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[en] The monomer poly-N,N'-bis(2-pyrrol-1-yl-propyl)-4,4'-bipyridine(bpb) was electrochemically polymerized on the glassy carbon electrode surface, which was modified with 1:1 ratio of eriochrome black T(EBT) and glutathione(GSSG) to give a type of GC/poly-bpb, EBT, GSSG electrode for depositing Zn(II). The diffusion coefficients of the incorporated ions were 2.43x10-15 and 9.14x10-15 cm2s-1 before taking Zn(II) ions and after them respectively. The modified electrodes are stable at the electrode process. The polymerized poly-bpb of 2.83x104 gmol-1 can deposit 2.15x104 gmol-1 of Zn(II). The number of pumping ions involving in the redox procedure at 0.77 V was 81.7% of the captured 180 ions into the polymer matrix, which was 3 times larger than that of the electrode modified with EBT alone
[en] A new chemosensor with pyreneamide derivative of bipyridine is synthesized. In the free ligand, pyreneamide derivative has nearly no fluorescence in acetonitrile solution. However, in the presence of fluoride ion, a 'turn-on' fluorescence was observed. Simultaneously, the colorless ligand solution became markedly orange when fluoride ion was added to pyreneamide derivative in acetonitrile. This phenomenon suggest that the PET (photoinduced electron transfer) between anion electron and pyrene unit was changed the π-π interaction between bipyridine and pyrene that was modified structure by deprotonation. On account of the important roles of anion in biological, clinical, environmental, catalysis, and chemical processes, the selective and efficient recognition of anion is an area of growing interest in supramolecular chemistry. In particular, the studies of chemosensors toward F- anion are quite intriguing because of its beneficial effects in human physiology. Also, fluoride is interest due to its established role in dental care and osteoporosis. However, an excess of fluoride ion can lead to fluorosis. Therefore, the development of reliable sensors for F- is needed for environment and human health care. Color changes that can be detected by the naked eye are widely used as signals for events owing to the inexpensive equipment required or no equipment at all
[en] New complexes of 2,2'-dipyridyl and 4,4'-dipyridyl with thulium salts TmX3 (where X=Cl-, Br-, NO3-, NCS-, and ClO4-) have been prepared and their solubilities in water at 21 deg C were determined. The IR spectra of these compounds are discussed. The conditions of thermal decomposition of the complexes were also studied. (author)
[en] Complete text of publication follows. The intense absorption spectrum of the hydrated electron, with maximum at 720 nm in room temperature water, shifts strongly to the red as the temperature is raised. In order to use this strong signal for dosimetry and calculation of second order reaction rates, the extinction coefficient must be measured as a function of temperature (and also pressure in supercritical water). Determination of the absolute extinction coefficient of a transient is a difficult undertaking. We have used two pulse radiolysis methods. In the first, we directly observe the kinetics of hydrated electron scavenging by methyl viologen, to form the strongly colored MV+ cation. The extinction coefficient of this long-lived radical was carefully measured by electrochemical and temperature cycling many years ago, so the measured ratio of hydrated electron absorption to MV+ absorption gives the desired extinction coefficient of (e-)aq. The MV+ spectrum has only been quantitatively measured up to 200 deg C, so the method is not valid at higher temperature. In the second method, transient absorption of hydrated electron is recorded as it is being scavenged by N2O or SF6. Direct comparison of the transient absorption with the measured (N2 or F-) product yield allows the extinction coefficient to be calculated. While the purpose of our study was to investigate high temperature water, we were astonished to discover that the room temperature hydrated electron extinction coefficient has been incorrectly reported (low) by 10%. We can now demonstrate how this error arose in calibration of pulse radiolysis yields. It has been remarked for decades that the integrated oscillator strength of the hydrated electron is less than unity. Our new measurements rectify this problem for room temperature, and we will present results for high temperature water.
[en] Synthesis of 5-aryl-2,2'-bipyridines with electron-donor substituents at the C6 position by reacting 5-substituted 6-aryl-3-(2-pyridyl)-1,2,4-triazines with 2,5-norbornadiene under high pressure conditions was performed.
[en] Three novel Ir(III)/TiO2-codoped zeolite Y photocatalytic assemblies (L = 2,2'-bipyridine (bpy) , 2,2'-bipyridine- 4,4'-carboxylic acid (bpydc) and 1,10-phenanthroline (phen)) were synthesized and characterized using the ''ship-in-a-bottle'' technique in incorporating the iridium (El) sensitizers to the supercages of zeolite Y and a sol- gel route to immobilize TiO2 nanoparticles into the zeolite Y surface. The green to brown colored Ir(in)-exchanged zeolite Y powder was obtained through the reaction of IrCl3·3H2O and 25 % NH3 to form [Ir(NH3)6]3+ that was later exchanged to Na+. The orange to yellow colored zeolite Y/[IrL3]3+ photocatalytic assemblies were synthesized from the reaction of Ir(III)-exchanged zeolite Y and L (where L = bpy, bpydc and phen) in ethylene glycol. The incorporation of TiO2 through the sol-gel route used titanium (IV) tetraisopropoxide (Ti(TV) source), 2- propanol (solvent) and HN03 (catalyst) to form the sol under N2 gas and vigorous stirring. The gelation of the sol in the zeolite Y/[IrL3]3+ surface was done through the hydrolysis by air followed by a mild calcination at 473 K. The Diffuse Reflectance FTIR Spectra of the photocatalytic assemblies showed the characteristic peaks (bpydc: C=O stretching at 1728.22 cm-1; bpy: C=N stretching at 1539.2 cm-1; phen C=N sretching at 1554.63 cm-1; TiO2: Ti-O-Ti stretching at 1411.89 cm-1 and Ti-0 stretching at 551.64 cm-1) successful synthesis of the sensitizer and the TiO2 particles. The SEM/EDX analyses confirmed the presence nanometer size (< 1μm) of the TiO2 particles on the zeolite surface. The solid-state reflectance spectra and the diffused-state absorption spectra showed the intense absorption of the photocatalytic assemblies in the 200-700 nm range which is attributed to the LLCT (200-300 nm) , 1MLCT (300- 350 nm), 3MLCT (350-400 nm) and the interaction of the dye and the TiO2 nanoparticles (near-IR). The photoluminescence spectra and diffused-state emission spectra showed the intense emission of the photocatalytic assemblies (γmax solid state: -650 nm and γmax diffused state: 450-500 nm) confirmed the election withdrawing effect of the -COOH group of the bpydc ligand and the TiO2 nanoparticles' characteristic of being an election acceptor. The differential pulse voltammograms confirmed the encapsulation of the iridium (in) dyes in the zeolite Y supercages as supported by the presence of te 1.6-1.7 eV oxidation potential of the fr(IV)/fr(III) couple. The photocatalytic assemblies were also tested for their efficiency in election transfer photocatalysis. The [IrL3]3+/TiO2-codoped zeolite Y photocatalytic assembly- catalyzed photodegradation of Rhodamine B under a solar light model showed the superior efficiency of the zeolite Y/ [Ir(bpydc)3]3+/Ti02 (rate constant: 5.1 x 10-2 M min-1; percent degradation: 78 %) photocatalytic assembly over the zeolite Y/ [Ir(bpy)3]3+/TiO2 (rate constant: 1.8 x 10-2 M min-1; percent degradation: 26.4 %) and zeolite Y/ [Ir(phen)3]34VTi02 (rate constant: 2.3 x 10-2 M min-1; percent degradation: 23.5 %) photocatalytic assemblies. These represent the first photocatalytic assemblies that contain the iridium (III) metal center and the bpydc and phen chelates. (author)