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https://www.readbyqxmd.com/read/28207252/metal-metal-bridging-using-the-dppp-dye-system-electronic-configurations-within-multiple-redox-series
#1
Arijit Singha Hazari, Abhishek Mandal, Katharina Beyer, Alexa Paretzki, Wolfgang Kaim, Goutam Kumar Lahiri
Redox series [LnRu(μ-DPPP)RuLn](k), H2DPPP = 2,5-dihydro-3,6-di-2-pyridylpyrrolo(3,4-c)pyrrole-1,4-dione and L = 2,4-pentanedionato (acac(-)), 2,2'-bipyridine (bpy), and 2-phenylazopyridine (pap), have been studied by voltammetry (CV, DPV), EPR, and UV-vis-NIR spectroelectrochemistry, supported by TD-DFT calculations. Crystal structure analysis and (1)H NMR revealed oxidation states [(acac)2Ru(III)(μ-DPPP(2-))Ru(III)(acac)2] and [(bpy)2Ru(II)(μ-DPPP(2-))Ru(II)(bpy)2](2+) for the corresponding precursors, isolated as rac diastereomers...
February 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28207244/terminal-titanyl-complexes-of-tri-and-tetrametaphosphate-synthesis-structures-and-reactivity-with-hydrogen-peroxide
#2
Julia M Stauber, Christopher C Cummins
The synthesis and characterization of tri- and tetrametaphosphate titanium(IV) oxo and peroxo complexes is described. Addition of 0.5 equiv of [OTi(acac)2]2 to dihydrogen tetrametaphosphate ([P4O12H2](2-)) and monohydrogen trimetaphosphate ([P3O9H](2-)) provided a bis(μ2,κ(2),κ(2)) tetrametaphosphate titanyl dimer, [OTiP4O12]2(4-) (1; 70% yield), and a trimetaphosphate titanyl acetylacetonate complex, [OTiP3O9(acac)](2-) (2; 59% yield). Both 1 and 2 have been structurally characterized, crystallizing in the triclinic P1̅ and monoclinic P21 space groups, respectively...
February 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28198611/pdcu-pd-nanocube-with-pt-like-activity-for-hydrogen-evolution-reaction
#3
Jing Li, Feng Li, Si-Xuan Guo, Jie Zhang, Jiantai Ma
The electronic properties of metal surfaces can be modulated to weaken the binding energy of adsorbed H-intermediates on the catalyst surface thus enhance the catalytic activity for the hydrogen evolution reaction (HER). Here we firstly prepare PdCu alloy nanocubes (NCs) by co-reduction of Cu(acac)2 (acac =acetylacetonate) and Na2PdCl4 in the presence of oleylamine (OAm) and trioctylphosphine (TOP). The PdCu NC coated glassy carbon electrode is then anodized at a constant potential of 0.51 V vs. Ag/AgCl at room temperature in 0...
February 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28186721/ionic-liquid-as-reaction-medium-for-synthesis-of-hierarchically-structured-one-dimensional-moo2-for-efficient-hydrogen-evolution
#4
Baohua Zhang, Yiguo Xue, Anning Jiang, Zhimin Xue, Zhonghao Li, Jingcheng Hao
Hierarchically structured one-dimensional (1D) MoO2 is synthesized for the first time in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][Tf2N]). The synthesis system is very simple (single [BMIM][Tf2N] solvent plus MoO2(acac)2 reactant). [BMIM][Tf2N] itself works as both the reaction medium and the template for the formation of these interesting 1D MoO2 particles with ultrathin nanosheet subunits. The as-synthesized hierarchically 1D MoO2_40 particles exhibit remarkable electrocatalytic activity with good long-term cycle stability for the hydrogen evolution reaction (HER) in acidic media...
February 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28165085/steric-effect-on-excimer-formation-in-planar-pt-ii-complexes
#5
Yang-Jin Cho, So-Yoen Kim, Ho-Jin Son, Dae Won Cho, Sang Ook Kang
In order to understand the steric influence on excimer formation in square planar metal complexes, three different Pt(ii) complexes were prepared by modifying the substituents in the main ligand: Pt(ii)(dfppy)(acac) (Pt-1, where dfppy is difluorophenylpyridine, acac is acetylacetonate); the bulky triphenyl silyl (Ph3Si-) group was substituted at the pyridine moiety (Pt-2) and at the phenyl moiety (Pt-3) of the main ligand of Pt-1. The Pt-complexes showed sky-blue emission at ∼460 nm. In addition, Pt-1 and Pt-3 showed excimer emission at ∼600 nm in the concentrated solution and the solid sample...
February 6, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28156109/long-range-intramolecular-electronic-communication-in-a-trinuclear-ruthenium-tropolonate-complex
#6
Jun Yoshida, Kyohei Kuwahara, Kota Suzuki, Hidetaka Yuge
Dinuclear and trinuclear ruthenium complexes, [Ru(trop)2(C2trop)Ru(dppe)Cp] [2b; trop = tropolonato, C2trop = ethynyltropolonato, dppe = 1,2-bis(diphenylphosphino)ethane] and [Ru(trop){(C2trop)Ru(dppe)Cp}2] (3), were synthesized, and their electronic and electrochemical properties were investigated in comparison with our previously reported complex [Ru(acac)2(C2trop)Ru(dppe)Cp] (2a). The electron-donating Ru(II)(dppe)Cp unit and electron-accepting Ru(III)O6 unit are connected by C2trop in these complexes. 2a incorporates acetylacetonate as an ancillary ligand, while 2b and 3 incorporate tropolonate as an ancillary ligand...
February 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28144673/heterometallic-molecular-precursors-for-a-lithium-iron-oxide-material-synthesis-solid-state-structure-solution-and-gas-phase-behaviour-and-thermal-decomposition
#7
Haixiang Han, Zheng Wei, Matthew C Barry, Alexander S Filatov, Evgeny V Dikarev
Three heterometallic single-source precursors with a Li : Fe = 1 : 1 ratio for a LiFeO2 oxide material are reported. Heterometallic compounds LiFeL3 (L = tbaoac (1), ptac (2), and acac(3)) have been obtained on a large scale, in nearly quantitative yields by one-step reactions that employ readily available reagents. The heterometallic precursor LiFe(acac)3 (3) with small, symmetric substituents on the ligand (acac = pentane-2,4-dionate), maintains a 1D polymeric structure in the solid state that limits its volatility and prevents solubility in non-coordinating solvents...
February 1, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28138791/effect-of-pulse-polarity-on-thresholds-and-on-non-monotonic-loudness-growth-in-cochlear-implant-users
#8
Olivier Macherey, Robert P Carlyon, Jacques Chatron, Stéphane Roman
Most cochlear implants (CIs) activate their electrodes non-simultaneously in order to eliminate electrical field interactions. However, the membrane of auditory nerve fibers needs time to return to its resting state, causing the probability of firing to a pulse to be affected by previous pulses. Here, we provide new evidence on the effect of pulse polarity and current level on these interactions. In experiment 1, detection thresholds and most comfortable levels (MCLs) were measured in CI users for 100-Hz pulse trains consisting of two consecutive biphasic pulses of the same or of opposite polarity...
January 30, 2017: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/28103036/paramagnetic-enhancement-of-nuclear-spin-spin-coupling
#9
Peter John Cherry, Syed Awais Rouf, Juha Vaara
We present a derivation and computations of the paramagnetic enhancement of the nuclear magnetic resonance (NMR) spin-spin coupling, which may be expressed in terms of the hyperfine coupling (HFC) and (for systems with multiple unpaired electrons) zero-field splitting (ZFS) tensors. This enhancement is formally analogous to the hyperfine contributions to the NMR shielding tensor as formulated by Kurland and McGarvey. The significance of the spin-spin coupling enhancement is demonstrated by using a combination of density-functional theory and correlated ab initio calculations, to determine the HFC and ZFS tensors, respectively, for two paramagnetic 3d metallocenes, a Cr(II)(acac)2 complex, a Co(II) pyrazolylborate complex, and a lanthanide system, Gd-DOTA...
February 9, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28078748/low-temperature-hydrogenation-of-carbon-dioxide-to-methanol-with-a-homogeneous-cobalt-catalyst
#10
Jacob Schneidewind, Rosa Adam, Wolfgang Baumann, Ralf Jackstell, Matthias Beller
Herein we describe the first homogeneous non-noble metal catalyst for the hydrogenation of CO2 to methanol. The catalyst is formed in situ from [Co(acac)3 ], Triphos, and HNTf2 and enables the reaction to be performed at 100 °C without a decrease in activity. Kinetic studies suggest an inner-sphere mechanism, and in situ NMR and MS experiments reveal the formation of the active catalyst through slow removal of the acetylacetonate ligands.
January 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28075589/water-soluble-ruthenium-ii-chiral-heteroleptic-complexes-with-amoebicidal-in-vitro-and-in-vivo-activity
#11
Yanis Toledano-Magaña, Juan C García-Ramos, Carolina Torres-Gutiérrez, Cristina Vázquez-Gasser, José M Esquivel-Sánchez, Marcos Flores-Alamo, Luis Ortiz-Frade, Rodrigo Galindo-Murillo, Mario Nequiz, Marco Gudiño-Zayas, Juan P Laclette, Julio C Carrero, Lena Ruiz-Azuara
Three water-soluble Ru(II) chiral heteroleptic coordination compounds [Ru(en)(pdto)]Cl2 (1), [Ru(gly)(pdto)]Cl (2), and [Ru(acac)(pdto)]Cl (3), where pdto = 2,2'-[1,2-ethanediylbis-(sulfanediyl-2,1-ethanediyl)]dipyridine, en = ethylendiamine, gly = glycinate, and acac = acetylacetonate, have been synthezised and fully characterized. The crystal structures of compounds 1-3 are described. The IC50 values for compounds 1-3 are within nanomolar range (14, 12, and 6 nM, respectively). The cytotoxicity for human peripheral blood lymphocytes is extremely low (>100 μM)...
February 9, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28066996/selective-hydrogenation-of-nitriles-to-primary-amines-using-a-new-cobalt-phosphine-catalyst
#12
Rosa Adam, Charles Bheeter, Jose Cabrero-Antonino, Kathrin Junge, Ralf Jackstell, Matthias Beller
A general protocol for the catalytic hydrogenation of nitriles to primary amines using a non-noble metal based system is presented. Co(acac)3 in combination with tris(2-(dicyclohexylphosphanyl)ethyl) phosphane L3 catalyses efficiently the selective hydrogenation of a wide range of (hetero)aromatic and aliphatic nitriles to the corresponding amines.
January 9, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28044210/cobalt-complexes-as-internal-standards-for-capillary-zone-electrophoresis-mass-spectrometry-studies-in-biological-inorganic-chemistry
#13
Hannah U Holtkamp, Stuart J Morrow, Mario Kubanik, Christian G Hartinger
Run-by-run variations are very common in capillary electrophoretic (CE) separations and cause imprecision in both the migration times and the peak areas. This makes peak and kinetic trend identification difficult and error prone. With the aim to identify suitable standards for CE separations which are compatible with the common detectors UV, ESI-MS, and ICP-MS, the Co(III) complexes [Co(en)3]Cl3, [Co(acac)3] and K[Co(EDTA)] were evaluated as internal standards in the reaction of the anticancer drug cisplatin and guanosine 5'-monophosphate as an example of a classical biological inorganic chemistry experiment...
January 2, 2017: Journal of Biological Inorganic Chemistry: JBIC
https://www.readbyqxmd.com/read/28036181/efficient-synthesis-of-tris-heteroleptic-iridium-iii-complexes-based-on-the-zn-2-promoted-degradation-of-tris-cyclometalated-iridium-iii-complexes-and-their-photophysical-properties
#14
Yuichi Tamura, Yosuke Hisamatsu, Sarvendra Kumar, Taiki Itoh, Kyouhei Sato, Reiko Kuroda, Shin Aoki
We report on the efficient synthesis of tris-heteroleptic iridium (Ir) complexes based on the degradation of tris-cyclometalated Ir complexes (IrL3, L: cyclometalating ligand) in the presence of Brønsted and Lewis acids such as HCl (in 1,4-dioxane), AlCl3, TMSCl, and ZnX2 (X = Br or Cl), which affords the corresponding halogen-bridged Ir dimers (μ-complexes). Tris-cyclometalated Ir complexes containing electron-withdrawing groups such as fluorine, nitro, or CF3 moieties on the ligands were less reactive. This different reactivity was applied to the selective degradation of heteroleptic Ir complexes such as fac-Ir(tpy)2(F2ppy) (fac-12) (tpy: 2-(4'-tolyl)pyridine and F2ppy: 2-(4',6'-difluorophenyl)pyridine), mer-Ir(tpy)2(F2ppy) (mer-12), and mer-Ir(mpiq)2(F2ppy) (mer-15) (mpiq: 1-(4'-methylphenyl)isoquinoline)...
December 30, 2016: Inorganic Chemistry
https://www.readbyqxmd.com/read/28034314/highly-simplified-reddish-orange-phosphorescent-organic-light-emitting-diodes-incorporating-a-novel-carrier-and-exciton-confining-spiro-exciplex-forming-host-for-reduced-efficiency-roll-off
#15
Ting Xu, Ye-Xin Zhang, Bo Wang, Chen-Chao Huang, Imran Murtaza, Hong Meng, Liang-Sheng Liao
A novel exciplex-forming host is applied so as to design highly simplified reddish orange light-emitting diodes (OLEDs) with low driving voltage, high efficiency, and an extraordinarily low efficiency roll-off, by combining N,N-10-triphenyl-10H-spiro [acridine-9,9'-fluoren]-3'-amine (SAFDPA) with 4,7-diphenyl-1,10-phenanthroline (Bphen) doped with trivalent iridium complex bis(2-methyldibenzo[f,h]quinoxaline) (acetylacetonate)iridium(III) (Ir(MDQ)2(acac)). The reddish orange OLEDs achieve a strikingly high power efficiency (PE) of 31...
January 12, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28001382/bifunctional-photocatalysts-for-enantioselective-aerobic-oxidation-of-%C3%AE-ketoesters
#16
Wei Ding, Liang-Qiu Lu, Quan-Quan Zhou, Yi Wei, Jia-Rong Chen, Wen-Jing Xiao
A novel visible-light-responsive chiral ligand has been developed by grafting a triplet state photosensitizer to chiral bisoxazoline ligands. Complexation of this ligand with Ni(acac)2 results in a powerful catalyst for the asymmetric oxidation reaction of β-ketoesters, which uses oxygen or air as the green oxidant and visible light or sunlight as the ideal driving force. Using this protocol, products containing the α-hydroxy-β-dicarbonyl motif are produced in high yields and with excellent enantiopurities...
December 28, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27935701/cobalt-catalyzed-6-2-cycloaddition-of-alkynes-with-1-3-5-7-cyclooctatetraene-as-a-key-element-in-the-direct-construction-of-substituted-bicyclo-4-3-1-decanes
#17
Vladimir A D'yakonov, Gulnara N Kadikova, Lilya U Dzhemileva, Guzel F Gazizullina, Ilfir R Ramazanov, Usein M Dzhemilev
A new, effective catalytic system based on Co(acac)2 has been developed for [6 + 2] cycloaddition of terminal alkynes to 1,3,5,7-cyclooctatetraene to give substituted bicyclo[4.2.2]deca-2,4,7,9-tetraenes in high yields (68-85%). The electrophilic activation of double bonds in the bicyclic products with m-CPBA is an efficient method for the synthesis of substituted bicyclo[4.3.1]deca-2,4,8-triene-7,10-diols, which form the key structural moieties of numerous natural biologically active compounds. The structures of the obtained compounds were reliably proven by modern spectral methods and X-ray diffraction...
December 20, 2016: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/27934410/isomeric-diruthenium-complexes-of-a-heterocyclic-and-quinonoid-bridging-ligand-valence-and-spin-alternatives-for-the-metal-ligand-metal-arrangement
#18
Mohd Asif Ansari, Abhishek Mandal, Alexa Paretzki, Katharina Beyer, Wolfgang Kaim, Goutam Kumar Lahiri
5,7,12,14-Tetraazapentacene-6,13-quinone (L) reacts with 2 equiv of [Ru(acac)2(CH3CN)2] to form two linkage isomeric bis(chelate) compounds, [{Ru(II)(acac)2}2(μ-L)], blue 1, with 5,6;12,13 coordination and violet 2 with 5,6;13,14 coordination. The linkage isomers could be separated, structurally characterized in crystals as rac diastereomers (ΔΔ/ΛΛ), and studied by voltammetry (CV, DPV), EPR, and UV-vis-NIR spectroelectrochemistry (meso-1, rac-2). DFT and TD-DFT calculations support the structural and spectroscopic results and suggest a slight energy preference (ΔE = 263 cm(-1)) for the rac-isomer 1 as compared to 2...
December 5, 2016: Inorganic Chemistry
https://www.readbyqxmd.com/read/27910921/bipolar-and-unipolar-silylene-diphenylene-%C3%AF-%C3%AF-conjugated-polymer-route-for-highly-efficient-electrophosphorescence
#19
Yao-Tang Chang, Sunil Sharma, Miao-Ken Hung, Yu-Hsuan Lee, Show-An Chen
σ-π conjugated polymer strategy is proposed for designing electroluminescent host polymers with silylene-diphenylene as the backbone repeat unit giving a high triplet energy (ET = 2.67 eV). By incorporation of high ET (3.0 eV) electron (oxadiazole, OXD) and hole (triphenyl amine, TPA) transport moieties, or TPA alone (in this case, the main chain acts as electron transport channel) as side arms on the silylene, the high ET bipolar and unipolar polymers are formed, allowing a use of iridium green phosphor (Ir(ppy)2(acac), Ir-G) (ET = 2...
December 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27878204/continuous-and-ultrathin-platinum-films-on-graphene-using-atomic-layer-deposition-a-combined-computational-and-experimental-study
#20
Bora Karasulu, René H J Vervuurt, Wilhelmus M M Kessels, Ageeth A Bol
Integrating metals and metal oxides with graphene is key in utilizing its extraordinary material properties that are ideal for nanoelectronic and catalyst applications. Atomic layer deposition (ALD) has become a key technique for depositing ultrathin, conformal metal(oxide) films. ALD of metal(oxide) films on graphene, however, remains a genuine challenge due to the chemical inertness of graphene. In this study we address this issue by combining first-principles density functional theory (DFT) simulations with ALD experiments...
December 1, 2016: Nanoscale
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