Abstract: An interaction model between the host and the guest of layered double hydroxides (LDHs) is proposed. The structure parameters and vibration frequencies of LDHs are calculated using density functional theory B3LYP method at the 6-31G(d) level, and the interaction energies are evaluated with the B3LYP/6-31G(d) and B3LYP/6-311++G(d, p) methods, respectively. The supra-molecular interaction between a host layer and a guest anion has been investigated by analyzing the geometric parameters, charge population, frontier orbital, interaction energy, and thermodynamic parameters. The results show that the binding process of the host layer and halide anion is spontaneous. There is a strong supra-molecular interaction between the host layer and a guest anion F- or Cl-. The host-guest interaction energies of Mg6Al(OH)14+:F- and Mg6Al(OH)14+:Cl- are -592.45 and -444.01 kJ·mol-1, respectively. Supra-molecular interactions are resulted mainly from the electrostatic interaction and the hydrogen-bond. The frontier orbital of the host layer interacts with that of the guest anion, and the electron is transferred from HOMO of halide anion to LUMO of the host layer. Moreover, Mg6Al(OH)14+:F-is more stable than the Mg6Al(OH)14+:Cl-.

Key words: Layered double hydroxides, Super-molecule interaction, Density functional theory