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

Abstract

AbstractA 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.