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Strong Fluorescence (strong + fluorescence)

Distribution by Scientific Domains

Chemistry	60%
Polymers and Materials Science	20%

Selected Abstracts

Tris(4-cyanophenyl)amine: Simple Synthesis via Self-assembly; Strong Fluorescence in Solution, Nano/microcrystals, and Solid,

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2007
A. Patra
Abstract The threefold symmetric molecule, tris(4-cyanophenyl)amine (TCPA) is synthesized from 4-fluorocyanobenzene by treatment with potassium carbonate in dimethylsulfoxide; the occurrence of the reaction without any amine reagent suggests the involvement of a novel self-assembly process. A reprecipitation strategy provides stable colloids containing highly monodisperse nano/microcrystals with well-defined cubic morphology and sizes tunable from 250 to 500,nm. The solution, colloid, and solid states of TCPA exhibit strong blue fluorescence; the colloid shows dual emission with an unusually small Stokes shift. Computational investigations are carried out on the molecule and supramolecular assemblies derived from the crystal structure. Coupled with detailed spectroscopic studies, they show that the emission in the colloidal and solid states can be attributed to energy levels resulting from the intermolecular interactions within different aggregation motifs in the condensed phase and energy cascades between them. The computations also reveal the presence of cooperative interactions in the molecular crystal contributing to its high thermal stability. The strong light emission exhibited by TCPA, concurrently in the solution, nano/microcrystal, and solid states establishes it as a novel molecular material of potential practical utility; it has led to the exploration of the underlying mechanism that describes the phenomena observed in the different physical states. [source]

Bandgap-Like Strong Fluorescence in Functionalized Carbon Nanoparticles,

ANGEWANDTE CHEMIE, Issue 31 2010
Xin Wang
Alternative gefunden: Gel-Säulenchromatographie lieferte fluoreszierende Kohlenstoff-Quantenpunkte (oberflächenpassivierte Kohlenstoff-Nanopartikel) mit Emissionsausbeuten nahe 60,%. Ihre optischen Eigenschaften deuten auf Bandlücken wie in nanoskaligen Halbleitern hin; daraus kann gefolgert werden, dass Kohlenstoff-Nanopartikel sich weitgehend halbleiterartig verhalten. [source]

Luminescent Zn and Cd Coordination Polymers

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2004
Chao Jiang
Abstract The hydrothermal reactions of Zn(ClO4)2·6H2O and Cd(ClO4)2·6H2O with 1,3-bis(2H -tetrazol-5-yl)benzene in an aqueous ethanol and an aqueous methanol/pyridine medium, respectively, yielded a 3D and a 2D metal-organic coordination framework [Zn(1,3-BTB)] (1) and [Cd(1,3-BTB)2(Py)2(H2O)2] [Cd[Cd(Py)(H2O)]2(1,3-BTB)2] (2) (1,3-BTB = 1,3-ditetrazolylbenzene, Py = pyridine), respectively. Species 1 possesses an open network structure with no guest molecules residing in its small cavities. The structural characterisation of 2 shows a 2D layered framework consisting of nano-sized polytube structures which are stacked one on top of another in the (110) plane giving small channels along the b and c axes. Additionally, compounds 1 and 2 exhibit strong fluorescence at room temperature in the solid state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Theoretical electronic spectra of 2-aminopurine in vapor and in water

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2006
Antonio Carlos Borin
Abstract The accurate quantum chemical CASSCF and CASPT2 methods combined with a Monte Carlo procedure to mimic solvation effects have been used in the calculation of the spectroscopic properties of two tautomers of 2-aminopurine (2AP). Absorption and emission spectra have been simulated both in vacuum and in aqueous environment. State and transition energies and properties have been obtained with high accuracy, leading to the assignment of the most important spectroscopic features. The lowest-lying 1(,,,*) (1La) state has been determined as responsible for the first band in the absorption spectrum and also for the strong fluorescence observed for the system in water. The combined approach used in the present work gives quantitatively accurate results. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

Highly soluble diphenylfluorene-based cardo copolyimides containing perylene units,

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7-8 2006
Shengang Xu
Abstract Two series of novel ternary copolyimides containing perylene and fluorene units in the backbone were synthesized by one-step polycondensation of diamine (4,4,-(9H-fluoren-9-ylidene)bisphenylamine, FBPA) with perylene dianhydride (3,4,9,10-perylenetetracarboxylic dianhydride, PTCDA) and a comonomer [4,4,-(hexafluoroisopropylidene) diphthalic anhydride, 6FDA or 3,3,,4,4,-benzophenonetetracarboxylic dianhydride, BDTA]. The polymers were named as PFFx (PTCDA-FBPA-6FDA) and PFBx (PTCDA-FBPA-BTDA), respectively, and their chemical structures were identified by FT-IR spectra and elemental analyses. Perylene contents in the copolyimides were determined through a quantitative UV-vis spectroscopy method, which are in agreement with the values calculated from the added raw materials both for PFFx and PFBx. Gel permeation chromatography (GPC) measurement suggested that the weight average molecular weight (Mw) is in the range 2.1,5.09,×,104 and the molecular weight distribution (MWD) is 1.86,2.72 for PFFx, and those for PFBx are 2.64,4.73,×,104 and 2.44,2.92, respectively. Thermogravimetric analysis (TGA) measurements showed that the copolyimides are very thermally stable with a temperature of 10% weight loss (T10) in the range 546,563°C for PFFx, and 538,548°C for PFBx. The copolyimides also have good solubility in common organic solvents such as chloroform and tetrahydrofuran. These unique properties can be attributed to the existence of the bulky diphenylfluorene moieties in the polymer backbone. All the copolyimides can emit strong fluorescence both in solution and in films, which make them possibly be used as thermostable light-emitting materials for organic light-emitting diodes. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Intermolecular C,H..., interactions in 1,5-diphenyl-3-(2-pyridyl)-2-pyrazoline

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010
Miquel Barceló-Oliver
The title compound, C20H17N3, is a derivative of 1,3,5-triaryl-2-pyrazoline and can act as an N,N,-bidentate ligand. This molecule features strong fluorescence that can be explained by an extended pyridyl,C=N,N,phenyl system. The three-dimensional structure is formed by means of an extended network of weak C,H..., hydrogen bonds supported by ,,, interactions. [source]

Formation of zinc protoporphyrin IX in Parma-like ham without nitrate or nitrite

ANIMAL SCIENCE JOURNAL, Issue 2 2009
Jun-ichi WAKAMATSU
ABSTRACT Zinc protoporphyrin IX (ZPP) is a characteristic red pigment in meat products that are manufactured without the addition of a curing agent such as nitrate or nitrite. To examine the effects of impurities such as mineral components in sea salt on the formation of ZPP, we manufactured Parmatype dry-cured hams that were salted with refined salt or sea salt and examined the involvement of oxidation-reduction potential (ORP) in the formation of ZPP. The content of ZPP was increased drastically after 40 weeks. Microscopic observation showed strong fluorescence caused by ZPP muscle fiber after 40 weeks. Conversely, heme content varied considerably during processing. ORP increased during processing. However, there was no obvious difference between ham salted with refined salt and that salted with sea salt. Therefore, it was concluded that impurities in sea salt were not involved in the formation of ZPP. [source]

Formation Mechanism of Maceral and Mineral Compositions of the "Barkinite" Liptobiolith from the Jinshan Mine, Anhui Province, China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2010
Yuzhuang SUN
Abstract: In order to study the accumulation mechanism of "barkinite", eight Late Permian channel benches (approximately 15-cm across and 10-cm deep) were taken from the Jinshan Mine, Anhui Province, China. The samples were analyzed by microscopical and geochemical methods. The microscopical observations indicate that the occurrence modes of "barkinite" in this area are different from those in other areas of China. The ratios of structureless "barkinite" are much higher in the Jinshan Mine, probably due to the flow-water and marine influenced environments. Furthermore, vitrinite macerals also show a strong fluorescence. The vitrinite fluorescence characteristics have not been observed in the Permian "barkinite" coals from northern China. The composition and variation of minerals in the column section also showed that the swamps in the study area were seriously influenced by seawater in the early and late stage during the peat accumulation. [source]

Multi-Input/Multi-Output Molecular Response System Based on the Dynamic Redox Behavior of 3,3,4,4-Tetraaryldihydro[5]helicene Derivatives: Reversible Formation/Destruction of Chiral Fluorophore and Modulation of Chiroptical Properties by Solvent Polarity

CHEMISTRY - A EUROPEAN JOURNAL, Issue 37 2009
Takanori Suzuki Prof.
Abstract 3,3,4,4-Tetaaryldihydro[5]helicenes (1) and 1,1,-binaphthyl-2,2,-diylbis(diarylcarbenium)s (22+) can be reversibly interconverted upon electron transfer, which is accompanied by a vivid color change (electrochromism) as well as by the formation/cleavage of a CC bond ("dynamic redox behavior"). Because only the neutral donor 1 exhibits strong fluorescence, electrochemical input can further modify the fluorescent properties of the pair. Due to the configurational stability of the helicity in 1 and axial chirality in 22+, the redox reaction of optically pure material proceeds stereospecifically, which induces a chiroptical change such as circular dichroism (CD) as an additional output. The CD spectra of dications 22+ exhibit solvent dependency (chiro-solvatochromism), which is accompanied by solvatochromic behavior based on the ,,, interaction of the two cationic chromophores as well as coordinative interaction of the Lewis basic solvent to the Lewis acidic triarylcarbenium moieties. Thus, the present system is endowed with multi-input functionality for modifying multiple output signals. [source]

Polysulfurated Pyrene-Cored Dendrimers: Luminescent and Electrochromic Properties

CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2008
Marc Gingras Prof.
Abstract We have synthesized a novel class of dendrimers, consisting of a polysulfurated pyrene core with appended poly(thiophenylene) dendrons (PyG0, PyG1, and PyG2, see Scheme,1), which exhibit remarkable photophysical and redox properties. In dichloromethane or cyclohexane solution they show a strong, dendron-localized absorption band with a maximum at around 260,nm and a band in the visible region with a maximum at 435,nm, which can be assigned to the pyrene core strongly perturbed by the four sulfur substituents. The dendrimers exhibit a strong (,=0.6), short-lived (,=2.5,ns) core-localized fluorescence band with maximum at approximately 460,nm in cyclohexane solution at 293,K. A strong fluorescence is also observed in dichloromethane solution at 293,K, in dichloromethane/chloroform rigid matrix at 77,K, and in the solid state (powder) at room temperature. The dendrimers undergo reversible chemical and electrochemical one-electron oxidation with formation of a strongly colored deep blue radical cation. A second, reversible one-electron oxidation is observed at more positive potential values. The photophysical and redox properties of the three dendrimers are finely tuned by the length of their branches. The strong blue fluorescence and the yellow to deep blue color change upon reversible one-electron oxidation can be exploited for optoelectronic devices. [source]