Controlling the Confinement and Alignment of Fullerene C70 in para-Substituted Calix[5]arenes

In toluene fullerene C-70 forms 2:1 complexes with p-benzylcalix[5]arene (1) and p-phenylcalix[5]arene (2), [C-70 subset of 1(2)].6 (C7H8) and [C-70 subset of 2(2)].7 (C7H8). The fullerene molecules are completely shrouded by two calix[5]arenes in addition to terminal benzyl groups from other supermolecules, [C-70 subset of 1(2)], and solvent. Within the capsule-like supermolecules the calixarenes have distinctly different arrangements relative to the principal axis of the fullerene; for [C-70 subset of 1(2)].6(C7H8) the oxygen planes of the two calixarenes are skewed by 37.0 and 47.5 degrees, whereas in [C-70 subset of 2(2)].7(C7H8) the principal axes of the fullerene and the two encapsulating calixarenes are more closely aligned with the corresponding angles at 9.7 and 8.6 degrees, and features a pentaphenyl inter-calixarene embrace. The Hirshfeld surfaces of these two complexes have been investigated for a detailed understanding of the orientation and nature of interactions of C-70 with the cavitand-type molecules and toluene.