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High Fluorescence Quantum Yields (high + fluorescence_quantum_yield)
Selected AbstractsSynthesis and Functionalization of Germanium Triphenylcorrolate: The First Example of a Partially Brominated CorroleEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2007Sara Nardis Abstract Ge complexes of 5,10,15-triphenylcorrole were prepared in refluxing dry DMF using GeCl4 as the source of Ge. Chromatographic separation of the crude reaction mixture afforded the ,-oxo dimer 1 and the methoxy derivative 2a. The corresponding chloride 2b can be obtained by treatment of 1 or 2a with HCl. The reaction of 2a with Br2 in CHCl3/py afforded the hexabromo derivative 3 as the main product, giving the first indication of the regioselective substitution of pyrroles B and C on the corrole ring. The fully brominated open-chain tetrapyrrole 4 was also characterized as a reaction by-product. Different partially brominated Ge complexes 5 and 6 have been obtained by variation of reaction conditions, while the heptabromo derivative was obtained in a mixture with the corresponding fully brominated Gecorrole. Photophysical characterization of Ge corrolates confirmed the high fluorescence quantum yield of such complexes, and also led to the first observation of phosphorescence emissions from corrole complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Enhanced Optical Properties and Opaline Self-Assembly of PPV Encapsulated in Mesoporous Silica SpheresADVANCED FUNCTIONAL MATERIALS, Issue 23 2009Timothy L. Kelly Abstract A new poly(p -phenylenevinylene) (PPV) composite material has been developed by the incorporation of insoluble PPV polymer chains in the pores of monodisperse mesoporous silica spheres through an ion-exchange and in situ polymerization method. The polymer distribution within the resultant colloidal particles is characterized by electron microscopy, energy dispersive X-ray microanalysis, powder X-ray diffraction, and nitrogen adsorption. It was found that the polymer was selectively incorporated into the mesopores of the silica host and was well distributed throughout the body of the particles. This confinement of the polymer influences the optical properties of the composite; these were examined by UV,vis and fluorescence spectroscopy and time-correlated single-photon counting. The results show a material that exhibits an extremely high fluorescence quantum yield (approaching 85%), and an improved resistance to oxidative photobleaching compared to PPV. These enhanced optical properties are further complemented by the overall processability of the colloidal material. In marked contrast to the insolubility of PPV, the material can be processed as a stable colloidal dispersion, and the individual composite spheres can be self-assembled into opaline films using the vertical deposition method. The bandgap of the opal can be engineered to overlap with the emission band of the polymer, which has significant ramifications for lasing. [source] Triphenylamine-based fluorescent conjugated copolymers with pendant terpyridyl ligands as chemosensors for metal ionsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2010Yi Cui Abstract Two well-defined triphenylamine-based fluorescent conjugated copolymers with pendant terpyridyl ligands were synthesized through Suzuki coupling polymerization and were further characterized by 1H-NMR, 13C-NMR, gel permeation chromatography, Infrared, and UV-vis spectra. Polymer P-1, terpyridine-bearing poly(triphenylamine- alt -fluorene) with a high fluorescence quantum yield (62%) shows much higher sensitivities toward Fe3+, Ni2+, and Cu2+ as compared with the other metal ions investigated. Especially, Fe3+ can lead to an almost complete fluorescence quenching of polymer P-1. Whereas, the analogous polymer P-2, in which N -ethylcarbazole repeat units replace the fluorene units in P-1, shows a very poor selectivity. It demonstrates that polymers with a same receptor may show different sensitivity to analytes owing to their different type of backbones. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1310,1316, 2010 [source] Systematic Investigation of Molecular Arrangements and Solid-State Fluorescence Properties on Salts of Anthracene-2,6-disulfonic Acid with Aliphatic Primary AminesCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2009Yuji Mizobe Dr. Abstract Organic salts of anthracene-2,6-disulfonic acid (ADS) with a wide variety of primary amines have been fabricated, and their arrangements of anthracene molecules and solid-state fluorescence properties investigated. Single-crystal X-ray studies reveal that the salts show seven types of crystal forms and corresponding molecular arrangements of anthracene moieties depending on the amine, while anthracene shows only one form and arrangement in the solid state. Depending on the molecular arrangements, the ADS salts exhibit various solid-state fluorescence properties: spectral shift (30,nm) and suppression and enhancement of the fluorescence intensity. Especially the ADS salt with n -heptylamine (nHepA), which shows discrete anthracene moieties in the crystal, exhibits the highest quantum yield (,F=46.1±0.2,%) in the series of ADS salts, which exceeds that of anthracene crystal (,F=42.9±0.2,%). From these systematic investigations on the arrangements and the solid-state properties, the following factors are essential for high fluorescence quantum yield in the solid state: prevention of contact between , planes of anthracene moieties and immobilization of anthracene rings. In addition, such organic salts have potential as a system for modulating the molecular arrangements of fluorophores and the concomitant solid-state properties. Thus, systematic investigation of this system constructs a library of arrangements and properties, and the library leads to remarkable strategies for the development of organic solid materials. [source] Synthesis and Characterization of Carbazole-Based Dendrimers with Porphyrin CoresEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2006Ting Hua Xu Abstract A series of novel dendritic carbazole-based porphyrins [T(Cz-Gn)Ps] have been synthesized by a combination of Ullmann coupling and Adler condensation reactions and their intramolecular energy-transfer properties have been studied by absorption and steady-state fluorescence spectroscopy. It has been found that the light-harvesting capabilities of T(Cz-Gn)Ps increase with increasing generation, but that the efficiency of the energy transfer decreases from T(Cz-G0)P to T(Cz-G2)P due to the Förster energy-transfer process. In addition, these dendritic macromolecules can emit intense red light with high fluorescence quantum yields and so may find applications in photonic devices. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Highly Fluorescent Mesostructured Films that consist of Oligo(phenylenevinylene),Silica Hybrid Frameworks,ADVANCED FUNCTIONAL MATERIALS, Issue 22 2008Norihiro Mizoshita Abstract Highly fluorescent and visible-light-responsive mesostructured organosilica films are successfully obtained by acidic sol,gel polycondensation of oligo(phenylenevinylene) (OPV)-bridged organosilane and tetraethoxysilane precursors in the presence of a template surfactant. The OPV-bridged organosilane precursors with different lateral alkoxy substituents, hexyloxy and 2-ethylhexyloxy, and no substituent, are synthesized by Rh-catalyzed silylation of corresponding aromatic iodides. From the organosilane precursors, three kinds of mesostructured OPV,silica hybrid films are prepared by spin-casting using evaporation-induced self-assembly. UV-vis absorption and fluorescence behavior of the OPV,silica hybrid films show that the optical properties and intermolecular interactions of the OPV moieties embedded within the organosilica frameworks strongly depend on the lateral alkoxy substituents in the precursors. The hexyloxy and 2-ethylhexyloxy substituents prevent aggregation of the OPV units in the organosilica frameworks; this result leads to high fluorescence quantum yields of 0.48,0.61 and 0.63,0.66, respectively, while non-substitution leads to lower fluorescence quantum yields of 0.25,0.34. Fluorescence decay profiles of the organosilica hybrid films also confirm a suppression of the aggregation of OPV moieties by the lateral substituents. These mesostructured organosilica films with significant optical properties in the visible-light region are promising as a new class of phosphor materials. [source] Electrogenerated chemiluminescence of benzo 15-crown-5 derivativesJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2009Xiao Jiang Abstract Novel electrogenerated chemiluminescence (ECL) reagents C1, C2, and C3 with high fluorescence quantum yields bearing 15-crown-5 moiety have been synthesized and characterized. The photophysical, electrochemical, and ECL characters of these compounds have been studied in a 1:1 (v/v) PhH/MeCN mixed solvent. The ECL intensity is enhanced distinctly with the increase in the fluorescence quantum yield. Their ECL behaviors have been studied using annihilation and co-reactant methods (tri- n -propylamine (TPrA) was used as a co-reactant), respectively. The stable ECL emissions of compounds C1,C3 can be ascribed to the typical and simple monomer ECL emission via S-route. Copyright © 2008 John Wiley & Sons, Ltd. [source] Red-Emitting Rhodamine Dyes for Fluorescence Microscopy and NanoscopyCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2010Kirill Kolmakov Dr. Abstract Fluorescent markers emitting in the red are extremely valuable in biological microscopy since they minimize cellular autofluorescence and increase flexibility in multicolor experiments. Novel rhodamine dyes excitable with 630,nm laser light and emitting at around 660,nm have been developed. The new rhodamines are very photostable and have high fluorescence quantum yields of up to 80,%, long excited state lifetimes of 3.4,ns, and comparatively low intersystem-crossing rates. They perform very well both in conventional and in subdiffraction-resolution microscopy such as STED (stimulated emission depletion) and GSDIM (ground-state depletion with individual molecular return), as well as in single-molecule-based experiments such as fluorescence correlation spectroscopy (FCS). Syntheses of lipophilic and hydrophilic derivatives starting from the same chromophore-containing scaffold are described. Introduction of two sulfo groups provides high solubility in water and a considerable rise in fluorescence quantum yield. The attachment of amino or thiol reactive groups allows the dyes to be used as fluorescent markers in biology. Dyes deuterated at certain positions have narrow and symmetrical molecular mass distribution patterns, and are proposed as new tags in MS or LC-MS for identification and quantification of various substance classes (e.g., amines and thiols) in complex mixtures. High-resolution GSDIM images and live-cell STED-FCS experiments on labeled microtubules and lipids prove the versatility of the novel probes for modern fluorescence microscopy and nanoscopy. [source] Pyrrolopyrrole Cyanine Dyes: A New Class of Near-Infrared Dyes and FluorophoresCHEMISTRY - A EUROPEAN JOURNAL, Issue 19 2009Georg Abstract NIRer there: Pyrrolopyrrole cyanine (PPCys) dyes, a new class of near-infrared (NIR) fluorophores, are obtained by condensation of heteroarylacetonitrile and diketopyrrolopyrrole compounds (see picture). Complexation with BF2 or BPh2 yields strongly fluorescent, photostable NIR dyes that show high absorption cross-sections and fluorescence quantum yields. Furthermore, alteration of the heterocycle can tune the main absorption between ,,=,684 and 864,nm. Pyrrolopyrrole cyanine (PPCy) dyes are presented as a novel class of near-infrared (NIR) chromophores, which are synthesized in a condensation reaction of diketopyrrolopyrrole with heteroarylacetonitrile compounds. Their optical properties are marked by strong and narrow-band NIR absorptions. Complexation products with BF2 and BPh2 show strong NIR fluorescence and hardly any absorption in the visible range. We synthesized a series of new PPCys that differ only in the heterocyclic peripheral groups of the chromophore. With this strategy, the absorption spectra can be tuned between 684 and 864,nm, while high fluorescence quantum yields are maintained. The influence of the heterocycle on the optical properties of the dyes is discussed. [source] Highly Fluorescent Conjugated Pyrenes in Nucleic Acid Probes: (Phenylethynyl)pyrenecarbonyl-Functionalized Locked Nucleic AcidsCHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2008Irina Abstract In recent years, fluorescently labeled oligonucleotides have become a widely used tool in diagnostics, DNA sequencing, and nanotechnology. The recently developed (phenylethynyl)pyrenes are attractive dyes for nucleic acid labeling, with the advantages of long-wave emission relative to the parent pyrene, high fluorescence quantum yields, and the ability to form excimers. Herein, the synthesis of six (phenylethynyl)pyrene-functionalized locked nucleic acid (LNA) monomers M1,M6 and their incorporation into DNA oligomers is described. Multilabeled duplexes display higher thermal stabilities than singly modified analogues. An increase in the number of phenylethynyl substituents attached to the pyrene results in decreased binding affinity towards complementary DNA and RNA and remarkable bathochromic shifts of absorption/emission maxima relative to the parent pyrene fluorochrome. This bathochromic shift leads to the bright fluorescence colors of the probes, which differ drastically from the blue emission of unsubstituted pyrene. The formation of intra- and interstrand excimers was observed for duplexes that have monomers M1,M6 in both complementary strands and in numerous single-stranded probes. If more phenylethynyl groups are inserted, the detected excimer signals become more intense. In addition, (phenylethynyl)pyrenecarbonyl,LNA monomers M4, M5, and M6 proved highly useful for the detection of single mismatches in DNA/RNA targets. [source] Synthesis and Electronic Properties of Monodisperse OligophenothiazinesCHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2008Markus Sailer Dr. Abstract Starting from N -hexylphenothiazine, a versatile construction kit of brominated and borylated phenothiazines can be easily prepared by a sequence of bromination, bromo,lithium exchange/borylation, and Suzuki coupling. Subsequent Suzuki arylation of the building blocks gives soluble, monodisperse, and structurally well defined oligophenothiazines in good yields. The molecular weights at the peak maximum (Mp), obtained by GPC (gel permeation chromatography), and the actual molecular weights of the oligomer series, obtained by mass spectrometry, show excellent correlation. A QM/MM conformational analysis for the complete series reveals that the obvious butterfly-shaped phenothiazine structure multiplies and significantly reduces the hydrodynamic volume of the oligomers. The electronic properties (absorption and emission spectroscopy and cyclic voltammetry) give reasonable correlations with the chain length. With regard to the emission maxima, the effective conjugation length is already reached with the hexamer. Oligophenothiazines are highly fluorescent, with high fluorescence quantum yields, and are simultaneously highly electroactive, with low oxidation potentials. Ausgehend von N -Hexylphenothiazin kann leicht ein vielseitiger Baukasten aus bromierten und borylierten Phenothiazinen über eine Sequenz aus Bromierung, Bromo,Lithium-Austausch/Borylierung und Suzuki Kupplung hergestellt werden. Die nachfolgende Suzuki-Arylierung der Bausteine führt in guten Ausbeuten zu löslichen, monodispersen und strukturtreuen Oligophenothiazinen. Die Molekulargewichte beim Peakmaximum (Mp), die aus GPC (Gelpermeationschromatographie) erhalten werden und die tatsächlichen Molekulargewichte der Oligomeren, erhalten durch Massenspektrometrie, ergeben eine exzellente Korrelation. Die QM/MM-Konformationsanalyse der gesamten Serie zeigt, das der Effekt der Schmetterlingsstruktur der Phenothiazine sich vervielfältigt und so das hydrodynamische Volumen der Oligomere deutlich verkleinert. Die elektronischen Eigenschaften der Oligomere (Absorptions- und Emissionsspektroskopie und Cyclovoltammetrie) korrelieren mit der Kettenlänge. Im Falle der Emissionsmaxima wird die effektive Konjugationslänge bereits mit dem Hexamer erreicht. Oligophenothiazine fluoreszieren mit hohen Fluoreszenzquantenausbeuten und erweisen sich gleichzeitig wegen ihrer niedrigen Oxidationspotenziale als äußerst elektroaktiv. [source] Benzo[b]phosphole-Containing ,-Electron Systems: Synthesis Based on an Intramolecular trans -Halophosphanylation and Some Insights into Their PropertiesCHEMISTRY - AN ASIAN JOURNAL, Issue 11 2009Aiko Fukazawa Dr. Abstract The intramolecular trans -halophosphanylation of 2-(aminophosphanyl)phenylacetylenes mediated by PBr3 followed by the oxidation with H2O2, produces 3-bromobenzo[b]phosphole oxide derivatives. This cyclization is also used for the synthesis of a 3-iodo derivative by conducting the reaction in the presence of LiI. Based on this synthetic method, various benzophosphole-containing ,-conjugated compounds, including a phosphoryl and methylene-bridged stilbene 10, 2,3,6,7-tetraphenylbenzo[1,2- b:4,5- b,]diphosphole- P,P, -dioxides 11, and their phosphine sulfide derivatives 12, are synthesized. The study of the structure,property relationships in a series of the bridged stilbenes, including a bis(methylene)-bridged stilbene 10, and a bis(phosphoryl)-bridged stilbene, reveals that as the contribution of the phosphoryl groups increased, the absorption and emission maxima substantially shift to longer wavelengths. The intrinsic substituent effects of the phosphoryl group in this skeleton are to decrease the oscillator strength of the electronic transition and thus decrease the radiative decay rate constants from the singlet excited state. Nevertheless, these compounds maintain high fluorescence quantum yields (,F>0.8) owing to the significantly retarded nonradiative decay process. In the study of the benzodiphosphole derivatives 11 and 12, their cyclic voltammetry revealed that both of the phosphoryl and phosphine sulfide derivatives have low reduction potentials (,1.7 to ,1.8,V vs ferrocene/ferrocenium couple) with the high reversibility of the redox waves. These compounds also showed high thermal stabilities with the high glass transition temperatures of 147,159,°C, indicative of their potential utilities as amorphous materials. [source] | |||||||||||||