Tuning of emission: Synthesis, structure and photophysical properties of imidazole, oxazole and thiazole-based iridium (III) complexes

Three new iridium (III) complexes with two cyclometalated (CN)-N-boolean AND ligands (imidazole, oxazole and thiazole-based, respectively) and one acetylacetone (acac) ancillary ligand have been synthesized and fully characterized. The structure of the thiazole-based complex has been determined by single crystal X-ray diffraction analysis. The Ir center was located in a distorted octahedral environment by three chelating ligands with the N-N in the trans and C-C in the cis configuration. By changing the hetero-atom of (CN)-N-boolean AND ligands the order S, O and N, a marked and systematic hypsochromic shift of the maximum emission peak of the complexes was realized. The imidazole-based complex emits at a wavelength of 500 nm, which is in the blue to green region. The tuning of emission wavelengths is consistent with the variation of the energy gap estimated front electrochemistry results. An electroluminescent device using the thiazole-based complex as a dopant in the emitting layer has been fabricated. A highly efficient yellow emission with a maximum luminous efficiency of 9.8 cd/A at a current density of 24.2 mA/cm(2) and a maximum brightness of 7985 cd/m(2) at 19.6 V has been achieved.

Luminescence properties of lanthanide complexes doped in hybrid material from tetraethoxysilane and 3-glycidyioxyropyl-trimethoxysilane

Hybrid materials, containing in-situ synthesized lanthanide complexes with intense green light, have been prepared via sol-gel process. The luminescence properties and the decay times of as-synthesized samples were investigated. The excitation spectrum of the samples indicates the formation of complexes between terbium (III) and P-Sulfosalicylic acid. The hybrid materials that contain in-situ synthesized terbium complexes exhibit the characteristic emission bands of the rare earth ions. In addition, the effect of concentration of terbium on the luminescence properties as well as the thermal stability were also studied.

Preparation and luminescence properties of hybrid materials containing europium(III) complexes covalently bonded to a silica matrix

A new kind of luminescent organic-inorganic hybrid material (denoted Hybrid I) consisting of europium 1,10-phenanthroline complexes covalently attached to a silica-based network was prepared by a sol-gel process. 1,10-Phenanthroline grafted to 3-(triethoxysilyl)propyl isocyanate was used as one of the precursors for the preparation of an organic-inorganic hybrid materials. For comparison purposes, the hybrid material (denoted Hybrid II) in which phenanthroline was not grafted onto the silica backbone of the frameworks was also prepared. Elemental analysis; NMR, FT-IR, UV/vis absorption, and luminescence spectroscopies, and luminescence decay analysis were used to characterize the obtained hybrid materials. It is shown that the homogeneity of Hybrid I is superior to that of Hybrid II, and a higher concentration europium can be incorporated into Hybrid I than Hybrid II. Excitation at the ligand absorption wavelength (283 nm) resulted in the strong emission of the Eu3+ D-5(0)-F-7(J) (J = 0-4) transition lines as a result of the efficient energy transfer from the ligands to the EU3+ in Hybrid I. The number of water molecules coordinated to the europium ion was estimated, and the structure of the as-synthesized Hybrid I was predicted on the basis of the experimental results.

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.