Extra contribution to the crystal stability of insensitive explosive TATB: The cooperativity of intermolecular interactions

An in-depth analysis on the cooperativity of intermolecular interactions including hydrogen bonding and π-π stacking in 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystal was studied. Two quantities, cooperativity rate and energy, were defined to evaluate the nature and strength of cooperativity in a series of clusters diverging from 1D to 3D prototypes. The origin and mechanism of the cooperative effect were settled to demonstrate that the nature of cooperativity is determined by whether the non-covalent interactions compete or promote with each other, which is manifested by the changing trend of electron transfer. There exists obvious cooperative effect in intra-layer and inter-layer structures as they own the equivalent non-covalent interactions, while anti-cooperative effect is also observed if two interactions correlate with each other. On the whole, in the process of crystal formation, the apparent cooperativity is the check and balance of the two effects, which is capable to support a global interaction among all of molecules and contribute to the stabilization of system. Based on the results, one may get a new insight to understand the relationship between non-covalent interactions and low impact sensitivity. The check and balance of different non-covalent interactions brings apparent cooperativity that contributes to the stabilization of system.