Monte Carlo simulations on intercalation of tris(1,10-phenanthroline)metal(II) by saponite clay

The adsorption behaviors of tris(1,10-phenanthroline)metal(II) ([M(phen)(3)](2)) by saponite clay have been simulated by the Monte Carlo method. A two-dimensional sheet of linked [SiO4](4-) and [AlO4](5-) tetrahedra is used for the model tetrahedral sheet of a saponite day. The thermal distributions of the configurations are obtained using the Metropolis algorithm at 300 K for the systems which have racemic or enantiomeric metal complex molecules intercalated between two sheets. For adsorption within the cation exchange capacity (CEC), the interlayer distance at the thermal equilibrium is obtained to be 10.5 Angstrom for both the racemic and enantiomeric chelates. For adsorption over the CEC, the interlayer distance is 18.5 and 20.7 Angstrom for the racemic and enantiomeric chelates in the presence of SO42- anions, respectively. The racemic mixture with SO42- has a mean binding energy 31.1 kJ/mol lower than that of the pure enantiomer. In both cases, the adsorbed molecules form a bimolecular layer with the anions at the middle of two sheets. These predictions are compared with the experimental observations of adsorption of [Ru(phen)(3)]SO4 by colloidally dispersed synthetic saponite.