Perfluorophenylcalix[4]arenes: prospective hosts for nucleophilic guests. Synthesis, structure and quantum chemical calculations

Calixarenes substituted at the upper rim by electron-deficient pentafluorophenyl groups have been synthesized by reaction of hexafluorobenzene with organolithium derivatives of calixarenes. The single crystal structures indicate stacking interactions between the two perfluorinated aromatic rings. The thermodynamic characteristics of the flattened cone-flattened cone inversion process have been studied using dynamic NMR and quantum chemical methods. The calculated activation free energy for tetra(pentafluorophenyl)-substituted species is higher than that derived for tetraphenyl calixarene. The calixarenes substituted at the upper rim by electron-deficient pentafluorophenyl groups are potential hosts for anion recognition.