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  • 1995-1999  (11)
  • Chemistry  (11)
  • Polymer and Materials Science  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 139-151 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein neuartiges organisch-anorganisches Hybridmaterial wurde durch den Einbau des Minerals Böhmit mittels eines Sol-Gel-Prozesses in ein Kevlar-Nomex-Copolymeres hergestellt. Durch Reaktion eines Gemisches aus m- und p-Phenylendiamin mit Terephthaloylchlorid und anschließender Umsetzung mit Aminophenyltrimethoxysilan wurden Poly(phenylenterephthalamid)-Ketten mit Aminophenyltri-methoxysilan-Endgruppen synthetisiert. In dieser Polymermatrix wurde die Hydrolyse der Alkoxygruppen einer Lösung von Aluminium-sec-butanolat in Butanol durchgeführt. Dadurch wurde ein chemisch an die Aramid-Ketten gebundenes anorganisches Netzwerk aufgebaut. Aus den hergestellten Hybridmaterialien mit unterschiedlichen Böhmit-Gehalten in der Aramidmatrix wurden Filme gegossen. Die Filme aus Hybridmaterial mit bis zu 15 Gew.-% Böhmit waren transparent gelb, während bei 20 und mehr Gew.-% Böhmit opake Filme erhalten wurden. Die mechanischen Eigenschaften dieser Filme wurden untersucht. Zugfestigkeit, Zugmodul, Härte und maximale Bruchdehnung nahmen mit steigendem Böhmitgehalt zunächst zu, vemngerten sich jedoch bei weiterer Erhöhung des Mineralanteils wieder. Der Zugmodul des Hybridmaterials bei 25°C lag zwischen 3,0 und 4,5 GPa. Die Materialien hielten einer maximalen Zugspannung von 252 MPa stand und zeigten Zersetzungstemperaturen von etwa 450°C. Die rnit DMTA ermittelten Werte für den Speichemodul lagen im Bereich 7,6-18,9 GPa. Das tan δ-Signal verbreiterte sich mit zunehmendem Böhmitanteil und ging bei hohen Böhmitgehalten in eine Schulter über. Die Signalpositionen des Verlustfaktors wurden infolge der zunehmenden sterischen Einschränkung der Segmentbewegungen rnit steigendem anorganischen Anteil zu höheren Temperaturen verschoben.
    Notes: A new organic-inorganic hybrid material was prepared by incorporating boehmite into a Kevlar-Nomex copolymer via a sol-gel process. Poly(phenylene-terephthalamide) chains having aminophenyltrimethoxysilane end groups were prepared by reacting a mixture of m-and p-phenylenediamine with terephthaloyl chloride, followed by end-capping with aminophenyltrimethoxysilane. The hydrolysis of the alkoxy groups of an aluminium sec-butoxide solution in butanol was carried out in the polymer matrix, thus creating an inorganic network structure combined chemically with the aramid chains. Hybrid materials containing different proportions of boehmite in aramid were thus produced and films were cast by solvent evaporation technique. These films with up to 15 wt.-% of boehmite were yellow and transparent, whereas the films with 20 wt.-% or more contents of boehmite were opaque. Mechanical properties of these films were analyzed. The values of tensile strength, initial modulus, toughness and maximum strain at rupture were initially found to increase and then decrease with further addition of boehmite. The tensile modulus of the hybrid material was found to be in the range of 3.0-4.5 GPa at 25°C. These ceramers were found to withstand maximum tensile stress of the order of 252 MPa, and the thermal decomposition temperature was around 450°C. The storage modulus as measured using DMTA was in the range of 7.6-18.9 GPa. The tan δ peak which in general became broader with increasing boehmite content showed a shoulder for composites containing large amounts of boehmite. The position of the peaks shifted towards high temperature with the increase in the inorganic contents showing hindrance in motion with increasing boehmite contents.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0009-2940
    Keywords: M2P2 tetrahedral complexes ; Phosphido ligand complexes as intermediates ; Ni2P4O distorted prismane framework ; CO incorporation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes with Metal-Phosphorus Triple Bonds as Possible Intermediates in the Reactions between Chlorophosphinidenes and Metalates of Various Transition MetalsThe reaction of [{M′(CO)5}2PCl] (M′ = Cr, W) with various metalates ([Cp′Mo(CO)3]-, [Cp * Ni(CO)]-, [Cr2(CO)10]2-) yields the M2P2 tetrahedral complexes [(MLn)2(μ,η2- P2){M′(CO)5}2] (MLn = Cp*Ni, M′= Cr (1), W (2); MLn = Cp′Mo(CO)2, M′ = Cr (4); Cp* = η5-C5Me5, Cp* = η5C5H3tBu2) and the cyclo-P4 compound [{Cr(CO)4}(η4-P4){Cr(CO)5}4] 6. As side products the distorted prismane [(Cp*Ni)2{μ4,η4-(P2-O-P2)}{W(CO)5}2] 3 and the diphosphino-methanone complex [{Cp′Mo(CO)2}2{μ4η2-PC(O)P}-{Cr(CO)5}2] 5 are formed. The complexes are characterised by NMR, IR, MS, and X-ray structure analysis (1-5). Studying the reaction pathway provided evidence of phosphido intermediates of the type [LnM≡P→M′Ln].
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2940
    Keywords: P ligands ; P-P bond formation reaction ; Molybdenum ; Chromium ; Nickel ; Carbonyl complexes ; Main group elements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [Cr(CO)5PCl3] reacts with different metallates K[CpxMo(CO)3] [Cpx = ·5-C5H4tBu (Cp]), ·5-C5H3tBu2-1,3 (Cp))], K[CpFe(CO)2], K[Cp]Cr(CO)3], K[C}*Ni(CO)] and Na2[Cr2(CO)10] at -78°C in THF to yiel various P2, cyclo- P3 and cyclo-P5 ligand complexes of the formulae [Cp] Mo(CO)2 (.2-P3)] (1a), [Cp]Mo(CO)2(.3-P3)] (1b), [{CP'Mo-(CO)2}2(μ,.2-P2)] (2a), [{Cp]Mo(CO)2}2(μ, ·2-P2)] (2b), [Cp]Fe).5-P5)] (3), [(Cp'Cr)2(μ,.5-P5)] (4), [{Cp]Cr(CO)2}2-(μ,.2-P2)] (5), [(Cp*Ni)2(μ,.2-P2){Cr(CO)5}2] (6). [{(CO)5Cr}Cl2PPCl2{Cr(CO)5}] (7) and [{Cr(CO)5}2PCl (8). Comprehensive studies of the reaction pathway leading to formation of the cyclo-P3 product 1a give strong indications that a sequence involving metal-halogen exchange and stepwise P-P bond formation takes place, proceeding via [{CO}5Cr}Cl2PPCl2{Cr(CO)5}] (7) and the cyclo-P3 precursor compond [{Cp]Mo(CO)3}{Cp'Mo(CO)2}2{Cr(CO)5}(μ,.3:1:1-P3)] (9). The latter two complexes have been isolated and structurally characterized.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 26 (1995), S. 22-26 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Die Orientierung der Säulen in der Mikrostruktur schräg aufgedampfter dünner SchichtenSchräg aufgedampfte dünne Schichten entwickeln gewöhnlich eine Mikrostruktur aus Sälen, deren Wachstumswinkel relativ zur Substratnormalen, β, nicht mit dem Einfallswinkel α übereinstimmt. Hier wird gezeigt, daß der funktionale Zusammenhang β(α) durch die Gleichung tan β=tan α + ρ-1(dρ/δα) in universeller Weise mit der Winkelabhängigkeit der Schichtdichte ρ verknüpft ist. Ein Vergleich mit numerischen Daten aus Simulationen der ballistischen Abscheidung von Scheiben und Kugeln bestätigt die Theorie.
    Notes: Vapor-deposited thin films grown under conditions of oblique incidence commonly develop a microstructure of columns, inclined at an angle β relative to the substrate normal, which differs from the angle of incidence α. Here it is shown that the functional relation β(α) is universally linked to the dependence of the film density ρ on the angle of incidence, through the equation tan β=tan α + ρ-1(dρ/dα). The theory is supported by an analysis of published numerical data obtained from simulations of ballistic deposition of disks and spheres.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 7 (1997), S. 123-133 
    ISSN: 1057-9257
    Keywords: nanocomposites ; sol-gel ; heteropolymetallates ; photochromics ; holographic data storage ; amplitude grating ; two-wave-mixing recording ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: This paper describes the properties of some new organic-inorganic photochromic layers. They are based on a hybrid organic-inorganic matrix in which tungsten heteropolyoxometallates (SiW12O4-40, PW12O3-40) are entrapped in a network obtained from the reaction of 3-glycidoxy-propyltrimethoxysilane. The high homogeneity of these materials on the nanoscale leads to transparent monoliths and layers of controlled thicknesses up to 40 μm. The optical properties of the blend are emphasised and the construction of amplitude gratings in the materials by two-wave-mixing experiments is described. The results of the optical experiments and the comparison with the theoretical background are used as a model for photochromic holographic storage processes. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 71 (1999), S. 1029-1029 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 70 (1998), S. 711-713 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 1 (1995), S. 201-206 
    ISSN: 1075-2617
    Keywords: All-aza peptide ; renin inhibitor analogue ; X-ray ; conformation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the first all-aza-amino acid analogue (2) of a peptidic renin inhibitor is described. The X-ray structural analysis and molecular modelling investigations of this novel compound reveal interesting conformational features which have a significant impact on its biological activity. In addition, insight into conformational features of azapeptides in general in comparison with the corresponding purely peptidic compounds is given.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 69 (1997), S. 1287-1288 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 63-71 
    ISSN: 0044-2313
    Keywords: diethyl triorganostannylmethyl N-acyl aminomalonates ; ethyl 3-(trimethylstannyl)-N-acyl alaninates ; 1,2-oxastannolane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: C-Stannylmethylated N-Acetyl- and N-Formyl-aminomalonic Acid DerivativesTin compounds of the type Me3SnCH2C(NHCOR) · (COOEt)2 (1: R = CH3; 2: R = H) are synthesized by reaction of acylaminomalonates with iodomethyl trimethylstannane. The halogenation of 1 and 2 yields the halostannylsubstituted compounds Me3-nXnSnCH2C(NHCOR)(COOEt)2 3-6 (R = Me, H; n = 1, 2; X = Cl, Br). The decarbethoxylation (KRAPCHO reaction) of 1 and 2 gives ethyl 3-(trimethylstannyl)-N-acyl alaninates (7 and 8). With one equivalent KOH 1 and 2 are transformed into the monoethyl malonates of the type Me3SnCH2C(NHCOR)(COOH)(COOEt) (9: R = CH3), which convert simultaneously under decarboxylation into 7 and 8 and by cyclisation under elimination of methane into the 1,2-oxastannolane derivatives 10 and 11. IR, NMR data and the determination of the crystal structure reveal for MeBr2SnCH2C(NHCOCH3)(COOEt)2 (5) hexacoordinated tin by intramolecular coordination of the amide-CO and one of the ester-CO groups.
    Notes: Zinnverbindungen des Typs Me3SnCH2C(NHCOR)(COOEt)2 (1: R = CH3; 2: R = H) werden durch Umsetzung von Acylaminomalonsäureestern mit Iodomethyltrimethylstannan dargestellt. Die Halogenierung von 1 und 2 liefert die halogenostannylsubstituierten Verbindungen Me3-nXnSnCH2C(NHCOR)(COOEt)2 3-6 (R = Me, H; n = 1, 2; X = Cl, Br). Die Decarbethoxylierung (KRAPCHO-Reaktion) von 1 und 2 führt zu 3-(Trimethylstannyl)-N-acyl-alaninethylestern (7 und 8). Mit einem Äquivalent KOH werden 1 und 2 in die Monoethylester des Typs Me3SnCH2C(NHCOR)(COOH)(COOEt) (9: R = CH3) überführt, die sich in Folgereaktionen sowohl unter Decarboxylierung zu 7 bzw. 8 als auch durch Cyclisierung unter Methanabspaltung zu den 1,2-Oxastannolanderivaten 10 bzw. 11 umwandeln. IR-, NMR-Daten und die Bestimmung der Kristallstruktur beweisen für MeBr2SnCH2C(NHCOCH3)(COOEt)2 (5) hexakoordiniertes Zinn durch intramolekulare Koordination der Amid-CO- sowie einer Ester-CO-Gruppe.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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