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  • 1
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 177-188 
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simple statistical extension of the Flory theory of excluded volume is developed, and applied to random heteropolymer collapse and a simple model of protein folding. Sequence heterogeneity is found to lead to new effects. The nucleation of protein folding is also briefly considered.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 37 (1995), S. 213-219 
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The solid phase synthesis and generation of libraries of “unnatural biopolymers” is described. These polymers are characterized by novel backbones and building blocks, the properties of which may modify their pharmacological and folding properties. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 2198-2205 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis and characterization of some reversible acetylcholinesterase inhibitors are described in detail. They are structurally related to the natural substrate acetylcholine. All of them bear a trimethylammonium moiety as ‘cationic head’. Instead of an electrophilic ester group, the title compounds include a variety of functionalities, such as halide, ether, thioether, epoxide, amide, ketone and a double bond. The substances are thus suited as probes for the investigation of the esteratic subsite of the acetylcholinesterase active center.Most of the synthesized compounds inhibit the enzyme in a competitive manner with inhibition constants in the range of 10-5 M to 10-3 M. With respect to acetylcholine (KD ≤ 10-5 M and Km = (1.6±0.5) 10-4 M) their affinity to acetylcholinesterase is in the same order of magnitude.
    Materialart: Digitale Medien
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  • 4
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 3,5,3″,5″-Tetra(tert-butyl)-p-terphenoquinone (12b) was synthesized and characterized by its spectroscopic and X-ray structural data. The ground state of 12b is singlet with a strong contribution of a biradical structure. Paramagnetic derivative of 12b, such as the semiquinone radical anion (12bτ) and its O-protonated form, the phenoxy radical (18), were studied by ESR and ENDOR spectroscopy.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1975-1978 
    ISSN: 0009-2940
    Schlagwort(e): Gold complexes ; Selenium ligands ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: (Triphenylphosphine)phenylselenolatogold(I), Ph3PAuSePh (1), and the corresponding dppm derivative, [(dppm)(AuSePh)2] (3), are prepared from Me3SiSePh and the appropriate (phosphine)chlorogold(I) complex. The reaction between Ph3PAuCl, Ph2Se2 and AgSbF6 leads to the salt [(Ph3PAu)2SePh]+SbF-6 (2), with a bridging PhSe ligand. X-ray structure analyses of 1 and 2 confirm the expected linear geometry at gold and reveal short Au-Au contacts; both compounds may thus be regarded as loose dimers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 0009-2940
    Schlagwort(e): Dithiacyclophanes ; DNMR ; Molecular mechanics ; Cyclophanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The syntheses of 2,11-dithia[3,3]orthometacyclophane (5) and 2,11-dithia[3,3]orthoparacyclophane (6) by dithiol-dibromide coupling are described. Whereas the yield of 5 is not significantly affected by the substrate pairing, that of 6 is. Both compounds exhibit a temperature-dependent 1H-NMR spectrum. An energy barrier of 11.0 ± 0.2 kcal/mol (45.7 ± 0.8 kJ/mol) has been calculated for 5, but that of 6 was too low to be determined. Slightly contrasting results were obtained from two different molecular mechanics programs for the relative energies of the six limiting conformations of 5. Crystal structure determinations of 5 and 6 have been carried out, and the conformational behavior of 5 and 6 in solution and in the solid state is discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 7
    ISSN: 0009-2940
    Schlagwort(e): Diphosphorus compounds, mixed valence λ4P+λ4P+, PP-bonded ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Preparation and Single-Crystal X-ray Structure Investigations of some N,N′-Dimethylurea-Bridged Diphosphorus Compounds: NMR Studies of a λ4P+ λ4P+ -Diphosphorus CompoundThe synthesis of N,N′-dimethylurea-bridged diphosphorus compounds involving the structural elements λ3Pλ4P+ (3b, 3c, and 7) and λ4P+λ4P+ (4 and 8) is described. The salts 4 and 8 were obtained by methylation of the λ3Pλ4P+ compounds 3c and 7 with MeOSO2CF3. The λ3P atom in 3c and 7 coordinates to tungsten(0) with formation of the ionic pentacarbonyl derivatives 9 and 10. The NMR spectra of the diphosphonium salt 4 were completely analyzed using NOE and 2D shift correlation experiments (13C,1H and 31P,1H). The single crystal X-ray structure determinations of 3b and 9 are reported. 3b found to crystallize as a hemisolvate with dichloromethane. The RR/SS diastereomer is present in the crystal. The PP distance amounts to 219.1 pm. Both phosphorus atoms interact weakly with the chloride ion (293, 312 pm). 9 crystallizes as a hemisolvate with toluene, the RS/SR diastereomer being present. A PP distance of 224.7 pm and weak interactions between the phosphorus atoms and an oxygen atom of the anion (305, 308 pm) are found.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1471-1475 
    ISSN: 0009-2940
    Schlagwort(e): Polyacetylenes ; Cross conjugation ; Alkenes, tetraethynyl ; π-Systems, planar ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New Planar π-Systems, II1). - On the Preparation and Structure of Tetrakis(phenylethynyl)etheneThe preparation of tetrakis(phenylethynyl)ethene (1 b) has been repeated. Among various routes to this highly unsaturated cross-conjugated π-system, the dimerization of bromide 2 via the carbene 3 is the most simple one. Full spectroscopic data for 1 b are reported for the first time, as is its X-ray structural analysis at - 95°C.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2015-2022 
    ISSN: 0009-2940
    Schlagwort(e): Dienophiles, triple-bond ; Cyclobutadiene ; Cyclophanes ; Diels-Alder adducts ; Nenitzescu systems ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New Dienophiles and Dienes, III.  -  On the Addition of Cyanoacetylene to [2.2]ParacyclophaneHeating a benzene solution of [2.2]paracyclophane (2) in the presence of excess cyanoacetylene (1b) at 160°C in a sealed ampoule provides the novel 2:1-addition product 10, as well as the previously obtained cycloadducts 7-9. It is suggested that these Nenitzescu hydrocarbon systems are formed via the cyclobutadiene intermediates 17 and 18. This hypothesis is supported by the isolation of the side-products 1,2,4-and 1,2,3-tricyanobenzene (11 and 12). When a mixture of 7 and 8 is pyrolyzed at 220°C the novel dihydronaphthalene 24 is formed; the mechanism of this isomerization is discussed. The structures of 10 and 24 were confirmed by X-ray structure determination.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2187-2197 
    ISSN: 0009-2940
    Schlagwort(e): (9-Anthracenyl)phosphanes ; photo-dimerization of ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The syntheses of the (9-anthracenyl)phosphanes 2 to 7 and of the metal carbonyl complexes 8 and 9 are described. Both 1 and 4 undergo [4 + 4] cycloaddition when irradiated, forming the dimers 10 and 11. Only one of the six possible rotamers for 10 is formed. For 11 one additional rotational isomer is observed. The relationship between the [4 + 4] dimerization and steric effects of the PR2 group is discussed. The compounds 6, 8 and 11 were characterized by X-ray diffraction. The structure of 6 was rendered imprecise by the presence of disordered toluene, but the influence of the bulky anthracenyl groups was clear, with wide C—P—C angles of 110.4°. The molecule displays imposed threefold symmetry. The two independent molecules of complex 8, which crystallizes as a dichloromethane hemisolvate, are closely similar to each other; the W—P bond lengths are 254.3 and 253.4 pm. The W—C bonds trans to phosphorus are 4 pm shorter than those cis. The phosphane dimer 11 crystallizes with imposed centrosymmetry. The H atom positions, which could be tentatively identified from difference syntheses, indicate a different rotamer than was formed for the analogous fluorophosphane dimer 10.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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