SYNTHESIS OF A FULLERENE DERIVATIVE OF BENZO[18]CROWN-6 BY DIELS-ALDER REACTION - COMPLEXATION ABILITY, AMPHIPHILIC PROPERTIES, AND X-RAY CRYSTAL-STRUCTURE OF A DIMETHOXY-1,9-(METHANO[1,2]BENZENOMETHANO)FULLERENE[60]BENZENE CLATHRATE

A fullerene derivative 1 of benzo[18]crown-6 was obtained by Diels-Alder addition of fullerene[60](C60) to the ortho-quinodimethane prepared in situ from 4,5-bis(bromomethyl)benzo[18]crown-6 (3) with Bu4NI in toluene. Extraction experiments show that the complexation of K+ ions strongly increases the solubility of 1 in protic solvents like MeOH. Using Langmuir-Blodgett techniques, monolayers of the highly amphiphilic fullerene-derived crown ether 1 and its K+ ion complex were prepared. An X-ray crystal structure was obtained from a benzene clathrate of comparison compound 2, synthesized by Diels-Alder reaction of C60 with the ortho-quinodimethane derived from 1,2-bis(bromomethyl)4,5-dimethoxybenzene (4). Both the fullerene molecule 2 and the benzene molecule are fully ordered in a crystal packing which is stabilized by intermolecular van-der-Waals contacts between the benzene ring and the C-spheres, intermolecular C...C contacts between the C60 moieties, and intermolecular O...C contacts between the O-atoms of the veratrole moieties and fullerene C-atoms.