Red-light-emitting iridium complexes with hole-transporting 9-arylcarbazole moieties for electrophosphorescence efficiency/color purity trade-off optimizationE

The synthesis, structures, photophysics, electrochemistry and electrophosphorescent properties of new red phosphorescent cyclometalated iridium(III) isoquinoline complexes, bearing 9-arylcarbazolyl chromophores, are reported. The functional properties of these red phosphors correlate well with the results of density functional theory calculations

Red-Light-Emitting Iridium Complexes with Hole-Transporting 9-Arylcarbazole Moieties for Electrophosphorescence Efficiency/ Color Purity Trade-off Optimization

The synthesis, structures, photophysics, electrochemistry and electrophosphorescent properties of new red phosphorescent cyclometalated iridium(III) isoquinoline complexes, bearing 9-arylcarbazolyl chromophores, are reported. The functional properties of these red phosphors correlate well with the results of density functional theory calculations. The highest occupied molecular orbital levels of these complexes are raised by the integration of a carbazole unit to the iridium isoquinoline core so that the hole-transporting ability is improved in the resulting complexes relative to those with I-phenylisoquinoline ligands. All of the complexes are highly thermally stable and emit an intense red light at room temperature with relatively short lifetimes that are beneficial for highly efficient organic light-emitting diodes (OLEDs).

Hole-transporting polymers containing carbazol-3,9-diyl and 1,4-phenylene fragments in the main chain

New carbazole-based polymers, which contain various content of electro-active fragments in the main chain connected via alkylene spacers, have been synthesized by Ni(0)-catalyzed Yamamoto-type aryl-aryl coupling reactions. These compounds represent amorphous materials of high thermal stability with glass-transition temperatures of 139-151 degrees C and thermal decomposition starting at temperatures above 400 degrees C. UV-vis absorption and photoluminescence emission spectra of the materials confirmed that the conjugated segments in the macromolecules are rather short.

Effect of core structure on the fluorescence properties of hyperbranched poly(phenylene sulfide)

We functionalize the focal group of hyperbranched poly(phenylene sulfide) (HPPS) with benzyl, phenyl, and naphthyl group, respectively. DSC analysis shows that T-g of HPPS is increased from 55 to 93 degrees C by functionalization of the focal group with a conjugated naphthyl group. The fluorescence properties of the three core-functionalized HPPS' are studied under the comparison with the original HPPS.

On the chemical synthesis and drug delivery response of folate receptor-activated, polyethylene glycol-functionalized magnetite nanoparticles

We describe here the chemical synthesis and in vitro drug delivery response of polyethylene glycol (PEG)-functionalized magnetite (Fe3O4) nanoparticles, which were activated with a stable ligand, folic acid, and conjugated with an anticancer drug, doxorubicin. The functionalization and conjugation steps in the chemical synthesis were confirmed using Fourier transform infrared spectroscopy. The drug-release behavior of PEG-functionalized and folic acid-doxorubicin-conjugated magnetic nanoparticles was characterized by two stages involving an initial rapid release, followed by a controlled release. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Facile synthesis of 9,10-diarylphenanthrenes and poly(9,10-diarylphenanthrene)s

One-pot reduction of 9,10-diaryl-9,10-dihydrophenanthrene-9,10-diols to 9,10-diarylphenanthrenes was achieved with Zn/H+ in acetic acid. Accordingly, various novel phenanthrenes and polyphenanthrenes with efficient blue emission were easily synthesized.

Crystal packing motifs of oligothiophenes end-capped with N-containing aryls

Oligothiophenes (OThs) end-capped with 3-quinolyl or pyridyl with nitrogen atom at meta-, ortho- or para-position were synthesized. The single-crystal structures of the resulting molecules, i.e., o-PyTh4, m-PyTh4, p-PyTh4, QuTh2, and QuTh3, were successfully determined by single-crystal X-ray analysis. Pyridyl end-capped OThs; o-PyTh4, m-PyTh4, and p-PyTh4, adopt the different herringbone packing arrangement in crystals depending on the position of the nitrogen atom because of the presence of weak C-H center dot center dot center dot N hydrogen bonds. The p-PyTh4 molecules are linked each other along the long axis of the molecules to form the extended chains by C-H center dot center dot center dot N dimer synthon. For m-PyTh4, the C-H center dot center dot center dot N interactions two-dimensionally extend through C-H center dot center dot center dot N trimer synthon.

Phase transition behavior and molecular orientation of oligo(9,9 '-dioctylfluorene-alt-bithiophene)

A novel conjugated oligomer, oligo(9,9'-dioctylfluorene-alt-bithiophene) (OF8T2), was found to exhibit a unique phase transition between crystalline and liquid-crystalline states, and a liquid-crystalline glass was easily generated, offering better TFT device performance. In thin films, upon annealing the OF8T2 molecules oriented preferentially with their planes of conjugation being normal to the substrate, and both film thickness and annealing temperature were critical to the film morphology and the molecular orientation. When the OF8T2 film was deposited on a rubbed polyimide surface and annealed, the molecules aligned their long axes along the rubbing direction.

Film Morphology and Molecular Orientation in Oligothiophene-fluorene Films

The effects of processing conditions on film morphology and molecular orientation were studied for a novel conjugated fluorene-bithiophene oligomer, oligo(9,9-dioctylfluorene-alt-bithiophene) (OF8T2). Depending on the method of film preparation, OF8T2 molecules adopt different orientations in the films. X-ray diffraction peak at 4.9 degrees of the OF8T2 film deposited from petroleum ether/dichloromethane mixture is attributed to a layering distance between sheets of OF8T2 chains, which are separated by the octyl side chains. Preferred orientation is clearly inferred through the absence of peaks corresponding to pi-pi stacking.

Tin (IV) phthalocyanine oxide: An air-stable semiconductor with high electron mobility

Air-stable n-type field effect transistors were fabricated with an axially oxygen substituted metal phthalocyanine, tin (IV) phthalocyanine oxide (SnOPc), as active layers. The SnOPc thin films showed highly crystallinity on modified dielectric layer, and the electron field-effect mobility reached 0.44 cm(2) V-1 s(-1). After storage in air for 32 days, the mobility and on/off ratio did not obviously change. The above results also indicated that it is an effective approach of seeking n-type semiconductor by incorporating the appropriate metal connected with electron-withdrawing group into pi-pi conjugated system.

Pyrazine-containing Acene-Type Molecular Ribbons with up to 16 Rectilinearly Arranged Fused Aromatic Rings

A series of acene-type conjugated molecules(1-5) containing 2-6 pyrazine units and up to 16 rectilinearly arranged fused aromatic rings were synthesized by condensation coupling of 1,2-diamines and 1,2-diketones. The energy gap of the molecules estimated from absorption edge decreases with an increase in molecular length, indicating the well-delocalized nature of the molecules. The cyclic voltarnmetry measurements suggest that the n-type properties of these ribbonlike pyrazine derivatives are dependent on the molecular length and the number of the pyrazine units.

Novel White Electroluminescent Single Polymer Derived from Fluorene and Quinacridone

A novel series of white light emitting single polymers are prepared by incorporating low contents of quinacridone into the main chain of polyfluorene. This is the first report of quinacridone-containing conjugated polymer. Single layer devices (ITO/PEDOT:PSS/polymer/Ca/Al) are fabricated with these polymers. Energy transfer from fluorene segments to quinacridone unit is observed. Moreover, in the EL process, quinacridone unit can trap electrons and cannot trap holes from fluorene segments.

Blue electroluminescent polymers with dopant-host systems and molecular dispersion features: polyfluorene as the deep blue host and 1,8-naphthalimide derivative units as the light blue dopants

We developed a series of highly efficient blue electroluminescent polymers with dopant-host systems and molecular dispersion features by selecting 1,8-naphthalimide derivatives as the light blue emissive dopant units, choosing polyfluorene as the deep blue emissive polymer host and covalently attaching the dopant units to the side chain of the polymer host. The polymers' EL spectra exhibited both deep blue emission from the polymer host and light blue emission from the dopant units because of the energy transfer and charge trapping from the polymer host to the dopant units.

Synthesis, characterization, and electroluminescence of PPV copolymers containing electron and hole-transporting units

Three series of poly(phenylene vinylene) (PPV) derivatives containing hole-transporting triphenylamine derivatives [N-(4-octoxylphenyl)diphenylamine, N,N'-di(4-octyloxylphenyl)-N,N'-diphenyl-1,4-phenylenediamine, and N,N'-di(4-octoxylphenyl)-N,N'-diphenylbenzidine] (donor) and electron-transporting oxadiazole unit (2,5-diphenyl-1,3,4-oxadiazole) (acceptor) in the main chain were synthesized by improved Wittig copolymerization. The resulting donor-acceptor (D-A) polymers are readily soluble in common organic solvents, such as chloroform, dichloroethane, THF, and toluene.

Synthesis and characterization of color-stable electroluminescent polymers: Poly(dinaphtho [1,2-a : 1 ',2 '-g]-s-indacene)s

Two new stepladder conjugated polymers, that is, poly(7,7,15,15-tetraoctyldinaphtho[1,2-a:1',2'-g]-s-indacene) (PONSI) and poly(7,7,15,15-tetra(4-octylphenyl)dinaphtho[1,2-a:1',2'-g]-s-indacene) (PANSI) with alkyl and aryl substituents, respectively, have been synthesized and characterized. In comparison with poly(indenofluorene)s, both polymers have extended conjugation at the direction perpendicular to the polymer backbone because of the introduction of naphthalene moieties. The emission color of the polymers in film state is strongly dependent on the substituents. While PONSI emits at a maximum of 463 nm, PANSI with the same backbone but aryl substituents displays dramatically redshifted emission with a maximum at 494 nm.