Theoretical Study On The Decomposition Reaction Of 3-sulfolene In The Inner Phase Of The Calix[4]arene-Based Carcerand

The molecular dynamic simulation and quantum chemistry methods were employed to study the thermal decomposition reaction of 3-sulfolene in the inner phase of the calix[4]arene-based carcerand. Firstly, seven reaction channels were set up on on the basis of the analyses of structural characteristics of the carcerand and 3-sulfolene. Then structures of reactants, products and transition states were optimized and intrinsic reaction coordinates and single point energies of optimized structures were calculated in each reaction channel. Finally, conclusions on configurations of the supramolecular system and the activation energy of the decomposition reaction were obtained.The main results of relative configurations of host and guest molecules are as follows: The co-rotating parallel configuration of two molecules does not possibly exist in the actual reaction. 3-sulfolene most possibly reacts in the middle of the host and its transverse axis points to the interspace between arrises of the carcerand. The change of the inclination angle of the guest does not result in much change of the activation energy of the decomposition reaction.The comparison result shows that the activation energies of the decomposition reaction in the carcerand is a little higher than that in the free situation. It is consistent with the result of the experiment. The activation energy itself is not too high, however, and it doesn't change much whether the reaction occurs in or out of the carcerand.According to the study of the interaction energies of the host-guest system and the carcerand's deformation energies in a reaction channel, it can be known that the change of the activation energy is due to the repulsion of the host-guest molecules.