SYNTHESIS, STRUCTURE AND ELECTRICAL PROPERTIES OF POLY(PHENYLENE VINYLENE) FILM DOPED WITH FERRIC CHLORIDE

Poly(phenylene vinylene) (PPV) film was synthesized via a soluble precursor poly-mer. Strong fluorescence at 500-600nm was observed in both precursor and PPV film.Room-temperature conductivity of PPV film doped with FeCl_3 depends on the eliminationtemperature, the concentration of FeCl_3 and doping time. The maximum conductivity ofdoped PPV at room-temperature can reach about 40 S·cm~(-1). The temperature depen-dence of conductivity was controlled by 1D-VRH (1 Dimension Variable Range Hopping)model with T_0 value of 3.9×10~3 K. Non-Ohmic conductivity resulting from Schottky effectwas observed and the value of converted voltage from Ohmic region into non-Ohmic regionat the current-voltage characteristic was found to be dependent upon the work function ofelectrodes.     

Novel pseudo-morphotactic synthesis and characterization of tungsten nitride nanoplates

A novel pseudo-morphotactic transformation route was developed to synthesize polycrystalline β-W₂N nanoplates by thermally treating tungstate-based inorganic-organic hybrid nanobelts with a lamellar microstructure in an NH₃ flow. The tungstate-based hybrid nanobelts were formed in a water-in-oil-microemulsion-like “commercial H₂WO₄ powders/n-octylamine/heptane” reaction system. The as-obtained hybrid nanobelts were thermally treated in an NH₃ atmosphere at 650-800 °C for 2 h to form cubic β-W₂N nanoplates. XRD, SEM, TEM, FT-IR and TG-DTA were used to characterize the precursors and their final products. The polycrystalline β-W₂N nanoplates derived from hybrid nanobelts, with side lengths of several hundred nanometers, consist of small nanocrystals with an average grain size of 3.2 nm. The formation of β-W₂N nanoplates involved two steps: decomposing tungstate-based hybrid nanobelts into WO_y and W species and then nitridizing the active W-containing species to β-W₂N nanocrystals in an NH₃ flow. The platelike morphology of the β-W₂N nanocrystals was inherited from the precursor of tungstate-based inorganic-organic hybrid nanobelts.     

Determination of hydroxyl radical in Fenton system

Under visible light illumination,2,3-diaminophenazine(DAPN) was generated from the oxidation of o-phenylenediamine (OPDA) in Fe~(3+)/H_2O_2 solution.Hydroxyl radical(~·OH) produced in this system was determined by directly measuring the concentration of DAPN.In comparison with the traditional methods,the determination is more accurate and simple.     

Fluorescent Immunoassay with a Copper Polymer as the Signal Label for Catalytic Oxidation of O-Phenylenediamine

This work suggested that Cu²⁺ ion coordinated by the peptide with a histidine (His or H) residue in the first position from the free N-terminal reveals oxidase-mimicking activity. A biotinylated polymer was prepared by modifying His residues on the side chain amino groups of lysine residues (denoted as K_H) to chelate multiple Cu²⁺ ions. The resulting biotin-poly-(K_H-Cu)₂₀ polymer with multiple catalytic sites was employed as the signal label for immunoassay. Prostate specific antigen (PSA) was determined as the model target. The captured biotin-poly-(K_H-Cu)₂₀ polymer could catalyze the oxidation of o-phenylenediamine (OPD) to produce fluorescent 2,3-diaminophenazine (OPDox). The signal was proportional to PSA concentration from 0.01 to 2 ng/mL, and the detection limit was found to be eight pg/mL. The high sensitivity of the method enabled the assays of PSA in real serum samples. The work should be valuable for the design of novel biosensors for clinical diagnosis.     

Crystal Structures, and Electrical Conducting and Magnetic Properties in the Plate Crystals of (Ethylenedithiotetrathiafulvalenoquinone-1,3-dithiolemethide)2·MX4 (M=Fe, Ga, X=Br; M=Fe, X=C1) Salts

By the reaction of a new donor molecule, ethylenedithiotetrathiafulvalenoquinone-1,3-dithiolemethide (1) with FeBr₃, GaBr₃ or FeCl₃ in CH₃CN/CS₂ charge transfer (CT) salts of 1 with counteranions of FeBr₄⁻, GaBr₄⁻ or FeCl₄⁻ (1₂·FeBr₄, 1₂·GaBr₄ and 1₂·FeCl₄) as plate crystals were obtained. Their crystal structures are apparently similar to each other, in which 1 molecules are dimerized in the parallel direction of their molecular long axes, and the dimers are stacked with changing the direction of the molecular long axes alternately to form a one- dimensional column. The counteranions intervene between the 1-stacked columns and are aligned in a zigzag manner. The room-temperature electrical conductivities of 1₂·FeBr₄ and 1₂·GaBr₄ are fairly high (10-15 S cm⁻¹), but a small value (0.8 S cm⁻¹) is obtained for 1₂·FeCl₄. For all CT salts, temperature dependences of electrical conductivity are semiconducting in spite of very small activation energies (30-90 meV). Based on the comparison between their electrical conducting and magnetic properties, it is suggested that the d spins of FeBr₄⁻ or FeCl₄⁻ ions exert almost no influence on the π conducting electrons in the 1-stacked column.     

Tetrachloroferrate (III) Salts of BDH-TTP [2,5-Bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene] and BDA-TTP [2,5-Bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene]: Crystal Structures and Physical Properties

Three FeCl₄ salts based on non-tetrathiafulvalene (TTF) donors, 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH-TTP) and 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP), have been prepared and characterized as κ-(BDH-TTP)₂FeCl₄, β-(BDA-TTP)₂FeCl₄, and (BDA-TTP)₃FeCl₄ · PhCl. The κ-(BDH-TTP)₂FeCl₄ salt, with a room-temperature conductivity (σ_rt) of 39 S cm⁻¹, is metallic down to 1.5 K, and its magnetic susceptibility obeys the Curie-Weiss law with a Curie constant (C) of 4.25 emu K mol⁻¹ and a Weiss constant (θ) of 0.041 K. β-(BDA-TTP)₂FeCl₄ exhibits metallic behavior (σ_rt=9.4 S cm⁻¹) with a sharp metal-to-insulator (MI) transition (T_MI=113 K) and antiferromagnetic ordering with the Néel temperature of near 8.5 K, whereas the solvated (BDA-TTP)₃FeCl₄ · PhCl salt is a semiconductor with a thermal activation energy of 0.11 eV (σ_rt=2.0× 10⁻² S cm⁻¹) and exhibits Curie-Weiss behavior (C=4.42 emu K mol⁻¹, θ=−0.35 K).     

Mg-doping experiment and electrical transport measurement of boron nanobelts

We measured electrical conductance of single crystalline boron nanobelts having α-tetragonal crystalline structure. The doping experiment of Mg was carried out by vapor diffusion method. The pure boron nanobelt is a p-type semiconductor and its electrical conductivity was estimated to be on the order of 10^-3 (Ω cm)⁻¹ at room temperature. The carrier mobility of pure boron nanobelt was measured to be on the order of 10⁻³ (cm² Vs⁻¹) at room temperature and has an activation energy of ∼0.19 eV. The Mg-doped boron nanobelts have the same α-tetragonal crystalline structure as the pristine nanobelts. After Mg vapor diffusion, the nanobelts were still semiconductor, while the electrical conductance increased by a factor of 100-500. Transition to metal or superconductor by doping was not observed.     

Dual-mode Detection of Dopamine Based on Enhanced Fluorescent and Colorimetric Signals of Fe3+-H2O2-o-Phenylenediamine System

A fluorescent and colorimetric dual-mode “light-on” assay for the detection of dopamine (DA) was developed based on Fe³⁺-H₂O₂-OPD system. In general, Fe³⁺ could catalyze the H₂O₂-mediated oxidation of colorless and nonfluorescent o-phenylenediamine (OPD), and the resultant 2,3-diaminophenazine (DAP) exhibits a visible yellow color and yellow fluorescence. However, the reaction rate is extremely slow. By comparison, the introduction of DA can trigger a typical Fenton reaction that generates hydroxyl radical (?OH) continuously, thus increasing the conversion rate of OPD to DAP. Correspondingly, both color and fluorescence of the sensing system are enhanced obviously. On the basis of this fact, a sensor with dual readout for the detection of DA was established via measuring the fluorescent and colorimetric signals of the Fe³⁺-H₂O₂-OPD system. The linear ranges were 0.05–20 mM and 0.10–18 mM, and the detection limits were calculated to be 15 and 65 nM (S/N = 3) for fluorescent and colorimetric detection, respectively. The proposed dual-readout method features with simplicity, high sensitivity, visualization and good accuracy. Moreover, the method has been successfully applied to the detection of DA in human urine with satisfactory results.     

Oxidative addition reaction of o-quinones to triphenylantimony: novel triphenylantimony catecholate complexes

New catecholate Sb(V) complexes triphenyl(3,6-di-tert-butylcatecholato)antimony(V) Ph₃Sb(3,6-DBCat) (1) and triphenyl(perchloroxanthrenecatecholato)antimony(V) Ph₃Sb(^OXCat_Cl) (2) were synthesized by the oxidative addition reaction of corresponding o-quinones (3,6-di-tert-butyl-o-benzoquinone and perchloroxanthrenequinone-2,3) with triphenylantimony. Catecholates 1 and 2 can alternatively be synthesized by reacting the appropriate thallium catecholate with triphenylantimony dichloride. The oxidative addition reaction of an equimolar ratio of 4,4′-di-(3-methyl-6-tert-butyl-o-benzoquinone) and triphenylantimony yielded 4-(2-methyl-5-tert-butyl-cyclohexadien-1,5-dion-3,4-yl)-(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V) Ph₃Sb(Cat-Q) (3); in the case of a 1:2 molar ratio, complex 4,4′-di-[(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V)] Ph₃Sb(Cat-Cat)SbPh₃ (4) resulted. Complexes 1-4 were characterized by IR- and ¹H NMR spectroscopy. Molecular structures of 1, 2 and 4 were determined by X-ray crystallography to be a distorted tetragonal-pyramidal.     

Fabrication of size-controllable and luminescent dysprosium benzenetricarboxylate nanobelts at room temperature

Lanthanide-based coordination polymer Dy(1,3,5-BTC)(H₂O)₆ nanobelts were successfully synthesized on a large scale through an extremely simple approach at room temperature; the size of the nanobelts can be easily tuned from several to several hundred micrometers in length, 70–600 nm in width, and 10–100 nm in thickness by varying concentrations, solvent, and surfactant reasonably. In addition, the as-obtained dysprosium benzenetricarboxylate nanobelts exhibit the characteristic emission of the Dy³⁺ ions, making the belt-like coordination polymer have potential applications in building minioptoelectronic devices.     

EPR study of mono-o-iminobenzosemiquinonato nickel(II) complexes with Ni-C σ-bond

New square-planar (Ph₃P)Ni^II(o-Tol)(ISQ-Prⁱ) (1), (Ph₃P)Ni^II(o-Tol)(ISQ-Me) (2), (Ph₃P)Ni^II(o-Tol)(ISQ-Bu^t) (3) nickel complexes (where ISQ-Prⁱ = 4,6-di-tert-butyl-N-(2,6-di-iso-propylphenyl)-o-iminobenzosemiquinonate, ISQ-Me = 4,6-di-tert-butyl-N-(2,6-di-methylphenyl)-o-iminobenzosemiquinonate, ISQ-Bu^t = 4,6-di-tert-butyl-N-(2,5-di-tert-butylphenyl)-o-iminobenzosemiquinonate, o-Tol = o-tolyl ligand) have been synthesized. Complexes contain σ-bound o-tolyl and neutral donor ligand Ph₃P. The sterical hindrances of N-aryl in o-iminobenzosemiquinonate ligands lead to the tetrahedral distortion of square-planar configurations of complexes as it was established using EPR spectroscopy.     

Asymmetric hydrogenation of alkenes with planar chiral 2-phosphino-1-aminoferrocene-iridium(I) complexes

The first highly enantioenriched and enantiopure planar chiral 2-phosphino-1-aminoferrocene ligands and their Ir(COD)BAr_F complexes are reported. The ligands display bidentate coordination behavior towards iridium, as indicated by trends in ³¹P and ¹H NMR spectra of the phosphine moieties and the α to nitrogen substituents of the amines. All of the new complexes showed good reactivity as catalysts in promoting asymmetric hydrogenation of several prochiral alkenes, with enantioselectivities up to 92%. Iridium complexes of dimethylaminoferrocene derivatives containing P-Ar groups [PPh₂ and P(o-tol)₂] gave the highest levels of asymmetric induction.     

Towards more controlled poly(n-butyl methacrylate) by atom transfer radical polymerization

The homogeneous controlled/‘living’ free radical polymerization of n-butyl methacrylate in toluene or o-xylene at 90 °C, in bulk and in solution, using the novel combination of the catalyst bis-triphenylphosphine iron(II)chloride tetrahydrate (FeCl₂ · 4H₂O(PPh₃)₂) with ethyl 2-bromoisobutyrate ((CH₃)₂CBrCO₂Et)) and α,α-dichloroacetophenone (CHCl₂COPh) as initiators has been investigated. The rate of polymerization initiated by the two initiators exhibited first-order kinetic with respect to the monomer. A linear increase of the number-average molecular weight (M_n) versus monomer conversion was observed for these systems. Among the two initiation systems, ethyl 2-bromoisobutyrate gave the fastest polymerization rate. A system with Fe³⁺ added at the beginning of the polymerization was examined and the lowest polydispersity (M_w/M_n∼1.2) was found when 10% Fe³⁺, relative to Fe²⁺ was added.     

Anion sensing by Phenazine-based urea/thiourea receptors

The novel colorimetric receptors 2,3-bis-N-(9,10-diaza-anthracen-1-yl)-N′-phenylurea and 2,3-bis-N-(9,10-diaza-anthracen-1-yl)-N′-phenylthiourea have been prepared by the reaction of 2,3-diaminophenazine with phenylisocyanate and phenylisothiocyanate, respectively, in quantitative yields. The interaction and colorimetric sensing properties of receptor = 2 and 3 with different anions were investigated by naked eye, UV-vis and fluorescence spectroscopy in DMSO. The receptors effectively and selectively recognized biologically important F⁻, CH₃COO⁻, H₂P in the presence of other anions, such as Cl⁻, Br⁻, I⁻ and HS in DMSO.     

M?ssbauer and other spectral studies of Fe(III) complexes of benzothiazolines

Different molar reactions of Fe(OPr¹)₃, and FeCl₃ with benzothiazolines having an NSH donor system. derived by the condensation ofo-aminothiophenol with heterocyclic aldehydes. viz. pyridine-2-aldehyde. furfuraldehyde and thiophene-2-aldehyde. lead to the formation of [Fe.Pr¹(NS)₂]₂, [Fc(NS)₃] and [Fe(NS)₂Cl| type of complexes. The resulting derivatives have been characterized by elemental analysis, conductivity measurements, molecular weight determinations and magnetic studies. IR, electronic, M?ssbauer and ESR spectral data have been used to deduce the structures of the resulting derivatives.     

Synthesis of a new donor, BEDT-HBDST and crystal structures, electrical and magnetic properties of (BEDT-HBDST)2MX4 (M=Fe, Ga, X=Cl, Br), where BEDT-HBDST=2,5-bis(4,5-ethylenedithio-1,3-diselenol-2-ylidene)-2,3,4,5-tetrahydrothiophene

A novel conjugation-elongated bis(ethylenedithio)tetraselenafulvalene (BETS) type donor, 2,5-bis(4,5-ethylenedithio-1,3-diselenol-2-ylidene)-2,3,4,5-tetrahydrothiophene (BEDT-HBDST) and its magnetic and non-magnetic anion salts, (BEDT-HBDST)₂MX₄ (MX₄⁻=FeCl₄⁻, GaCl₄⁻, FeBr₄⁻ and GaBr₄⁻), were prepared. These four salts are isostructural and belong to the space group of P2/c. They showed semiconducting behavior with small activation energies (59-64 meV). The band structures of these salts are quasi one-dimensional and there is a midgap between the upper band and the lower band, since the degree of dimerization is significant in the stacking direction. The MX₄⁻ ions are located between the donor columns and near to the ethylenedithio moieties of the donor molecules. The magnetic susceptibilities of the FeCl₄⁻ and FeBr₄⁻ salts follow the Curie-Weiss law with Curie constants of 4.6 and 4.8 emu K mol⁻¹ (sum of the spins of S=5/2 and S=1/2) and negative Weiss temperatures of θ=−1.2 and −4.9 K, respectively, revealing a weak antiferromagnetic interaction of 3d spins of the FeCl₄⁻ and FeBr₄⁻ anions. The Fe?Fe (6.66-7.60 Å), Cl?Cl (4.81-4.82 Å) and Br?Br (4.74-4.77 Å) distances in the crystal structures of these salts are significantly long. Therefore, the direct magnetic interaction between the 3d spins of the nearest neighboring Fe³⁺ ions appears to be not readily accessible.     

SnO2 Quantum Dots Distributed along V2O5 Nanobelts for Utilization as a High-Capacity Storage Hybrid Material in Li-Ion Batteries

In this study, the facile synthesis of SnO₂ quantum dot (QD)-garnished V₂O₅ nanobelts exhibiting significantly enhanced reversible capacity and outstanding cyclic stability for Li⁺ storage was achieved. Electrochemical impedance analysis revealed strong charge transfer kinetics related to that of V₂O₅ nanobelts. The SnO₂ QD-garnished V₂O₅ nanobelts exhibited the highest discharge capacity of ca. 760 mAhg⁻¹ at a density of 441 mAg⁻¹ between the voltage ranges of 0.0 to 3.0 V, while the pristine V₂O₅ nanobelts samples recorded a discharge capacity of ca. 403 mAhg⁻¹. The high capacity of QD-garnished nanobelts was achieved as an outcome of their huge surface area of 50.49 m²g⁻¹ and improved electronic conductivity. Therefore, the as-presented SnO₂ QD-garnished V₂O₅ nanobelts synthesis strategy could produce an ideal material for application in high-performance Li-ion batteries.     

Mass production of very thin single-crystal silicon nitride nanobelts

We report the large-scale synthesis of very thin single-crystalline Si₃N₄ nanobelts with high yield via catalyst-assisted pyrolysis of polymeric precursors. The obtained nanobelts, which show a perfect crystal structure and smooth surface, are up to several millimeters in length with typical width and thickness of ∼800 nm and tens of nanometers, respectively. It is believed that the nanobelts were grown via a vapor-solid process, in which Al catalyst played a key role. This result provides a possibility for mass producing high quality, very thin Si₃N₄ nanobelts.     

Engineering the Electrical Conductivity of Lamellar Silver‐Doped Cobalt(II) Selenide Nanobelts for Enhanced Oxygen Evolution

Precisely engineering the electrical conductivity represents a promising strategy to design efficient catalysts towards oxygen evolution reaction (OER). Here, we demonstrate a versatile partial cation exchange method to fabricate lamellar Ag‐CoSe₂ nanobelts with controllable conductivity. The electrical conductivity of the materials was significantly enhanced by the addition of Ag⁺ cations of less than 1.0 %. Moreover, such a trace amount of Ag induced a negligible loss of active sites which was compensated through the effective generation of active sites as shown by the excellent conductivity. Both the enhanced conductivity and the retained active sites contributed to the remarkable electrocatalytic performance of the Ag‐CoSe₂ nanobelts. Relative to the CoSe₂ nanobelts, the as‐prepared Ag‐CoSe₂ nanobelts exhibited a higher current density and a lower Tafel slope towards OER. This strategy represents a rational design of efficient electrocatalysts through finely tuning their electrical conductivities.     

Étude par spectrométrie raman laser de l'extraction liquide-liquide du FeCl3 par le chlorhydrate de trilaurylamine

Raman spectra of aqueous 1 M chloroferrate(III) solutions indicate the presence of FeCl₃ and FeCl₄^- in proportion to the hydrochloric acid concentration, but FeCl₄^- is only present in solutions of acidity higher than 5 M HCl. The liquid-liquid extraction of the aqueous chloroferrate phases ( 1 M HCl) by trilaurylamine hydrochloride in cyclohexane, shows that iron(III) is extracted only in its FeCl₄^- form, even though this species does not appear in the aqueous solutions. A quantitative spectroscopic study of the organic phases by means of the v₁ line of FeCl₄^- at 332 cm^-1 leads to the following conclusions: (a) the plot of the scattering coefficient of the 332 cm^-1 line versus iron(III) concentration shows the presence of two complex species in the organic phase; (b) the distribution curves of the complex species could be calculated. On the basis of the Raman results, an ion-pair type compound is proposed for the two complexes.