Layered Double Hydroxides (LDH) described by the general formula [M²⁺_1-xM³⁺_x(OH)₂]A^m-_x/m·nH₂O (M²⁺ and M³⁺are divalent and trivalent cations forming the hydroxide layers and A^m- the interlayer anions surrounded by water molecules) have been widely studies in recent years as a layered host structure particularly suitable for the preparation of hybrid materials.

In order to achieve the objectives in materials synthesis, a good knowledge of the synthesis fundamental mechanisms is required. Although the exchange properties of LDH have been widely discussed into the litterature, only a few papers have dealt with the exchange reaction mechanism so far. Recent technological and experimental advances in energy dispersive X-ray diffraction (EDXRD) using synchrotron radiation and recent developments in computational molecular modeling techniques provide new possibilities for the study of solid-state kinetics.

By means of EDXRD, we have shown the formation of second-stage intermediates during the exchange reaction of chloride anions in Zn₂Al(OH)₆.Cl,nH₂O with a series of dicarboxylate anions. This phenomenon has only been observed for inorganic-organic anion exchange reactions so far while inorganic-inorganic exchange reactions occur in one-step process. The formation of such heterostructures offers new perspectives for LDH intercalation chemistry, particularly in direction of multifunctional materials.

Microcalorimetric measurements were performed indicating endothermic exchange enthalpies in the case of inorganic-organic anion exchange reactions and suggesting that staging is needed to overcome the energy barrier.

An other interesting aspect of the present work is the use of MD simulations combined with powder X-ray diffraction data to get better insights into the structure of Zn₂Al(OH)₆.Cl,nH₂O, Zn₂Al(OH)₆.(tartrate)_1/2,nH₂O and Zn₂Al(OH)₆.(succinate)_1/2,nH₂O with major emphasis on the interlayer structure and dynamical behavior of interlayer species.

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