Dicopper complexes catalyzed coupling/cyclization of 2‐bromobenzoic acids with amidines leading to quinazolinones

Dicopper(I) complexes {Cu₂(bpnp)(CH₃CN)₄}(PF₆)₂] ( 2 ), [{Cu₂(bpnp)(CH₃CN)₄}(BAr₄^F)₂] ( 3 ) and [Cu₂(bpnp)Cl₂] ( 4 ) were prepared from the complexation of [Cu(CH₃CN)₄](PF₆) with 2,7‐bis(2‐pyridyl)‐1,8‐naphthyridine (bpnp) followed by anion metathesis and treatment of chloride sequentially. The X‐ray structural analysis of 4 indicates the molecule to have a twofold axis passing through the Cu₂Cl₂ core, which has the shape of a butterfly, and that the Cu atom is tetrahedrally coordinated with in a Cl₂N₂ donor set. In preliminary experiments 2 was found to be an effective catalyst in the coupling/cyclization of 2‐bromobenzoic acids with amidines, providing the corresponding quinazolinones in good yields. Copyright © 2014 John Wiley & Sons, Ltd.     

Novel fabrication of Janus particles from the surfaces of electrospun polymer fibers

A novel synthetic approach for the efficient fabrication of Janus silica particles was demonstrated by embedment of zero-dimensional colloids on one-dimensional polymer fiber surfaces, followed by the surface modification on the exposed silica hemispheres. Electrospinning of poly(methyl methacrylate) and poly(4-vinyl pyridine) blends produced polymer fibers with high specific surface area and desired surface hydrophilicities. Fiber compositions determined the colloid adsorption density and uniformity. The colloid embedding resulted from the polymer softening was manipulated by the isothermal heat treatment. Subsequent silianization completed the amino functionalities on hemispherical surfaces of embedded silica colloids. Janus particles with uniform asymmetric chemical features were further labeled with gold nanoparticles before their recovery from fiber substrates. Fabrication of Janus particles, including colloid adsorption, temperature-driven embedding, and hemispherical surface modification, were investigated and are discussed.     

Haemoglobin immobilized on nafion modified multi-walled carbon nanotubes for O2, H2O2 and CCl3COOH sensors

A conductive biocomposite film (MWCNTs-NF-Hb) containing multi-walled carbon nanotubes (MWCNTs) incorporated with entrapped haemoglobin (Hb) in nafion (NF) has been synthesized on glassy carbon electrode (GCE), gold (Au), indium tin oxide (ITO) and screen printed carbon electrode (SPCE) separately by potentiostatic methods. The presence of both MWCNTs and NF in the biocomposite film enhances the surface coverage concentration (Γ), and increases the electron transfer rate constant (K_s) to 132%. The biocomposite film exhibits a promising enhanced electrocatalytic activity towards the reduction of O₂, H₂O₂ and CCl₃COOH. The cyclic voltammetry has been used for the measurement of electrocatalysis results of analytes by means of biocomposite film-modified GCEs. The MWCNTs-NF-Hb-modified GCEs’ sensitivity values are higher than the values obtained for other film modified GCEs. The surface morphology of the biocomposite films which have been deposited on ITO has been studied using scanning electron microscopy and atomic force microscopy. The studies have revealed that there was an incorporation of NF and immobilization of Hb on MWCNTs. Finally, the flow injection analysis has been used for the amperometric studies of analytes at MWCNTs-Hb and MWCNTs-NF-Hb film modified SPCEs. The amperometric study results have shown higher slope values for MWCNTs-NF-Hb biocomposite film.     

Ab Initio Calculations of Structure and Energetics of the Hypermetalated Hydrogen Oxide Molecules: Li2NaOH and LiNa2OH

We made ab initio electronic calculations of the structure and energetics of mixed hypermetalated hydrogen oxides, Li₂NaOH and LiNa₂OH. There exist five equilibrium geometries for each complex. In all levels of calculation the global minimum structure for Li₂NaOH has C_2v symmetry and a large distance between sodium and oxygen, 4.24 Å (MP2/6-31G*). The dissociation energies to all possible products were also calculated. Li₂NaOH → Na + Li₂OH δH = +25.33 kcal/mol (at MP4/6-311++G**//6-31G* + ZPE scaled by 0.9). All other dissociation processes are highly endothermic. Similar procedures were applied to LiNa₂OH. The global minimum structure for LiNa₂OH belongs to point group C_s. It is also endothermic to all possible dissociation paths. LiNa₂OH →Na + LiNaOH δH = +12.72 kcal/mol (at MP4/6-311++G*//6-31G* + ZPE scaled by 0.9). The nuclear repulsion energy is crucial in energetics of the structures. The distribution of electron density and bonding properties for these equilibrium structures were analyzed.     

Chirality Control of Quadruple Helixes of Metal Strings by Peripheral Chiral Ligands

Chirality control of helixes with the Δ (P) or Λ (M) form is interesting in various fields such as extended metal atom chains (EMACs), in which the metal backbones are helically wrapped by four ligands. Herein, we report two EMACs, Δ‐[Ni₅((?)camnpda)₄] and Λ‐[Ni₅((+)camnpda)₄], whose chiralities are controlled by chiral ligands with naphthyridine and camphorsulfonyl groups. There is a large energy difference (108 kcal mol^?1) between the two helical structures with one chiral ligand. Furthermore, the electron communication between [Ni₂]³⁺ units is more pronounced than in [Ni₅(bna)₄Cl₂]²⁺ (bna=binaphthyridylamido). The results demonstrate control of small‐scale helical structure and set the stage for future development of chiral controlled base and nanoelectronic devices.     

Enhanced lithium intercalation and conduction in LiαFeTaxOyCz films by the addition of lithium oxides with an atmospheric pressure plasma jet

Journal of Solid State Electrochemistry - An enhancement of lithium ionic intercalation and conduction performance of lithiated-organo-iron-tantalum oxide (LiαFeTaxOyCz) films has been...     

Sedimentation of a cylindrical particle in a Carreau fluid

The drag coefficient of an isolated, rigid cylindrical particle in a Carreau fluid is evaluated. The result of numerical simulation reveals that, in general, the shear-thinning nature of a Carreau fluid yields a drag coefficient smaller than that for the corresponding Newtonian fluid. Also, the smaller the Reynolds number, the more appreciable the decrease of the drag coefficient as the relaxation time constant of the Carreau fluid increases. The influence of the index parameter of a Carreau fluid on the drag coefficient depends largely on the magnitude of the relaxation time constant and is insensitive to the Reynolds number. Only if the relaxation time constant is sufficiently large is the influence of the index parameter on the drag coefficient significant. If the Reynolds number and/or the relaxation time constant is sufficiently large, the flow field upstream of a particle becomes asymmetric to that downstream. In general, the influence of the index parameter, the relaxation time constant, and the Reynolds number on the flow field follows the order index parameter相似文献