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  • 1
    Electronic Resource
    Electronic Resource
    Conformational studies of N-acetyl-N′-methylamide derivatives of α-aminobutyric acid, norvaline, and valine. I. Preferred conformations in solution as studied by 1H-nmr spectroscopy (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 969-984 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H-nmr studies were extensively carried out to elucidate preferred conformations of dipeptides CH3C*O - X - NHCH3, with X = Abu, nVal, and Val in various solvents. The vicinal 1H - 1H coupling constants for the NH - CαH moiety and those around the Cα - Cβ bond in the articulated side chain provided the information regarding the average conformation of these molecules. The results indicate that transformation of skeletal conformations takes place in solution among conformers having similar dihedral angles, θHN - CαH, in the Karplus expression.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270607
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  • 2
    Electronic Resource
    Electronic Resource
    Conformational characteristics of polyglutamic acid esters: Persistence of orientational correlation along the side chain flanking the α-helical backbone (1989)
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1959-1967 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The side chain conformations of α-helical poly(L-glutamic acid) esters \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--}[NHCH(CH_2 CH_2 COOR)CO\rlap{--}]_x $\end{document}, carrying a homologous series of ester residues such as R = —(CH2)nφ with n = 1-3, have been studied in the lyotropic liquid crystalline state (chloroform 20 v/v%) by the deuterium nmr method. In order to study the surface chirality of the molecule, the phenyl groups situated at the terminal of the side chain have been deuterated. From the observed deuterium quadrupolar splittings, the average inclination θp of the para-axis of the phenyl group with respect to the α-helical backbone was elucidated. A distinct odd-even oscillation in the quantity such as 〈 cos2 θp〉 was observed with the number of methylene units n. A rotational isomeric state analysis has indicated that the observed orientational correlation arises from the interdependence of the neighboring bond rotation along the side chain. Preference of the “extended” conformations is also enhanced by the mutual conformational exclusion of neighboring side chains.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360281112
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  • 3
    Electronic Resource
    Electronic Resource
    Conformational studies of N-acetyl-N′-methylamide derivatives of α-aminobutyric acid, norvaline, and valine. II. Conformational energy calculations and comparison with experimental results (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 985-999 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational analyses on a series of dipeptides CH3 - C*O - NH - CH(R) - C*O - HN - CH3 with side chains such as R = CH2CH3, CH2CH2CH3, and CH(CH3)2 are described. Calculations were carried out by using semiempirical potential energy functions of Brant et al. The results were compared with those reported by Vásquez et al. and Chuman et al., who employed the ECEPP program in their analyses. The averages of the vicinal coupling constant JNH - CαH and the side-chain conformer fractions p(χ1) and p(χ2)′ were estimated therefrom for preferred conformations. The characteristic features of the experimental observations derived from the 1H-nmr measurements are reasonably well reproduced by these calculations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270608
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  • 4
    Electronic Resource
    Electronic Resource
    Spatial configurations, transformation, and reorganization of mesophase structures of polyaspartates - A highly intelligent molecular system (1997)
    New York : Wiley-Blackwell
    Biopolymers 43 (1997), S. 405-412 
    Details
    ISSN: 0006-3525
    Keywords: poly(β-phenethyl L-asparate ; right-handed α-helix ; left-handed α-helix ; 1,1,2,2-tetrachloroethane ; lyotropic liquid crystalline state ; helix-helix transition ; 2H-nmr method ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(β-phenethyl L-aspartate) (PPLA) takes the right-handed α-helical form in 1,1,2,2-tetrachloroethane at moderate temperatures. The transition to the left-handed α-helix occurs at around 85°C in the isotropic solution as well as in the lyotropic liquid crystalline state. In the presence of a denaturant acid, PPLA also exhibits a transformation to the left-handed form by lowering temperature. Accordingly, a ternary mixture such as PPLA trifluoroacetic acid/chloroform possibly exhibits as many as five phases above certain concentration. The primary cause responsible for such a highly cooperative helix-helix transition was found to reside in a small free-energy difference in the conformational states of the side chain flanking the spiral backbone of the two opposite handedness. © 1998 John Wiley & Sons, Inc. Biopoly 43: 405-412, 1997
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Small-angle x-ray scattering of distorted lamellar structures (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1179-1186 
    Details
    ISSN: 0887-6266
    Keywords: small angle x-ray scattering (SAXS) of distorted lamellar structures ; polypropylene, hard elastic, SAXS of, electron micrograph of, density of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Small-angle x-ray scattering (SAXS) intensity for the lamellar structure of polymeric materials has been formulated with consideration of structural defects such as the finiteness of the lamellar stack, the lamellar bend, and the paracrystalline distortions. In particular, the effects of the lamellar bend on the SAXS profile have been elucidated on the basis of Vonk'xss formula γ1(x) - γ01(x)exp(-2x/d). Here, the scattering profile due to the lamellar bend is shown to be expressed by a Cauchy function. The integral breadth is equal to 2π/d, being independent of the order of scattering. As an example of the SAXS analysis based on the theory, the characterization of the lamellar structure in the “hard” elastic polypropylene films is reported. The long period and the lamellar thickness are evaluated from the correlation function, and the distortion length and Hosemann's g factor are estimated according to the procedure presented here. On the basis of these structural parameters, the relationship between the manufacturing process and the lamellar structure of the polypropylene films is discussed. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090310912
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  • 6
    Electronic Resource
    Electronic Resource
    Optically active polymers (1967)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science: Macromolecular Reviews 1 (1967), S. 1-33 
    Details
    ISSN: 0076-2083
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.230010101
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  • 7
    Electronic Resource
    Electronic Resource
    Conformation of 4-ethoxy-4′-biphenylyl cyanide in the isotropic and anisotropic liquid-crystalline state  -  a rotational isomeric state simulation of 2H NMR spectra (1992)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 1 (1992), S. 401-413 
    Details
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformation of the ethoxy tail flanking the cyanobiphenyl core has been studied in the liquid-crystalline phase as well as in the isotropic solution. In solution, the vicinal coupling constant 3JCH for the moiety CphO—CH (Cph: phenyl carbon) provided the information regarding the rotation around the O—C bond. Phenetole was mostly used as a model compound. The conventional rotational isomeric state (RIS) analysis yielded the energy difference between the gauche and trans state to be of the order of 1,6 to 1,4 kcal/mol in CDCl3, C6D6 and dimethyl-d6 sulfoxide. In this treatment, the rotational state around the neighboring bond (Cph—O) was taken to occur at 0 or π. The deuterated compound, 4-ethoxy-4′-biphenylyl-d7 cyanide, was prepared and studied in the liquid-crystalline state by 2H NMR. The orientational order parameters of the mesogenic core were determined by the analysis of dipolar and quadrupolar splitting data due to aromatic deuterons. The quadrupolar splitting data were also obtained for the deuterated ethoxy tail. The conformation of the tail was elucidated according to the RIS simulation scheme previously proposed. The fraction of the trans conformation ft was estimated to be 0,79 around the nematic-isotropic transition temperature (TNI = 91,9°C). It was suggested that the conformation of the ethoxy tail remains nearly unaffected by the phase transition in the immediate vicinity of TNI. The fraction ft increases moderately toward an asymptotic value as temperature decreases.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1992.040010606
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis of optically active polyaldehydes (1962)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 59 (1962), S. S37 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1962.1205916821
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of optically active polyaldehydes (1962)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 59 (1962), S. S37 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1962.1205916830
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  • 10
    Electronic Resource
    Electronic Resource
    Optical rotatory studies of poly(R)(-)-3.7-dimethyloctene-1 and its model compound (1964)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 72 (1964), S. 131-142 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde optisch-aktives (R)(-)-3,7-Dimethylocten-1 aus (R)(+)-Citronellylacetat durch Hydrierung und anschließende Pyrolyse hergestellt. Die Polymerisation wurde mit einem Katalysator bestehend aus Lithium-Aluminium-Hydrid, Monomerem und Titan-Tetrachlorid in trockenem Benzol durchageführt. Die optische Aktivität und die Rotations-dispersion des erhaltenen Poly-(R)(-)-3,7-Dimethylocten-1 und einiger Modellverbindungen dieses Polymeren wurden studiert; das Polymere zeigte eine größere optische Aktivität als die Modellverbindungen. Die Rotationsdispersion des Polymeren und der Modellverbindung folgen jedoch derselben DRUDE-Gleichung mit demselben λc. Wir erklären diese Resultate durch den Einfluß der Konfiguration und der Konformation kurzer Segmente der Polymerkette.
    Notes: We have prepared optically active (R)( - )-3,7-dimethyloctene-1 from (R)(+)-citronellyl acetate by hydrogenation followed by pyrolysis. The polymerization was carried out using a catalyst derived from lithium aluminum hydride, monomer and titanium tetrachloride in dry benzene. We then studied the optical rotatory properties of the resulting poly(R)( - )-3,7-dimethyloctene-1 and the model compound of this polymer and found an optical activity enhancement of the former over the latter. However, the rotatory dispersions for polymer and model compound fit one term DRUDE equations with the same λc.We explain these results in terms of the rigid spatial requirements of the polymer structure which lead to a preference of certain configurations and conformations for short segments of the polymer chain.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1964.020720111
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