- Dendritic, nanosized building block for Siloxane-based materials: A spherosilicate dendrimer
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A spherosilicate dendrimer (DMS-1) with closely spaced reaction sites (Si-H groups) on the dendrimer surface has been synthesized by stepwise silylation of double-four-ring silicate with chlorotriethoxysilane (ClSi(OEt)3) and subsequently with chlorodimethylsilane (ClSiHMe2). DMS-1 consists of a maximum of 40 Si atoms in the interior frameworks and 24 reactive Si-H groups on the surface. Because DMS-1 is spherical and about 1.5 nm in diameter, it can be regarded as the smallest well-defined silica-based nanoparticle. DMS-1 also forms molecular crystals and is soluble in typical organic solvents. A molecularly ordered silica-based hybrid can be prepared by heating a cast film of DMS-1 at 180 °C for 5 days. The surface of DMS-1 can be modified by hydrosilylation with 1-hexadecene, triethoxyvinylsilane, and allylic-terminated tetraethylene glycol monomethyl ether. More than 20 Si-H groups out of 24 react with these reagents. The solubilities of the products depend on the modification. DMS-1 is not only a building block for nanohybrids, but also the smallest and most precisely designed siloxane-based nanoparticle.
- Kawahara, Kazufumi,Hagiwara, Yoshiaki,Kuroda, Kazuyuki
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Read Online
- Thiol - Ene click reaction as a general route to functional trialkoxysilanes for surface coating applications
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Functionalized trialkoxysilanes are widely used to modify the surface properties of materials and devices. It will be shown that the photoinitiated radical-based thiol - ene "click" reaction provides a simple and efficient route to diverse trialkoxysilanes. A total of 15 trialkoxysilanes were synthesized by reacting either alkenes with 3-mercaptopropyltrialkoxysilane or thiols with allyltrialkoxysilanes in the presence of a photoinitiator. The functionalized trialkoxysilanes were obtained in quantitative to near-quantitative yields with high purity. The photochemical reactions can be run neat in standard borosilicate glassware using a low power 15-W blacklight. A wide range of functional groups is tolerated in this approach, and even complex alkenes click with the silane precursors. To demonstrate that these silanes can be used as surface coating agents, several were reacted with iron oxide superparamagnetic nanoparticles and the loadings quantified. The photoinitiated thiol - ene reaction thus offers a facile and efficient method for preparing surface-active functional trialkoxysilanes.
- Tucker-Schwartz, Alexander K.,Farrell, Richard A.,Garrell, Robin L.
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Read Online
- Ruthenium-catalyzed selective hydrosilylation reaction of allyl-functionalized PEG derivatives
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Reactions of allyl-functionalized poly(ethylene glycol) (PEG) derivatives with alkoxysilanes proceeded efficiently to furnish the corresponding hydrosilylated products in good to excellent yields using a ruthenium catalyst, [RuCl2(nbd)]n. A preliminary mechanistic study supported the pivotal role of the PEG moiety, which coordinated to the ruthenium atom during the reaction to achieve high reaction selectivity. This method may be applicable to the synthesis of various PEGs with a silyl terminus, which is useful as biocompatible and low toxic silane coupling agents.
- Inomata, Koya,Naganawa, Yuki,Guo, Haiqing,Sato, Kazuhiko,Nakajima, Yumiko
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supporting information
(2019/09/17)
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- Careful investigation of the hydrosilylation of olefins at poly(ethylene glycol) chain ends and development of a new silyl hydride to avoid side reactions
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Hydrosilylation of olefin groups at poly(ethylene glycol) chain ends catalyzed by Karstedt catalyst often results in undesired side reactions such as olefin isomerization, hydrogenation, and dehydrosilylation. Since unwanted polymers obtained by side reactions deteriorate the quality of end-functional polymers, maximizing the hydrosilylation efficiency at polymer chain ends becomes crucial. After careful investigation of the factors that govern side reactions under various conditions, it was related that the short lifetime of the unstable Pt catalyst intermediate led to the formation of more side products under the inherently dilute conditions for polymers. Based on these results, two new chelating hydrosilylation reagents, tris(2-methoxyethoxy)silane (5) and 2,10-dimethyl-3,6,9-trioxa-2,10-disilaundecane (6), have been developed. It was demonstrated that the hydrosilylation efficiency at polymer chain ends was significantly increased by employing the internally coordinating hydrosilane 5. In addition, employment of the internally coordinating disilane species 6 in an addition polymerization with 1,5-hexadiene by hydrosilylation reaction yielded a polymer with high molecular weight (Mn = 9300 g/mol), which was significantly higher than that (Mn = 2600 g/mol) of the corresponding polymer obtained with non-chelating dihydrosilane, 1,1,3,3-tetramethyldisiloxane.
- Shin, Hyunseo,Moon, Bongjin
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p. 527 - 536
(2018/01/27)
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- Anion Receptor, Electrolyte Containing the Anion Receptor and Lithium Ion Battery and Lithium Ion Capacitor Using the Electrolyte
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The present invention relates to a novel anion acceptor having a high cation transport rate and improved lifespan, an electrolyte containing the same, and a lithium ion battery and a lithium ion capacitor manufactured using the electrolyte and, more specifically, to a compound represented by chemical formula 1. In the chemical formula 1, n is an integer from 1 to 50, and X is one or more selected from the group consisting of -NR_1R_2, -NR_3R_4, -Ph(-(m)-R_5), and -O-(CH_2CH_2O)_y-CH_3.COPYRIGHT KIPO 2018
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Paragraph 0088-0090
(2018/09/30)
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- Plasticizing Li single-ion conductors with low-volatility siloxane copolymers and oligomers containing ethylene oxide and cyclic carbonates
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To prepare a safe electrolyte for lithium ion batteries, two groups of novel low-volatility plasticizers combining pendant cyclic carbonates and short ethylene oxide chains have been successfully synthesized, as confirmed by 1H, 13C and 29Si NMR spectroscopy. The Fox equation describes the composition dependence of the glass transition temperature (Tg) very well for the random polysiloxane-based copolymer plasticizers (11000 g as much as 20 K lower than the Fox equation prediction because of their lower molecular weight (450 g. Mixing with 20 wt% polysiloxane tetraphenyl borate-Li ionomer (14 mol% borate and 86 mol% cyclic carbonate) increases conductivity relative to the neat ionomer by lowering Tg, increasing dielectric constant and providing better solvation of Li+. The best oligomeric plasticizer only has Tg 10 K lower than the Fox prediction but has dielectric constant 30% larger than expected by the Landau-Lifshitz mixing rule, owing to a surprisingly low viscosity, resulting in ambient conductivity 2 × 10-5 S cm-1. For both groups of plasticizers, the fraction of cyclic carbonates relative to ethylene oxide governs the magnitude and temperature dependence of the ionic conductivity.
- Liang, Siwei,Chen, Quan,Choi, U Hyeok,Bartels, Joshua,Bao, Nanqi,Runt, James,Colby, Ralph H.
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p. 21269 - 21276
(2015/11/09)
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- Thermodynamic Properties of Carbosilane Dendrimers of the Sixth Generation with Ethylene Oxide Terminal Groups
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The temperature dependences of heat capacities of carbosilane dendrimers of the sixth generation with ethyleneoxide terminal groups, denoted as G6[(OCH2CH2)1OCH3]256 and G6[(OCH2CH2)3OCH3]256, were measured in the temperature range from T = (6 to 520) K by precision adiabatic calorimetry and differential scanning calorimetry (DSC). In the above temperature range the physical transformations, such as glass transition and high-temperature relaxation transition, were detected. The standard thermodynamic characteristics of the revealed transformations were determined and analyzed. The standard thermodynamic functions, namely, heat capacity Cp°(T), enthalpy H°(T) - H°(0), entropy S°(T) - S°(0), and Gibbs energy G°(T) - H°(0) for the range from T → 0 to 520 K, and the standard entropies of formation ΔfS°of the investigated dendrimers in the devitrified state at T = 298.15 K, were calculated per corresponding moles of the notional structural units. The standard thermodynamic properties of dendrimers under study were discussed and compared with literature data for carbosilane dendrimers with different functional terminal groups.
- Sologubov, Semen S.,Markin, Alexey V.,Smirnova, Natalia N.,Novozhilova, Natalia A.,Tatarinova, Elena A.,Muzafarov, Aziz M.
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p. 14527 - 14535
(2015/11/23)
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- High ion content siloxane phosphonium ionomers with very low T g
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Polysiloxane phosphonium single-ion conductors grafted with oligomeric PEO and with ion contents ranging from 5 to 22 mol % were synthesized via hydrosilylation reaction. The parent Br- anion was exchanged to F- or bis(trifluoromethanesulfonyl)imide (TFSI-). X-ray scattering data suggest ion aggregation is absent in these phosphonium ionomers, which contributes to low glass transition temperatures (below -70 °C) with only a weak dependence on both ion content and counteranion type. Conductivities weakly increase with ion content but exhibit a strong dependence on anion type. The highest conductivity at 30 °C is 20 μS/cm for dry neat ionomer, with the TFSI- anion, consistent with its relatively delocalized negative charge and large size that weaken interactions between TFSI- and the phosphonium cation.
- Liang, Siwei,Oreilly, Michael V.,Choi, U Hyeok,Shiau, Huai-Suen,Bartels, Joshua,Chen, Quan,Runt, James,Winey, Karen I.,Colby, Ralph H.
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p. 4428 - 4437
(2014/07/22)
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- SYMMETRICAL AND UNSYMMETRICAL ORGANOSILICON MOLECULES AND ELECTROLYTE COMPOSITIONS
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Described are organosilicon electrolyte compositions having improved thermostability and electrochemical properties and electrochemical devices that contain the organosilicon electrolyte compositions.
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Page/Page column 40
(2014/03/26)
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- Synthesis and properties of carbosilane dendrimers of the third and sixth generations with the ethylene oxide surface layer in bulk and in monolayers at the air-water interface
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A number of carbosilane dendrimers with the ethylene oxide surface layer was synthesized. The density of the surface layer determines their capability to form a physical network due to intermolecular entanglements. The specific interactions of the ethylene oxide fragments exert a minor effect on the thermal behavior of dendritic macromolecules. The compression-expansion isotherms of Langmuir films together with Brewster angle microscopy data show that an increase in the core rigidity with increasing the generation number favors the formation of ordered molecular multilayers. The appearance of a pronounced hysteresis in the compression-expansion cycles is a common phenomenon for amphiphilic dendrimers of high generations.
- Novozhilova,Malakhova,Buzin,Buzin,Tatarinova,Vasilenko,Muzafarov
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p. 2514 - 2526
(2014/11/08)
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- SYNTHESIS OF THIOETHER CONTAINING TRIALKOXYSILANES
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The invention relates to a radical-initiated thiol-ene or thiol-yne "click" reaction that provides a simple and efficient route to diverse trialkoxysilanes. Trialkoxysilanes made in this way are obtained in quantitative to near-quantitative yields with high purity without any or minimal purification. A wide range of functional groups is tolerated in this approach, and even complex alkenes click with the silane precursors. The modular nature of these radical-based thiol-ene or thiol-yne "click" reactions allows a wide variety of pendant groups to be coupled to silane compounds that can then be coupled to a wide variety surfaces in order to modify their material properties. Consequently, such radical initiated thiol-ene and thiol-yne reactions provide facile and efficient methods for preparing an enormous number of surface-active functional trialkoxysilanes.
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Page/Page column 37-38
(2012/10/08)
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- OLEFIN METATHESIS REACTIONS OF AMINO ACIDS, PEPTIDES AND PROTEINS CONTAINING ALLYL SULFIDE GROUPS
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A method for the modification of an amino acid, protein or peptide is disclosed. The method comprises reacting a carbon-carbon double bond-containing compound with an amino acid, a protein or a peptide containing an allyl sulfide group in the presence of a catalyst which promotes olefin metathesis, to form a modified amino acid, protein or peptide. Preferred carbon-carbon double bond-containing compounds include carbohydrates.
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Page/Page column 12
(2012/07/27)
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- Novel perfluoroalkylated oligo(oxyethylene) methyl ethers with high hemocompatibility and excellent co-emulsifying properties for potential biomedical uses
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Two series of novel perfluoroalkylated amphiphilic compounds were synthesized from monomethyl ethers of mono-, di- and tri-(oxyethylene) glycols. The first series CH3(OCH2CH2)nOCH2CH(OH)CH2-CF2(CF2CF2)nCF3 (n = 1-3) bearing the hydroxy group at the spacer between hydrophilic and hydrophobic parts was prepared by the reactions of the monomethyl ethers with 2-(perfluoroalkylmethyl)oxiranes in 76-97% yields. The second series CH3(OCH2CH2)nOCH2CH2CH2-CF2(CF2CF2)nCF3 (n = 1-3) possessing the non-hydroxylated spacer was synthesized from allyl methyl ethers of oligo(oxyethylene) glycols using radical additions of perfluoroalkyl iodides and subsequent selective reductions of the C-I bond in the adducts in overall yields of 23-69%. Some of the novel amphiphilic compounds displayed very low hemolytic activity to erythrocytes and excellent co-emulsifying properties on testing on perfluorodecalin/Pluronic F-68 microemulsions. 1-O-(2-Hydroxy-4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluorononyl)-d-xylitol was prepared by a novelized synthesis and employed as a standard compound in the testing.
- Kaplánek, Robert,Paleta, Old?ich,Ferjentsiková, Ivana,Kodí?ek, Milan
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experimental part
p. 308 - 316
(2009/12/03)
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- Highly stable giant supramolecular vesicles composed of 2D hydrogen-bonded sheet structures of guanosine derivatives
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(Figure Presented) Stabilized net: A molecular design approach to protect a 2D hydrogen-bonding network with nonpolar shielding layers has allowed the fabrication of micrometer-scale supramolecular vesicles in water (see picture). These hydrogen-bond-dire
- Yoshikawa, Isao,Sawayama, Jun,Araki, Koji
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p. 1038 - 1041
(2008/09/21)
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- Allyl sulfides are privileged substrates in aqueous cross-metathesis: Application to site-selective protein modification
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Allyl sulfides undergo efficient cross-metathesis in aqueous media with Hoveyda-Grubbs second generation catalyst 1. The high reactivity of allyl sulfides in cross-metathesis was exploited in the first examples of cross-metathesis on a protein surface. S-Allylcysteine was incorporated chemically into the protein, providing the requisite allyl sulfide handle. Preliminary efforts to genetically incorporate S-allylcysteine into proteins are also reported. Copyright
- Lin, Yuya A.,Chalker, Justin M.,Floyd, Nicola,Bernardes, Goncalo J. L.,Davis, Benjamin G.
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supporting information; experimental part
p. 9642 - 9643
(2009/02/04)
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- Network-type ionic conductors based on oligoethyleneoxy-functionalized pentamethylcyclopentasiloxanes
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Network-type solid polymer electrolytes (NSPEs) were synthesized containing oligoethylene oxide chains, CH3(OCH2CH2) 3(CH2)3-, within the network structures. Hydrosilylation reactions of precursors 1 and 2 (oligoethyleneoxy partially substituted pentamethylccyclopentasiloxanes (D5H)) with an α,ω-diallyloligo(ethylene glycol) were employed for the formation of the cross-linked networks. The conductivities of the network polymer/LiX complexes with variable EO/Li ratios were measured by impedance experiments. NSPE-2, with 36.0% cross-linking density, exhibited higher conductivity than NSPE-1, with 43.8%. The optimum conductivity (σ = 9.24 × 10 -5 S/cm at 25°C, 2.11 × 10-4 S/cm at 37°C) was found for NSPE-2 with lithium bis(oxalato)borate (LiBOB). LiBOB-doped polymers exhibited higher conductivity than those doped with LiTFSI at the same salt concentration.
- Zhang, Zhengcheng,Lyons, Leslie J.,Amine, Khalil,West, Robert
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p. 5714 - 5720
(2008/02/02)
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- Synthesis of hydrophilic Fischer carbene complexes as organometallic marker and PEGylating agent for proteins
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Syntheses of Fischer carbene complexes with various hydrophilic tethers (4, 6a, 6b, 6c, 8a, 8b, 14a, 14b, 15 and 19) are described. The water-soluble carbene complex, 14b, was used to label and pegylate bovine serum albumin (BSA) without affecting its conformation. The red complex, 19, underwent a sharp color change to yellow on reaction with BSA, a feature that is potentially useful for developing assay methods.
- Samanta, Debasis,Sawoo, Sudeshna,Patra, Subrata,Ray, Manju,Salmain, Michèle,Sarkar, Amitabha
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p. 5581 - 5590
(2007/10/03)
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- MULTIVALENT INHIBITORS OF SERUM AMYLOID P COMPONENT
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Novel glycerol cyclic pyruvate derivates were prepared and demonstrated to inhibit the binding of an immobilized D-proline derivative to serum amyloid P component (SAP) have been prepared. As such, the compounds of the invention are useful for treating am
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- Cross-Linked Network Polymer Electrolytes Based on a Polysiloxane Backbone with Oligo(oxyethylene) Side Chains: Synthesis and Conductivity
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A novel cross-linked siloxane-based solid polymer network has been synthesized by the hydrosilylation of polymethylhydrosiloxane (PMHS) partly substituted with oligo(ethylene glycol) methyl ether side groups and a α,ω-diallyl poly(ethylene glycol) cross-linking reagent. The ionic conductivities of the networks doped with LiTFSI are high at ambient temperature (σ = 1.33 × 10-4 S cm-1 at the optimum LiTFSI concentration EO/Li+ = 20:1). The temperature dependence of the conductivity followed the VTF form, indicating that polymer segmental motion assists the ion transport in the solid networks.
- Zhang, Zhengcheng,Sherlock, David,West, Ryan,West, Robert,Amine, Khalil,Lyons, Leslie J.
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p. 9176 - 9180
(2007/10/03)
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- SmI2/water/amine mediates cleavage of allyl ether protected alcohols: application in carbohydrate synthesis and mechanistic considerations.
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[reaction: see text]. SmI2/H2O/amine provides selective cleavage of unsubstituted allyl ethers in good to excellent yields. This method is therefore useful in deprotection of alcohols and carbohydrates.
- Dahlen, Anders,Sundgren, Andreas,Lahmann, Martina,Oscarson, Stefan,Hilmersson, Goeran
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p. 4085 - 4088
(2007/10/03)
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- Quantification of grafted poly(ethylene glycol)-silanes on silicon by time-of-flight secondary ion mass spectrometry
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Silicon grafted monodisperse poly(ethylene glycol) (PEG) silanes with various PEG chain lengths and mixtures of these were systematically analyzed with static time-of-flight secondary ion mass spectrometry (TOF-SIMS). The mass spectra show differences in the various relative signal intensities, an observation that was used to elucidate important aspects of the grafting process. The relationship between PEG-silane fragment ion abundances and Si+ ion abundances were used to (i) qualitatively describe layer thicknesses of grafted mixtures of PEG-silanes on silicon, (ii) construct a calibration curve from which PEG chain length (or molecular mass) can be determined and (iii) quantitatively determine surface mixture compositions of grafted monodisperse PEG-silanes of different chain lengths (3, 7 and 11 PEG units). The results suggest that discrimination does take place in the adsorption process. The PEG-silane with the shorter PEG chain is discriminated for mixtures containing PEG3-silane, whereas the PEG-silane with the longer PEG chain is discriminated in PEG7/PEG11-silane mixtures. The origin of this difference in adsorption behavior is not well understood. Aspects of the grafting process and the TOF-SIMS analyses are discussed. Copyrigh
- Norrman,Papra,Kamounah,Gadegaard,Larsen
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p. 699 - 708
(2007/10/03)
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- Thermochromism and solvatochromism of non-ionic polar polysilanes
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Polar polysilanes bearing ethereal side groups [{CH3-Si-(CH2)m-O-(CH2CH 2O)n-CH3}x, m = 3-5 and n = 0-3}] were prepared and were found to be soluble in a wide range of polar solvents. UV spectroscopic behavior is highly dependent on the nature of the solvents used but no simple relationship between λmax and specific solvent parameter is found. Small molar absorbance (ε 3)2CHOH (HFIP) in non-polar solvent (benzene, CH2Cl2) or even in (CH3)2CHOH solution, where higher HFIP concentration brings about longer wavelength absorption. This type of solvatochromism is originated by strong hydrogen bond formation between the ethereal side groups and HFIP. Because non-dissociative nature of HFIP-concerned hydrogen bonding, increased bulkiness of the side moieties brings about disentanglement. Polysilanes 1-5, though having long side chains, show thermochromism of continuous spectral shift on cooling. The same λmax value in thermochromism and solvatochromism indicates that nearly the same degree of disentanglement is caused by HFIP and thermally.
- Oka, Kunio,Fujiue, Naofumi,Nakanishi, Saburo,Takata, Toshikazu,West, Robert,Dohmaru, Takaaki
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- New inorganic-organic hybrid Li+ ion conducting polymer electrolytes
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A new series of inorganic-organic hybrid polymer electrolytes containing the aluminate structure were prepared. Incorporation of stronger Lewis acid sites into the polymer in the region of the aluminate bond was effective for enhancing ionic conductivity. The materials were shown to be single Li+ ion conductors.
- Fujinami, Tatsuo,Sugie, Kazuhiro,Mori, Kenji,Mehta, Mary Anne
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p. 619 - 620
(2007/10/03)
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- Approaches to new water soluble phosphines
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Approaches to water-soluble phosphines are described which involve conversion of ethylene glycol derivatives and sugar diacetonides into monoallyl ethers, and hydrophosphorylation of the latter.In the case of the sugars, water-solubility is conferred by a subsequent hydrolysis.
- Mitchell, Terence N.,Heesche-Wagner, Kerstin
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- Synthese et reactivite d'un nouvel hydrure organostannique a "queue polaire": le dibutyl-4,7,10-trioxaundecylstannane
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A new tin hydride was prepared by reduction of the tin chloride obtained in the addition of hydrogenochlorodibutylstannane to the allyl methyl ether of diethylenehglycol.The efficiency of this compound in reductions and reductive additions to alkenes of alkyl halides was demonstrated as well as the easy separation of the organic products of reaction from the organotin compounds by liquid-solid chromatography over silica.
- Ferkous, F.,Messadi, D.,Jeso, B. De,Degueil-Castaing, M.,Maillard, B.
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p. 315 - 320
(2007/10/02)
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- A WATER SOLUBLE TIN HYDRIDE REAGENT
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A water soluble tin hydride has been synthesized carrying three methoxyethoxypropyl groups.It reduces various alkyl halides in water, or in organic solvents.
- Light, James,Breslow, Ronald
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p. 2957 - 2958
(2007/10/02)
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- Stable silica-based ether bonded phases for biopolymer separations
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Fast high resolution separations of biopolymers with retention of biological activity have been achieved by hydrophobic interaction chromatography using trialkoxy silyl ethers of the general formula chemically bonded to silica-based chromatographic supports. In the formula R is alkyl of from one to five carbons, m is an integer from two to five, n is an integer from one to five, p is an integer from zero of ten, and R' is methyl, phenyl, or substituted phenyl. Stable and reproducible bonded phases are prepared in a novel solventless procedure by a bonding process which uses a defined and controlled amount of water on the silica surface and a gaseous or volatile basic catalyst such as ammonia to produce a controlled amount of silane polymerization and cross-linking in addition to extensive bonding between silane and silica. High performance liquid chromatography on such weakly hydrophobic stationary phases using aqueous eluents and decreasing salt gradients under mild conditions permits high speed, high resolution separations of biopolymers such as proteins without destruction of their biological activity and without column degradation. Size exclusion chromatography can also be performed on these phases using low ionic strength eluents.
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- Deamination Reactions, 41. Reactions of Aliphatic Diazonium Ions and Carbocations with Ethers
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Aliphatic diazonium ions and carbocations were generated by deacylation of appropriate nitrosoureas (1, 5, 9) in alcohol-ether mixtures or in 2-alkoxyethanols.Ethers were generally inferior to alcohols in capturing cationic intermediates.Formation of trialkyloxonium ions led to alkyl exchange or ring opening.The observed reactivity orders were n-butyl > isobutyl for the diazonium ions, allyl > sec-butyl > tert-butyl for the carbocations, methoxy > ethoxy and oxirane > oxetane > tetrahydrofuran for the ethers, indicating the predominance of steric effects.Neighboring group participation in 4-methoxy-1-butanediazonium ions (58) and 4,5-epoxy-1-pentanediazonium ions (74) was detectable but inefficient ( 20percent of cyclic oxonium ions).
- Kirmse, Wolfgang,Jansen, Ulrich
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p. 2607 - 2625
(2007/10/02)
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- 246. Monofunctional (Dimethylamino)silane as Silylating Agent
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The reaction of triorganyl(dimethylamino)silanes with surface-hydrated silicon dioxide has been studied.These silylating agents are easy to prepare from the corresponding chloro or bromosilanes with dimethylamine.The resulting products are thermally stable and relatively volatile.Reaction with surface-hydrated silicon-dioxide preparations at a50-250 deg C for 170 h yields a dense grafted layer.However, with (dimethylamino)silanes having strongly polar substituents, a retreatment of the surface-modified silica seems to be necessary in order to attain maximum coverage.
- Szabo, Katalin,Le Ha, Ngoc,Schneider, Philippe,Zeltner, Peter,sz. Kovacs, Ervin
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p. 2128 - 2142
(2007/10/02)
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- Autoxidation of Allyl Ether Compounds. Part 1. Reactivity of Allyl Ether Alcohols.
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Cobalt catalyzed liquid phase autoxidations of some primary and secondary allyl ether alcohols were studied at 30 and 40 deg C.An optimum concentration for the catalyst was found, above which cobalt behaved like an inhibitor.Autoxidations of secondary allyl ether alcohols started immediately after adding the catalyst but the reactions of the allyl ethers of primary diols were preceded by induction periods.Induction periods depended on the carbon chain length of the diol and were not observed after methylating the hydroxyl group of the allyl ether alcohol.The phenomena are explained as resulting from inter- and intramolecular hydrogen bonding, which controls the autoxidation by decreasing the electron density on the etheral oxygen.
- Toivonen, Hannu
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