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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 409-412 
    ISSN: 0935-6304
    Schlagwort(e): Cyclodextrin ; capillary electrophoresis ; system peak ; CHES 1 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Using a running buffer containing cyclodextrins (CDs) and 2-[N-cyclohexylamino]-ethanesulfonic acid (CHES), positive system peaks were observed in the analysis of a ganglioside mixture by CE-UV. These system peaks were related to CDs in the running buffer because these peaks were also detected when a plug of solution devoid of CDs but having the same CHES concentration and pH as the running buffer was injected. Neutral CDs were separated owing to the formation of inclusion complexes with the anionic CHES ion. One possible explanation for the positive system peaks is that the anionic CD-CHES inclusion complex is displaced by co-ions with higher UV absorptivity.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 604-608 
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Many C60 derivatives form stable complexes with γ-cyclodextrin in a ratio of 1:2. These complexes can be easily analyzed by fast-atom bombardment mass spectrometry (FAB). Unlike the analysis of C60 derivatives directly by FAB, the spectra of these complexes were characterized by molecular ions with little or no fragmentation. The analysis of these complexes by FAB provides an easy and useful approach for the characterization of C60 derivatives. Most likely due to the size of the cavity, this approach is limited to C60 derivatives with molecular weights not significantly larger than that of C60 itself.
    Zusätzliches Material: 5 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
    Rapid Communications in Mass Spectrometry 9 (1995), S. 93-96 
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Without performing any charge transfer chemical reaction, C60 and its derivatives could be analyzed directly by electrospray mass spectrometry. Oxidation or reduction at the metal/solution interface of the probe tip was probably responsible for the formation of these radical cations and anions. This technique appeared to be superior to desorption chemical ionization and fast-atom bombardment ionization in the analysis of C60 derivatives because the mass spectra were characterized by molecular ions with little or no fragmentation.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 0947-6539
    Schlagwort(e): azide adducts ; fullerenes ; reaction mechanisms ; regioselectivity ; thermolysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reactions of organic azides with [60]fullerene have paved the way for the synthesis of adducts with a variety of structures. Treatment of [60]fullerene with 2,2-dibenzyl-1,3-diazidopropane (10) in refluxing chlorobenzene afforded three products, namely, 8, 9, and 11 in 18, 25, and 11% yields, respectively. Thermolysis of 9a in refluxing chlorobenzene gave a 40:54:6 mixture of 8, 11, and C60 in quantitative yield. No interconversion between 8 and 11 was observed. Whereas 11 was stable towards thermolysis, 8 decomposed to C60 (35% yield) on refluxing in chlorobenzene for 24 h, but it did not produce any 11. This indicates that 9a is an intermediate in the formation of 8 and 11. A general mechanism for the addition of azides to C60 is proposed. A similar mechanistic pathway is suggested for the thermolysis of 9a.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 21 (1986), S. 329-334 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Hydrogen radical/molecule reactions are postulated to rationalize the formation of major fragment ions in the methane negative and positive chemical ionization mass spectrometry of the dicyanomethane derivatives of 9-fluorenone and benzophenone. Evidence for the formation of [M + H]- anions that are not represented by significant peaks in the mass spectra is provided by mass spectra of deuterium-labeled analogs and by tandem mass spectrometry studies of the [M + 1]- anions of the analyte.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1983), S. 457-461 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The dicyanomethylene derivative of a benzophenone analog significantly alters the fragmentation pattern observed during electron impact ionization of the underivatized parent compound. A double bond connecting the dicyanomethylene moiety to the parent compound is cleaved during a major fragmentation pathway for many of these compounds. A mechanism involving rearrangement of two hydrogen atoms is proposed to rationalize cleavage of this double bond. Conventional mass spectra as well as collisionally activated dissociation mass spectra of selected ions of several model compounds are reported and described in support of a proposed fragmentation mechanism.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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