Nickel and cationic palladium complexes bearing (imino)pyridyl alcohol ligands: Synthesis, characterization and vinyl polymerization of norbornene

A series of nickel and palladium complexes bearing (imino)pyridyl alcohol tridentate [N,N,O] ligands, 2-(ArNCMe)-6-{(HO)CR₂}C₅H₃N (L1-L4), were synthesized and sufficiently characterized by elemental and spectroscopic analysis along with X-ray diffraction analysis. The X-ray diffraction demonstrated that five-coordinated nickel halide complexes (1a-4a and 1b) and six-coordinated nickel acetate complex (1c) were prepared, and cationic palladium complexes (1d and 2d) formed with the [PdCl₄]²⁻ counterion. All these complexes displayed high catalytic activities up to 1.883 × 10⁷ g(PNB) mol⁻¹(cat) h⁻¹ (2d) for the vinyl polymerization of norbornene on treatment with excess methylaluminoxane (MAO), affording the vinyl-type PNBs with high molecular weights and relatively narrow molecular weight distributions. The parameters of reaction conditions, the type of metals and steric effects of coordinative ligands had influences on the catalytic properties.     

Voltammetric sensing of paracetamol, dopamine and 4-aminophenol at a glassy carbon electrode coated with gold nanoparticles and an organophillic layered double hydroxide

A differential pulse voltammetric method was developed for the simultaneous determination of paracetamol, 4-aminophenol and dopamine at pH 7.0 using a glassy carbon electrode (GCE) coated with gold nanoparticles (AuNPs) and a layered double hydroxide sodium modified with dodecyl sulfate (SDS-LDH). The modified electrode displays excellent redox activity towards paracetamol, and the redox current is increased (and the corresponding over-potential decreased) compared to those of the bare GCE, the AuNPs-modified GCE, and the SDS-LDH-modified GCE. The modified electrode enables the determination of paracetamol in the concentration range from 0.5 to 400???M, with a detection limit of 0.13???M (at an S/N of 3). The sensor was successfully applied to the stimultaneous determination of paracetamol and dopamine, and of paracetamol and 4-aminophenol, respectively, in pharmaceutical tablets and in spiked human serum samples.

Asymmetric synthesis of piperidines and octahydroindolizines using a one-pot ring-closure/N-debenzylation procedure

The conjugate addition of an enantiopure lithium amide to a ζ-hydroxy-α,β-unsaturated ester followed by a one-pot ring-closure/N-debenzylation protocol has been used in the asymmetric syntheses of (S)-coniine and (R)-δ-coniceine (isolated as the corresponding hydrochloride salts), and (R,R)-1-(hydroxymethyl)octahydroindolizine (the bicyclic fragment of stellettamides A-C).     

Electrocatalysis Oxidation of GMP Based on Layered Double Hydroxide Functionalized with Anionic Surfactant and Room Temperature Ionic Liquid Modified Glassy Carbon Electrode

The electrocatalysis oxidation of guanosine‐5′‐monophosphate (GMP) was investigated on Mg‐Al layered double hydroxide (LDH) functionalized with sodium dodecyl sulfate (SDS) and room temperature ionic liquid (RTIL) modified glass carbon electrode (GCE). The cyclic voltammogram of GMP on the modified electrode (RTIL/ LDH‐SDS/GCE) exhibited a well defined anodic peak at 1.091 V in 0.2 mol·L^?1 pH 4.4 acetate buffer solution. The GMP oxidation was enhanced in the presence of anionic surfactant in the ?lms. The results suggest that the surfactant molecules intercalate the LDH layers to preconcentrate GMP molecules and the RTIL showed good ionic conductivity. The experimental parameters were optimized, the kinetic parameters were investigated and the probable oxidation mechanism was proposed. Under the optimized conditions, the oxidation peak current was proportional to GMP concentration in the range from 5.0×10^?7 to 1.0×10^?4 mol·L^?1 with the correlation coefficient of 0.9987 and the detection limit was 1.0×10^?7 mol·L^?1. The RTIL/LDH‐SDS/GCE showed a good electrochemical response to the oxidation of GMP and would be developed into a new biosensor.     

Synthesis and bioactivity of novel coumarin derivatives containing(E)-methyl 2-(methoxyimino)-2-phenylacetates

Ten coumarin derivatives containing(E)-methyl 2-(methoxyimino)-2-phenylacetate were synthesized and bioassayed.The compounds were identified by IR,~1H NMR and elemental analyses.The test results indicated that compound 5j(R~1 is methyl and R~2 is n-C_6H_(13)) was the optimal structure in this paper with good fungicidal activity against CDM(85%) at 6.25 mg/L concentration.     

Simple preparation and catalytic properties of ZnO for ozonation degradation of phenol in water

ZnO particles about 200 nm were prepared through a facile hydrothermal method.Compared with single ozonation,the degradation efficiency of phenol increased about 23.7%and the degradation efficiency of intermediates improved about four times in the presence of ZnO at 298 K.In addition,the catalyst had good stability in the ozonation process.The influence of temperature was investigated and it was found that the better catalysis efficiency could be obtained at lower temperature.     

High performance liquid chromatography with immobilized Ru(bpy)_3~(2+)-KMnO_4 chemiluminescence detection and its application in metabolism of repaglinide in pig liver microsomes

A novel high performance liquid chromatography-chemiluminescence（HPLC-CL） method for investigation of in vitro metabolism of repaglinide in pig liver microsomes with microdialysis sampling technique was developed.The chromatographic separation was performed on a Hypersil BDS-C18 column with an isocratic mobile phase consisting of methanol and 0.01 mol/L KH₂PO₄（pH 3.0）（volume ratio 75:25） at a flow rate of 1.0 mL/min.The detection was based on the chemiluminescence reaction of repaglinide with acidic potassium permanganate（KMnO₄） and tris（2,2’-bipyridyl）ruthenium（Ⅲ）(Ru（bpy）₃³⁺),which was immobilized on the cationic ion-exchange resin for obtaining high sensitivity and reducing consumption of expensive reagent.     

Preparation of Li_4Ti_5O_(12) submicrospheres and their application as anode materials of rechargeable lithium-ion batteries

We report on the preparation of spinel Li4Ti5O12 submicrospheres and their application as anode materials of rechargeable lithium-ion batteries. The spinel Li4Ti5O12 submicrospheres are synthesized with three steps of the hydrolysis of TiCl4 to form rutile TiO2, the hydrothermal treatment of rutile TiO2 with LiOH to prepare an intermediate phase of LiTi2O4+δ, and the calcinations of LiTi2O4+δ to obtain spinel Li4Ti5O12. The as-prepared products are investigated by X-ray powder diffraction (XRD), scanning el...     

Expeditious one-pot synthesis of C3-piperazinyl-substituted quinolines: key precursors to potent c-Met inhibitors

An effective one-pot synthesis of quinolines bearing diverse C3-piperazinyl functions was developed by using a modified Friedl?nder's protocol. The method not only enables the synthesis of our early reported c-Met inhibitor on a large scale, but also provides a way to generate novel multi-substituted quinolines for further structure-activity relationship (SAR) study.     

A novel hydrazide type organocatalyst for enantioselective Diels-Alder reactions

The development of a new class of hydrazide type organocatalyst, (4R,5R)-1,3-bis(isopropylamino)-4,5-dihenylimidazolidin-2-one 2a, for enantioselective Diels-Alder reactions between cyclopentadiene and α,β-unsaturated aldehydes are presented. The new organocatalyst 2a promoted the reaction, affording Diels-Alder adducts in good yields with good levels of enantioselectivity.