Synthesis, characterization and crystal structure of a new layered heterometallic coordination polymer {[(CuL) Sr-2(H2O)center dot Sr-2(H2O)(7)]center dot 2H(2)O center dot 0.5CH(3)OH}(n)

A copper-strontium heterometallic coordination polymer was synthesized and characterized by elemental analysis and IR spectra. The crystal structure was determined by single-crystal X-ray diffraction analyses. The title complex is a 2 D coordination polymer with the chemical formula [[(CuL)(2)Sr (H2O) center dot Sr-2 ((HO)-O-2)(7)]center dot 2H(2)O center dot 0.5CH(3)OH](n), where H4L = N-(2-hydroxybenzamido)-N'-(3-carboxylsalicylidene) ethylenediamine. Its structural unit is comprised of two adjacent units, which polymerized with each other to form a new layered heterometallic coordination polymer.

Anion coordination and molecular assembly in C2-substituted thiamine-anion systems: effects of the anion and molecular conformation

The compounds (het)(PtCl6)2H(2)O 1, (het)(HgI4).H2O 2 (het = 2-(alpha-hydroxyethyl)thiamine) and (hpt)(Hg2Br6) 3 (hpt = 2-(alpha-hydroxypropyl)thiamine) have been prepared and structurally characterized by X-ray crystallography in order to study the influence of the anion and molecular conformation on the formation of supramolecular architectures that adsorb anionic species. Both het and hpt molecules adopt the usual S conformation for C2-substituted thiamine but differ from the F conformation for C2-free thiamine derivatives. Two types of characteristic ligand-anion complexation are observed, being of the forms C(6')-H...anion...thiazolium-ring (in 1 and 2) and N(4'1)-H...anion...thiazolium-ring (in 3). The reaction of het with PtCl62- or HgI42- gives a 1-D double-chain in 1, consisting of two hydrogen-bonded het chains, which are cross-linked by anions through hydrogen bonding and anion...aromatic-ring interactions, or a cationic 3-D framework in 2 formed by the stacking of hydrogen-bonded sheets with anion-and-water-filled channels. In the case of 3, hydrogen-bonded hpt dimers and HgBr62- anions form alternate cation-anion columns. A comparison with the cases of C2-free thiamine-anion complexes indicates that the change in molecular conformation results in novel supramolecular assemblies in 1 and 2 and an analogous architecture in 3, which also depends on the nature of the anions.

Studies of electron-transfer and charge-transfer coupling processes at a liquid/liquid interface by double-barrel micropipet technique

Investigation of a heterogeneous electron-transfer (ET) reaction at the water/1,2-dichloroethane interface employing a double-barrel micropipet technique is reported. The chosen system was the reaction between Fe(CN)(6)(3-) in the aqueous phase (W) and ferrocene in 1,2-dichloroethane (DCE). According to the generation and the collection currents as well as collection efficiency, the ET-ion-transfer (IT) coupling process at such an interface and competing reactions with the organic supporting electrolyte in the organic phase can be studied. In addition, this technique has been found to be an efficient method to distinguish and measure the charge-transfer coupling reaction between two ions (IT-IT) processes occurring simultaneously at a liquid/liquid interface. On this basis, the formal Gibbs energies of transfer of some ions across the W/DCE interface, such as NO3-, NO2-, Cl-, COO-, TBA(+), IPAs+, Cs+, Rb+, K+, Na+, and Li+, for which their direct transfers are usually difficult to obtain because of the IT-IT coupling processes, were quantitatively evaluated.

Synthesis, crystal structure, and magnetic properties of {[Cu(oxbe)]Mn(H2O)[Cu(oxbe)(DMF)]}(n)center dot nDMF center dot nH(2)O: From dissymmetrical mononuclear entities to a 3D heterometallic supramolecular coordination polymer

Self-assembly of the building block [Cu(oxbe)](-) with Mn(II) led to a novel coordination polymer {[Cu(oxbe)]Mn(H2O)(Cu(oxbe)(DMF)]}(n).nDMF.nH(2)O, where H(3)oxbe is a new dissymmetrical ligand N-benzoato-N'-(2-aminoethyl)-oxamido and DMF = dimethylformamide. The crystal forms in the triclinic system, space group P(1)over-bar, with a = 9.260(4) angstorm, b = 12.833(5) angstrom, c = 15.274(6) angstrom , alpha = 76.18(3)degrees, beta = 82.7(3)degrees, gamma = 82.31(3)degrees, and Z = 2. The crystal structure of the title complex reveals that the two-dimensional bimetallic layers are constructed of (CuMnII)-Mn-II-Cu-II chains linked together by carboxylate bridge and hydrogen bonds help to produce a novel three-dimensional channel-like structure. The magnetic susceptibility measurements (5-300 K) were analyzed by means of the Hamiltonian (H)over-cap = -2J(S)over-cap (Mn)((S)over-cap(Cu1) + (S)over-cap(Cu2)), leading to J = -17.4 cm(-1).

Fabrication of integrated microelectrodes for electrochemical detection on electrophoresis microchip by electroless deposition and micromolding in capillary technique

A new method for the fabrication of an integrated microelectrode for electrochemical detection (ECD) on an electrophoresis microchip is described. The pattern of the microelectrode was directly made on the surface of a microscope slide through an electroless deposition procedure. The surface of the slide was first selectively coated with a thin layer of sodium silicate through a micromolding in capillary technique provided by a poly(dimethylsiloxane) (PDMS) microchannel; this left a rough patterned area for the anchoring of catalytic particles. A metal layer was deposited on the pattern guided by these catalytic particles and was used as the working electrode. Factors influencing the fabrication procedure were discussed. The whole chip was built by reversibly sealing the slide to another PDMS layer with electrophoresis microchannels at room temperature. This approach eliminates the need of clean room facilities and expensive apparatus such as for vacuum deposition or sputtering and makes it possible to produce patterned electrodes suitable for ECD on microchip under ordinary chemistry laboratory conditions. Also once the micropattern is ready, it allows the researchers to rebuild the electrode in a short period of time when an electrode failure occurs. Copper and gold microelectrodes were fabricated by this technique. Glucose, dopamine, and catechol as model analytes were tested.

A novel 3D network coordination polymer consisting of paddlewheel Co-3 clusters connected by PO4 and 4-pyridinecarboxylate

The synthesis, structural characterization and preliminary magnetic studies of a novel coordination polymer with paddlewheel Co-3 clusters are reported firstly. In the polymer, Co-3 clusters are covalently linked through PO4 tetrahedra and 4-pyridinecarboxylate (4-pya) ligands into interpenetrated three-dimensional network.

Copolymerization of carbon dioxide and propylene oxide with neodymium trichloroacetate-based coordination catalyst

The copolymerizations of carbon dioxide (CO2) and propylene oxide (PO) were performed using new ternary rare-earth catalyst, It was found that the rare-earth coordination catalyst consisting of Nd(CCl3COO)(3), ZnEt2 and glycerine was very effective for the copolymerization of PO with CO2. The effects of the relative molar ratio and addition order of the catalyst components, copolymerization reaction time, and operating pressure as well as temperature on the copolymerization were systematically investigated. At an appropriate combination of all variables, the yield could be as high as 6875 g/mol Nd per hour at 90 degreesC in a 8 h reaction period.

Extraction mechanism of rare earths with sec-octylphenoxy acetic acid by two-phase titration technique

The compositions of the extracted complexes of La, Gd, Er and Y with sec-octyl-phenoxy acetic acid in heptane and the related apparent extraction equilibrium constants K-M were determined using two-phase titration technique. The stoichiometric compounds for La, Gd, Er and Y should be LaA(3) . 2.5HA, GdA(3) . 3HA, ErA(3) . 3.1HA and YA(3) . 4.3HA respectively. And their pK(M) are 3.43, 3.46, 3.08 and 2.58 respectively.

New technique for capillary electrophoresis directly coupled with end-column electrochemiluminescence detection

capillary electrophoresis (CE) is characterized. A 300 mum diameter Pt working electrode was used to directly couple with a 75 mum inner diameter separation capillary without an electric field decoupler. The hydrodynamic cyclic voltammogram (CV) of Ru(bpy)(3)(2+) showed that electrophoretic current did not affect the ECL reaction. The presence of high-voltage (HV) field only resulted in the shift of the ECL detection potential. The distance of capillary to electrode was an important parameter for optimizing detection performance as it determined the characteristics of mass transport toward the electrode and the actual concentration of Ru(bpy)(3)(2+) in the detection region. The optimum distance of capillary to electrode was decided by the inner diameter of the capillary, too. For a 75 mum capillary, the working electrode should be placed away from the capillary outlet at a distance within the range of 20-260 mum. The effects of pH value of ECL solution and molecular structure of analytes on peak height and theoretical plate numbers were discussed. Using the 75 mum capillary, under the optimum conditions, the method provided a linear range for tripropylamine (TPA) between 1 x 10(-10) and 1 X 10(-5) mol/L with correlation coefficient of 0.998. The detection limit (signal-to-noise ratio S/N = 3) was 5.0 x 10(-11) mol/L. The relative standard deviation in peak height for eight consecutive injections was 5.6%. By this new technique lidocaine spiked in a urine sample was determined. The method exhibited the linear range for lidocaine from 5.0 x 10(-8) to 1.0 X 10(-5) mol/L with correlation efficient of 0.998. The limit of detection (S/N = 3) was 2.0 x 10(-1) mol/L.

A relocated technique of atomic force microscopy (AFM) samples and its application in molecular biology

A kind of simple atomic force microscopy (AFM) relocated technique, which takes advantage of homemade sample locator system, is used for investigating repeatedly imaging of some specific species on the whole substrate (over 1 x 1 cm(2)) with resolution about 400 nm. As applications of this sample locator system, single extended DNA molecules and plasmid DNA network are shown in different AFM operational modes: tapping mode and contact mode with different tips after the substrates have been moved.

Polydispersity of ethylene sequence length in metallocene ethylene/alpha-olefin copolymers. I. Characterized by thermal-fractionation technique

In this article, the polydispersity of the ethylene sequence length (ESL) in ethylene/alpha-olefin copolymers was studied by atomic force microscopy (AFM) and the thermal-fractionation technique. The crystal morphology observation by AFM showed that morphology changed gradually with decreasing average ESL from complete lamellae over shorter and more curved lamellae to a granular-like morphology, and the mixed morphology was observed after stepwise crystallization from phase-separated melt. This result indicated that the ethylene sequence with different lengths crystallized into a crystalline phase with a different size and stability at the copolymer systems. The thermal-fractionation technique was used to characterize the polydispersity of ESL. Three of the following statistical terms were introduced to describe the distribution of ESL and the lamellar thickness: the arithmetic mean (L) over bar (n), the weight mean (L) over bar (w), and the broadness index I = (L) over bar (w)/(L) over bar (n). It was concluded that the polydispersity of ESL could be quantitatively characterized by the thermal-fractionation technique. The effects of temperature range, temperature-dependent specific heat capacity C-p of copolymer, and the molecular weight on the results of thermal fractionation were discussed,

Construction of CdS nanostructures on DNA template by LB technique

Mixed monolayer films of octadecylamine (ODA) and oligo-DNA were prepared by Langmuir-Blodgett technique and the monolayer films were used as template to direct the formation of different CdS nanostructures. It was found that CdS nanowire was observed when the monolayer film prepared at low surface pressure was used as template, and aggregate of CdS spheres was obtained when the monolayer film deposited at high surface pressure was used as template.

Improved thermal fractionation technique for chain structure analysis of ethylene/alpha-olefin copolymers

In this report, we describe an improved thermal fractionation technique used to characterize the polydispersity of crystalline ethylene sequence length (CESL) of ethylene/alpha -olefin copolymers. After stepwise isothermal crystallization, the crystalline ethylene sequences are sorted into groups by their lengths. The CESLs are estimated using melting points of known hydrocarbons. The content of each group is determined using the calibrated peak area. The statistical terms: the arithmetic mean (L) over bar (n), the weighted mean (L) over bar (w) and the broadness index I = (L) over bar (w)/(L) over bar (n) are used to describe the distribution of CESL. Results show that improved thermal fractionation technique can quantitatively characterize the polydispersity of CESL with a high degree of accuracy.

Two new coordination polymers of Co(II) with 1,1 '-(1,4-butanediyl)bis(benzimidazole)

Two new compounds, [CoL2(H2O)(2)](NO3)(2). 8H(2)O (1) and [CoL(H2O)(2)(CH3CO2)(2)]. H2O (2), were obtained from self-assembly of the corresponding metal salts with 1,1'-(1,4-butanediyl)bis(benzimidazole) (L). In 1, each cobalt ion is coordinated to four nitrogen atoms from four molecules of L, and to two water molecules. Metal ions are bridged by L ligands to form infinite (4, 4) networks that contain 44-membered rings. The (4, 4) networks of 1 stack in a parallel fashion, resulting in the formation of large channels in the material. In 2, each cobalt ion is coordinated to two N atoms from two L molecules, two water molecules and two carboxylate O atoms from two acetate anions. Each L molecule is coordinated to two cobalt ions, acting as a bridging ligand as in 1. The bridged cobalt ions form an infinite zigzag chain structure.

Structure of coordination polymer, [Zn(bipy)(H2O)(3)SO4] center dot 2H(2)O (bipy=4,4 '-bipyridine)

The crystal of the title compound (C10H18N2O9SZn M-r=407.69) belongs to the hexagonal system, space group P 6(5) with cell parameters: a=11.411 (2), c=20.908(4) Angstrom, V=2357.7(7) Angstrom(3), Z=6, D-c=1.723g/cm(3), F(000)=1260, mu(MoKa)=1.743mm(-1). The final R and omega R factors are 0.072 and 0.178 respectively for 1335 observed reflections. in the structure, zinc ions are bridged by 4,4'-bipyridine to form infinite chains. The sheets containing parallel chains stack along a 65 screw axis to give a helical staircase motif. The helical structure is mainly controlled by the hydrogen bonds.