Tracking the Structural Dynamics of Hybrid Layered Double Hydroxides
Résumé
The present study aims at investigating the structural and dynamics properties of intercalated tartrate and succinate anions in Zn2Al layered double hydroxides (LDHs). The comparison between these two anions allows the estimation of the impact of the presence of hydroxyl groups in tartrate on the dynamics, orientational, and rotational behaviors of the species in the interlayer domain. A variety of experimental techniques (X-ray diffraction, H-1-C-13 MAS NMR variable contact time, proton conductivity, microcalorimetry) is used in association with molecular dynamics (MD) simulations. A specific behavior is then established for the tartrate in terms of rotation around the backbone, diffusion, and organization of the water molecules in the interlayer domain. The difference in the enthalpies of exchange between the two LDHs is calculated from MD simulations and compared to that obtained by microcalorimetry experiments. This energy calculation evidences for the existence of anion-anion interactions that are more favorable for tartrate than for succinate. The combination of experimental and theoretical methods performs very well for the structural, energetic, and dynamics characterization of the interlayer species.