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  • 1
    Electronic Resource
    Electronic Resource
    Laser Raman studies of the 5 S rRNA-protein L5 complex of rat liver ribosomes
    Amsterdam : Elsevier
    FEBS Letters 155 (1983), S. 285-290 
    Details
    ISSN: 0014-5793
    Keywords: 5 S rRNA ; RNA-protein complex ; Raman spectroscopy ; Rat liver ; Ribosomal protein L5
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0014-5793(82)80622-4
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  • 2
    Electronic Resource
    Electronic Resource
    Conformational properties of streptokinase-secondary structure and localization of aromatic amino acids
    Amsterdam : Elsevier
    International Journal of Biological Macromolecules 14 (1992), S. 9-18 
    Details
    ISSN: 0141-8130
    Keywords: Raman spectroscopy ; Streptokinase ; [abr] Gu.HCl ; [abr] N-(1-oxy-2,2,5,5-tetramethyl-4-pyrrolidinyl)-bromoacetamide ; [abr] N-Ac-l-Trp-OET ; [abr] N-Ac-l-Tyr-OET ; [abr] N-acetyl-l-tryptophan-ethylester ; [abr] N-acetyl-l-tyrosine-ethylester ; [abr] SL-BrAA ; [abr] guanidine hydrochloride ; circular dichroism ; e.p.r. spectroscopy ; i.r. spectroscopy ; protein structure
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0141-8130(05)80013-3
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of eubacterial and eukaryotic 5S RNA structures: a Raman spectroscopic study
    Amsterdam : Elsevier
    International Journal of Biological Macromolecules 9 (1987), S. 349-356 
    Details
    ISSN: 0141-8130
    Keywords: Raman spectroscopy ; Ribosomal 5S RNA ; conformation
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0141-8130(87)90008-0
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  • 4
    Electronic Resource
    Electronic Resource
    The Radical Anion of 1,2-Diphenylcyclopentene (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 2517-2524 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ESR. and ENDOR. studies are reported for the radical anions of 1,2-diphenylcyclopentene (3) and its di(pe+deuteriophenyl)-derivative (3-D10). Comparison of the coupling constants of the phenyl protons in 3\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. with the analogous values for the radical anions of 1,2-diphenyl substituted cyclopropene (1) and cyclobutene (2) reveals regular changes in the sequence 1\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, 2\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, 3\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, which are caused by an increasing twist of the phenyl groups about the C(1), C(1′)- and C(2), C(1″)-bonds linking them to the ethylene fragment. Such a twist is shown to be also responsible for the large difference in the coupling constants of the methylene β-protons in 3\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. (0.659 and 0.293 mT). It is suggested that - in order to minimize the losses caused by this twist in the π-delocalization energy - the 2 pz-axes at the centres 1 and 2 deviate from a perpendicular orientation to the mean plane of the cyclopentene ring. A deviation by 19° from such an orientation is required to account for the observed β-proton coupling constants in terms of their conventional cos2-dependence on the dihedral angles θ.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620802
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  • 5
    Electronic Resource
    Electronic Resource
    The Radical Ions of Naphtho [1,8-cd]-[1,2,6]thiadiazine and Some of Its Derivatives (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 2144-2151 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical cations and anions of naphtho [1,8-cd]-[1,2,6]thiadiazine (1) and 6,7-dihydroacenaphtho [5, 6-cd]-[1,2,6]thiadiazine (2), as well as the radical anion of acenaphtho [5, 6-cd]-[1,2,6]thiadiazine (3) have been characterized by ESR. spectroscopy. The π-spin distributions in the radical cations \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\oplus \atop \dot{}}$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ 2^{\oplus \atop \dot{}}$\end{document} strongly resemble those in the iso-π-electronic phenalenyl radical. A prominent feature of the radical anions \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{\ominus \atop \dot{}}$\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$ 2^{\ominus \atop \dot{}}$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ 3^{\ominus \atop \dot{}}$\end{document} is the substantial localization of the π-spin population on the thiadiazine fragment. These findings are satisfactorily accounted for by HMO models using conventional heteroatom parameters.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630803
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  • 6
    Electronic Resource
    Electronic Resource
    The ESR. Spectrum of the Radical Anion of 1,1,2,2,9,9,10,10-Octafluoro [2.2]paracyclophane (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 551-555 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical anion of 1,1,2.2,9,9,10, 10-octafluoro[2.2]paracyclophane (1) has been generated by electrolytic reduction of 1 in 1,2-dimethoxyethane (tetrabutylammonium perchlorate as the supporting salt). The hyperfine coupling constants of the eight 19F-nuclei and the eight protons, af = 3.35 and aH ≈ 0.10 mT, are qualitatively reproduced by INDO. calculations. According to these calculations, the singly occupied orbital of 1⊖ can be represented by an Ag-combination of two ‘symmetric’ benzene LUMO's, with a substantial transfer of spin population into the 2s-AO's of the F-atoms. Line-width alternation in the ESR. spectrum of 1⊖ indicates an ion pairing of the radical anion with its counter-ion Bu4N⊖. The energy barrier to the migration of the cation between two equivalent sites at the radical anion is determined as 14±2 kJ/mol.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650213
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  • 7
    Electronic Resource
    Electronic Resource
    Persistance of the Cyclopnane Radical Anions and its Relation to Structure (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 1391-1397 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of [2N]cyclophanes (N = 2,⃛6) with solvated electrons in 1,2-di-methoxyethane at 193 K have been studied by ESR. and ENDOR. spectroscopy. All but the two most highly bridged cyclophanes (N = 5 and 6) are reduced to paramagnetic species under these conditions. Whereas the radical anions of [2.2]-paracyclophane and [23](1,2,4)- and [24](l,2,4,5)cyclophanes are sufficiently persistent to be characterized by their hyperfine data, those of the remaining five cyclophanes undergo a rapid cyclization to the radical anions of 4,5,9,10-tetrahydropyrenes. These have been identified as the unsubstituted tetrahydropyrene (from [2.2]-metacyclophane and [23](l,2,3)cyclophane), the 2,7-dimethyl-derivative (from [23](1,3,5)- and [24](l,2,3,5)cyclophanes) and the 1,8-dimethyl-derivative (from (24l,2,3,4)cyclophane). The persistence of the cyclophane radical anions seems to depend on the numbers, nmeta and npara, of the meta-and para-positions of the bridging ethano groups in the two benzene rings. The prerequisite for the radical anion to be persistent is nmeta≤npara.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650510
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  • 8
    Electronic Resource
    Electronic Resource
    The Radical Ions of Indolizino [6,5,4,3-aij]quinoline and Some of its Derivatives (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 2031-2043 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Indolizino [6,5,4,3-aij]quinoline (1) and its 3,9-dimethyl- (2), di-tert-butyl- (3) and diphenyl-(4) derivatives yield persistent radical cations which have been studied by ESR and ENDOR spectroscopy. The corresponding radical anions have also been prepared, but only that of 3 was amenable to a complete characterization by hyperfine data. The π-spin populations in the radical anions are essentially localized on the 13-membered C-perimeter, and thus both the HOMO and LUMO of 1 exhibit an ‘annulenyl character’. The radical anions of 1 and 2 have gradually been converted into those of the corresponding 3,4-dihydro derivatives (1-H2 and 2-H2) which have been unambiguously identified by a combination of preparative and spectroscopic methods.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660714
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  • 9
    Electronic Resource
    Electronic Resource
    Intermolecular Electron Spin Transfer between Naphthalene π-Systems Separated by a Variable Number of Spirobonded Cyclobutane Rings, An. ESR and ENDOR Study (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 416-424 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical anions of the compounds N1N, N3N and N5N, in which two naphthalen π-systems are separated by 1, 3 and 5 spirobonded cyclobutane rings, respectively, and tha tof the reference compound N1, containing one naphthalene π-system and one cyclobutane ring, have been studied by ESR and ENDOR spectroscopy under a variety of experimental conditions. The intramolecular electrons spin transfer between the two π-moieties in N3N.⊖ and N5N.⊖ is slow on the hyperfine time-scale, irrespective of the applied conditions. It is also slow in N1N.⊖, except for media of high solvating power. In such media, with a slight reduction of N1N to its radical anion, a paramagnetic species is observed, the hyperfine data for which are consistent with N1N to its radical anion, a paramagnetic species is observed, the hyperfine data of which are consistent with N1N.⊖, undergoing a fast intramolecular electron spin tansfer. The ESR and ENDOR spectra of this species are superimposed on those characteristic of a slow transfer. It is suggested that the fast and slow transfer involve the syn- and anti-conformations, respectively, since the distance, r, between the two naphthalene π-systems of N1N.⊖ is considerably shorter in the former than in the latter (r = 740 vs. 880 Pm for the distance between the centres of the π-systems). Glassy solutions of exhaustively reduced N1N display signals of the dianion triplet state, whereas no such signals are found for N3N and N5N. The zero-field splitting parameter, D, is 4.7 mT, corresponding to r ≈ 480 pm.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670210
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  • 10
    Electronic Resource
    Electronic Resource
    An ESR Study of the Radical Cations of Tetrathiafulvalene (TTF) and Electron Donors Containing the TTF Moiety (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 141-151 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hyperfine data and g factors are reported for the radical cations of tetrathiafulvalene (TTF; 1) and of its derivatives 2-13. From the intense satellite spectra of 1+-13+ not only the coupling constants of the 33S isotopes in the TTF moiety could be determined, but also, in favourable cases, those of the 13C isotopes in the central double bond. The former values range from 0.370 (8+) to 0.470 mT (4+) and the latter from 0.255 (8+) to 0.360 mT (4+) in the radical cations of bis(ethylenedithio)-TTF (8+) and tetracyano-TTF (4+). The radical cation of TTF (1+) exhibits intermediate values, 0.425 for the 33S and 0.285 mT for the 13C isotopes. The spin population in 1+-13+ resides, to a large extent, in the central S2C = CS2 part of the π-system. It tends to increase (decrease) by substitution with electron-accepting (donating) groups in the 2,3,6,7-positions of TTF.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690117
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