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Molecular Designing of Luminescent Europium-Metal Complexes for OLEDs: An Overview
Published in Sanjay J. Dhoble, B. Deva Prasad Raju, Vijay Singh, Phosphors Synthesis and Applications, 2018
Similarly, You et al. [158] synthesized a pure-red-emitting binuclear Eu complex containing pyridine N-oxide as a ligand. The usual quenching effects thus observed due to the presence of binuclear complex BZ were decreased due to the presence of oxygen atoms in the same plane, encapsulating the Eu(III) ions. The devices showed pure-red emission at a peak wavelength of 612 nm with an FWHM of 3 nm, which is a characteristic emission from the Eu3+ ion based on electric dipole (ED)5D0^7F2 transition. The maximum brightness and EL efficiency reached 340 cd/m2 at a driving voltage of 19 V and 2.4 cd/A (0.78 lm/W) at a current density of 0.14 mA/ cm2, respectively. Also it was seen that the transitions at 652 nm (5D0-7F3) and 702 nm (5D0-7F4) increased in intensity with the applied bias. This may be attributed to the increased probability for the ED transition, which is caused by the increase of the electric field surrounding the microenvironment.
Supercritical Microemulsions
Published in Promod Kumar, K. L. Mittal, Handbook of Microemulsion Science and Technology, 2018
Gregory J. McFann, Keith P. Johnston
Figure 1 shows the aggregation behavior of AOT in liquid cyclohexane and supercritical fluid ethane. The systems are one-phase without added water. Surfactant aggregation is indicated by the solvatochromic probe pyridine N-oxide. Pyridine N-oxide was used because of its small size and large dipole moment (μ = 4.3 D), which allow it to partition to the center of reverse micelles instead of being trapped at the surfactant interface. This molecule is a “blue shift” indicator in that its UV absorption maximum shifts to lower wavelengths as the polarity of its surroundings increases. The λmax is 281 nm in an alkane environment and 254 nm in an aqueous environment such as would be found in a reverse micelle water pool. It can be seen from Fig. 1 that the behavior indicated by the probe is the same in both solvents. AOT aggregation becomes prevalent at a concentration of about 0.002 M and is essentially fully developed at 0.01 M, which is consistent with other studies of AOT aggregation behavior [17,18].
Physical Properties of Individual Groundwater Chemicals
Published in John H. Montgomery, Thomas Roy Crompton, Environmental Chemicals Desk Reference, 2017
John H. Montgomery, Thomas Roy Crompton
Chemical/Physical. The gas-phase reaction of ozone with pyridine in synthetic air at 23°C yielded a nitrated salt having the formula: [C6H5NH]+NO3− (Atkinson et al., 1987). Ozonation of pyridine in aqueous solutions at 25°C was studied with and without the addition of tert-butyl alcohol (20 mM) as a radical scavenger. With tert-butyl alcohol, ozonation of pyridine yielded mainly pyridine N-oxide (80% yield), which was very stable toward ozone. Without tert-butyl alcohol, the heterocyclic ring is rapidly cleaved, forming ammonia, nitrate, and the amidic compound N-formyl oxamic acid (Andreozzi et al., 1991).
Synthesis, structure and magnetic properties of catena-diaqua-bis(pyridine-N-oxide)(μ-pyrazine)copper(II) perchlorate and the monomeric structure tetrakis(pyridine-N-oxide)copper(II) perchlorate
Published in Journal of Coordination Chemistry, 2020
Christopher P. Landee, Emma Kirkman-Davis, Matthew I. J. Polson, Mark M. Turnbull, Jan L. Wikaira
Pyridine-N-oxide and pyrazine were obtained from Aldrich Chemical Company. Copper perchlorate hexahydrate and methanol were purchased from J.T. Baker. All were used without purification. IR spectra were recorded via ATR on a Perkin-Elmer Spectrum 100 IR spectrophotometer. X-Ray powder diffraction data were collected on a Bruker AXS-D8 X-ray Powder Diffractometer. Elemental analyses were determined by the Marine Science Institute, University of California, Santa Barbara, CA 93106, USA. EPR measurements were made at room temperature on a Bruker EMX EPR spectrometer operating at 9.7 GHz (X-Band frequency) employing a traditional rectangular cavity and 100 kHz field modulation. Bruker Xenon 1.1 b.159 software was used to set instrument parameters and perform data processing [19]. EasySpin [20] was implemented in MATLAB [21] to fit all the data to determine the g-factors and linewidths. The magnetic field was periodically calibrated using DPPH.
Adsorption capacity of oxidized nitrogen-doped bamboo-like carbon nanotubes
Published in Journal of Dispersion Science and Technology, 2020
László Vanyorek, Gábor Muránszky, Béla Fiser, Emőke Sikora, Zsuzsanna G. Hutkai, Béla Viskolcz
Electro-kinetic (Zeta) potential measurements were applied, in order to compare the surface charge of the samples. For the analysis, dispersions of the oxidized nanotubes have been prepared and the pH of the samples was set to 5.0. In each case, due to the deprotonation of the dissociable functional groups (hydroxyl, carboxyl) negative electro-kinetic potential was detected (Table 3). The zeta potential of the nitric acid treated nanotubes was the lowest, −27.1 mV. However, the pyridine N-oxide species have also been contributed to the surface charge of the oxidized N-BCNTs. The zeta potential of the other two oxidized carbon nanotubes are similar, −18.3 eV and −19.8 eV, for the H2O2 and HClO4 sample, respectively. In case of the non-oxidized sample the zeta potential was −7.4 mV.
Iron(III) chloride and its coordination chemistry
Published in Journal of Coordination Chemistry, 2018
Pyridine N-oxide forms two complexes with FeCl3. Reaction in solvents like ethanol affords Fe(pyO)2Cl3, a 1:1 electrolyte in nitrobenzene, which spectroscopic evidence (e.g. bands for [FeCl4]−) indicates to be another auto-ionized compound, trans-[Fe(pyO)4Cl2]+ [FeCl4]− [100]. Similar compounds with 4-substituted pyridine N-oxides Fe(4-RpyO)2Cl3 (R = CH3, CH3O, Cl, NO2) have also been assigned similar structures [101]. Reaction with anhydrous FeCl3 in ether gives [Fe(pyO)3Cl3], a non-electrolyte evidently with a molecular structure. No structural data are available for either type of compound.