Dual Emission (dual + emission)

Distribution by Scientific Domains

Selected Abstracts

Synthesis, Structure and Spectroscopic Properties of Novel9,10-Bis{[6-(diphenylphosphanyl)-2-pyridylmethyl]propylaminomethyl}anthracene-Bridged Group 11 Metal (M = CuI and AgI) Dinuclear Complexes

Hu Xu
Abstract Dinuclear complexes [M2(,-BPNNAn)]X2 (M = CuI, X = ClO4,1, X = BF4,2; M = AgI, X = BF4,3, X = ClO4,4) have been prepared by treating 9,10-bis{[6-(diphenylphosphanyl)-2-pyridylmethyl]propylaminomethyl}anthracene (BPNNAn) with M(CH3CN)4X in CH2Cl2. The structures of complexes 1, 2 and 3 have been determined by single-crystal X-ray diffraction studies. In the complexes, BPNNAn acts as a chelating ligand and two metal ions riding on two bridgehead carbon atoms in the anthracene group leads to the deformation of the anthracenyl ring. The Cu,Arene charge transfer interaction is observed from the nonfluorescent emission of Cu complex 1, while the Ag complex 3 exhibits dual emission at high concentrations in a CH2Cl2 solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Exploiting a Dual-Fluorescence Process in Fluorene,Dibenzothiophene- S,S -dioxideCo-Polymers to Give Efficient Single Polymer LEDs with Broadened Emission

Simon M. King
Abstract A description of the synthesis of random (9,9-dioctylfluorene-2,7-diyl),(dibenzothiophene- S,S -dioxide-3,7-diyl) co-polymers (p(F-S)x) by palladium-catalyzed Suzuki cross-coupling polymerization where the feed ratio of the latter is varied from 2 to 30,mol % (i.e., x,=,2,30) is given. Polymer light emitting devices are fabricated with the configuration indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid)/p(F,S)x/Ba/Al. The device external quantum efficiency increased as the ratio of the S co-monomer was increased, up to a maximum of 1.3% at 100,mA cm,2 for p(F-S)30 and a brightness of 3 770,cd m,2 (at 10,V). The S units impart improved electron injection, more balanced mobilities, and markedly improved device performance compared to poly(9,9-dioctylfluorene) under similar conditions. These co-polymers display broad emission, observed as greenish-white light, which arises from dual fluorescence, viz. both local excited states and charge transfer states. Utilizing dual emission can reduce problems associated with Förster energy transfer from high-energy to-low energy excited states. [source]

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

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]

Pressure-Induced Emission Enhancement of a Series of Dicyanovinyl-Substituted Aromatics: Pressure Tuning of the Molecular Population with Different Conformations

CHEMPHYSCHEM, Issue 8 2008
Qian Wang Dr.
Abstract A series of dicyanovinyl-substituted aromatic compounds (Ar-DCV; Ar=9-anthracenyl, 1-naphthyl, 1-pyrenyl) with dual fluorescence are prepared, and their emission properties,when molecularly dispersed in a polymer medium,are investigated under pressure perturbation. The total emission intensity is enhanced drastically from ambient pressure up to 70 kbar. Emission 30,107 times more intense than that at ambient pressure is observed at higher pressure. In dual emission, the enhancement of the local excited state (LE state) is significantly different from that of the intramolecular charge-transfer state (ICT state). The intensity of the ICT emission increases faster (30,370 times) than that of the LE emission (less than 20 times). In accordance with spectroscopic data, emission dynamics at different pressures, and computational studies on the molecular conformations of these compounds, a kinetic model is proposed to explain the effect of pressure on the emissive properties of the Ar-DCV compounds from the point of view of pressure-dependent populations of the species in the ground state. [source]