Fluorous osmium tetraoxide (OsO4): a recoverable and reusable catalyst for dihydroxylation of olefins

A fluorous osmium catalyst was firstly developed. It had been effectively used as recoverable and reusable catalyst in the dihydroxylation of olefins.     

Synthesis of 3-hydroxyindolin-2-one alkaloids, (±)-donaxaridine and (±)-convolutamydines A and E, through enolization-Claisen rearrangement of 2-allyloxyindolin-3-ones

Claisen rearrangement triggered by enolization of 2-allyloxyindolin-3-ones with DBU was performed in order to prepare 3-allyl-3-hydroxyindolin-2-ones. Total synthesis of 3-hydroxyindolin-2-one alkaloids, (±)-donaxaridine, as well as (±)-convolutamydines A and E, was achieved by transformation of the allyl moiety of 3-allyl-3-hydroxyindolin-2-ones.     

Chiral Dinuclear EuIII,TbIII, and YIII Complexes Supported by P-Stereogenic Linear Tetraphosphine Tetraoxide

A P-stereogenic linear tetraphosphine tetraoxide, (R,R)- or (S,S)-dpmppm(=O)₄, was synthesized to prepare C₂ dinuclear M(hfa)₃ complexes (M=Eu, Tb, Y) as the first example of lanthanide(III) complexes with P-chiral multidentate phosphine oxides. The mononuclear M(hfa)₃ complexes (M=Eu, Y) with a P-chiral diphosphine dioxide, tpdpb(=O)₂, were also prepared, and comparison of their photophysical properties for the Eu^III complexes revealed that significant chiral induction from the P-chiral centers arises on the achiral M(hfa)₃ units through intramolecular π-π stacking constraint in the dinuclear system.     

Strong Morphological Effect of Mn3O4 Nanocrystallites on the Catalytic Activity of Mn3O4 and Au/Mn3O4 in Benzene Combustion

Gold nanoparticles (3–4 nm) were deposited on Mn₃O₄ nanocrystallites with three distinct morphologies (cubic, hexagonal, and octahedral). The resulting structures were characterized, and their activities for benzene combustion were evaluated. The dominant exposed facets for the three kinds of Mn₃O₄ polyhedrons show the activity order: (103)≈(200)>(101). A similar activity order was derived for the interfaces between the Au and the Mn₃O₄ facet: Au/(200)≈Au/(103)>Au/(101). The metal–support interactions between the Au nanoclusters and specific facets of the Mn₃O₄ polyhedrons lead to a unique interfacial synergism in which the electronic modification of the Au nanoparticles and the morphology of the Mn₃O₄ substrate have a joint effect that is responsible for a significant enhancement in the catalytic activity of the Au/Mn₃O₄ system.     

Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds using iodine and bromine or their sodium salts in the presence of the Fe(NO3)3·1.5N2O4/charcoal system

Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds with iodine and bromine or their sodium salts proceed well in the presence of Fe(NO₃)₃·1.5N₂O₄/charcoal in CH₂Cl₂ at room temperature.     

Herstellung keramischer Pulver. IX. Zur Bildung von NiMn2 O4 und ZnMn2O4 durch Zersetzung von [Ni(H2O)6] (MnO4)2 und [Zn(H2O)6] (MnO4)2

Preparation of Ceramic Powders. IX. NiMn₂O₄ and ZnMn₂O₄ Formation by Decomposition of [Ni(H₂O)₆] (MnO₄)₂ and [Zn(H₂O)₆] (MnO₄)₂ Improved preparation of Ba(MnO₄)₂ from BaMnO₄ is reported. Thermal or hydrothermal decomposition of [Ni(H₂O)₆] (MnO₄)₂ yields intermediately an amorphous manganate(IV) which forms crystalline NiMnO₃ and α-Mn₂O₃ in the range T > 400°C. NiMn₂O₄ is formed above 730°C in accordance with the phase diagram. On the other hand, ZnMn₂O₄ is already at 300°C obtained from [Zn(H₂O)₆](MnO₄)₂ at hydrothermal conditions.     

Excited states of OsO4: A comprehensive time‐dependent relativistic density functional theory study

A large number of scalar as well as spinor excited states of OsO₄, in the experimentally accessible energy range of 3–11 eV, have been captured by time‐dependent relativistic density functional linear response theory based on an exact two‐component Hamiltonian resulting from the symmetrized elimination of the small component. The results are grossly in good agreement with those by the singles and doubles coupled‐cluster linear response theory in conjunction with relativistic effective core potentials. The simulated‐excitation spectrum is also in line with the available experiment. Furthermore, combined with detailed analysis of the excited states, the nature of the observed optical transitions is clearly elucidated. It is found that a few scalar states of ³T₁ and ³T₂ symmetries are split significantly by the spin‐orbit coupling. The possible source for the substantial spin‐orbit splittings of ligand molecular orbitals is carefully examined, leading to a new interpretation on the primary valence photoelectron ionization spectrum of OsO₄. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Facile Synthesis of Reduced Graphene Oxide-octahedral Mn3O4 Nanocomposites as a Platform for the Electrochemical Determination of Metronidazole and Sulfamonomethoxine

A facile synthesis strategy of reduced graphene oxide (RGO)-octahedral Mn₃O₄ (oct-Mn₃O₄) nanocomposites using in situ one-pot hydrothermal reaction was reported. The RGO-oct-Mn₃O₄ nanocomposites were drop-casted onto the surface of glassy carbon electrode (GCE) to obtain RGO-oct-Mn₃O₄/GCE. DPV results revealed that the performance of RGO-oct-Mn₃O₄/GCE towards metronidazole displayed a linear ranging from 0.1 to 9.5 μM with a detection limit of 0.037 μM. For sulfamonomethoxine, it exhibited a linear ranging from 1 to 95 μM with a detection limit of 0.27 μM. Moreover, the proposed sensor had good anti-interference capability, high stability, satisfactory reproducibility, and was successfully applied in real samples.     

钒酸银/氧化石墨烯复合物的制备和可见光催化性能

通过改进Hummers法制备了氧化石墨烯(GO),采用液相沉淀法合成了Ag₃VO₄/GO复合物,利用X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外-可见(UV-Vis)漫反射光谱等技术手段对样品进行了测试表征;并在可见光辐射下(λ≥420 nm)考察了复合物催化剂中GO含量对Ag₃VO₄光催化降解甲基橙溶液(MO)的性能影响。 结果表明,掺杂质量分数2%的GO复合物光催化活性提高最显著,30 min内对MO的降解率可达到89%以上,是纯Ag₃VO₄光催化活性的3倍。