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Ether Groups (ether + groups)
Selected AbstractsMultifunctional Crosslinkable Iridium Complexes as Hole Transporting/Electron Blocking and Emitting Materials for Solution-Processed Multilayer Organic Light-Emitting DiodesADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Biwu Ma Abstract Here, a new series of crosslinkable heteroleptic iridium (III) complexes for use in solution processed phosphorescent organic light emitting diodes (OLEDs) is reported. These iridium compounds have the general formula of (PPZ-VB)2Ir(C,N), where PPZ-VB is phenylpyrazole (PPZ) vinyl benzyl (VB) ether; and the C,N ligands represent a family of four different cyclometallating ligands including 1-phenylpyrazolyl (PPZ) (1), 2-(4,6-difluorophenyl)pyridyl (DFPPY) (2), 2-(p-tolyl)pyridyl (TPY) (3), and 2-phenylquinolyl (PQ) (4). With the incorporation of two crosslinkable VB ether groups, these compounds can be fully crosslinked after heating at 180,°C for 30,min. The crosslinked films exhibit excellent solvent resistance and film smoothness which enables fabrication of high-performance multilayer OLEDs by sequential solution processing of multiple layers. Furthermore, the photophysical properties of these compounds can be easily controlled by simply changing the cyclometallating C,N ligand in order to tune the triplet energy within the range of 3.0,2.2,eV. This diversity makes these materials not only suitable for use in hole transporting and electron blocking but also as emissive layers of several colors. Therefore, these compounds are applied as effective materials for all-solution processed OLEDs with (PPZ-VB)2IrPPZ (1) acting as hole transporting and electron blocking layer and host material, as well as three other compounds, (PPZ-VB)2IrDFPPY (2), (PPZ-VB)2IrTPY(3), and (PPZ-VB)2IrPQ(4), used as crosslinkable phosphorescent emitters. [source] Sulfobutyl Ether-,-Cyclodextrins: Promising Supramolecular Carriers for Aqueous Organometallic CatalysisADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005Philippe Blach Abstract The potentialities of sulfobutyl ether-,-CDs derivatives as supramolecular carrier in a biphasic Tsuji,Trost reaction catalyzed by a water-soluble palladium complex of trisulfonated triphenylphosphine have been investigated. The efficiency of these cyclodextrins (CDs) strongly depends on the average molar substitution degree of cyclodextrin and the highest rate enhancements were obtained with cyclodextrins containing about 7 sulfobutyl ether groups. This result was attributed to the absence of a strong interaction between this cyclodextrin and the trisulfonated triphenylphosphine used to dissolve the catalyst in the aqueous phase and to the presence of an extended hydrophobic cavity allowing a better molecular recognition between the substrate and the cyclodextrin. This constitutes the first example of a non-interacting ,-cyclodextrin/phosphine couple with high catalytic activities. [source] A positive-working photosensitive polyimide based on thermal cross-linking and acidolytic cleavageJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Myung-Sup Jung Abstract A novel positive-working photosensitive polyimide (PSPI) based on a poly(hydroxyimide) (PHI), a crosslinking agent having vinyl ether groups, and a photoacid generator (PAG) was prepared. The PHI as a base resin of the three-component PSPI was synthesized from 4,4,-oxydiphthalic anhydride and 2,2,-bis(3-amino-4-hydroxyphenyl)hexafluoropropane through ring-opening polymerization and subsequent thermal cyclization. 2,2,-bis(4-(2-(vinyloxy)ethoxy)phenyl)propane (BPA-DEVE) was used as a vinylether compound and diphenyliodonium 5-hydroxynaphthalene-1-sulfonate was used as a PAG. The phenolic hydroxyl groups of the PHI and the vinyl ether groups of BPA-DEVE are thermally crosslinked with acetal structures during prebake step, and the crosslinked PHI becomes completely insoluble in an aqueous basic solution. Upon exposure to UV light (365 nm) and subsequent postexposure bake (PEB), a strong acid generated from the PAG cleaves the crosslinked structures, and the exposed area is effectively solubilized in the alkaline developer. The dissolution behavior of the PSPI containing each 11.5 wt % of BPA-DEVE and of the PAG was studied after UV exposure (365 nm) and PEB. It was found that the difference in dissolution rates between exposed and unexposed areas was enough to get high resolution. A fine positive pattern with a resolution of 5 ,m in a 3.7-,m-thick film was obtained from the three-component PSPI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis of dibenzo-16-crown-5 compounds with pendant ester and ether groupsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2004David A. Babb Structurally related dibenzo-16-crown-5 lariat ethers with pendant ester and ether groups are prepared. Structural variations within the series of alkyl lariat ether esters include changes in the O-alkyl group, attachment site and nature of the lipophilic group, and length of the spacer, which connects the ester group to the polyether framework. Also synthesized are bis(crown ether) diesters with two dibenzo-16-crown-5 or two dicyclohexano-16-crown-5 units and two ester groups connected to each other by a linker of varying length. Synthetic strategies for the preparation of these lariat ethers with pendant ester- and ether-containing side arms are described. [source] Synthesis and self-assembly of well-defined cyclodextrin-centered amphiphilic A14B7 multimiktoarm star copolymers based on poly(,-caprolactone) and poly(acrylic acid)JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2010Peng-Fei Gou Abstract Novel amphiphilic A14B7 multimiktoarm star copolymers composed of 14 poly(,-caprolactone) (PCL) arms and 7 poly(acrylic acid) (PAA) arms with ,-cyclodextrin (,-CD) as core moiety were synthesized by the combination of controlled ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). 14-Arm star PCL homopolymers (CDSi-SPCL) were first synthesized by the CROP of CL using per-6-(tert -butyldimethylsilyl)-,-CD as the multifunctional initiator in the presence of Sn(Oct)2 at 125 °C. Subsequently, the hydroxyl end groups of CDSi-SPCL were blocked by acetyl chloride. After desilylation of the tert -butyldimethylsilyl ether groups from the ,-CD core, 7 ATRP initiating sites were introduced by treating with 2-bromoisobutyryl bromide, which further initiated ATRP of tert -butyl acrylate (tBA) to prepare well-defined A14B7 multimiktoarm star copolymers [CDS(PCL-PtBA)]. Their molecular structures and physical properties were in detail characterized by 1H NMR, SEC-MALLS, and DSC. The selective hydrolysis of tert -butyl ester groups of the PtBA block gave the amphiphilic A14B7 multimiktoarm star copolymers [CDS(PCL-PAA)]. These amphiphilic copolymers could self-assemble into multimorphological aggregates in aqueous solution, which were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2961,2974, 2010 [source] A novel thermotropic liquid crystalline copolyester containing phosphorus and aromatic ether moity toward high flame retardancy and low mesophase temperatureJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2010Xiang-Cheng Bian Abstract A series of thermotropic liquid crystalline polyesters containing phosphorus and aromatic ether groups (TLCP-AEs) were synthesized from p -acetoxybenzoic acid (p -ABA), terephthalic acid (TPA), 4,4,-oxybis(benzoic acid) (OBBA), and acetylated 2-(6-oxid-6H-dibenz(c,e) (1,2) oxaphosphorin 6-yl) 1,4-benzenediol (DOPO-AHQ). The chemical structure and the properties of TLCP-AEs were characterized by Fourier-transform spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetry analysis (TGA), scanning electronic microscopy (SEM), polarizing optical microscopy (POM), limiting oxygen index, and UL-94 tests, respectively. The results showed that TLCP-AEs had low and broad mesophase temperatures (230,400 °C). TLCP-AEs also showed excellent thermal stability; their 5%-weight-loss temperatures were above 440 °C and the char yields at 700 °C were higher than 45 wt %. All TLCP-AE polyesters exhibited high flame retardancy with a LOI value of higher than 70 and UL-94 V-0 rating. The SEM observation revealed that TLCP-AEs had good fibrillation ability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1182,1189, 2010 [source] Synthesis of epoxy monomers that undergo synergistic photopolymerization by a radical-induced cationic mechanismJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2001James V. Crivello Abstract A series of novel, cycloaliphatic, cationically photopolymerizable epoxide monomers bearing benzyl ether groups were prepared. These monomers display a considerable enhancement in the rate of their cationic ring-opening polymerizations in comparison with monomers that do not contain such groups. In this article, a synergistic free-radical mechanism is proposed that accounts for this effect, and supporting evidence is offered for its verification. During UV irradiation of an onium salt cationic photoinitiator, the aryl radicals that are generated abstract labile benzyl hydrogens present in such monomers to generate the corresponding carbon-centered radicals. Subsequently, these radicals are oxidized to benzyl carbocations by the onium salt via a nonphotochemical chain process. The observed increase in the rate and extent of the cationic ring-opening polymerization of the epoxide monomers is due to the aforementioned mechanism, which effectively increases the number of reactive cationic species present during polymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3578,3592, 2001 [source] Synthesis of thermally crosslinkable fluorine-containing poly(arylene ether ketone)s,II.POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2004Propargyl ether terminated poly(arylene ether ketone)s Abstract Novel thermally crosslinkable fluorine-containing poly(arylene ether ketone)s comprised of 2,3,5, 6-tetrafluoro-1,4-phenylene moiety were synthesized by the termination of polymer chain ends with propargyl ether groups in order to improve solvent resistance. Crosslinking reaction occurred over 250°C through the formation of both chromen ring and polyene structure. This structure change brought about not only the outstanding solvent resistance but also the increase in glass transition temperature (Tg). The cured films also exhibited excellent thermal stability, transparency and hydrophobicity derived from fluorine atoms. Copyright © 2004 John Wiley & Sons, Ltd. [source] Comparative Study of Copper- and Silver-Catalyzed Protodecarboxylations of Carboxylic AcidsCHEMCATCHEM, Issue 4 2010Lukas Abstract The protodecarboxylation of aromatic carboxylic acids by various copper and silver catalysts is investigated with the help of density functional calculations and experimental studies. The computational results reveal that the catalytic activity of copper(I),1,10-phenanthroline catalysts increases with the introduction of electron-rich substituents at the phenanthroline ligand. They also predicted that for some substrates, silver complexes should possess a substantially higher decarboxylating activity than copper, which is confirmed by experimental studies, leading to the discovery of a silver(I) catalyst that effectively promotes the protodecarboxylation of various carboxylic acids at temperatures in the range of 80,120,°C,more than 50,°C below those of the best known copper(I) catalyst. The scope of the new system complements that of the copper(I)-based method as it includes benzoates for example, with halogen or ether groups in the ortho positions. [source] Can [M(H)2(H2)(PXP)] Pincer Complexes (M=Fe, Ru, Os; X=N, O, S) Serve as Catalyst Lead Structures for NH3 Synthesis from N2 and H2?CHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2007Markus Hölscher Dr. Abstract The potential of pincer complexes [M(H)2(H2)(PXP)] (M=Fe, Ru, Os; X=N, O, S) to coordinate, activate, and thus catalyze the reaction of N2 with classical or nonclassical hydrogen centers present at the metal center, with the aim of forming NH3 with H2 as the only other reagent, was explored by means of DF (density functional) calculations. Screening of various complexes for their ability to perform initial hydrogen transfer to coordinated N2 showed ruthenium pincer complexes to be more promising than the corresponding iron and osmium analogues. The ligand backbone influences the reaction dramatically: the presence of pyridine and thioether groups as backbones in the ligand result in inactive catalysts, whereas ether groups such as ,-pyran and furan enable the reaction and result in unprecedented low activation barriers (23.7 and 22.1,kcal,mol,1, respectively), low enough to be interesting for practical application. Catalytic cycles were calculated for [Ru(H)2(H2)(POP)] catalysts (POP=2,5-bis(dimethylphosphanylmethyl)furan and 2,6-bis(dimethylphosphanylmethyl)-,-pyran). The height of activation barriers for the furan system is somewhat more advantageous. Formation of inactive metal nitrides has not been observed. SCRF calculations were used to introduce solvent (toluene) effects. The Gibbs free energies of activation of the numerous single reaction steps do not change significantly when solvent is included. The reaction steps associated with the formation of the active catalyst from precursors [M(H)2(H2)(PXP)] were also calculated. The otherwise inactive pyridine ligand system allows for the generation of the active catalyst species, whereas the ether ligand systems show activation barriers that could prohibit practical application. Consequently the generation of the active catalyst species needs to be addressed in further studies. [source] | |||||||||||||