Preparation of Co3O4 Nanofibers via an Electrospinning Technique

Thin PVA/cobalt acetate composite fibers were prepared by using sol-gel processing and electrospinning technique.After calcination of the above precursor fibers,Co3O4 nanofibers with a diameter of 50-150 nm could be successfully obtained.The fibers were characterized by SEM,FT-IR,WAXD,respectively.     

Preparation of silica capsules via an acid-catalyzed sol–gel process in inverse miniemulsions

Silica capsules were prepared via a sol–gel process using tetraethyl orthosilicate (TEOS) in inverse miniemulsions under highly acidic conditions (pH?<?2). Formation of silica capsules under acidic conditions proceeded via internal phase separation of silica species in the droplets. This mechanism is different from the well-known interfacial reaction mechanism for most syntheses of silica capsules. The driving force for the formation of capsules was the interaction between silica species and cetyltrimethylammonium bromide (CTAB) as well as between silica species and the hydrophilic block of the block copolymer surfactant, poly(ethylene-co-butylene)-b-poly(ethylene oxide) (P(E/B)-PEO). The effects of synthetic parameters on the particle morphology and size were systematically investigated in terms of the reaction time, amount of TEOS, CTAB, P(E/B)-PEO, and hydrochloric acid concentration, as well as addition of ethanol.     

Preparation and CO2 capture properties of nanocrystalline Li2ZrO3 via an epoxide-mediated sol–gel process

Journal of Sol-Gel Science and Technology - Nanocrystalline lithium zirconate (Li2ZrO3) was successfully prepared by an epoxide-mediated sol–gel process. The compositions and morphologies of...     

Preparation and properties of barium-ferrite-containing glass ceramic fibers via an electrospinning/sol–gel process

Barium-ferrite-containing glass ceramic fibers were successfully prepared by the combination of a sol–gel process and electrospinning technique using basic iron formate, barium acetate and boric acid as the starting materials. After leaching of barium borate matrix, pure phase BaFe₁₂O₁₉ fibers were obtained. The relationship of aged time and viscosity of the precursor solution was studied and the results showed that the viscosity corresponding to the spinnable state was 1–4 Pa s. The morphology, structure and magnetic properties of the obtained fibers were characterized with scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, thermo gravimetric analysis–differential scanning calorimetry, vibrating sample magnetometer. The X-ray diffraction results indicate that only the M-type Ba-ferrite and Ba-borate exist. The fibers had rough surface and hollow structure with the diameter no more than 1 μm. The fibers were composed of 40 nm BaFe₁₂O₁₉ nanoparticles embedded in the borate matrix. The coercivity and saturation magnetization of the synthesized fibers were 4,106.9 Oe and 17.8 emu/g, respectively.     

Preparation of C-arylglycals via Suzuki–Miyaura cross-coupling of dihydropyranylphosphates

The preparation of C-arylglycals has been accomplished by employing the Suzuki–Miyaura cross-coupling reaction of dihydropyranylphosphates with arylboronate esters. The reaction is tolerant of both electron-donating (EDG) and electron-withdrawing (EWG) groups on the aromatic ring and affords the corresponding C-arylglycals in good to excellent yields (68–97%). Additionally, the ketene acetal phosphate derived from 6-deoxy-3,4-di-O-benzyl-l-rhamnal also couples efficiently to yield C-arylglycals in excellent yields.     

Efficient Synthesis of 2-Methylene-3phosphorylalkanoates: Phosphorylation of Baylis–Hillman Bromides via an S N 2-S N 2′ Strategy

A novel synthesis of 2-methylene-3-phosphorylalkanoates under mild conditions is described. Thus, Balyis–Hillman bromides react with secondary phosphine oxides or H-phosphonites in the presence of DABCO via an S _N 2-S _N 2′ protocol to produce the target compounds in good yields.     

Preparation of yolk-shell sulfur/carbon nanocomposite via an organic solvent route for lithium–sulfur batteries

A yolk-shell sulfur/carbon (S/C) composite for the cathode of lithium–sulfur batteries was successfully prepared by an accessible method with tetrahydrofuran as solvent. The as-prepared composites are characterized by thermal gravimetric, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption and desorption. In this composite, sulfur particle is encapsulated in the carbon shell even entering into the micropores of carbon Bp2000. The electrochemical performance of the S/C composites is evaluated. The results indicate that the S/C composite with 50 wt% sulfur content shows good reversibility, excellent rate capability, and slow degradation. It delivers an initial capacity of 784.4 mAh g^?1 (based on sulfur weight) and preserves at 598.3 mAh g^?1 after 195 cycles at 1C. It achieves a high-capacity retention of 76.27 % from the 5th to 200th cycle, and as high as 91.19 % during the latter 150 cycles. The improvement is mainly attributed to the favorable structure of the S/C composite, in which the carbon cannot only facilitate transport of electrons and Li⁺ ions but also trap polysulfides and retard the shuttle effect during charge/discharge process.     

Preparation of α-Fe2O3 Nanofiber via Electrospinning Process

A thin PVA/FeCl3 composite fiber was prepared by using sol-gel processing and electrospinning tech niques. A nanofiber of α-Fe2O3 with the diameter of 50-150 nm was obtained via high temperature calcina tion of the PVA/FeCl3 composite fiber. The material was characterized by infra-red(IR) spectroscopy, X-ray diffraction(XRD), and scanning electron microscopy(SEM). The results show that the fiber after the calci nation at 700 ℃ was a pure α-Fe2O3 nanofiber.     

Preparation of Mn3O4 Nanofibres via An Electrospinning Technique

Thin PVA/manganese acetate composite fibres were prepared by using sol-gel processing and electrospinning technique.After calcinations of the above precursor fibres,Mn3O4 nanofibres with a diameter of 50-200 nm could be successfully obtained.The fibres were characterized by SEM,FT-IR,XRD.The results showed that the crystalline phase and morphology of nanofibres were largely influenced by the calcination temperature.     

Preparation of α-Fe2O3 Nanofiber via Electrospinning Process

A thin PVA/FeCl3 composite fiber was prepared by using sol-gel processing and electrospinning techniques. A nanofiber of α-Fe2O3 with the diameter of 50-150 nm was obtained via high temperature calcination of the PVA/FeCl3 composite fiber. The material was characterized by infra-red (IR) spectroscopy, X-ray diffraction(XRD), and scanning electron microscopy(SEM). The results show that the fiber after the calcination at 700℃ was a pure α-Fe2O3 nanofiber.     

Thorium–ligand multiple bonds via reductive deprotection of a trityl group

Reaction of [Th(I)(NR₂)₃] (R = SiMe₃) (2) with KECPh₃ (E = O, S) affords the thorium chalcogenates, [Th(ECPh₃)(NR₂)₃] (3, E = O; 4, E = S), in moderate yields. Reductive deprotection of the trityl group from 3 and 4 by reaction with KC₈, in the presence of 18-crown-6, affords the thorium oxo complex, [K(18-crown-6)][Th(O)(NR₂)₃] (6), and the thorium sulphide complex, [K(18-crown-6)][Th(S)(NR₂)₃] (7), respectively. The natural bond orbital and quantum theory of atoms-in-molecules approaches are employed to explore the metal–ligand bonding in 6 and 7 and their uranium analogues, and in particular the relative roles of the actinide 5f and 6d orbitals.     

N‐Benzyl‐DABCO‐tribromide as an efficient and mild reagent for deprotection of dithioacetals

N‐Benzyl‐DABCO‐ammonium tribromide was found to be an efficient and recyclable reagent for the deprotection of dithioacetals in dichloromethane/methanol at room temperature. The reaction can be performed cleanly, in short time, and in high yield.     

Preparation of novel cross-linked fluoroalkyl end-capped cooligomeric nanoparticles–encapsulated cytochrome c in water and ionic liquids

Cross-linked fluoroalkyl end-capped acrylic acid cooligomer containing poly(oxyethylene) units can form the nanometer size-controlled fine particles in aqueous solutions, and these cross-linked nanoparticles interact with cytochrome c (Cyto-c) to afford the corresponding cooligomeric nanoparticles–encapsulated Cyto-c effectively. Interestingly, we can easily isolate the fluorinated nanoparticles–encapsulated Cyto-c powder by the simple centrifugal separation of the corresponding aqueous solutions. The cross-linked fluorinated cooligomer also enables an effective transfer of Cyto-c from aqueous solution to ionic liquids such as 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to afford the immobilized Cyto-c with the corresponding fluorinated cooligomer in quantitatively immobilized ratio (～100%). The immobilized Cyto-c exhibited a good dispersibility in the parent ionic liquid to afford the nanometer size-controlled fluorinated particles–encapsulated Cyto-c. Similarly, the cross-linked fluorinated cooligomer in ionic liquids such as 3-methylpyrazolium tetrafluoroborate (3MP-BF4) interacted with Cyto-c to afford the corresponding nanoparticles–encapsulated Cyto-c in quantitatively encapsulated ratio (～100%). These cross-linked fluorinated nanoparticles–encapsulated Cyto-c in water and ionic liquids were applied to the oxidation of guaiacol with hydrogen peroxide, and an extremely higher catalytic activity for this oxidation was observed in the ionic liquid (3MP-BF4).     

Preparation of 5-chloropyrazoles via tandem Meyer–Schuster/von Auwers rearrangements

A new, practical preparation of β,β-dichloroenones in three to four steps allows for a straightforward synthesis of 5-chloropyrazoles. Addition of various propargyl anions to commercially available 4-methyl-4-(trichloromethyl)cyclohexa-2,5-dien-1-one gives high yields of the corresponding propargyl alcohols. These are then transformed, in a single step, via two consecutive rearrangements, a Meyer–Schuster and a (sometimes spontaneous) von Auwers rearomatizing rearrangement, to deliver α,α-aryl-trichloromethylketones. After elimination of HCl, cyclization of the β,β-dichloroenones with various hydrazines delivers 5-chloropyrazoles. The four to five step sequence to 5-chloropyrazoles is very atom economical, expelling only water and two molecules of HCl from all the building blocks.     

Preparation of SiO2–wood composites by an ultrasonic-assisted sol–gel technique

The vacuum impregnation assisted sol–gel technique is a promising and environmentally-friendly method for the inorganic modification of wood by the formation of wood-inorganic composites. However, vacuum impregnation is relatively cumbersome and time-consuming. In this study, SiO₂–wood composites were prepared by an ultrasonic-assisted sol–gel method, which is an innovative and simple method. Using this method, we found an increase in the degree of silicon incorporation into the cell walls of the wood. The impregnation of silica inside the cell walls were verified by Fourier-transform infrared spectra, X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry. Leaching test proved that the internal cross-linking silica is stably bonded to the wood cell walls. This modified method significantly reduced the hygroscopicity of the wood and consequently improved the mechanical performance of the modified wood. Thermogravimetric and differential thermal analyses showed that the incorporation of silicon retards thermal decomposition and the complete combustion of the wood matrix and it enhances the thermal stability of wood.     

Preparation of mesoporous hydroxyapatite films used as biomaterials via sol–gel technology

The mesoporous hydroxyapatite films (MHFs) have been developed on glass slides by sol–gel dip-coating technology using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent and the effects of pH value and calcination temperatures on the surface morphology and the mesostructure have been discussed. The phase composition, surface morphology, mesostructure and surface wettability were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, N₂ adsorption–desorption isotherms and water contact angle analyzer, respectively. The continuous thin films consisted of mesoporous hydroxyapatite particles (~50 nm) with mesopores (~2 nm) within the particles have been obtained after being prepared in the condition of concentration of CTAB 0.09 M, pH of sol 3.0, reaction temperature 60 °C and calcination temperature 550 °C. In vitro cell culture, the mesoporous films, which possessed favorable surface wettability resulting from the special pore structure, have exhibited a high degree of MC3T3-E1 cell attachment and spreading, suggesting a better bioactivity. Therefore, the MHFs can be expected to have potential application for decreasing the ion release of implant and improving the bioactivity as a coating on material surface.     

Preparation of Mn2O3 catalyst with core–shell structure via spray pyrolysis assisted with glucose

A novel core–shell Mn₂O₃ catalyst is obtained by facile spray pyrolysis assisted with glucose acting as a structure-directing agent. The detail characterizations include X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, and the thermogravimetric method (TG/DTA). In the probe test of the aqueous degradation of methylene blue (MB), the high catalytic peroxidization activity of core–shell Mn₂O₃ catalyst, compared to the commercial Mn₂O₃, is attributed to the high crystallization of α-Mn₂O₃, the large surface area that resulted from the core–shell structure with porous architecture, and the special core–shell structure that acted as a micro-reactor.     

Synthesis of new 4-methyl-3-piperidones via an iron-catalyzed intramolecular tandem isomerization–aldolisation process

A new versatile synthesis of 3-piperidones is described, starting from amino acids. It uses, as a key step, an iron carbonyl-mediated intramolecular tandem isomerization–aldolisation reaction. These new heterocycles appear as useful scaffolds for the total synthesis of various types of bioactive molecules.