Hydrothermal synthesis and crystal structure of a hybrid material based on [Co-4(phen)(8)(H2O)(2)(HPO3)(2)](4+) and a highly reduced polyoxoanion

An unusual composite hybrid material [Co-4 (phen)(8) (H2O)(2) (HPO3)(2)](H3O)(3) [PMo8VI V-4(IV) O-40 ((VO)-O-IV) 2] 1 (phen = 1,10-phenanthroline) has been hydrothermally synthesized from a mixture of NH4VO3, Na2MoO4.2H(2)O, CoCl2.6H(2)O, phen, H3PO3 and water. It was characterized by elemental analysis, IR, UV-vis, XPS, EPR, TG and single crystal X-ray diffraction. The title compound is constructed from the organic-inorganic hybrid [Co-4(phen)(8)(H2O)(2) (HPO3)(2)](4+) and highly reduced bi-capped pseudo-Keggin [(PMo8V4O40)-V-VI-O-IV ((VO)-O-IV)(2)](7-) polyoxoanions The structure exhibits an extended 2D network through hydrogen bonds among cations, anions and H2O, combining polyoxometalates with metal phosphonates for the first time.

A novel terbium (III) beta-diketonate complex as thin film for optical device application

A novel terbium complex, Tb(acac)(3)AAP (acac: acetylacetone, AAP: 4-amino-antipyrine), was synthesized and its luminescent properties were studied. When it was used as an emitting center, triple-layer-type device with a structure of glass substrate/ITO (indium-tin oxide)/TPD (N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine)./Tb(acac)(3)AAP/PBD (2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole) or Alq(3) (tris(8-hydroxyquinolinato) aluminum)/Al (aluminum) exhibited bright characteristic emission of terbium ion upon applying d.c. voltage. The maximum luminance of the device is 56 cd/m(2) at 19 V and the maximum luminance efficiency is 0.357 lm/W.

Hydrothermal synthesis, crystal structure and properties of [HPDA][H(2)PDA](2)[As-2(III)-AsMo8V4O40]center dot 3H(2)O (PDA = propane diamine)

[NH3CH2CH2CH2NH2][NH3CH2CH2CH2NH3](2)[(As2AsMo8V4O40)-As-III-Mo-V-O-IV].3H(2)O was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Crystal data: monoclinic, C2/c, a = 45.375(9) Angstrom, b = 11.774(2) Angstrom, c = 23.438(5) Angstrom, beta = 96.62(3)degrees. X-ray crystallographic study showed that the crystal structure was constructed by bicapped alpha-Keggin fragments [(As2AsMo8V4O40)-As-III-Mo-V-O-IV](5-) polyoxoanion. The title compound had a high catalytic activity for the oxidation of benzaldehyde to benzoic acid using H2O2 as oxidant in a liquid-solid biphase system.

Bienzymatic amperometric biosensor for glucose based on polypyrrole/ceramic carbon as electrode material

A novel amperometric biosensor utilizing two enzymes, glucose oxidase (GOD) and horseradish peroxidase (HRP), was developed for the cathodic detection of glucose. The glucose biosensor was constructed by electrochemical formation of a polypyrrole (PPy) membrane in the presence of GOD on the surface of a HRP-modified sol-gel derived-mediated ceramic carbon electrode. Ferrocenecarboxylic acid (FCA) was used as mediator to transfer electron between enzyme and electrode. In the hetero-bilayer configuration of electrode, all enzymes were well immobilized in electrode matrices and showed favorable enzymatic activities. The amperometric detection of glucose was carried out at +0.16 V (versus saturated calomel reference electrode (SCE)) in 0.1 M phosphate buffer solution (pH 6.9) with a linear response range between 8.0 x 10(-5) and 1.3 x 10(-3) M glucose. The biosensor showed a good suppression of interference in the amperometric detection.

Sol-gel-derived alpha(2)-K7P2W17VO62/graphite/organoceramic composite as the electrode material for a renewable amperometric hydrogen peroxide sensor

The conductive alpha (2)-K7P2W17VO62/graphite/organoceramic composite was prepared by dispersing alpha (2)-K7P2W17VO62 and graphite powder in a propyltrimethoxysilane-based sol-gel solution; it was used as the electrode material for an amperometric hydrogen peroxide sensor. The modified electrode had a homogeneous mirror-like surface and showed well defined cyclic voltammograms. Square-wave voltammetry was employed to study the pH-dependent electrochemical behavior of c alpha (2)-K7P2W17VO62 doped in the graphite organoceramic matrix, and the experiment showed that both protons and sodium cations participated in the odor process. A hydrodynamic voltammetric experiment was performed to characterize the electrode as an amperometric sensor for the determination of hydrogen peroxide. The sensor can be renewed easily in a repeatable manner by a mechanical polishing step and has a long operational lifetime. (C) 2000 Elsevier Science B.V. All rights reserved.

Preparation and luminescence properties of ormosil material doped with Eu(TTA)(3)phen complex

The europium complex, Eu(TTA)(3)phen (TTA = thenoyltrifluoroacetone, phen = 1,10-phenanthroline) was successfully doped into organically modified silicate (ormosil) matrix-SiO2/(VTMOS+PMMA) (VTMOS = vinyltrimethoxysilane, PMMA = polymethylmethacrylate) via sol-gel process, and the luminescence properties of the resultant ormosil composite phosphors [ormosil: Eu(TTA)(3)phen were investigated compared with those of the pure Eu(TTA)(3)phen complex powder. The ormosil composite materials incorporated with Eu(TTA)(3)phen show the characteristic red emission of Eu3+ ion. The Eu3+ possesses fewer emission lines and longer lifetime in the hybrid phosphor than in the pure Eu(TTA)(3)phen complex. This has been explained from the viewpoint of the surrounding environment where the Eu3+ ion lies. (C) 2000 Elsevier Science B.V. All rights reserved.

Surface renewable graphite organosilicate composite electrode containing indium(III) hexacyanoferrate(II/III)

Indium(III) hexacyanoferrate(II/III) (InHCF) supported on graphite powder was prepared using the in situ chemical deposition procedure and subsequently dispersed into methyltrimethoxysilane-derived gels to yield a conductive graphite organosilicate composite. The composite was used as the electrode material to fabricate a three-dimensional InHCF-modified electrode. InHCF acts as a catalyst, graphite powder ensures conductivity by percolation, the silicate provides a rigid porous backbone and the methyl groups endow hydrophobicity and thus limit the wetting section of the modified electrode. The chemically modified electrode can electrocatalyze the oxidation of thiosulfate, and exhibits a good repeatability of surface-renewal by simple mechanical polishing, as well as simple preparation, good chemical and mechanical stability.

Surface photovoltage spectra and photoelectrochemical properties of semiconductor-sensitized nanostructured TiO2 electrodes

Three kinds of TiO2 nanostructured thin films and their CdS-sensitized films, consisting of different sizes of TiO2 nanoparticles prepared with different methods, have been investigated. The surface photovoltage spectra (SPS) measurements indicate that the density of surface states on TiO2 is likely dependent upon the details of prepared methods. TiO2 particles prepared from basic sol have more surface states than that prepared from acidic sol. When the TiO2 thin films prepared using the TiO2 sols were sensitized by CdS particles, the SPS responses relative to the surface states on TiO2 from 350 to 800 nm were decreased. The photoelectrochemical properties of nanostructured TiO2 electrodes suggest that the fewer the surface states and the smaller the particle sizes of TiO2, the larger the photocurrent response. For CdS sensitized TiO2 thin film electrode, it is shown that the semiconductor sensitization is an efficient way to decrease the influence of surface states on the charge separation, and can improve the intensity of photocurrent response. (C) 2001 Elsevier Science B.V. All rights reserved.

Synthesis and luminescence properties of organic-inorganic hybrid thin films doped with Eu(III)

In this study, silica-based transparent organic-inorganic hybrid films were prepared by the sol-gel method. Tetraethoxysilane and 3-(trimethoxysilyl)propyl methacrylate were used as the inorganic and organic compounds, respectively. Lanthanide complexes [Eu(phen)(2)]Cl-3 were incorporated into the organically modified silicates (ORMOSIL) and the luminescence properties of the resultant hybrid films (ORMOSIL:[Eu(phen)(2)]Cl-3) were characterized. The relative quantum efficiency was observed higher and the lifetimes were longer in hybrid films than those in pure silica films. Furthermore, thermal stability of hybrid films incorporating various concentration of Eu(III) complex was studied. (C) 2001 Elsevier Science B.V. All rights reserved.

Hydrothermal synthesis and structural characterization of a mixed-valence molybdenum (IV,VI) arsenate (III): Ni(H2NCH2CH2NH2)(3)[((MoO6)-O-IV)(Mo6O18)-O-VI((As3O3)-O-III)(2)]H2O

A novel mixed-valence molybdenum(IV, VI) arsenate(III), Ni(H2NCH2CH2NH2)(3)[((MoO6)-O-IV)(Mo6O18)-O-VI((As3O3)-O-III)(2)]H2O, hydrothermally synthesized and characterized by single-crystal X-ray diffraction and thermogravimetric analysis. The polyanion cage derives from the Anderson structure, in which the central octahedron was filled up by molybdenum(IV) and it was capped on both sides by a novel As3O63- cyclo-triarsenate(III). The title compound had a high catalytic activity for the oxidation of benzaldehyde to benzoic acid using H2O2 as oxidant in a liquid-solid biphase system. (C) 1999 Elsevier Science B.V. All rights reserved.

Analysis of mussel standard reference material by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry

A method for the analysis of mussel standard reference material by inductively coupled plasma atomic emission spectrometry( ICP-AES) and inductively coupled plasma mass spectrometry(ICP-MS) was developed. K, Na, Ca, Mg, P, Al, Fe, Zn, Mn and Sr were determined by ICP-AES and As, B, Cd, Co, Cr, Cu, Ga, Ge, Mn, Mo, Ni, Pb, Se, Sr, U and V by ICP-MS, The interference coefficients at the Mn-55, Se-78, Cu-63, Co-59, Ni-58, Ni-60, As-75, Se-77, V-51, Cr-53 and Cr-52 originating from polyatomic ion of the matrix elements (KO)-K-39-O-16, K-39(2), (ArNa)-Ar-40-Na-23, (CaO)-Ca-43-O-16, (CaO)-Ca-42-O-16, (CaO)-Ca-44-O-16, (PO2)-P-31-O-16, (ArCl)-Ar-40-Cl-35, (ArCl)-Ar-40-Cl-37, (ClO)-Cl-35-O-16, (ClO)-Cl-37-O-16 and (ArC)-Ar-40-C-12 were determined under the selected operation parameters. The major matrix elements, such as K, Na and Ca, result in the suppression of analytes signals. The apparent concentration at the significant biological element which was produced by the different digestion methods, (.) HNO3 + H2O2 (3 + 2), HNO3 + HClO4 (3 + 0.5) and HNO3 + H2SO4 (3 + 0.5),was determined. The sample digested by HNO3 + H2O2 did not give rise to interfere on the analyte, and the backgrounds of Se-77, Ga-69, Zn-67, As-75, V-51, Cr-53 and Cr-52 were increased by HNO3 + HClO4 digestion method, that affected the determination of these elements, especially the monoisotope As and V. Sample digested by HNO3 + H2SO4 increased the backgrounds at Cu-65, Zn-64 and Zn-67. Detection limits of ICP-AES are 0.001 similar to 0.75 mg/L and those of ICP-MS are 0.005 similar to 1.01 mu g/L. The relative standard derivations of ICP-AES and ICP-MS are 2.7% similar to 12.8%, 3.4% similar to 24.8%, respectively.

Observations on photochemical fluorescence enhancement of the terbium(III) sparfloxacin system

Fluorescence of terbium(III) was sensitized when excited in the presence of sparfloxacin (SPFX) in the aqueous solution because a Tb(III)-SPFX complex was formed. The sensitized fluorescence was further enhanced when this system was exposed to 365 nm ultraviolet light. By the spectral properties and contrast experiments, it is proved that irradiation makes this system undergo photochemical reactions and a new terbium complex which is more favorable to the intramolecular energy transfer is formed. The mechanism of photochemical fluorescence enhancement of the Tb(III)-SPFX system is discussed and a new sensitive and selective photochemical fluorimetry for the determination of SPFX is established. Under the optimum conditions, the linear range is 1.0-50 x 10(-7) M for SPFX, the detection limit is 3.0 x 10(-9) M and the R.S.D. for 5.0 x 10(-7) M SPFX is 1.3% (n = 9). Without any pretreatment the recovery of SPFX in human urine was determined with satisfaction. (C) 1999 Elsevier Science B.V. All rights reserved.

Functionalized inorganic-organic composite material derivated by sol-gel for construction of mediated amperometric hydrogen peroxide biosensor

A novel functionalized inorganic-organic hybrid material with cation exchange property was prepared by sol-gel method. The H2O2 biosensor was fabricated by simply dipping the horseradish peroxidase-containing functionalized membrane modified electrode into Meldola's blue (MDB) solution. MDB was adsorbed and firmly immobilized within the membrane. The electrochemical behavior of MDB incorporated in the membrane was more reversible compared with that of the solution species and suitable as mediator for the horseradish peroxidase. The response time was less than 25 s. Linear range is up to 0.6 mM (COH. coeff. 0.9998) with detection Limit of 9 x 10(-7) M. High sensitivity of 75 nA mu M cm(-2) was obtained due to high MDB-loading. The biosensor exhibited a good stability. (C) 1999 Elsevier Science B.V. All rights reserved.

Recovery of Ce(IV) and Th(IV) from rare earths(III) with Cyanex 923

Solvent extraction of Ce(IV), Th(IV) with Cyanex 923 in n-hexane from sulphuric acid medium was studied with the dependence of the extraction on acidity and temperature being investigated. The Ce(IV) and Th(IV) extraction mechanism was proposed by slope analysis and the IR spectra of purified Cyanex 923 saturated with Ce(IV) were employed to determine the composition of the Ce(IV) complex. The equilibrium constant and thermodynamic functions of Th(IV) extraction were calculated and the characteristics of the stripping of Ce(IV), Th(IV) from the loaded organic phase were studied. (C) 1998 Elsevier Science B.V. All rights reserved.

Synthesis and crystal structure of a polymeric erbium(III)-sodium(I) coordination complex of picolinic acid N-oxide

A new Er(III)-Na(I) coordination polymer of stoichiometry [NaEr2L5(H2O)(6)(NO3)](NO3). 3.5H(2)O (HL = picolinic acid N-oxide) has been synthesized and characterized by single-crystal X-ray analysis. Crystals are triclinic, P (1) over bar with a = 9.823(2), b = 12.453(2), c = 20.643(4) Angstrom; alpha = 98.49(3), beta = 101.40(3), gamma = 108.69(3)degrees; V = 2284(1) Angstrom(3); Z = 2. Of the two independent eight-coordinate erbium(III) ions in this complex, one is surrounded by four bidentate chelating L ligands, and the other by one bidentate chelating L ligand, four aqua ligands and two anti-carboxylate oxygen atoms from two neighboring [ErL4] units. The sodium(I) ion is in a distorted octahedral environment, being coordinated by a unidentate nitrate anion, three aqua ligands and two anti-carboxylate oxygen atoms from two adjacent [ErL4] units. The complex is built from zigzag chains of syn-anti carboxylate-bridged erbium(III) moieties directed in the a direction, which are cross-linked pairwise by aqua-bridged dimeric sodium(I) units. The resulting composite polymeric chains are further connected by hydrogen bonds to form a three-dimensional network.