Theoretical Studies on Intermolecular Interactions between Azacalix[6] arene and HMX

Four optimized structures of azacalix[6]arene host monomers(Ma-Md) and their complexes(a-d) with HMX were obtained at B3LYP/6-31G(d) level.Natural bond orbital(NBO) analysis was performed to reveal the origin of the interaction between hosts and objects.The intermolecular interaction energy was evaluated with basis set superposition error correction(BSSE) and zero point energy correction(ZPEC).The B3LYP/6-31G(d) calculations on the four complexes show that the largest interaction energy is-13.98 kJ·mol-1 in the complex composed of HMX and hexaazacalix[3]-p-triarene[3]-2-amido-1,3,5-triazine.Results show that intermolecular interaction energies of azacalix[6]arenes with substituted groups are stronger than that without substituted groups,and intermolecular interaction energies of azacalix[6]arenes with amido groups are stronger than that with nitryl groups.