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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of Pyrazinoporphyrazine Derivatives Functionalised with Tetrathiafulvalene (TTF) Units: X-Ray Crystal Structures of Two Related ttf Cyclophanes and Two Bis(1,3-Dithiole-2-Thione) IntermediatesDedicated to Professor Fabian Gerson on the occasion of his retirement (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1679-1690 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; cyclophanes ; electrochemistry ; porphyrazines ; tetrathiafulvalenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrazinoporphyrazine system 13 (metal-free, zinc and copper derivatives) has been synthesised by tetramerisation of 2,3-dicyanopyrazine monomer unit 10. The structure of 13a-c has been established by 1H NMR spectroscopy, UV/Vis spectrophotometry, MALDI-TOF mass spectrometry, cyclic voltammetry and differential pulse voltammetry. The electrochemical redox behaviour of 13a-c is strongly solvent dependent. The expected two-stage oxidation of the tetrathiafulvalene (TTF) units of 13a-c was observed in a range of solvents; in addition, oxidation and reduction of the pyrazinoporphyrazine core of the metal-free derivative 13a was detected in benzonitrile. On excitation of 13 in the Q-band region no fluorescence was observed, which is presumably the consequence of intramolecular charge transfer between the TTF moieties and the excited state of the central porphyrazine. Molecular modelling studies on 13a and 13c are reported. During the course of this work, the novel TTF macrocycles 11 and 20 were synthesised; their X-ray crystal structures reveal severely bent TTF units, the conformations of which are discussed in detail. The X-ray crystal structures of the bis(1,3-dithiole) systems 15 and 18 have also been determined.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970031018
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  • 2
    Electronic Resource
    Electronic Resource
    Holographic grating relaxation studies of probe diffusion in amorphous polymers (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 899-908 
    Details
    ISSN: 0887-6266
    Keywords: probe diffusion ; holographic grating relaxation ; temperature dependence ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Probe diffusion of camphorquinone, thymoquinone, and diacetyl in polymers was studied by the laser-induced holographic grating relaxation (HGR) technique in polymers. The effects of changing the probe size and various parameters of the polymer, such as the molecular weight, chain conformation, and the glass transition temperature, on the probe diffusion coefficient have been investigated. Furthermore, effects of cross-linking and plasticizing the chains of the polymer host on the probe diffusion coefficient were also studied. Temperature-dependent studies show that except for the very low molecular weight poly(methyl methacrylate), all probe diffusion coefficient data above the glass transition temperature fit well to the WLF equation. ©1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330605
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  • 3
    Electronic Resource
    Electronic Resource
    Ab initio calculations of the magnetic exchange coupling in sulfur-bridged binuclear Ni(II) complexes (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 65 (1997), S. 633-641 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The geometry dependence of the exchange integrals and the total energies of sulfur-bridged complexes of the types L5NiSNiL5, L4NiS2NiL4, and L3NiS3NiL3 is studied by quantum chemical ab initio methods. The linear monobridged complex is antiferromagnetic, the bi- and triply-bridged complexes are ferromagnetic for NiSNi angles between 85° and 100° and antiferromagnetic for smaller and larger angles. The superexchange mechanism is analyzed, and a comparison with oxygen-bridged complexes and experimental data is performed.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65: 633-641, 1997
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Surface excitation parameters of low-energy electrons crossing solid surfaces (1998)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 682-688 
    Details
    ISSN: 0142-2421
    Keywords: surface ; surface excitation ; surface effect ; electron ; inelastic mean free path ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface excitation parameter, which describes the influence of surface excitations by electrons for the vacuum side in electron spectroscopies, has been calculated for electrons of 200-2000 eV energies crossing surfaces of Cu, Ag, Au, Fe, Pd, Ni, MgO and SiO2. These calculations were performed for both incident and escaping electrons by the use of dielectric response theory. Spatially varying differential inverse mean free paths for surface excitations as a function of electron distance from the surface were found. The results showed that small differences existed in the surface excitation parameter among different metals but large differences occurred between metals and semiconductors or insulators. Calculated surface excitation parameters were fitted very well to a simple formula, i.e. Ps=aE-b, where Ps is the surface excitation parameter and E is the electron energy. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chemoselective polycondensation of isophthaloyl chloride with multifunctional monomers containing hydroxyl groups and sulfamino acid or amino acid moiety (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 493-495 
    Details
    ISSN: 0887-624X
    Keywords: chemoselective polycondensation ; functional polymer ; aromatic polyester ; hydroxyl group ; sulfamino acid moiety ; amino acid moiety ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of copolyester having quaternary ammonium groups in the main chain (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2517-2519 
    Details
    ISSN: 0887-624X
    Keywords: functional polyester ; liquid/solid biphase polycondensation ; tertiary amine group ; heterogeneous polymer reaction ; quaternary ammonium group ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Preliminary X-ray crystallographic analysis of Tritrichomonas foetus inosine-5′-monophosphate dehydrogenase (1995)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 598-603 
    Details
    ISSN: 0887-3585
    Keywords: inosine monophosphate dehydrogenase ; Tritrichomonas foetus ; crystallization ; X-ray diffraction ; purine ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Inosine-5′-monophosphate dehydrogenase (IMPDH) from the protozoan parasite Tritrichomonas foetus has been expressed in E. coli and crystallized. Crystals were grown to 0.1 mm in each dimension in 18 to 72 h using ammonium sulfate and low-molecular-weight polyethylene glycols. The crystals belong to the cubic space group P432 with unit cell edge = 157.25 Å. The enzyme is a homotetramer with each monomer having a molecular weight of 55,534 Da. There is one monomer per asymmetric unit, based on a volume/mass ratio of 2.7 Å3/Da and self-rotation analysis. The crystals are adequately stable to allow a complete data set to be collected from a single crystal. Complete native data sets have been collected to 2.3 Å resolution at 4°C using synchrotron radiation. High-quality complete data extending to 3.0 Å resolution have been collected from crystals of four putative derivatives, and the data appear to be isomorphous with that of the native crystals in each case. Efforts to solve the derivatives for use in MIR phasing are underway. © 1995 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340230417
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  • 8
    Electronic Resource
    Electronic Resource
    Multidimensional benzobisoxazole rigid-rod polymers. II. Processing, characterization, and morphology (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3457-3466 
    Details
    ISSN: 0887-624X
    Keywords: PBO ; rigid-rod polymer ; multidimensional polymer ; compressive strength ; fiber morphology ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A high-torque rheometer was used to facilitate the polycondensation of 4-[5-amino-6-hydroxybenzoxazol-2-yl]benzoic acid (ABA) with trimesic acid and 1,3,5,7-tetrakis(4-carboxylatophenyl)adamantane to yield two- and three-dimensional benzobisoxazole polymers, respectively. Although the resultant polymer dopes exhibited improved homogeneity compared to polymer dopes previously prepared in glassware, improved polymer solution viscosities were not achieved. Fibers spun from the two- and three-dimensional polymers did not show a significant increase in compressive strength compared to fibers of the linear or one-dimensional benzobisoxazole polymer derived from the homopolymerization of ABA. Morphological studies of the polymer fibers and films by wide-angle X-ray scattering and scanning electron microscopy strongly indicated more lateral disorder and a more isotropic character for the three-dimensional structures compared to the one-dimensional structures. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3457-3466, 1997
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Langmuir-Blodgett deposition and second-order non-linear optics of several azobenzene dye polymers (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 6 (1996), S. 33-38 
    Details
    ISSN: 1057-9257
    Keywords: LB films ; non-linear optics ; azobenzene derivatives ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The Langmuir-Blodgett (LB) film-forming properties of a number of novel azobenzene dye polymers are reported. The linear and second-order non-linear optical properties of the films have been studied using ellipsometry, visible spectroscopy and Pockels effect measurements. As monolayers, the effective electro-optic r-coefficients ranged from 1 to 8.7 pm V.-1 When one of the polymers was combined in an alternate layer film (230 layers in total), an r13-coefficient of 13 pm V-1 was achieved. This is one of the highest values reported for a ‘thick’ LB film.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of the conductivity of sulfonated poly(phenylene oxide) lithium by the complexation of poly(ethylene oxide) (1996)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 7 (1996), S. 697-700 
    Details
    ISSN: 1042-7147
    Keywords: complexation ; sulfonated poly(phenylene oxide) lithium ; poly(ethylene oxide) ; conductivity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In the present paper, the structure and conductivity for the complex of sulfonated poly(phenylene oxide) lithium (SPPOLi) and poly(ethylene oxide) (PEG) were studied. Glass transition temperature change determined by differential scanning calorimeter analysis desmonstrated that the two components had some compatibility. X-ray diffraction showed that PEG could decrease the regularity of SPPOLi to some extent. The compatibility and PEG's effect on the regularity may be due to the interaction between the lithium ions of SPPOLi and the oxygen atoms of PEG. Under polarization by electric field, the bands between lithium ions and sulfonation groups relaxed. Meanwhile, the complexation of oxygen atoms could enhance the dissociation of the polymeric lithium salts. Then lithium ions were transported in the process of alternate complexing and decomplexing. The action between lithium ions and oxygen atoms could explain the improvement on the conductivity of SPPOLi.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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