Competitive thermodynamic and kinetic processes during dissociation of some host-guest complexes of calix[4]arene derivatives

The formation-dissociation dynamics of the calixarenes’ host-guest complexes is one of the key features both in sensor applications and in use as molecular containers. The thermodynamic and kinetic description of the formation-dissociation processes could help in developing procedures to design new molecular capsules. In this work the dissociation dynamics of calix[4]arenes and p-chloro-trifluoromethylbenzene complexes was studied with molecular dynamics calculations. According to their binding selectivity, calix[4]arene, 4-methylcalix[4]arene and 4-tert-butylcalix[4]arene were chosen as host model-compounds. Results show significantly different temperature dependence of the reaction rate on various groups (H, Me, tBu) substituted at the upper rim of calixarene skeleton. This property reflects the competitive thermodynamic and kinetic processes during the complex dissociation. Our related experimental results obtained by DSC method seem to validate the theoretical results.