Theoretical Studies on the Intermolecular Interactions of Aza-calix[2]arene[2]-triazines with RDX

Six fully optimized structures of the aza-calix[2]arene[2]-triazines/RDX supramolecular complexes have been obtained at the DFT-B3LYP/6-311++G** level, and the corresponding intermolecular interactions have been investigated using the B3LYP, mPWPW91 and MP2 methods at the 6-311++G** level, respectively. The natural bond orbital (NBO) and atoms in molecules (AIM) analyses have been performed to reveal the origin of interactions. To our interest, the result indicates that the strongest interaction is up to -22.34 kJ/mol after basis set superposition error (BSSE) and zero point energy (ZPE) correction at the MP2/6-311++G** level. Furthermore, the intermolecular interactions between aza-calix[2]arene[2]-triazines with the substituted amidos and RDX are stronger than those of other complexes. Thus, the complexes with amidos can be used as the candidates to increase the stability of explosive and eliminate the explosive wastewater.