Dalton Transactions (Dalton Trans)

Publications in this journal

• Article: Surface modified Eu:GdVO4 nanocrystals for optical and MRI imaging.

  Nuria O Nuñez, Sara Rivera, David Alcantara, Jesus M de la Fuente, Jorge García-Sevillano, Manuel Ocaña
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  ABSTRACT: A facile solvothermal route has been developed for the preparation of europium doped gadolinium orthovanadate nanoparticles (∼70 nm) with tetragonal structure, based on a homogenous precipitation reaction at 120 °C from rare earth precursors (yttrium nitrate and europium nitrate) and sodium orthovanadate solutions using an ethylene glycol-water mixture as the solvent. The effects of the doping level on the luminescence properties were evaluated in order to find the optimum nanophosphors. These nanocrystals were successfully functionalized with amino (two step process) and carboxylate (one-pot process) groups provided by amino-dextran polymers (AMD) and polyacrylic acid (PAA), respectively. It was found that while the luminescent properties of both kinds of functionalized systems were similar, the colloidal stability of the PAA-modified sample was higher, because of which, it was selected to study their cytotoxicity and magnetic properties (relaxivity and phantom analyses) to assess their potentiality as multifunctional probes for both "in vitro" optical biolabels and negative contrast agents for magnetic resonance imaging.
  Dalton Transactions 06/2013;
• Article: Stabilization of diborane(4) by transition metal fragments and a novel metal to π Dewar-Chatt-Duncanson model of back donation.

  K Hari Krishna Reddy, Eluvathingal D Jemmis
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  ABSTRACT: The feasibility of using transition metal fragments to stabilize B2H4 in planar configuration by donating 2 electrons to the boron moiety is investigated. Building upon the existing theoretical and experimental data and aided by the isolobal analogy, the model transition metal complexes Cr(CO)4B2H4 (), Mn(CO)CpB2H4 (), Fe(CO)3B2H4 () and CoCpB2H4 () are chosen to illustrate this unique bonding feature - bond strengthening with π-back donation. Other possible types of complexes with B2H4 and the metal fragment are also explored and the energies are compared. One of the low energy isomers wherein the planar B2H4 interacts with the metal fragment in an in-plane fashion represents a unique case study for the Dewar-Chatt-Duncanson model. In this complex the back-donation from the metal fills the π bonding orbital between the two boron atoms thus forming a B[double bond, length as m-dash]B double bond.
  Dalton Transactions 06/2013;
• Article: Synthesis of carbon quantum dots/SiO2 porous nanocomposites and their catalytic ability for photo-enhanced hydrocarbon selective oxidation.

  Xiao Han, Yuzhi Han, Hui Huang, Hengchao Zhang, Xing Zhang, Ruihua Liu, Yang Liu, Zhenhui Kang
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  ABSTRACT: We report a facile hydrolytic process for the preparation of CQDs/SiO2 porous nanocomposites, which show high catalytic activity and stability for the selective oxidation of cis-cyclooctene under visible light irradiation, with TBHP as a radical initiator and oxygen (in the air) as an oxidant at 80 °C.
  Dalton Transactions 06/2013;
• Article: Au-based bimetallic nanoparticles for the intramolecular aminoalkene hydroamination.

  Sanjay K Singh, Munendra Yadav, Silke Behrens, Peter W Roesky
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  ABSTRACT: Bimetallic Au-based nanoparticles (Au-M where M = Pt, Pd, Cu, Ni), synthesized by simultaneous reduction of the Au salt with noble/non-noble metal salts, exhibit a high activity for the aminoalkene (2,2-diphenylpent-4-en-1-amine) hydroamination affording the 5-membered Markovnikov product. Even though the particle size and morphology of Au-M nanoparticles are comparable to the corresponding monometallic Au nanoparticles, Au-M nanoparticles display superior catalytic activity, where the selectivity for the formation of the hydroaminated product depends on the alloying metal component in the bimetallic Au nanoparticle catalyst.
  Dalton Transactions 06/2013;
• Article: A comparative vibrational CD study of homo- and heteroleptic complexes of the type [Cu(trans-1,2-diaminocyclohexane)2L](ClO4)2.

  Christian Merten, Yunjie Xu
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  ABSTRACT: Vibrational circular dichroism (VCD) spectroscopy is a powerful tool to characterize absolute configurations and conformations of chiral organometallic systems. Such characterizations rely on the corresponding density functional theory (DFT) spectral simulations which may become very time consuming and sometimes even impossible for systems with increasing complexity. Systematic studies on small model compounds can lead to empirical structure-spectra relationships. The present work continues the systematic investigations of transition metal complexes of chiral trans-1,2-diamino-cyclohexane (chxn). VA and VCD spectra of the mixed-ligand complexes [Cu(chxn)2L](2+) with L being either ethylene diamine (en) or N,N'-dimethylethylene diamine (dmen) are measured. The comparison of the experimental spectra of the mixed-ligand complexes with those of the distorted octahedral complex [Cu(chxn)3](2+) reveals that the VA and VCD patterns below 1500 cm(-1) of the three complexes are not significantly affected by the nature of the third ligand, while the VCD pattern of the NH2-bending modes in the 1500 to 1800 cm(-1) region features some characteristic changes. Comparison with the corresponding DFT spectral calculations shows that these spectral differences are related to the relative abundance of the Δ- and Λ-configurations at the metal ion. In addition, the results of this study highlight that the VCD pattern of the NH2-bending modes is characteristic of the coordination number and the configuration of the metal center.
  Dalton Transactions 06/2013;
• Article: A bis(terpyridine)iron network polymer on carbon for a potential energy storage material.

  Kuo-Hui Wu, Hiroaki Maeda, Tetsuya Kambe, Ken Hoshiko, Eunice Jia Han Phua, Ryota Sakamoto, Hiroshi Nishihara
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  ABSTRACT: A bis(terpyridine)iron network polymer was fabricated by electropolymerisation on a glassy carbon electrode. The modified electrode allowed high-speed charging and discharging with a minor capacity decay (only 5% after 3000 cycles at 1 V s(-1)).
  Dalton Transactions 06/2013;
• Article: Syntheses, structures, tunable emission and white light emitting Eu(3+) and Tb(3+) doped lanthanide metal-organic framework materials.

  Ming-Li Ma, Can Ji, Shuang-Quan Zang
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  ABSTRACT: A series of novel lanthanide metal-organic frameworks, namely, {[Ln2(L)2]·(H2O)3·(Me2NH2)2}n (Ln = La (), Ce (), Pr (), Nd (), Sm (), Eu (), Gd (), Tb (), Ho (), Er ()), have been synthesized with hydro(solvo)thermal conditions based on a flexible multicarboxylic acid (H4L = 5-(3,5-dicarboxybenzyloxy)isophthalic acid). Single crystal X-ray diffraction reveals that all of them are isomorphous and possess a (6,6) topological net with a Schläfli symbol of {4(8)·6(7)}. Considering the blue-emission of compound and the intense emission of the Eu and Tb compounds, we successfully construct isostructural Eu(3+) doped Tb compounds whose color can be tuned easily by adjusting the different concentration of the doped ions, and we also obtained white light emitting materials through the doping of Eu and Tb ions in the La compounds.
  Dalton Transactions 06/2013;
• Article: Synthesis and properties of a novel quarternerized imidazolium [α-PW12O40](3-) salt as a recoverable photo-polymerization catalyst.

  Dianyu Chen, Atharva Sahasrabudhe, Peng Wang, Arijit Dasgupta, Rongxin Yuan, Soumyajit Roy
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  ABSTRACT: A recoverable photo-polymerization catalyst based on an imidazolium and a polyoxometalate, viz., (BMIm)2(DMIm)PW12O40 (where, BMIm = 1-butyl-3-methylimidazolium, DMIm = 3,3'-dimethyl-1,1'-diimidazolium) is reported. It catalyzes photo-polymerization of several industrially important monomers like styrene, methyl methacrylate, butyl methacrylate and vinyl acetate. The catalyst is recoverable and hence can be reused. The molecular weight and polydispersity index can be controlled reasonably and a reaction pathway is proposed. The synthesis of this novel catalyst is reported and the catalyst has been characterized using standard techniques such as single crystal X-ray diffraction studies, cyclic voltammetry and various spectroscopic methods such as Fourier transform infrared spectroscopy, (1)H NMR spectroscopy, EPR spectroscopy and UV-Vis spectroscopy. DFT calculations have been used to explain the catalyst's photo-chemical activity.
  Dalton Transactions 06/2013;
• Article: Facile tuning of plasmon bands in hollow silver nanoshells using mild reductant and mild stabilizer.

  Satarupa Pattanayak, Amiya Priyam, Pradip Paik
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  ABSTRACT: Hollow silver nanoshells with tunable plasmon bands have been synthesized using Ag2O nanoparticles at an optimized temperature of 20 °C. The plasmon peak has been tuned in a wide range from 460 nm to 605 nm employing a combination of mild reductant and a mild stabilizer, hydrazine hydrate and sodium citrate, respectively. In contrast, the combination of strong reductant and strong stabilizer, NaBH4 and hydrophilic thiols, resulted in limited plasmon tunability (455-510 nm). The differential behaviour is attributed to the change in dynamics of the diffusion-reaction process. For thiols, the effect of free end-groups was quite evident as plasmon peak shifted from 449 nm to 470 nm on replacing thioglycolic acid (HS-CH2-COOH) with mercaptoethanol (HS-CH2-CH2-OH). Transmission electron microscopy (TEM) revealed that the aspect ratio [outer diameter (d)/shell thickness (t)] was 2.8 (d: 40.0 ± 1.6 nm, t: 14.0 ± 1.3 nm) and 5 (d: 84 ± 2.3 nm, t: 16.8 ± 1.9 nm) for the nanoshells exhibiting a plasmon peak at 460 nm and 605 nm, respectively. The crystal phase of nanoshells was found to be face centered cubic (fcc) as deduced from HR-TEM and electron diffraction data. Using the same Ag2O template, morphological transformation from non-porous to mesoporous has also been achieved by simply reversing the order of addition.
  Dalton Transactions 06/2013;
• Article: Trinuclear palladium addition to unsaturated carbocycles.

  Tetsuro Murahashi, Kohei Takase, Kentaro Usui, Seita Kimura, Mayu Fujimoto, Tomohito Uemura, Sensuke Ogoshi, Koji Yamamoto
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  ABSTRACT: The trinuclear palladium addition to monocyclic unsaturated hydrocarbons was revealed. The trinuclear adduct of [2.2]paracyclophane, cycloheptatriene (CHT), or cyclooctatetraene (COT) was obtained by treatment of the corresponding tripalladium sandwich complexes with 3 equiv. of 1,10-phenanthroline. In the trinuclear adduct of [2.2]paracyclophane or CHT, a Pd2 unit and a Pd1 unit synfacially coordinate through a (μ-η(3)-allyl):(η(3)-allyl) manner. A trinuclear adduct of COT exhibited an unusual bonding structure in which a formally tetraanionic COT coordinates to three Pd(II) centers through a synfacial η(3):η(1):η(3):η(1) coordination mode. The tetraanionic COT ligand bearing three Pd(II) moieties undergoes a unique intramolecular 1,5-C-C coupling.
  Dalton Transactions 06/2013;
• Article: DFT characterization on the mechanism of water splitting catalyzed by single-Ru-substituted polyoxometalates.

  Zhong-Ling Lang, Guo-Chun Yang, Na-Na Ma, Shi-Zheng Wen, Li-Kai Yan, Wei Guan, Zhong-Min Su
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  ABSTRACT: Water oxidation is a key half reaction in the energy conversion scheme. The reaction mechanism for the oxidation of H2O to O2 catalyzed by single-Ru-substituted polyoxometalates, [Ru(III)(H2O)XW11O39](n-) (X = Si(IV), Ge(IV)), was investigated by means of density functional calculations. The electronic structure of the pre-activation intermediates indicates that the aqua ligand is prone to accommodate the proton coupled electron transfer (PCET) process to achieve the active group [Ru(V)[double bond, length as m-dash]Oa], and the high valent oxo-ruthenium(v) species are responsible for the O-O forming event. Three possible proton acceptors were designed for the rate-determining step (Ob, Oa, and H2O), the calculated results support that the bridge Ob atom of the polytungstate ligand will act as the most favorable proton acceptor in the O-O bond formation, with an energy barrier of 28.43 kcal mol(-1). A detailed information of the peroxidic intermediates in the oxidation process was also characterized, both the peroxo-species [Ru(IV)(OO)SiW11O39](6-) and [Ru(V)(OO)SiW11O39](5-) show the six-coordinate isomer with an open terminal geometry is more favorable than the close seven-coordinate ones. In addition, the replacement of the heteroatom in XO4(n-) can effectively tune the catalytic activity of polyoxometalates, in the order of Ge(IV) > Si(IV).
  Dalton Transactions 06/2013;
• Article: Cp* as a removable protecting group: low valent Zn(i) compounds by reductive elimination, protolytic and oxidative cleavage of Zn-Cp*

  Kerstin Freitag, Hung Banh, Chelladurai Ganesamoorthy, Christian Gemel, Rüdiger W Seidel, Roland A Fischer
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  ABSTRACT: Zn-Cp* bond cleavage reactions leading to novel monovalent cationic zinc species are presented (Cp* = pentamethylcyclopentadienyl). The treatment of [Zn2Cp*2] with two equiv. of [H(Et2O)2][BAr4(F)] (BAr4(F) = B{C6H3(CF3)2}4) yields the triple-decker complex [Cp*3Zn4(Et2O)2][BAr4(F)] () via protolytic removal of a Cp* ligand as Cp*H, whereas the reaction with an equimolar amount of [FeCp2][BAr4(F)] (Cp = cyclopentadienyl) results in the formation of [Cp*Zn2(Et2O)3][BAr4(F)] () under oxidative cleavage of a Cp* ring giving decamethylfulvalene, (Cp*)2, and [FeCp2] as by-products. The molecular structures of compounds and are established by single-crystal X-ray diffraction studies. A new synthetic pathway for the formation of [Zn2Cp*2] based on the reductive elimination of Cp*H from in situ formed Cp*ZnH is presented.
  Dalton Transactions 06/2013;
• Article: The role of the Cys-X-X-X-Cys motif on the kinetics of cupric ion loading to the Streptomyces lividans Sco protein.

  Katie L I M Blundell, Michael T Wilson, Erik Vijgenboom, Jonathan A R Worrall
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  ABSTRACT: The mechanisms and spectroscopic properties generated by intermediate states upon cupric ion binding to flexible peptide motifs in proteins are of considerable interest. One such motif is the Cys-X-X-X-Cys motif characteristic to members of the Sco family of proteins. In the antibiotic producing bacterium, Streptomyces lividans, a role for its Sco protein (Sco(Sl)) as a cupric metallochaperone to the extracytoplasmic CuA domain of cytochrome c oxidase has been revealed. Stopped-flow kinetic studies have revealed a mechanism of cupric ion capture by Sco(Sl), which passes through a monothiolate intermediate, with distinct spectral features. In the present study we have used two site directed mutants of Sco(Sl), C86A and C90A, to determine which Cys in the CXXXC motif acts as the capture ligand. Comparison of kinetic and thermodynamic parameters obtained from cupric ion binding to the C86A and C90A mutants clearly indicate that Cys86 is the capture ligand and this finding can be reconciled with structural data. At subsaturating levels of cupric ions both mutants bind copper rapidly, but the absorbance properties are distinctly different from wild type Sco(Sl). This is most extreme for the C86A mutant where the Cys90 thiolate bond is considered to be weaker than the Cys86 thiolate bond in the C90A mutant. We put forward an explanation for this behaviour whereby we propose that the cupric ion is moving to a second site with no thiolate coordination.
  Dalton Transactions 06/2013;
• Article: A triangular dysprosium with asymmetric central caps featuring ferromagnetic coupling and single-molecule magnet behaviour.

  Si Shen, Shufang Xue, Shuang-Yan Lin, Lang Zhao, Jinkui Tang
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  ABSTRACT: A new Dy3 triangle bridged by a deprotonated alkoxyl group of a Schiff-base ligand together with a μ3-OH group has been prepared, in which intramolecular ferromagnetic interactions and single molecule magnet behaviour have been observed.
  Dalton Transactions 06/2013;
• Article: Syntheses of Cu2SnS3 and Cu2ZnSnS4 nanoparticles with tunable Zn/Sn ratios under multibubble sonoluminescence conditions.

  Jongpil Park, Miyeon Song, Won Mok Jung, Won Young Lee, Hanggeun Kim, Youngkwon Kim, Chahwan Hwang, Il-Wun Shim
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  ABSTRACT: Cu2ZnSnS4 (CZTS) nanoparticles were synthesized by sonochemical reactions under multibubble sonoluminescence (MBSL) conditions. First, Cu2SnS3 (CTS) nanoparticles were synthesized by the sonochemical method with a 91.3% yield. Second, ZnS was coated on Cu2SnS3 nanoparticles by the same method. Then, they were transformed into CZTS nanoparticles of 90-300 nm diameter by heating them at 450 °C for 1 hour. The ratios between Zn and Sn could be controlled from 0.20 to 1.32 by adjusting the relative concentrations of Cu2SnS3 and ZnCl2. With relatively lower Zn : Sn ratios (0.20-0.41), there was a mixture of CTS and CZTS nanoparticles. The prepared nanoparticles show different band gaps from 1.19 to 1.52 eV depending on the zinc to tin ratio. In this sonochemical method without using any toxic or high temperature solvents, the specific stoichiometric element ratios in CZTS were controllable on demand and their experimental results were always reproducible in separate syntheses. The CZTS nanoparticles were investigated by using X-ray diffraction, a UV-Vis spectrophotometer, a scanning electron microscope, Raman spectroscopy, and a high resolution-transmission electron microscope.
  Dalton Transactions 06/2013;
• Article: Tungstic acid functionalized mesoporous SBA-15: A novel heterogeneous catalyst for facile one-pot synthesis of 2-amino-4H-chromenes in aqueous medium.

  Sudipta K Kundu, John Mondal, Asim Bhaumik
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  ABSTRACT: A new highly ordered mesoporous tungstic acid functionalized SBA-15, TAFMC-1 has been synthesized via post-synthesis modification of mesoporous SBA-15 with (3-chloropropyl) triethoxysilane followed by substitution reaction of chlorine atom of the 3-chloropropyl group by tungstic acid group under refluxing conditions in n-hexane. The tungstic acid functionalized mesoporous silica material has been characterized by using small angle powder X-ray diffraction, N2 sorption, HR-TEM, FE-SEM, FT-IR and solid state MAS NMR studies. TAFMC-1 catalyzes the facile one-pot catalytic three-component condensation reaction of resorcinol, aromatic aldehyde and malononitrile for the synthesis of a diverse range of 2-amino-4H-chromenes in aqueous medium. This heterogeneous catalyst can be recycled very efficiently for six consecutive reaction cycles without significant loss of catalytic activity.
  Dalton Transactions 06/2013;
• Article: Uranyl-copper(ii) heterometallic oxalate complexes: coordination polymers and frameworks.

  Pierre Thuéry, Eric Rivière
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  ABSTRACT: Five oxalate complexes containing both uranyl and copper(ii) ions and 2,2'-bipyridine (bipy), 2,2'-bipyrimidine (bipym) or 1,10-phenanthroline (phen) as co-ligands have been synthesized under hydrothermal conditions and their crystal structures were determined. [UO2Cu(C2O4)(NO3)2(bipy)(H2O)] () is a molecular complex in which the two cations are connected by the bis-chelating oxalate. A one-dimensional uranyl oxalate ribbon is formed in [UO2Cu(C2O4)2(bipym)(H2O)] (), with uranyl ions bound to two chelating anions and to a third, monodentate oxalate which holds the decorating [Cu(bipym)(H2O)](2+) groups. Complex [(UO2)2Cu2(C2O4)2(bipym)3(OH)2]·2NO3 () is a two-dimensional assembly in which uranyl oxalate chains are linked to one another by [Cu2(bipym)3](4+) dinuclear units through bridging hydroxide ions. Finally, [UO2Cu(C2O4)2(bipy)] () and [UO2Cu(C2O4)2(phen)] () display identical three-dimensional arrangements containing uranyl oxalate sheets connected to one another by copper oxalate dinuclear units. The magnetic properties of compounds and have been investigated. Weak inter-chain antiferromagnetic interactions between copper(ii) atoms are present in , while displays strong oxalate-mediated antiferromagnetic exchange (J = -335 cm(-1)). These complexes are the first uranyl-d block metal oxalate complexes to be reported.
  Dalton Transactions 06/2013;
• Article: Synthesis and reactivity of ruthenium tridentate bis-phosphinite ligand complexes.

  Michael J Sgro, Douglas W Stephan
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  ABSTRACT: The tridentate ligands E(CH2CH2OPiPr2)2 (E = NH , E = S ) were employed in the synthesis of a number of ruthenium complexes. Reaction of these ligands with (Ph3P)3RuCl2 afforded the dimers [Ru(HN(CH2CH2OPiPr2)2)Cl(μ-Cl)]2 () and [(Ru(E(CH2CH2OPiPr2)2))2(μ-Cl)3][X] (E = NH, X = PF6, E = S, X = Cl ), respectively. Using (Ph3P)3RuHCl in reactions with gave Ru(NH(CH2CH2OPiPr2)2)(PPh3)HCl () while addition of pyridine and , gave Ru(S(CH2CH2OPiPr2)2)(py)HCl (). Treatment of or with NaBPh4 resulted in the formation of the η(6)-arene complexes RuH(E(CH2CH2OPiPr2)2)2(η(6)-C6H5BPh3) (E = NH , E = S ) while reactions with K[B(C6F5)4] gave the salts [RuH(E(CH2CH2OPiPr2)2)(L)][B(C6F5)4] (E = NH, L = PPh3, E = S, L = py ). Compounds and react with CO giving RuH(HN(CH2CH2OPiPr2)2)(CO)Cl () and [RuH(S(CH2CH2OPiPr2)2(py)(CO)]Cl () respectively, while reaction of , or with dihydrogen gave RuH(HN(CH2CH2OPiPr2)2)(H2)Cl () and RuH(E(CH2CH2OPiPr2)2)(L)(H2)][B(C6F5)4] (E = NH, L = PPh3, E = S, L = py ). The complexes , and are shown to catalyze the dehydrogenation of HMe2NBH3.
  Dalton Transactions 06/2013;
• Article: Iridium(iii) complexes with enhanced film amorphism as guests for efficient orange solution-processed single-layer PhOLEDs with low efficiency roll-off.

  Jun Dai, Kaifeng Zhou, Ming Li, Huiqin Sun, Yunqing Chen, Shijian Su, Xuemei Pu, Yan Huang, Zhiyun Lu
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  ABSTRACT: By introducing a phenyl substituent into the meta-site of the phenyl segment of the 2-phenylbenzothiazole ligand, two novel orange iridium(iii) complexes, namely, and , have been synthesized. Compared with their parent compound , both of them possess much enhanced thermostability and film amorphism, making them suitable candidates as guests for high performance solution-processed phosphorescent organic light-emitting diodes (PhOLEDs). However, bearing para-phenyl possesses worse processability relative to due to spontaneous crystallization stemming from the intense intermolecular interactions. Single-layer solution-processed PhOLEDs with and as guests show peak current efficiency of 17.2 cd A(-1) and 15.2 cd A(-1), and maximum brightness of 28 270 cd m(-2) and 27 900 cd m(-2), respectively. Both are greatly improved compared to the devices employing (10.2 cd A(-1) and 14 350 cd m(-2)) and (5.0 cd A(-1) and 13 790 cd m(-2)) as phosphors. Moreover, quite low efficiency roll-off is acquired in these devices at high luminance. The much improved electroluminescence performances of these objective complexes could be mainly attributed to the presence of a rigid phenyl on the appropriate substitution site of the cyclometallate ligand, which leads to improved thermostability with compatible alleviated intermolecular interactions, and consequently enhanced film amorphism.
  Dalton Transactions 06/2013;