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Luminescence Characteristics (luminescence + characteristic)
Selected AbstractsLuminescence characteristics and X-ray crystal structure of [Cd(bipy)3][PF6]2 (bipy = 2,2,-bipyridine)APPLIED ORGANOMETALLIC CHEMISTRY, Issue 12 2005Nabanita Kundu Abstract The photoluminescence characteristics of the [Cd(bipy)3][PF6]2 complex are reported. A moderately large quantum yield (,) of 1.07 × 10,2 is exhibited in acetonitrile solution at 298 K. Crystallography shows the dication to have a distorted octahedral geometry and the crystal structure to be stabilized by CH···, and CH···F interactions. Copyright © 2005 John Wiley & Sons, Ltd. [source] Crystal growth, optical and luminescence properties of (Ce,Sr)-doped PrAlO3 single crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2007A. Novoselov Abstract Using the micro-pulling-down method, (Ce,Sr)-doped PrAlO3 square-shaped single crystals (4×4×12 mm) were grown. Structural parameters studied by X-ray powder diffraction were consistent with R3m space group. Compositional homogeneity was checked with electron probe micro-analysis and found quite uniform. Absorption spectra and luminescence characteristics under UV and X-ray excitations were measured at room temperature with no Ce-related emission appeared. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] [Re6Q7O(3,5-Me2PzH)6]Br2·3,5-Me2PzH (Q = S, Se) , New Octahedral Rhenium Cluster Complexes with Organic Ligands: Original Synthetic Approach and Unexpected Ligand Exchange in the Cluster CoreEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2005Yuri V. Mironov Abstract Two new octahedral rhenium cluster complexes, [Re6S7O(3,5-Me2PzH)6]Br2·3,5-Me2PzH (1) and [Re6Se7O(3,5-Me2PzH)6]Br2·3,5-Me2PzH (2), with the organic ligand 3,5-dimethylpyrazole (3,5-Me2PzH), have been synthesised by reaction of rhenium chalcobromides Cs3[Re6(µ3 -Q7Br)Br6] (Q = S, Se) with molten dimethylpyrazole. During the reaction, all six apical bromine ligands of the cluster complexes are substituted by the organic ligand, which is coordinated through the aromatic nitrogen atom N2. Additionally, the inner ligand µ3 -Br in the cluster core [Re6(µ3 -Q7Br)]3+ is substituted by oxygen, giving cluster cores [Re6(µ3 -Q7O)]2+ with mixed chalcogen/oxygen ligands. Compounds 1 and 2 have been characterised by single-crystal X-ray diffraction analysis. They are isostructural and crystallise with four formula units in the unit cell. Absorption spectra and luminescence characteristics of these two cluster compounds have been investigated in methanol. Absorption starts below 400 nm. For both compounds, broad emissions were found. The fluorescence decays of the two compounds follow a diexponential decay behaviour. The main fluorescence intensity decays have longer fluorescence lifetimes of 3.07 ± 0.03 (1) and 3.96 ± 0.02 µs (2). Studying the thermal stability of both compounds in vacuo showed that the release of 3,5-dimethylpyrazole ligands begins near 200 °C, and decomposition, with the removal of 7 molecules of 3,5-Me2PzH, is complete at 330 °C. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] High Mobility and Luminescent Efficiency in Organic Single-Crystal Light-Emitting TransistorsADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Satria Zulkarnaen Bisri Abstract A high-performance ambipolar light-emitting transistor (LET) that has high hole and electron mobilities and excellent luminescence characteristics is described. By using this device, a conspicuous light-confined edge emission and current-density-dependent spectral evolution are observed. These findings will result in broader utilization of device potential and they provide a promising route for realizing electrically driven organic lasers. [source] Xanthene dye functionalized norbornenes for the use in ring opening metathesis polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2007Martina Sandholzer Abstract A convenient synthetic route towards polymerizable fluorescein, dicholorofluorescein, and eosin dyes is presented. Polymerizability was provided by linking 2-norbornene carboxylic acid, 11-bromo-undecyl ester to the dye's carboxylate functionality. Although the monomers bearing dichlorofluorescein and eosin were obtained in high yield, the related fluorescein bearing monomer could only be obtained in low yield. In the latter case, concurring etherification and esterification led to a product mixture of the desired carboxy modified monomer and a double substituted by-product. The dye-monomers were used successfully for the preparation of statistical copolymers with endo,exo -2,3-norbornene dicarboxylic acid dimethylester by ROMP. Absorption and luminescence characteristics and, in particular, the acid/base sensitive behavior of the parent dyes were preserved in the monomers and copolymers. The absorption and emission maxima in THF solution and in the solid state were red shifted in comparison to the aqueous samples of the parent dyes. Dye-copolymers exhibited good film forming properties. Solid state luminescence studies of the copolymers revealed an increasing sensitivity towards NEt3 vapor in the order fluorescein < dichlorofluorescein < eosin bearing copolymer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1336,1348, 2007 [source] The Effect of Protonation on the Optical Properties of Conjugated Fluorene,Pyridine CopolymersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 20 2008Stefan Kappaun Abstract A series of conjugated alternating and statistical copolymers of fluorene and pyridine are synthesized and characterized. The compounds under investigation, namely poly[2,7-(9,9-dihexylfluorenyl)- alt -(2,6-pyridinyl)] and poly[2,7-(9,9-dihexylfluorenyl)- stat -(2,6-pyridinyl)], are prepared by a Suzuki-type cross-coupling reaction starting from commercially available materials utilizing the recently described catalyst trans -bis(dicyclohexylamine) palladiumdiacetate ("DAPCy"). The target compounds are investigated by nuclear magnetic resonance and infrared spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, thermal analysis, UV,Vis absorption spectroscopy, and luminescence measurements in solution and in the solid state. Special emphasis is placed on studying the consequences of protonation on the photophysical properties of the described materials. Achieving a concise microscopic understanding of the effects of protonation on the absorption and luminescence characteristics is crucial for potential applications in, e.g., optical sensors. To that aim, the results of the systematic studies of the photophysical properties are explained by quantum mechanical calculations. [source] METHODOLOGICAL DEVELOPMENTS IN THE LUMINESCENCE DATING OF BRICK FROM ENGLISH LATE-MEDIEVAL AND POST-MEDIEVAL BUILDINGS,ARCHAEOMETRY, Issue 4 2007I. K. BAILIFF Fired clay brick samples, obtained from a group of seven high-status late-medieval and post-medieval buildings in England ranging in age from c. ad 1390 to 1740, were dated by the luminescence method using an optically stimulated luminescence (OSL) technique. The results obtained indicate that, when applied to quartz extracted from brick, the technique is capable of producing dates that are in consistently good agreement with independent dating evidence for the buildings. For six samples taken from a group of four dating ,control' buildings the mean difference between the central values of luminescence and assigned ages was 5 ± 10 years (SD, n = 6). The methodology used is appropriate for application to other standing buildings in other temporal and geographic regions, and may be used with confidence where conventional dating methods are less certain. The study also examines the luminescence characteristics of quartz and the characteristics of the lithogenic radionuclides in brick samples and identifies various aspects related to the assessment of experimental uncertainty in testing the reliability of the method. [source] | |||||||||||||