Fullerene inclusion based on Horning-crown macrocycles

Horning-crown macrocycles, 1(R = (CH2)2) and 2(R = (CH2)3) form inclusion complexes with C60 and C70 fullerenes which have been structurally authenticated using X-ray diffraction data. Macrocycle 1 affords a C60 complex as a toluene solvate with overall composition C60(1)2(tol)2, 3, whereas the larger macrocycle, 2, affords complexes with both C60 and C70 fullerenes, also as toluene solvates: C60(2)(tol)2, (4); C70(2)(tol)2, (5); and C70(2)2(tol)2, (6). The higher degree of flexibility of such macrocyles relative to classical calixarenes is noteworthy in forming fullerene complexes, with the smaller ring size of 1 favoring fullerene complexation toward the smaller C60 molecule. The supramolecular assemblies involve host−guest interactions as well as interaction of fullerenes in zigzag chains with interfullerene contacts close to the van der Waals limit.