title: Giant fullerene polyelectrolytes composed of C60 building blocks with an octahedral addition pattern and discovery of a new cyclopropanation reaction involving dibromomalonates.
abstract: We report here on the facile synthetic access of a new family of bis-, tetra-, hexa-, and heptafullerenes (prototypes I-IV), which can be easily converted into very water soluble polyelectrolytes with up to 60 charges located on their periphery. Their very regioselective formation is based on the use of C(2v)-symmetrical pentakisadducts 3 and hexakisadducts 2 as key intermediates. All fullerene moieties incorporated in these macromolecular structures involve a complete or partial octahedral addition pattern. Tripod-shaped tetrafullerenes 9a,b (type II), which can accumulate up to thirty positive or negative charges, are very soluble in acidic or basic water, respectively. Hexafullerenes 13a,b (type III) were synthesized via isoxazolinofullerenes 10 followed by photolytic cleavage of the isoxazoline group. The giant heptafullerene 1b (type IV) representing the anionic counterpart of the previously synthesized polyelectrolyte 1a can store up to 60 negative charges on its periphery within a defined three-dimensional structure. We also discovered a new cyclopropanation reaction of C(60) involving dibromomalonates and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). This reaction allows even for the highly regioselective formation of hexakisadducts with an octahedral addition pattern without requiring activation with reversibly binding addends such as 9,10-dimethylanthracene (DMA).
authors: Department of Chemistry and Pharmacy & Interdisciplinary Center of Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany.
authors: Frank
authors: F
authors: Hörmann
authors: Andreas
authors: A
authors: Hirsch