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  • 1
    Electronic Resource
    Electronic Resource
    The Addition Patterns of C60 Trisadducts Involving the Positional Relationships e and trans-n (n = 2-4): Isolation, Properties, and Determination of the Absolute Configuration of Tris(malonates) and Tris[bis(oxazolines)] (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3027-3039 
    Details
    ISSN: 1434-193X
    Keywords: Chirality ; Circular dichroism ; Cycloadditions ; Fullerenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of regioisomeric trisadducts of C60 (5-11, 14-18) having the positional relationships e and trans-n (n = 2-4) resulting from successive additions of malonates or bis(oxazolines) to [6,6]-double bonds of the fullerene framework has been isolated and characterized. The new adducts 8-11 and 15-17 represent examples of unprecedented addition patterns. The addition patterns of the new trisadducts with C2, Cs or C1 symmetry have been assigned on the basis of the known positional relationships of the addends in their precursor bisadducts, and those of the C2- or Cs-symmetric representatives have been verified by analysis of their NMR spectra. The absolute configurations of the adducts with inherently chiral addition patterns could be determined either by comparison of the calculated and experimental CD spectra of the bis(oxazoline) adducts or with knowledge of the absolute configurations of the chiral bisadduct precursors containing bis(oxazoline) addends. The CD spectra of the pairs of diastereomers with an enantiomeric addition pattern fA -15/fC -15, fA -16/fC -16, and fA -18/fC -18 show mirror image behavior and pronounced Cotton effects.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and Electrochemical Properties of New C60-Acceptor and -Donor Dyads (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1111-1121 
    Details
    ISSN: 1434-193X
    Keywords: Cyclic voltammetry ; Donor-acceptor systems ; EPR spectroscopy ; Fullerenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of new C60-acceptor and C60-donor dyads 6-8 by facile and irreversible [4+2]cycloadditions of anthraquinone- and anthraquinodimethane-based dienes with C60, as well as by direct oxidative amination of C60 with N, N′-dimethyl-o-phenylenediamine is described. The complete electrochemical characterization and ESR-spectroscopic data of the C60-acceptor dyads allows an unambiguous assignment of the location of each reduction step to one or other of the electroactive groups. The locations of the first oxidation and reduction events in all type A and -B systems investigated in this study correspond to the PM3-calculated HOMOs of the neutral species or the SOMOs of the singly reduced species. Whereas the anthraquinone moiety in 6 is a weaker acceptor than C60, the introduction of the more electron-withdrawing cyanoimino groups at the 9,10-positions of the anthracene unit in the dyad 7 causes the first reduction to take place on the addend. This experimental and computational study has shown that both the C60-acceptor dyad 7 and the C60-donor dyad 8 are suitable precursors for the synthesis of the proposed type-D triads, which contain both a donor and an acceptor building block attached to the fullerene core in a stereochemically defined arrangement.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Regioselectivity of Multiple Cyclopropanations of C60 and Introduction of a General Bond-Labeling Algorithm for Fullerenes and Their Derivatives (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1725-1734 
    Details
    ISSN: 0947-3440
    Keywords: Fullerenes ; Regioselectivity ; Bond labeling ; Methanofullerenes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A computational (AM1) analysis is presented which shows that the observed regioselectivities of multiple cyclopropanations of C60 are due to orbital-allowed processes. Next to the coefficients of frontier orbitals the characteristic cage distortions of the oligomethanofullerenes are discussed. For further experimental corroboration the synthesis and characterization of an unsymmetrical trisadduct with a I, eI, III*-addition pattern are described. Moreover, since a systematic and descriptive assignment of addition patterns in derivatives of C60 and higher fullerenes becomes more and more important, a simple and general algorithm is introduced, which enables unambiguous bond labeling of both [6,6]- and [5,6]-bonds as well as the assignment of the absolute configuration of any fullerene derivative.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961105
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  • 4
    Electronic Resource
    Electronic Resource
    Side-Chain Modifications of C60 via Activation of the Easily Accessible Fulleromalonic Acid C61(COOH)2 (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 253-258 
    Details
    ISSN: 0947-3440
    Keywords: Fullerenes ; Active ester ; Coupling reactions ; Side-chain modifications ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Side-chain modifications of fullerenes can be achieved starting from the malonic acid 2, which is easily accessible by saponification of the corresponding diethyl malonate adduct 1 and is therefore an ideal building block for side chain chemistry on fullerenes. Coupling reactions are carried out via the synthesis of the fullerene active ester 4, which is formed by the reaction of the malonic acid 2 with N-hydroxysuccinimide. During this reaction the malonic acid undergoes decarboxylation, yielding an acetic acid derivative instead of a malonic system. The active ester 4 is isolable and represents an ideal building block for fullerene chemistry. Sidechain modifications can also be carried out as one-step reactions by preparing 4 in situ. We have performed coupling reactions with various compounds containing primary or secondary amino groups.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970136
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and Electrochemistry of Diels-Alder Adducts of [60] Fullerene with a Phthalocyanine and a Hemiporphyrazine (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1375-1378 
    Details
    ISSN: 0009-2940
    Keywords: Phthalocyanines ; Hemiporphyrazines ; Fullerenes ; Diels-Alder reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a new Diels-Alder adduct 7 of [60]fullerene and a phthalocyaninenickel compound containing a longer spacer than the originally reported Diels-Alder adduct 1 is described. The bisenophilic hemiporphyrazinenickel compound 11 reacts with [60]fullerene to form a Diels-Alder adduct 12 containing two fullerene units. Spectroelectrochemical investigations of 7 and 12 reveal multiple reductions, which are attributed to the corresponding subunits of the molecules. In contrast to 1, the election acceptor properties of the [60]fullerene unit in both molecules have no influence on the electronic properties of the phthalocyanine and hemiporphyrazine, respectively.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301005
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