Synthesis of a Fullerene Derivative of Benzo[18]crown‐6 by <i>Diels‐Alder</i> Reaction: Complexation Ability, Amphiphilic Properties, and X‐Ray Crystal Structure of a Dimethoxy‐1,9‐(methano[1,2]benzenomethano)fullerene[60] Benzene Clathrate

Abstract

Abstract A fullerene derivative 1 of benzo[18]crown‐6 was obtained by Diels‐Alder addition of fullerene[60](C 60 ) to the ortho ‐quinodimethane prepared in situ from 4,5‐bis(bromomethyl)benzo[18]crown‐6 ( 3 ) with Bu 4 NI 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 C 60 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 C 60 moieties, and intermolecular O…︁C contacts between the O‐atoms of the veratrole moieties and fullerene C‐atoms.