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  • Amino acids  (1)
  • Polymer and Materials Science  (1)
  • Theoretical, Physical and Computational Chemistry  (1)
  • Wiley-Blackwell  (3)
  • American Physical Society
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  • Wiley-Blackwell  (3)
  • American Physical Society
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  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2341-2347 
    ISSN: 0887-624X
    Keywords: piezoelectric ; pyroelectric ; cyano-containing copolymers ; methyl vinylidene cyanide ; Lewis acid ; acrylonitrile ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a series of novel cyano-containing copolymers is described. Alternating copolymers of acrylonitrile with vinyl esters are obtained by increasing the electrophilic character of the nitrile monomers by complexation with zinc chloride. Copolymers of methyl and ethyl α-cyanoacrylates with vinyl esters are prepared using radical initiators in the presence of 7% acetic acid as inhibitor for anionic polymerization. The copolymers of methyl α-cyanoacrylate with the vinyl esters have Tg's above 140°C. Methyl vinylidene cyanide (MVCN) copolymerizes spontaneously with para-substituted styrenes to yield copolymers with high inherent viscosities and high Tg (160°C) and the copolymer of MVCN with vinyl acetate is also synthesized. The pyroelectric constants p for these polymers were measured and the values of p for the copolymers of vinyl acetate with methyl β,β-dicyanoacrylate, methyl α-cyanoacrylate, or MVCN were in the same range as the well-studied vinylidene cyanide/vinyl acetate copolymer. A higher concentration of dipoles generally results in higher Tg's and higher pyroelectric coefficients. © 1992 John Wiley & Sons, Inc.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 877-886 
    ISSN: 0020-7608
    Keywords: potential functions ; nitrate anion ; nitrate-water interaction ; nitrate-water cluster geometries ; vibrational frequencies ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction between nitrate anion and water has been investigated by Hartree-Fock calculations with the 6-311+G(d, p) basis set and by B3LYP density functional calculations with the aug-cc-pVTZ basis set. It is found that the global energy minimum is a planar configuration where both hydrogen atoms of water are coordinated to two oxygen atoms of NO3- by distorted hydrogen bonds. In contrast to former studies on NO3-/H2O this configuration is found to be asymmetric at the highest theoretical level employed. The corresponding structure with C2v symmetry is a saddle point at slightly higher energy. A singly hydrogen-bonded configuration is still about 2.4 kcal/mol higher in energy. The shifts in the vibrational frequencies of water and nitrate upon complexation were calculated. A compact analytical potential function of NO3-/H2O for use in statistical thermodynamic simulations was obtained from 390 points of the energy surface and an intramolecular force field for the nitrate anion is presented.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 877-886, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-193X
    Keywords: Calixarenes ; Chiral hosts ; Amino acids ; L-Alanine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetic routes were developed to link L-alanine methyl ester or L-alanyl-L-alanine methyl ester at the upper rim of calix[4]arenes blocked in the cone conformation. Several tetra- (3 and 6) and difunctionalized (11 and 12) amino acids containing macrocycles were obtained. Reaction of these compounds with hydrazine gave the corresponding hydrazido derivatives 4, 13, and 14, while the hydrolysis of 3 with LiOH produced the tetraacid 5 whose lithium salt is water soluble at neutral pH. The structural properties of all amino acids containing calix[4]arenes were studied by mono- and bidimensional 1H NMR experiments. The X-ray crystal structure of the difunctionalized receptor 11 shows three different conformations in the solid state, none of them having intrachain hydrogen bonding.
    Type of Medium: Electronic Resource
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