Efficient anchorage of Pt clusters on N-doped carbon nanotubes and their catalytic activity

We report an efficient method for anchoring Pt clusters (e.g., 6 nm in size) on the surfaces of N-doped multi-walled carbon nanotubes (MWNTs-CN_x) using a relatively simple method consisting of a hydrothermal treatment of Na₂[PtCl₆] · 6H₂O and N-doped nanotubes dispersed in acetic acid. The catalytic properties of this material were evaluated finding that the conversion of cinnamaldehyde using Pt-coated MWNTs-CN_x could increase up to 6 times with respect to that obtained for uncoated MWNTs-CN_x and pure carbon CNTs. Therefore, we envisage this material could be either used as an efficient catalyst or as a sensor.     

Cadinane‐Type Sesquiterpenoids,Strobilols E – K,from the Liquid Culture of Strobilurus ohshimae

New cadinane sequiterpenoids, strobilols E–K ( 5 – 11 , resp.) have been isolated from a liquid culture of Strobilurus ohshimae. Their structures have been established on the basis of spectral analyses.     

Synthesis, stability, and complexation behavior of isolable salen-type N2S2 and N2SO ligands based on thiol and oxime functionalities

The new salen-type N(2)S(2) tetradentate ligands, H(2)L(1) and H(2)L(2), which have a donor set comprising oxime and thiol groups, were synthesized. These ligands are obtained as isolable colorless crystals, whereas the imine analogues are too unstable to be isolated. The unsymmetrical N(2)SO ligands, H(2)L(3) and H(2)L(4), were also obtained as stable compounds. When ligands H(2)L(1)-H(2)L(4) are heated above the melting points, they mainly decompose via cleavage of the N-O bonds of a thiosalicylaldoxime moiety to give 1,2-benzisothiazole derivatives. The complexation of the N(2)S(2) ligands (H(2)L(1) and H(2)L(2)) with nickel(II) acetate afforded square-planar mononuclear complexes [Ni(L(1))] and [Ni(L(2))], respectively. In contrast, the complexation of the N(2)SO ligand H(2)L(3) with nickel(II) acetate resulted in cleavage of the N-O bond, giving a tetranuclear complex having a cubane-type Ni(4)O(4) core. The N-O bonds of H(2)L(1)-H(2)L(4) are more readily cleaved when the ligands are allowed to react with copper(II) acetate. In these cases, the alkoxo-bridged dinuclear complexes having a Cu-O-Cu-O four-membered ring are obtained. On the other hand, mononuclear complexes can be obtained by complexation of the ligands (H(2)L(1) or H(2)L(3)) with palladium(II) acetate without N-O bond cleavage.     

Aerobic Direct Dioxygenation of Terminal/Internal Alkynes to α-Hydroxyketones by an Fe Porphyrin Catalyst

We herein report a new synthetic method for the preparation of α-hydroxyketones by the dioxygenation of alkynes. The reaction proceeds at room temperature under the action of Fe porphyrin and pinacolborane under air as a green oxidant to produce α-hydroxyketones. The mild reaction conditions allow chemoselective oxidation with functional group tolerance. Terminal alkynes in addition to internal alkynes are applicable, affording unsymmetrical α-hydroxyketones that are difficult to obtain by any reported dioxygenation of unsaturated C−C bonds.     

In situ synthesis of Cu nanocatalysts on ZnO whiskers embedded in a microstructured paper composite for autothermal hydrogen production

Cu nanoparticles (CuNPs) were successfully synthesized in situ on ZnO whiskers as a selective scaffold, which were supported in a microstructured paper matrix composed of inorganic fibers; as-prepared paper composites were easy to handle in practical use and demonstrated excellent catalytic performance in the methanol reforming process for effective hydrogen production.     

Solubilisation of [60]fullerenes using block copolymers and evaluation of their photodynamic activities

Unmodified [60]fullerenes (C60) were solubilised with high stability using various type of poly(ethylene glycol) (PEG) based block copolymer micelles. Block copolymer micelle-incorporated C60 fullerenes were studied in cultures for biological activities using human cervical cancer HeLa cells. As a result, the cationic block copolymer micelles delivered C60 into the cells depending on their surface densities and showed cytotoxicity under photoirradiation.     

Syntheses of manzacidins: a stage for the demonstration of synthetic methodologies

Manzacidins, a family of bromopyrrole alkaloids, have attracted much attention from the synthetic community due to their intriguing structures, bearing chiral tertiary and secondary stereocentres in a 1,3-relationship, and biological activities. In this article, we summarise the approaches for the preparation of manzacidins using novel synthetic methodologies. Organocatalysis and Lewis acid catalysis, as well as transition-metal catalysis, offered efficient ways to access these molecules.     

Degrees of polymerization (DP) and DP distribution of dilute acid-hydrolyzed products of alkali-treated native and regenerated celluloses

Three groups of cellulose II samples, 20% NaOH-treated native celluloses (M-native celluloses), commercial regenerated celluloses and those treated with 20% NaOH (M-regenerated celluloses), were subjected to dilute acid hydrolysis at 105 °C to obtain so-called leveling-off degrees of polymerization (LODP). Molecular mass parameters of the acid-hydrolyzed products were analyzed by SEC-MALLS using 1% LiCl/DMAc as an eluent. The LODP values were in the order of M-native celluloses ≅ M-regenerated celluloses > regenerated celluloses. The LODP values of M-regenerated celluloses are 1.5–1.7 times as much as those of the regenerated celluloses; the cellulose II crystallites in regenerated celluloses increase in size to the longitudinal direction by the alkali treatment and the successive acid hydrolysis at 105 °C. This increase in the longitudinal crystal sizes might primarily occur during acid hydrolysis. All the acid-hydrolyzed products had bimodal SEC elution patterns, i.e. the predominant high-molecular-mass and minor low-molecular-mass components, the latter of which corresponded to DP 20.     

Architecture of brush-on-brush copolymers by photoinduced ATRP approach

We established a preparation method of brush-on-brush copolymers by grafting from photoinduced ATRP of multifunctional polystyrene having N,N-diethyldithiocarbamate (DC) pendant groups with stearyl methacrylate (STM). We studied the solution properties of brush-on-brush copolymers from the view point of crowding effect of PSTM brush side chains. It was speculated from angular dependence on dynamic light scattering (DLS) that the brush-on-brush copolymer (BB1:PSTM brushes were grafted at regular intervals of 1/4 styrene units on the backbone) with large aspect ratio took a geometrical anisotropic conformation such as a cylinder due to crowding of brush side chains. In fact, transmission electron microscopy (TEM) photograph of such brush-on-brush showed a rigid rod-like morphology.