Theoretical investigation into the cooperativity effect and thermodynamic property of β-nitroguanidine∙C₂F₄∙H₂O ternary complex

Abstract

The H-bonding cooperativity effects in β-NQ (nitroguanidine)∙∙∙C₂F₄∙∙∙H₂O ternary complex are investigated by the B3LYP and MP2(full) methods with the 6-311++G(2df,2p) basis set. The thermodynamic cooperativity effects are evaluated at 298.15 K. The result shows that C₂F₄ can be used as a wastewater treatment agent for β-NQ. The influence of the N–H∙∙∙O or O–H∙∙∙F H-bonding interaction on the N–H∙∙∙F interaction is more pronounced than that of the latter on the former. The weak cooperativity effect appears in the linear complex while the notable anti-cooperativity effect is seen in the cyclic system. The enthalpy change is the major factor driving the cooperativity. There is no obvious correlation between the cooperativity effects evaluated by interaction energies and those from thermodynamic data. The complexation energies (<em>E</em>_int.) correlate well with the local minima of surface electrostatic potentials (<em>V</em>_S_,min) or internal charge separations (Π). AIM (atom in molecule) analysis is used to reveal the nature of cooperativity effect. It can be inferred that the wastewater treatment for explosives can be viewed as a cooperativity process of coexisting intermolecular interactions, and also a thermodynamic cooperativity process.