Intercalation of Sulfonate into Layered Double Hydroxide: Comparison of Simulation with Experiment

We perform computational modeling studies to explore the properties of functionalized Mg-Al layered double hydroxides (LDHs). Using molecular dynamics (MD) simulations we study the intercalation of C8H17SO3- sulfonate into a Mg:Al 2:1 LDH system for which the experimental data have recently been reported (J. Phys. Chem. C 2007, 111, 4021). An ab initio force field (condensed-phase optimized molecular potentials for atomistic simulation studies, COMPASS) is used for the MD simulations of the hybrid organic-inorganic system. Quantum mechanical density functional theory is also employed in order to establish structural and spectroscopic benchmarks for the sulfonate as a means of testing the force field. The interlayer structure, arrangement, and orientation of the intercalated species are examined and contrasted with the geometry of the isolated sulfonate. The self-diffusion coefficients of both the interlayer sulfonate and water are estimated to be 2.05 x 10(-7) and 3.07 x 10(-7) cm(2)/s at 300 K on the basis of 500 ps MD simulations. Computed powder X-ray diffraction patterns are in good accord with experiment. Computed infrared spectra are comparable with experiment in terms of line positions, while line intensities show room for improvement.