Thermodynamic study of the complexes of calix[4]naphthalenes with [60]fullerene in different solvents

Abstract

Calix[4]naphthalenes are a class of molecules which possess deeper cavities than those of the analogous calix[4]arenes. Preliminary data obtained for the complexation of [60]fullerene (“C₆₀”) with the C₄-symmetrical endo-calix[4]naphthalene 3 and its tert-butyl-substituted derivative 4 show that they form supramolecular 1∶1 complexes with C₆₀ in benzene, toluene or CS₂ solution with relatively high association equilibrium constants (K_assoc). Reported herein are thermodynamic parameters and additional K_assoc determined for the complexation of C₆₀ and calix[4]naphthalenes 3 and 4 which show that both a solvophobic effect and π–π interactions are major driving forces for the complexation process.