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  • Chemistry  (156)
  • Polymer and Materials Science  (22)
  • 1995-1999  (113)
  • 1975-1979  (42)
  • 1950-1954  (3)
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 37 (1995), S. 123-142 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Secondary structure investigations, affinities, and activities of neuropeptide Y analogues with respect to the Y1 and the Y2 receptor are reviewed. The results are discussed with respect to the different prerequisites for affinities to both receptor subtypes. The results from a systematic scanning of the hormone using L-alanine and from a large variety of discontinuous and cyclic analogs suggest that two different conformations of neuropeptide Y are adopted at the Y1 and Y2 receptors. Whereas a C-terminal turn structure is suggested for Y1 receptor affinity, an α-helical conformation of the C-terminus is afforded for good binding to the Y2 receptor. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 2
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new approach for evaluating the secondary structure of proteins by CD spectroscopy of overlapping peptide segments is applied to porcine adenylate kinase (AK1) and yeast guanylate kinase (GK3).One hundred seventy-six peptide segments of a length of 15 residues, overlapping by 13 residues and covering the complete sequences of AK1 and GK3, were synthesized in order to evaluate their secondary structure composition by CD spectroscopy.The peptides were prepared by solid phase multiple peptide synthesis method using the 9-fluorenylmethoxycarbonyl/tert-butyl strategy. The individual peptide secondary structures were studied with CD spectroscopy in a mixture of 30% trifluoroethanol in phosphate buffer (pH 7) and subsequently compared with x-ray data of AK1 and GK3.Peptide segments that cover α-helical regions of the AK1 or GK3 sequence mainly showed CD spectra with increasing and decreasing Cotton effects that were typical for appearing and disappearing α-helical structures. For segments with dominating β-sheet conformation, however, the application of this method is limited due to the stability and clustering of β-sheet segments in solution and due to the difficult interpretation of random-coiled superimposed β-sheet CD signals.Nevertheless, the results of this method especially for α-helical segments are very impressive. All α-helical and 71% of the β-sheet containing regions of the AK1 and GK3 could be identified. Moreover, it was shown that CD spectra of consecutive peptide content reveal the appearance and disappearance of α-helical secondary structure elements and help localizing them on the sequence string. © 1997 John Wiley & Sons, Inc. Biopoly 41: 213-231, 1997
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 965-969 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of the α-Methylene Group in (Glycinato)platinum(II) Chelate ComplexesThe reaction of the glycinato complex (n-Bu3P)Pt(Cl)NH2CH2CO2) (1)with aldehydes or alkylating agents (dimethyl sulfate, benzyl chloride) affords the chelate compounds 3-6 with substituted α-amino acids.
    Notes: Der Glycinato-Komplex (n-Bu3P)Pt(Cl)NH2CH2CO2) (1) setzt sich mit Aldehyden oder Alkylierungsmitteln (Dimethylsulfat, Benzylchlorid) zu entsprechenden Chelat-Verbindungen 3-6 mit Höheren α-Aminosäuren um.
    Additional Material: 3 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 970-993 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Transition Metal Complexes with Nucleic Acid bases and NucleosidesThe isolation of carbonylmetal complexes W(CO)5L (1), [W(CO)5L]- (2), [Mo(CO)3enL]- (3), (π-CH3C5H4)Mn(CO)2L (4), Rh(CO)2(CI)L (5), (H)(CO)(PPh3)2L2 (6), M(CO)(PPh3)2L (M = Rh, Ir) (7,8) and of phosphine and amine containing monomeric and polynuclear palladium(II) and platinum(II) complexes (9-14 with various neutral and anionic nucleic acid bases and nucleosides L is reported. Using i. r. and 1H n. m. r. data a tentative assignment of the coordination sites of the ambidentate ligands is given. The reaction of 1,3,7,9-tetramethylxanthinium perchlorate with Hg11 acetate affords the C-8 mercurated complex 15.
    Notes: Die Darstellung von Carbonylmetallkomplexen W(CO)5L (1), [W(CO)5L]- (2), [Mo(CO)3enL] (3)-, (π-CH3C5H4)Mn(CO)2L (4), Rh(CO)2(Cl)L (5), Ir(H)(CO)(PPh3)2L2 (6), M(CO)(PPh3)2L (M = Rh, Ir) (7,8) und von phosphin- und amin-haltigen monomeren sowie mehrkernigen Palladium(II)-und Platin(II)-und Platin (II)-Komplexen (9-14) mit einer Reihe von neutralen und anionischen Purin und Pyrimidin-Basen und Nucleosiden L wird beschrieben. Mit Hilfe von IR- und 1H-NMR- Daten wird versucht, die Koordinationsstellen der ambidenten Nucleinbasen zu bestimmen. 1,3,7,9-Tetramethylxanthinium-perchlorat wird mit Quecksilber (II)-acetat am C-8 metalliert (15).
    Additional Material: 6 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 314-321 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mono- and Bis(pheyltelluro)methyllithiumSolutions of the title compounds are readily prepared from bis(phenyltelluro)methane (7): the monosubstituted one by transmetallative C6H5Te/Li-exchange with alkyllithium, the disubstituted one by direct metalation with lithium diisopropylamide. This was proved in both cases by deuterolysis and derivatization with electrophiles. The new tellurium derivatives are compared with the sulfur and selenium analogues.
    Notes: Lösungen der Titelverbindungen lassen sich aus Bis(phenyltelluro)methan (7) leicht darstellen, das monosubstituierte Li-Derivat durch C6H5Te/Li-Austausch mit Alkyllithium, das disubstituierte durch direkte Metallierung mit Lithium-diisopropylamid. In beiden Fällen wurde dies durch Deuterolyse und Umsetzung mit Elektrophilen bewiesen. Die neuen Tellurderivate werden mit den Schwefel- und Selen-Isologen verglichen.
    Additional Material: 1 Tab.
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  • 6
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Carbyne Complexes, XVPhenylcarbyne as well as Methoxyphenyl-, (Dimethylamino)phenyl-, and Aminophenylcarbene as Ligands in Cationic or Neutral Complexes of the Type π-ArCr(CO)2LComplexes of the type π-ArCr(CO)3 1a-d are converted into the carbene complexes π-ArCr(CO)2-[C(C6H5)OCH3] 2a-d by treatment with phenyllithium followed by alkylation. On treatment with boron trichloride 2a-d yield the cationic carbyne complexes of the general formula {π-ArCr(CO)2[C(C6H5]}⊕[BCl4]⊖ 3a, c, d Aminolysis with ammonia or dimethylamine leads to the aminocarbene complexes π-ArCr(CO)2[C6H5)NR2] 4 and 5 which are not obtainable by direct aminolysis of 2a-d. These diamagnetic complexes, some of which are very thermolabile, were characterized by i. r., H n. m. r., and 13C n. m. r. spectroscopy.
    Notes: Aus Tricarbonyl-Aromaten-chrom(0)-Komplexen π-ArCr(CO)3 1a-d lassen sich durch Umsetzung mit Phenyllithium und anschließende Alkylierung die Carbenkomplexe π-ArCr(CO)2-[C(C6H5)OCH3] 2a-d darstellen, deren Reaktion mit Bortrichlorid zu kationischen Carbinkomplexen der allgemeinen Formel {π-ArCr(CO)2[C(C6H5]}⊕[BCl4]⊖ 3a, c, d führt. Bei der Aminolyse der kationischen Komplexe mit Ammoniak oder Dimethylamin entstehen - durch Aminolyse von 2a-d nicht zugängliche - Aminocarbenkomplexe π-ArCr(CO)2[C6H5)NR2] 4 und 5. Die diamagnetischen, teilweise sehr thermolabilen Verbindungen werden durch IR-, 1 H-NMR-und 13C-NMR-Spektren charakterisiert.
    Additional Material: 4 Tab.
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A systematic investigation of the rotational behavior of aryl substituents in α,α,α′,α′-tetraaryl-1,3-dioxolane-4,5-dimethanols (TADDOLs) is presented. In the use as chiral ligands for enantioselective metal-catalyzed reactions, a change from phenyl to bulkier substituents, e.g., 1-naphthyl, gives rise to an astounding alteration of the selectivity, The possible existence of preferred rotamers of TADDOLs has so far not been given due attention, which encouraged us to look at the validity of the Knowles model, originally formulated for diaryl substituted bisphosphines. 1H-NMR Investigations at various temperatures as well as X-ray powder diffraction were employed to study the rotation in the case of tetra(1-naphthyl) TADDOL 1. To support the interpretation of the experimental results, molecular mechanics, semiempirical, and ab initio calculations were performed. For comparison, the energy surface of tetraphenyl TADDOL 2 was calculated as well. Our results lead to the conclusion that for 1, only one major conformation is present in both solution and solid state, which determines the stereochemical outcome of the catalyzed reactions.
    Additional Material: 7 Ill.
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  • 8
    ISSN: 0009-2940
    Keywords: Fullerene ; Hydrofulleride ; Manganese complex ; Rhenium complex ; Iron complexes ; Ruthenium complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of Hydrofulleride [C60H]- to Coordinated, Unsaturated Hydrocarbons: Binding of Fullerene to Metal Complexes through Hydrocarbon BridgesHerrn Professor Herbert Walter Roesky zum 60. Geburtstag gewidmet.Hydrofulleride [C60H]- is added to the hydrocarbon ligands of the cationic complexes [(OC)5Re(η2-C2H4)]+, [(OC)3Mn-(η6-C6H6)]+, [(OC)3M(η5-C6H7)]+ (M = Fe, Ru), [(OC)3Fe(η5-C7H9)]+, and [(η5-C5H5)Fe(η6-C5H4CH2)]+.
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  • 9
    ISSN: 0009-2940
    Keywords: 1,7-Dimethylocta-2,6-diene-1,8-diyl ; Ruthenium complexes ; α-Amino carboxylates ; α-Amino acid esters ; Peptide esters ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes Containing Biologically Important Ligands, LXXXLXXIX. Mitteilung: Lit. .  -  (η3:η3-C10H16)Ru(IV) Complexes with α-Amino Carboxylates, α-Amino Acid Esters, and Peptide Esters as LigandsReactions of the chloro-bridged bis(allyl) complex [(η3:η3-C10H16)Ru(Cl)(μ-Cl)]2 with α-amino carboxylates and α-amino acid esters afford the complexes (η3:η3-C10H16)(Cl)RuNH2CHRCO2 (2) and (η3:η3-C10H16)(Cl)2-RuNH2CHRCO2R′ (3). Abstraction of chloride from 3 by Ag+ gives the N,O-chelates [(η3:η3-C10H16)(Cl)RuNH2CHRCO2R′]+BF4 (4). Cysteine methyl ester forms the N,S-chelate complex (η3:η3-C10H16)(Cl)RuNH2CH(CO2CH3)CH2S (5), and with histidine methyl ester a dinuclear complex 6 with N,N-histidine bridge is obtained. Compound 3d with L-PheOEt as ligand was characterized by X-ray diffraction.
    Additional Material: 3 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2507-2514 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A large number of TADDOL (α,α,α′, α′-tetraaryl-1,3-dioxolan-4,5-dimethanol) derivatives has been tested as chiral dopants for inducing conversion of nematic to cholesteric phases. With the Merck liquid-crystal materials ZLI-1695 and K15, it was demonstrated that some TADDOLs have unprecedentedly high helical twisting powers (HTP). Thus, the TADDOL with four 9-phenanthryl α-substituents has a HTP in the achiral mesophase 4-(4-pentylphenyl)benzonitrile of 405 μm-1 between 24 and 34°. The temperature-dependent HTP measurements have been performed by analyzing Grandjean textures microscopically (Cano method). The structure-dependent HTP of various types of TADDOL dopants is discussed. There are similarities between size and sign of HTP on the one hand, and between degree and relative topicity of enantioselectivity in reactions, on the other hand, as caused by TADDOLs and by 1,1′-binaphthols.
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