calcination in air at 550 °C for 4 h, rare earth oxide (RE2O3) submicrospheres were obtained. On calcination under an N2 atmosphere, LaN/La2O3/C composite spheres were obtained for La-based CPs. For Gd(Y)-based CPs, Gd2O3(Y2O3)/C composite spheres were obtained. Porous carbon submicrospheres were obtained after the removal of RE2O3 and REN from the composite spheres. Interestingly, under an NH3 atmosphere, La2O2CN2 submicrospheres were produced from the La-based CPs. In addition, the Gd-based and Y-based CPs submicrospheres gave Gd2O3/GdN/C and Y2O3/C submicrospheres, respectively. As examples of their potential applications, their upconversion properties and electrochemical properties of the as-prepared products were investigated. This facile microwave synthesis method may offer an attractive approach for the preparation of other RE-CP micro-/nanostructures, and many interesting materials may be derived. [ABSTRACT FROM AUTHOR]

A series of alkali metal complexes supported by two bulky tetraphenols were synthesized and characterized. The reactions of ɑ,ɑ,ɑ',ɑ'-tetra(3,5-di-ferf-butyl-2-hydroxyphenyl)-p-xylene(para-tetraphenol) with "BuLi, sodium, and KSi(NMe₂)₃ gave bimetallic complexes 1, 2, and 3, respectively. Treatments of the ɑ,ɑ,ɑ',ɑ'-tetra(3,5-di-ierf-butyl-2-hydroxyphenyl)-m-xylene(meta-tetraphenol) with 2 or 4 equiv of "BuLi afforded complexes 4 or 5, while the reactions of meta-tetraphenol with sodium and KSi(NMe₂)₃ gave only trimetallic complexes 6 and 7 for the additional p--π interaction. Complexes 1--7 were all characterized by single-crystal X-ray diffraction techniques. In the presence of benzyl alcohol, all complexes are active catalysts for the ring-opening polymerization of L-lactide. Comparatively, bimetallic complexes 1, 2, and 3 are more efficient catalysts because of their symmetric structures, in which complex 3 presents as a rare highly active potassium catalyst for the ring-opening polymerization of lactide, leading to polymers with good molecular weight control and narrow molecular weight distributions. [ABSTRACT FROM AUTHOR]

Benzo[b]furans were prepared in one pot based on the addition/palladium-catalyzed C–H bond functionalization of phenols with bromoalkynes. The addition reactions of phenols to bromoalkynes generated (Z)-2-bromovinyl phenyl ethers in high yields with excellent regio- and stereoselectivity. The obtained (Z)-2-bromovinyl phenyl ethers subsequently proceeded by intramolecular cyclization to afford 2-substituted benzo[b]furans in good yields through palladium-catalyzed direct C–H bond functionalizations. It is important to note that the transformation of phenols with bromoalkynes into benzo[b]furans could be carried out in one pot with a simple and efficient tandem procedure. [ABSTRACT FROM AUTHOR]

A metal-free novel, simple, and highly efficient method for the direct C2-alkylation of azoles with alcohols and ethers has been developed on the basis of an oxidative C–H activation process. The dehydrogenative C–C cross-coupling reactions of α-position sp3C–H in alcohols and ethers with the 2-position sp2C–H in azoles proceeded smoothly in the presence of tert-butyl hydroperoxide (TBHP) under neat reaction conditions, which generated the corresponding products in good yields. [ABSTRACT FROM AUTHOR]