oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Synthesis and NMR-Study of 1-Trimethylsilyl Substituted Silole Anion [Ph4C4Si(SiMe3)]??[Li]+ and 3-Silolenide 2,5-carbodianions {[Ph4C4Si(n-Bu)2]?2?2[Li]+, [Ph4C4Si(t-Bu)2]?2?2[Li]+} via Silole Dianion [Ph4C4Si]?2?2[Li]+  [PDF]
Jang-Hwan Hong
Molecules , 2013, DOI: 10.3390/molecules180910568
Abstract: 1-Trimethylsilyl, 1-R (R = Me, Et, i-Bu)-2,3,4,5-tetraphenyl-1-silacyclopentadiene [Ph 4C 4Si(SiMe 3)R] are synthesized from the reaction of 1-trimethylsilyl,1-lithio-2,3,4,5-tetraphenyl-1-silacyclopentadienide anion [Ph 4C 4SiMe 3] ??[Li] + ( 3) with methyl iodide, ethyl iodide, and i-butyl bromide. The versatile intermediate 3 is prepared by hemisilylation of the silole dianion [Ph 4C 4Si] ?2?2[Li] + ( 2) with trimethylsilyl chloride and characterized by 1H-, 13C-, and 29Si-NMR spectroscopy. 1,1-bis(R)-2,3,4,5-tetraphenyl-1-silacyclopentadiene [Ph 4C 4SiR 2] {R = n-Bu ( 7); t-Bu ( 8)} are synthesized from the reaction of 2 with n-butyl bromide and t-butyl bromide. Reduction of 7 and 8 with lithium under sonication gives the respective 3-silolenide 2,5-carbodianions {[Ph 4C 4Si( n-Bu) 2] ?2?2[Li] + ( 10) and [Ph 4C 4Si( t-Bu) 2] ?2?2[Li] + ( 11)}, which are characterized by 1H-, 13C-, and 29Si-NMR spectroscopy. Polarization of phenyl groups in 3 is compared with those of silole anion/dianion, germole anion/dianion, and 3-silolenide 2,5-carbodianions 10 and 11.
Dissociation of the Disilatricyclic Diallylic Dianion [(C4Ph4SiMe)2]?2 to the Silole Anion [MeSiC4Ph4]? by Halide Ion Coordination or Halide Ion Nucleophilic Substitution at the Silicon Atom  [PDF]
Jang-Hwan Hong
Molecules , 2011, DOI: 10.3390/molecules16108451
Abstract: The reductive cleavage of the Si-Si bond in 1,1-bis(1-methyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene) [(C4Ph4SiMe)2] (1) with either Li or Na in THF gives the silole anion [MeSiC4Ph4]? (2). The head-to-tail dimerization of the silole anion 2 gives crystals of the disilatricyclic diallylic dianion [(C4Ph4SiMe)2]?2 (3). The derivatization of 3 (crystals) with bromoethane (gas) under reduced pressure provides [(MeSiC4Ph4Et)2] (4) quantitatively. The reverse addition of 3 in THF to trimethylsilyl chloride, hydrogen chloride, and bromoethane in THF gives 1-methyl-1-trimethylsilyl-1-silole [Me3SiMeSiC4Ph4] (6), 1-methyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C4Ph4H2SiMe-MeSiC4Ph4] (7), and 1-methyl-2,5-diethyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C4Ph4Et2SiMe-MeSiC4Ph4] (8), respectively. The reaction products unambiguously suggest that the silole anion [MeSiC4Ph4]? is generated by coordination of the chloride ion at the silicon atom in 3 or by the nucleophilic substitution of either chloride or bromide ion at one of two silicon atoms in 3. The quenching reaction of 3 dissolved in THF with water gives 1,2,3,4-tetraphenyl-2-butene, the disiloxane of 1-methyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl [O(MeSiC4Ph4)2] (10) and methyl silicate.
含Silole共轭聚合物的光电性能  [PDF]
刘治田,胡钊,沈陟,胡双强,王子兴,戚欣
化学进展 , 2012,
Abstract: Silole是一类含硅杂环戊二烯,近年来,由于其独特的结构特性、分子的可设计性及多样性,在光电领域得到越来越多研究者们的关注。某些silole小分子在有机发光二极管中用作发光层和电子传输层有出色的表现,但近来对含silole聚合物的研究也颇受重视,在聚集态诱导发光、化学传感器、聚合物发光二极管、聚合物太阳能电池、场效应晶体管中的应用相继有报道。因此silole是一类很有潜力的构筑光电功能材料的杂环化合物。本文根据其母体结构的不同对含silole的聚合物光电性能研究进展进行了综述。
Br?nsted Acidic Ionic Liquid Accelerated Halogenation of Organic Compounds with N-Halosuccinimides (NXS)  [PDF]
Dejan Vra?i?,Marjan Jereb,Kenneth K. Laali,Stojan Stavber
Molecules , 2013, DOI: 10.3390/molecules18010074
Abstract: The Br?nsted-acidic ionic liquid 1-methyl-3-(4-sulfobutyl)imidazolium triflate [BMIM(SO 3H)][OTf] was demonstrated to act efficiently as solvent and catalyst for the halogenation of activated organic compounds with N-halosuccinimides (NXS) under mild conditions with short reaction times. Methyl aryl ketones were converted into α-halo and α,α-dihaloketones, depending on the quantity of NXS used. Ketones with activated aromatic rings were selectively halogenated, however in some cases mixtures of α-halogenated ketone and ring-halogenated ketones were obtained. Activated aromatics were regioselectively ring halogenated to give mono- and dihalo-substituted products. The [BMIM(SO 3H)][OTf] ionic liquid (IL-A) was successfully reused eight times in a representative monohalogenation reaction with no noticeable decrease in efficiency. An effective halogenation scale-up in this IL is also presented. The reactivity trend and the observed chemo- and regioselectiivities point to an ET process in these IL-promoted halofunctionalization reactions.
Bis(trimethylsilyl)chromate Catalyzed Oxidations of Alcohols to Aldehydes and Ketones with Periodic Acid  [PDF]
Karim Asadolah,Majid M Heravi,Rahim Hekmatshoar,Soma Majedi
Molecules , 2007, DOI: 10.3390/12050958
Abstract: A facile, selective and high yielding bis(trimethylsilyl) chromate (BTSC) catalyzed selective oxidation of alcohols to aldehydes and ketones with periodic acid is reported.
[η5-1,3-Bis(trimethylsilyl)cyclopentadienyl]dichlorido[η5-(trimethylsilyl)cyclopentadienyl]titanium(IV)
Franc Perdih
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811046228
Abstract: In the title compound, [Ti(C8H13Si)(C11H21Si2)Cl2], the TiIV atom is bonded to two Cl atoms, one 1,3-bis(trimethylsilyl)cyclopentadienyl (Si2Cp) and one (trimethylsilyl)cyclopentadienyl ring (SiCp). The Si2Cp centroid–titanium distance is 2.0763 (10) and the SiCp centroid–titanium distance is 2.0793 (10) . The angle subtended at the Ti atom by the centroids of both cyclopentadienyl rings is 131.22 (4)° and the Cl—Ti—Cl angle is 94.14 (2)°.
Evidence of environmental strains on charge injection in silole based organic light emitting diodes  [PDF]
Nolwenn Huby,Lionel Hirsch,Laurent Aubouy,Philippe Gerbier,Arie Van Der Lee,Fabrice Amy,Antoine Kahn
Physics , 2007, DOI: 10.1103/PhysRevB.75.115416
Abstract: Using d. functional theory (DFT) computations, the authors demonstrated a substantial skeletal relaxation when the structure of 2,5-bis-[4-anthracene-9-yl-phenyl]-1,1-dimethyl-3,4-diphenyl-silole (BAS) is optimized in the gas-phase comparing with the mol. structure detd. from monocrystal x-ray diffraction. The origin of such a relaxation is explained by a strong environmental strains induced by the presence of anthracene entities. Also, the estn. of the frontier orbital levels showed that this structural relaxation affects mainly the LUMO that is lowered of 190 meV in the gas phase. To check if these theor. findings would be confirmed for thin films of BAS, the authors turned to UV photoemission spectroscopy and/or inverse photoemission spectroscopy and electrooptical measurements. The study of the c.d. or voltage and luminance or voltage characteristics of an ITO/PEDOT/BAS/Au device clearly demonstrated a very unusual temp.-dependent behavior. Using a thermally assisted tunnel transfer model, this behavior likely originated from the variation of the electronic affinity of the silole deriv. with the temp. The thermal agitation relaxes the mol. strains in thin films as it is shown when passing from the cryst. to the gas phase. The relaxation of the intramol. thus induces an increase of the electronic affinity and, as a consequence, the more efficient electron injection in org. light-emitting diodes.
Ab Initio Study of Electronic Properties of a Armchair (7,7) Carbon Nanotube  [PDF]
Hamdollah Salehi, Khadigeh Gharbavi
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.23024
Abstract: The electronic structure, band gap and density of states of (7,7) Armchair carbon nanotube by the full potentiallin- earized augmented plane wave (FP-LAPW)method in the framework density functional theory (DFT) with the generalized gradient approximation (GGA) were studied. The calculated band structure and density of state of Armchair (7,7) carbon nanotube were in good agreement with theoretical and experimental results.
Effects of Molecular Structure on Intramolecular Charge Carrier Transport in Dithieno [3,2-b: -d] Pyrrole-Based Conjugated Copolymers  [PDF]
Yoshihito Honsho,Akinori Saeki,Shu Seki
International Journal of Spectroscopy , 2012, DOI: 10.1155/2012/983523
Abstract: Intramolecular mobility of positive charge carriers in conjugated polymer films based on dithieno [2,3-b: -d] pyrrole (DTP) is studied by time-resolved microwave conductivity (TRMC). A series of DTP homopolymer and copolymers combined with phenyl, 2, -biphenyl, thiophene, 2, -bithiophene, and 9, -dioctylfluorene were synthesized by Suzuki-Miyaura and Yamamoto coupling reactions. Polymers containing DTP unit are reported to show high value of hole mobility measured by FET method, and this type of polymers is expected to have stable HOMO orbitals which are important for hole transportation. Among these copolymers, DTP coupled with 9, -dioctylfluorene copolymer showed the highest charge carrier mobility as high as 1.7?cm2/Vs, demonstrating an excellent electrical property on rigid copolymer backbones. 1. Introduction Since the first observation of electrical conductivity in doped polyacetylene [1, 2], conjugated polymers have attracted much attention to intend a wide variety of optical and electrical applications such as batteries, sensors, photovoltaic cells, organic light-emitting diodes (OLEDs), and organic field effect transistors (OFETs) [3–12]. Maximization of charge carrier mobility plays a key role in the enhancement of the performance of these electronic devices. The charge carrier mobility has been usually measured by conventional direct current (DC) methods, for instance, time of flight (TOF), space-charge-limited current (SCLC), and field effect transistor (FET) techniques. In these DC measurements under strong and one-directional external electric field, charge carriers are forced to travel over a long distance between electrodes, and to repeat trapping and detrapping processes at impurities, defect sites, or interfacial barriers between semiconductors and electrodes. Accordingly, the mobility measured by DC methods is affected by extrinsic factors mentioned above leading to rate-determining processes which are not reflecting effective transport along the extended conjugation of molecules. In contrast to DC methods, time-resolved microwave conductivity (TRMC) technique is categorized into an AC method [13–19] and allows measurement of intrinsic mobility, because of proving nm-scale oscillating motion of charge carriers free from the above-mentioned extrinsic factors. In this AC measurement, the oscillating motion of charge carriers is induced by alternating electric field of microwave on conjugated molecules, and probed without electrodes (noncontact measurement). Dithieno??[3,2-b: 2′,3′-d]??pyrrole (DTP) has been expected as a new class of
[μ-Bis(trimethylsilyl)amido]bis[μ-N,N-dimethyl-N′,N′′-bis(trimethylsilyl)guanidinato]-triangulo-tricopper(I)  [cached]
Donglong Guo,Xiaoli Qiao,Hong-Bo Tong,Meisu Zhou
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809008745
Abstract: The title compound, [Cu3(C6H18NSi2)(C9H24N3Si2)2], is a trinuclear CuI complex. A crystallographic twofold axis passes through one CuI atom and the N atom of the bis(trimethylsilyl)amide ligand that bridges between the other two CuI atoms. The Cu—Cu bonds bridged by the guanadinate ligands [2.7913 (9) ] are slightly longer than the Cu—Cu bond bridged by the bis(trimethylsilyl)amide ligand [2.6405 (11) ].
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.