Molecular Dynamics Simulation of the Energetics and Structure of Layered Double Hydroxides Intercalated with Carboxylic Acids

Abstract

Molecular dynamics (MD) simulation of the Mg/Al (3:1) layered double hydroxide (LDH), hydrotalcite (HT), containing the monocarboxylic acids formate, acetate, and propanoate as the charge balancing interlayer anions provides new molecular-scale insight into the interlayer structure, hydrogen bonding, and energetics of hydration and consequent swelling of LDH compounds containing organic molecules and biomolecules with carboxylate functional groups. As for citrate−HT (Kumar, P. P.; Kalinichev, A. G.; Kirkpatrick, R. J. J. Phys. Chem. B 2006, 110, 3841), the hydration energy of these systems as a function of water content has no distinct minima, indicating the absence of energetically well-defined structural states with specific water contents. The hydration energies, however, approach the energy of bulk liquid water at lower water contents than for citrate−HT, suggesting that synthesis strategies involving delamination of the hydroxide layers in water are likely to be more successful using starting compoun...