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  • Intramolecular electron transfer  (3)
  • ESR spectroscopy  (2)
  • Zinc  (2)
  • (Escherichia coli)  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Shape of proteins S3 and S17 from the small subunit of Escherichia coli ribosome
    Amsterdam : Elsevier
    BBA - Protein Structure 578 (1979), S. 365-371 
    Details
    ISSN: 0005-2795
    Keywords: (Escherichia coli) ; Hydrodynamic properties ; Ribosome ; S17 protein ; S3 protein
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0005-2795(79)90167-3
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  • 2
    Electronic Resource
    Electronic Resource
    Verfeinerung der Kristallstruktur des Dicaesium-Tetraazido-Zinkates Cs2Zn(N3)4 und die Kristallstrukturen komplexer Zinkazide (1990)
    Springer
    Monatshefte für Chemie 121 (1990), S. 91-97 
    Details
    ISSN: 1434-4475
    Keywords: Azide ; Cesium ; Crystal structure ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The crystal structure of dicesium-tetraazido-zincate, Cs2Zn(N3)4, has been refined from single crystal X-ray-diffractometer data. The previously reported orthorhombic structure, consisting of isolated Zn(N3)4-tetrahedra was confirmed and improved lattice parameters and atomic distances were determined. The azide groups are asymmetric and the coordination of central nitrogen atoms to cesium was observed. A table of structure data and mean atomic distances for fourteen zinc-azide compounds is added and the structures are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00809520
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  • 3
    Electronic Resource
    Electronic Resource
    Kristallstrukturen von drei Addukten des Zinkazides mit Dimethylpyridinen (1992)
    Springer
    Monatshefte für Chemie 123 (1992), S. 325-331 
    Details
    ISSN: 1434-4475
    Keywords: Azide ; Crystal structure ; Dimethylpyridine ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three adducts of zinc azide with 2,4-/3,4- and 3,5-dimethylpyridine (DMP), respectively, were prepared and the crystal structures determined by single crystal X-ray diffraction methods. The three compounds crystallize in the monoclinic space group P21/c withZ=4: Zn(N3)2·2,4-DMP at 300 (2) K:a=1 098.6(4),b=1 600.2(6),c=608.8(3) pm, β=102.47(3)°;R=0.071 (R w =0.056). Zn(N3)2·3,4-DMP at 103 (3) K:a=1 102.1(3),b=1 649.0(4),c=611.8(1) pm, β=104.54(2)°;R=0.055 (R w =0.051). Zn(N3)2·3,5-DMP at 97 (3) K:a=602.1(2),b=2 037.9(7),c=853.8(3) pm, β=90.77(3)°;R=0.069 (R w =0.055). The molecular geometry is similar for the three adducts, but the packing of theDMP-molecules is different. The zinc atoms are surrounded by five nitrogen atoms, four belonging to the azide groups and one to theDMP-adduct. The trigonal bipyramidal shaped ZnN5-polyhedra share common edges to form chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810944
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  • 4
    Electronic Resource
    Electronic Resource
    On the Homoconjugation of Two Acceptor Groups (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1615-1623 
    Details
    ISSN: 1434-193X
    Keywords: Homoconjugation ; Cyclovoltammetry ; ESR spectroscopy ; Diketones ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclovoltammetric investigations have been carried out on 3,3,6,6-tetramethylcyclohexane-1,2,4,5-tetrone (4), bicyclo-[3.2.2]nonane-6,7,8,9-tetrone (5), and several of their congeners, such as 6,13-dihydro-6,6,13,13-tetramethylquin-oxalino[2.3-b]phenazine (13), 5,10-dihydro-5,5,10,10-tetra-methylpyrazino[2,3-g]quinoxaline (17), and 6,13-dihydro-6,13-propanoquinoxalino[2,3-b]phenazine (20). For 5 and 20 a large difference (ΔE° ≥400 mV) between the first and second reduction potentials was found. The ESR results of the radical anion 20•- are in support of a strong homoconjugation. ESR studies of 4•-, 13•-, and 17•- also reveal a symmetrical displacement of the unpaired electron over both acceptor groups on the ESR time scale which, however, based on the small potential difference ΔE° ≤ 200 mV can be most likely described to a fast electron exchange.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Intramolecular Electron Transfer between Terminal 1,4-Dimethoxybenzene Units in Radical Cations with a [2.2](1,4)Naphthalenophane, [2.2](1,4)Anthracenophane, and Pentacene Skeleton (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1161-1170 
    Details
    ISSN: 1434-193X
    Keywords: [2.2](1,4)Naphthalenophanes ; [2.2](1,4)Anthracenophane ; Pentacene ; Cyclic voltammetry ; Radical cations ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various radical cations, in which two terminal 1,4-dimethoxybenzene units are anellated to [2.2]paracyclophane (2b•+, 3b•+), [2.2](1,4)naphthalenophane (4d•+), and anthracene bridges (5•+), have been studied by ESR and ENDOR spectroscopy. In the syn- and anti-naphthalenophane radical cations 2b•+ and 3b•+ the delocalization of the unpaired electron over both π-moieties and the distinct difference between the first and second oxidation potentials, ΔE = E20 - E10, are evidence for a substantial intramolecular electronic interaction between the two electrophores. Extension of the bridge in 4d•+ and 5 by benzo anellation results in a localized radical cation. Strong intramolecular electronic interaction between the two electrophores is found in the 1,4,8,11-tetramethoxy-pentacene radical cation (5•+). The syntheses of 4d are described.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Phenazin-5(10H)-yls, 5Part 4: Ref[1].. - Intermolecular π-π Interactions (Pimerization) of tert-Butyl-Substituted Phenazin-5(10H)-yl Radicals in The Solid State: Syntheses, Crystal Structures and Magnetic Susceptibility Measurements (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 473-483 
    Details
    ISSN: 0947-3440
    Keywords: Phenazin-5(10H)-yl ; ESR spectroscopy ; Radical pairs ; π Interactions ; Dimer absorption ; Magnetic susceptibility ; Nitrogen heterocycles ; Radicals ; Magnetic properties ; Solid-state chemistry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Introduction of tert-butyl groups into the phenazine frame-work was accomplished by treatment of 5-acetyl-5,10-dihydrophenazine (2a) with tert-butyl chloride in the presence of AlCl3. Starting from the 2,8- or 3,7-di-tert-butyl-substituted derivatives 2c and 2b, a series of phenazin-5(10H)-yl radicals (1c-i) was synthesized and characterized by ESR and EN-DOR spectroscopy. With the exception of 1c, all phenazin-5(10H)-yls were obtained in crystalline form, and for 1d-f the long-wavelength absorption band at λ ≈ 870 nm indicates intermolecular π-π interactions in the solid state. For 1d, 1e and 1h the crystal structure could be determined. The unit cell of 1d consists of eight phenazin-5(10H)-yls. Surprisingly, four of them are arranged in radical pairs, whereas the other four lie independently in the lattice. In agreement with this structure, the magnetic susceptibility results correspond to a content of 50% monoradical and an almost complete spinpairing in the radical pairs up to T = 220 K. In 1e, the four phenazin-5(10H)-yls in the unit cell are arranged in two independent radical pairs, A and B, which are characterized by close interplanar distances and short intermolecular contacts between atoms with significant spin populations. Accordingly, the susceptibility data indicate strong spin-pairing at low temperature. Due to extensive steric shielding of the phenazin-5(10H)-yl framework, the crystal structure of 1h gives no evidence of any π-π interactions between adjacent radicals. As expected, the magnetic susceptibility of 1h corresponds to that of an ordinary monoradical.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970307
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  • 7
    Electronic Resource
    Electronic Resource
    [2.2]Paracyclophane-4,7,12,15-tetrone, [2.2](1,4)Naphthalenophane-4,7,14,17-tetrone, and 1,4,8,11-Pentacenetetrone Radical Anions - A Comparative ESR Study (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 221-227 
    Details
    ISSN: 1434-193X
    Keywords: 1,4-Benzoquinones ; [2.2]Paracyclophanes ; 1,4,8,11-Pentacenetetrones ; Cyclic voltammetry ; Radical anions ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three types of tetrone radical anions in which two 1,4-benzoquinone units are connected by ethano (1·-, 2·-), [2.2]paracyclophane (3·-, 4·-), and anthracene bridges (5·-, 6·-) have been studied by ESR and ENDOR spectroscopy. The displacement of the unpaired electron over the two π moieties in the [2.2]cyclophane radical anions 1·--4·- and the marked difference between the first and second reduction potentials, ΔE = |E20 - E10| ≥ 0.20 V, are evidence for a substantial intramolecular electronic interaction between the two electrophores. Similar ΔE data for the syn- (3) and anti-naphthalenophanes (4) indicate that most of the intramolecular electronic interaction takes place through the [2.2]paracyclophane bridge. When ion pairing is inhibited by complexation of the cation, the unpaired electron in 5·- and 6·- is also delocalized over the whole pentacenetetrone system at temperatures as low as 160 K.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Intramolecular Electron Transfer between 2,5-Dimethoxy-1,4-phenylene Units in [n.n]Paracyclophane Radical Cations (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 139-148 
    Details
    ISSN: 1434-193X
    Keywords: Paracyclophanes ; Cyclic voltammetry ; Radical cations ; ESR/ENDOR spectroscopy ; Intramolecular electron transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A range of [n.n]paracyclophane radical cations (4·+-12·+), in which two 2,5-dimethoxy-1,4-phenylene units are connected by alkano bridges of varying length, have been studied by ESR and ENDOR spectroscopy. In the [2.2]- and [3.3]paracyclophane radical cations 4·+-6·+, 10·+ and 11·+ the delocalization of the unpaired electron over both π-moieties and the distinct difference between the first and second oxidation potentials, ΔE = E20 - E10, are evidence for a strong intramolecular electronic interaction between the two electrophores. The [5.5] and [7.7] species (8·+ and 9·+) are localized radical cations at low temperature (ca. 220 K). At room temperature, the higher molecular flexibility leads to a significant increase in the number of internal collisions between the electrophores, resulting in a fast (ESR time scale) intramolecular electron transfer. The intermediate [4.4]paracyclophane radical cations 7·+ and 12·+ are apparently also localized radical cations. The close interplanar distance between the two π-moieties, however, facilitates their mutual contacts. In 7·+, the intramolecular electron transfer becomes fast on the ESR time scale at room temperature; in 12·+ the transfer is fast over the temperature range 200-300 K.
    Type of Medium: Electronic Resource
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